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Gomar
2012-Mar-31, 05:24 PM
http://www.rawstory.com/rs/2012/03/28/study-milky-way-may-harbor-billions-of-potentially-habitable-planets/


I suppose if that's the case, and any astronomers on those planets could, they probably have found Earth.
Say 10% are capable of sending probes, and they did 1million years ago, then Earth has been studied by
aliens. If any alien probes or beacons or ships are still around Earth, they have either made contact in the
past, or are waiting to do so. Perhaps, they wont at all as they are programmed not to interfere.
However, if that's the case, there must indeed be millions, if not billions, of planets with life in space.
As humans then, or intelligent life of any form, is nothing special nor rare.
Anything humans do, wars, bio/chem weapons, nukes, disease, eco/bio destruction, colonization of the Moon
or Mars, is not of any concern of aliens in the galaxy.

http://www.openminds.tv/planetary-tilt-could-affect-alien-life-870/

Rhaedas
2012-Apr-01, 02:18 PM
Maybe they're on the way.

Maybe their surveys looked for something different than Earth, so we got excluded.

Maybe they came by, but millions of years ago, and didn't see anything worth stopping for.

Or maybe we'll be the first to go looking.

Lots of maybes. All assuming a civilization could get past the fact of huge distances between the stars. Right now the only thing we know is that it would take millions of years to get anywhere, and that's just one destination, one way.

I think the chances of life out there is very good, and intelligent life likely. But for now I can't see how each occurrence will get far from their own system.

Jeff Root
2012-Apr-01, 04:32 PM
I've expressed my views in this sort of thread before. I don't make
any effort to keep those views consistent.

I pretty much agree with Rhaedas. I think there must be lots of life
around the galaxy, including a fair amount of intelligent life. And I
have no doubt that some of that intelligent life has travelled from
their home star systems to others, and more have sent probes to
return data. But I think it is *relatively* unlikely that anyone has
sent a probe to any particular star system, thus relatively unlikely
that any probe has ever reached Earth. Certainly unlikely that any
probe has reached Earth "recently". Meaning, oh, say, the last ten
million years.

I think it is *extremely* unlikely that anyone else has discovered
our (humanity's) existence yet. There may be others who are
close enough, and I have no doubt that there are many who
would be interested if they knew we were here, but I think it is
extremely unlikely that there is anyone close enough who has
the technical capability to discover us who would keep watching
Earth for long enough to have already detected our emergence.

Communication between widely-separated star systems appears
to be difficult and expensive. Travel between them fabulously so,
in addition to being prone to catastrophic failure and having no
commercial value.

That is not to say interstellar travel has no value! It would have
great scientific, cultural, and esthetic value. It just can't have
any *commercial* value because of the long trip times and very
high costs.

-- Jeff, in Minneapolis

swampyankee
2012-Apr-01, 05:18 PM
Probably Edward M Lerner, with his InterstellarNet (http://www.edwardmlerner.com/sample-page/list-of-books/#interstellarnet%20series) series has the most likely contact scenario. Trade in anything other than bits is very unlikely.

Ara Pacis
2012-Apr-01, 07:19 PM
... having no
commercial value.

Have you no idea how much people would pay to go to another star system. Not to mention the movie rights. There could be a reality TV show on the interstellar space ship. Not to mention how many spin offs we might get from a new Apollo-like effort. And then when someone comes back, there'd be trinkets to sell and more movie rights and new sit-coms to air about a human and an alien that just happen to get stuck living or working together. It's be a bonanza!

Jeff Root
2012-Apr-01, 11:06 PM
No good, I know it's April Fool's Day!

-- Jeff, in Minneapolis

kzb
2012-Apr-02, 12:24 PM
The billions of habitable planets number comes from extrapolating the HARPS data. They estimate that 41% (range 28-95%) of M-stars have a 1-10 Earth-mass planet in the liquid water range.

However only the other week we had someone extrapolating Kepler data to come up with an estimate of only 0.7% of stars host an Earth-like planet.

I don't think the occurrence of planets or Earth-like planets was ever much of a doubt to people studying this area -it was just assumed that our solar system would be typical, and so Earths should be common. It was other factors in the Drake equation that were more mysterious.

Anyway, although there are serious doubts in my mind about all this statistical data extrapolation, and even whether the methods are actually reliable, eventually these studies should at last give a serious estimate about this factor of the equation. But at the end of it all we'll still be asking "where is everyone ?"

mutleyeng
2012-Apr-03, 12:39 PM
im with Paul Davies on this issue. Untill you have data for a probability of the genesis of life, it is all just idle speculation.
To start answering that, going to Mars is important(but even if it was there, it might be our cousin), searching for second life genesis on earth is important, study of earth rock from the late heavy bombardment is important (maybe on the moon?).

kzb
2012-Apr-03, 04:49 PM
im with Paul Davies on this issue. Untill you have data for a probability of the genesis of life, it is all just idle speculation.
To start answering that, going to Mars is important(but even if it was there, it might be our cousin), searching for second life genesis on earth is important, study of earth rock from the late heavy bombardment is important (maybe on the moon?).

Well, if these habitable exoplanets can be studied in more detail, eventually it will become pretty obvious how common (or not) life is. This will be on planets that supposedly could have temperatures in the liquid water range. I doubt the question will be settled unambiguously in our lifetimes though.

The trouble with Mars life, and second-life genesis on Earth, is how can you be really sure if the life is truly independent? There have been at least two episodes connected with this so far: the fossils in the martian meteorite, and the arsenic-containing bacteria. Need I say more?

mutleyeng
2012-Apr-03, 06:28 PM
well i know next to nothing about biology, but in the case of the metorite, i think i recall it being said that it would be imposible to have been life because of its size. So if it had turned out to be life, thats the kind of thing that would have flagged that it was likely not related.
If you can give them living life there is a lot more they can do...like i say, im not strong on biology but there is all that left/right handed stuff that can give very good indications-this is why we have a whole new field of astrobiology these days

kzb
2012-Apr-04, 11:41 AM
^ I'm simply saying that at least two factors in the equation can be changed from "idle speculation" into hard numbers, by these studies. These factors are, the frequency of habitable planets and (eventually) the occurrence of life on said planets.

It's only the first factor that Kepler and HARPS are providing information on. Hopefully though, having identified potentially Earth-like planets, the race will be on to come up with measurements on atmospheric composition etc on these planets, and thereby come up with clues on life occurrence.

kzb
2012-Apr-04, 11:54 AM
Over on the Centauri Dreams site, there is an article about another very old star apparently hosting planets. It is estimated to be 12.8 billion years old, and has an iron content only 1% that of the sun. It is a "population II" star.

Nevertheless it has two giant planets. If planetary systems formed this early in the history of the Galaxy, it really does highlight the Fermi question.


Planets Around an Ancient Star

http://www.centauri-dreams.org/?p=22397

http://www.idw-online.de/en/attachmentdata15909.pdf

mutleyeng
2012-Apr-04, 01:18 PM
the fermi question is valid IMO,
but really the definition we are using for intelligent life is dictated by what it would require for us to be able to detect them the easy way. ie, being high technology civilisations.
For me, it dosnt matter a jot whether any life out there is intelligent or dumb. And if we do have ways of detecting life other than of advanced technological civilisations, then fermi is no longer problematic because we can redfine what we consider intelligent.

Jeff Root
2012-Apr-04, 03:19 PM
For me, it dosnt matter a jot whether any life out
there is intelligent or dumb.
That matters a lot to me. Intelligent life will talk
with us and tell us about all the worlds they know,
and all the ideas they know. Non-intelligent life
will just sit there and tell us nothing. Since it is
so far away, we will never know anything at all
about it except, possibly, that it exists, based on
observation of light reflected by the planet.

-- Jeff, in Minneapolis

mutleyeng
2012-Apr-04, 04:31 PM
well, you are a lot more optimistic than i am about life in the first place Jeff.
I'll take any life i can get and be thrilled with that.
The prospect of finding an earth like planet just the right distance from its star, which shows tantalising signs of biology....thats more than i have any right to hope for, so id settle for that.

filrabat
2012-Apr-04, 05:01 PM
Probably Edward M Lerner, with his InterstellarNet (http://www.edwardmlerner.com/sample-page/list-of-books/#interstellarnet%20series) series has the most likely contact scenario. Trade in anything other than bits is very unlikely.

That pretty much sums it all up. If another species out there is advanced enough to have an InterstellarNet, then it's highly likely it has a DNA (or equivalent) library of thousands of its native species. There's the problem of signal degradation though. So I guess we can "travel" to these planets the same way in which we can "travel" to the Andes when watching TV or YouTube. In principle, we can certainly trade scientific information* of various sorts

*If our species have different environmental requirements, we can DEFINITELY trade information about our "mundane, 'normal' temperature" chemical reactions. IOW, learn A LOT, and VERY quickly about high temperature and low temperature chemistry - including materials sciences. This lets us trade industrial processes. In fact, it might - just might - lead to a whole system of barter exchange (it'd have to be, as money would be useless or impractical in interstellar info exchanges).


Have you no idea how much people would pay to go to another star system. Not to mention the movie rights. There could be a reality TV show on the interstellar space ship. Not to mention how many spin offs we might get from a new Apollo-like effort. And then when someone comes back, there'd be trinkets to sell and more movie rights and new sit-coms to air about a human and an alien that just happen to get stuck living or working together. It's be a bonanza!

Oh God, Ara. Why did you have to bring THAT up <severely grimmacing face>

KABOOM
2012-Apr-04, 06:33 PM
Over on the Centauri Dreams site, there is an article about another very old star apparently hosting planets. It is estimated to be 12.8 billion years old, and has an iron content only 1% that of the sun. It is a "population II" star.

Nevertheless it has two giant planets. If planetary systems formed this early in the history of the Galaxy, it really does highlight the Fermi question.


Planets Around an Ancient Star

http://www.centauri-dreams.org/?p=22397

http://www.idw-online.de/en/attachmentdata15909.pdf

I've read about that "old" star/planet system. It doesn't change much at all for me. Since Hyrdrogen and Helium were essentially the only elements early on it would seem that early stars would have an exceedingly low metal contents and thus any leftover hyrdrogen/helium that didn't get bound into the star would essentially be only able to form "gas giant" planets (which would also lack metals) as its been said that big gas giant planets would have become small stars if they had been even bigger (and thus this would have resulted in a binary star system). Thus, really old gas giant planets should be expected.

Ara Pacis
2012-Apr-04, 11:17 PM
Hmm, can terrestrial-type bodies form around low metallicity stars (and possibly their gas giants) by means of passing through a nebula of appropriate material?

Selfsim
2012-Apr-05, 02:23 AM
For me, it dosnt matter a jot whether any life out there is intelligent or dumb.And, if the scientific approach is taken, it shouldn't matter 'a jot' whether there is any life out there or not, either !
To be clear, everything else is speculation.

Hopefully though, having identified potentially Earth-like planets, the race will be on to come up with measurements on atmospheric composition etc on these planets, and thereby come up with clues on life occurrence.Such would be close, in possibility, to a random chance discovery, as inferences drawn from exo-atmospheric composition, about the presence or absence of life, simply leads to more speculation.

I assert that remote exo-atmospheric gas detection methodologies, (over light year distances), as a way of drawing inferences about exo-life, is a fundamentally flawed strategy. The only way I can see, to substantiate the models underpinning them, is by acquiring knowledge from a local discovery of exo-life, or via direct ET contact. Such a discovery, has nothing to do with remote exo-gas/life inference modelling. In the case of unintelligent life, such discoveries can only be caused by the act of direct local exploration, and the evidence gathered from such.

Positing that: (i) exo-life exists and then; (ii) it produces the same metabolic by-products as Earth based life does, is only a way of exploring a speculative premise. This premise seems to give no weight to: (i) the evidence of exo-environmental diversity, (ii) the DNA permutation diversity space and, (iii) evidence of the effects of natural, unrelated, 'stacked' causality factors, which drive the evolutionary process.

It seems to be a strategy primarily aimed at driving ‘hype’ about exo-planet ‘habitability’, rather than leading to rational science.

Regards

mutleyeng
2012-Apr-05, 10:35 AM
thats a bit of a bleak view.
you may be right, as you say everything is speculation -
As a lay person, i try to apply critical thinking as best i can to what i believe to be true. There are plenty of things i would like to be true but do not have any grounds to believe they are.
Yes, i can see you are right, but heres the thing.
If we find an earth like planet just the right distance from its star, and we were able to build a new generation of space craft to carry out atmospheric analysis(is this unreasonable assumption?)- and they tell me they have strong indications of high oxygen, ozone, methane, water, co2 - and the temerature was a nice cosy 15c- yes, i would be wrong to go from my current agnostic position to a believer...but im pretty sure i would.
The science would be perfectly rational, but it would be fair for you to argue that i wasnt....maybe. To argue that on scientific grounds wouldnt you have to be able to demonstrate how those indicators could come about without biology?
It would then be up to you to try to dispell the hype that would surely follow, good luck with that.
I also think you are right we are making assumptions about the nature of life being as we know it, but what else can we do?
How could we possibly look for life that we have no knowledge of the enviroment and mechanisms that life requires...short of waiting for ET to call, i cant see what else we could do.

Selfsim
2012-Apr-05, 11:14 AM
Hi Mutleyang;
Thanks for your reply .. I'm not having a go at you, or your beliefs here (apologies if it seemed that way) .. but I do find the thinking quite fascinating ..

If we find an earth like planet just the right distance from its star, and we were able to build a new generation of space craft to carry out atmospheric analysis(is this unreasonable assumption?)- and they tell me they have strong indications of high oxygen, ozone, methane, water, co2 - and the temerature was a nice cosy 15c- yes, i would be wrong to go from my current agnostic position to a believer...but im pretty sure i would.
The science would be perfectly rational, but it would be fair for you to argue that i wasnt. It would then be up to you to try to dispell the hype that would surely follow, good luck with that.
... so help me to understand this ...
If all these things were to come together, (about one particular exo-planet), then you'd definitely believe that it harbours life, (presumably identical to our own) ?
And this belief would be satisfying, in spite of it not being feasible to confirm it, (by direct testing) ? This belief would then become reality for you.

So, the journey to the resulting hype, is more satisfying and conclusive for you, than embarking on some other journey where there exists an assured outcome, and finality ?

Once again .. I'm not out to criticise anything here .. I just find the whole concept, (and worldview), radically different to my own .. and thus, kinda interesting ! :)

Regards

mutleyeng
2012-Apr-05, 11:35 AM
no worries, its a conversation, i didnt feel you were attacking me at all.

If all those conditions came together, in my mind i would go from being neutral about exo planet life to having a very high confidence that it existed. Just how high would depend on whether there were actually any known non biological mechanisms that could explain it. If there were not any of merit, my confidence would be extremely high untill such time as new evidence may question it.
I would not necessarily presume it was simular to our own other than following our understanding of biology...maybe it is rna not dna, but yes i would have to assume it uses simular mechanisms.
would that be good enough for me? yes, it would make my day big time.
the rest of your questions seem to be contingent on my lifetime. I dont care if we are on a journey that will not give finality in my own lifetime...the journey will be ongoing over many generations, and im good with that. I want answers, and i want to know things i currently dont, but i also think we need the stimulation of questions that are very difficult to answer.

kzb
2012-Apr-05, 11:40 AM
Selfsim,
you are correct in many ways of course, in particular, it is unlikely that an Earth double will be found. Instead, it will be more likely that various strange combinations of atmospheric chemicals will be discovered and some people will argue that some of them are a sign of life, and others will argue they are no such thing.

But if an Earth-size planet is discovered with an atmosphere similar to Earth's, I think you'd have to be an extreme skeptic to say that is not 99.9% proof of life.

SO what do you suggest instead? Everything is political. There is not going to be a multi-trillion dollar interstellar probe, even in our grandchildrens' lifetime. It's got to go in stages, with the political will generated to move on to the next stage.

Selfsim
2012-Apr-05, 11:34 PM
Hi kzb;
Thanks for your replies .. I should also make it clear that I'm making a genuine attempt to understand (and respect) your viewpoints as well. :)


Selfsim,
you are correct in many ways of course, in particular, it is unlikely that an Earth double will be found. Instead, it will be more likely that various strange combinations of atmospheric chemicals will be discovered and some people will argue that some of them are a sign of life, and others will argue they are no such thing.Well, that wasn't really my point. Frankly, I have no idea whether a second Earth might be found or not (and I don't really care whether one is found, or not).

They might find some ! What is consistent so far, with the Kepler discoveries, is the environmental diversity. I'm also not solely focused on the environment factors. This is not the only variable effecting critically balanced causality factors in modern day biological systems, nor their evolution over time. Consideration of these latter aspects, is what leads me to a way less certain outcome, than most posters in this section of BAUT seem to hold 'true'.


But if an Earth-size planet is discovered with an atmosphere similar to Earth's, I think you'd have to be an extreme skeptic to say that is not 99.9% proof of life.Ok, so here's something I do have an issue with. :)
I notice you're using a statistic as an attempt to reinforce your point view. The statistic has zero basis in physical or theoretical reality. (If I am mistaken, and indeed it does, then please demonstrate it for us).
I can only conclude that its use is purely political (as per your confirmation of this in your next comment).
I have a problem with using mathematical-sounding language, in order to project a political viewpoint.
Every ounce and millisecond of training and time spent in acquiring mathematics and scientific skills is spent with the goal in mind, of stripping away such biases. To then reintroduce such biases into the discussion, demonstrates to me, a lack of consistency in a clearly scientific discussion, (ie: a lack of integrity, in the 'completeness and wholeness' sense of the word).

SO what do you suggest instead? Everything is political. There is not going to be a multi-trillion dollar interstellar probe, even in our grandchildrens' lifetime. It's got to go in stages, with the political will generated to move on to the next stage.'Everything' is not political. Science has been created specifically for us to focus on reality .. and to keep our perceptions as free from bias as is possible. Politics is about creating a reality amongst a community of humans (an alternate reality from physical reality). Much of science is counterintuitive, and we wouldn't know that, if we spent all our time in the alternate reality of 'community'.

I take a stand to make it clear that the 'alternate reality' of community, created by bandying about scientific (or mathematical) terminologies and concepts, is yet another abuse of science .. so we should at least, be aware of when this is happening in a conversation. The use of science in this way, leads to the creation of pseudo-sciences, and deception.

"Multi-trillion dollar interstellar probes": There is no need for such a thing. The Laws of Physics cannot be circumvented by expending our limited resources. Why would anyone even suggest this is feasible ?

"SO what do you suggest instead?": It is easily argued ('community reality', now :) ), that local exploration of our Solar System has resulted in scientific and sociological benefits way beyond most human and scientific value measures. In comparison with: 'exo-atmospheric-gas-detection-and-analysis-over-light-year-distances', its returns on investment, can at least be demonstrated to be certain.

Cheers

Selfsim
2012-Apr-05, 11:42 PM
I want answers, and i want to know things i currently dont, but i also think we need the stimulation of questions that are very difficult to answer.Science is fundamentally about posing questions and pursuing them. The result is almost always more questions. This is where the 'stimulation' you mention, comes from.

Pursuing answers, is the focus of philosophy.
The answers provided by philosophy, are not where the 'stimulation' comes from.
Philosophy is separate from science.

Regards

mutleyeng
2012-Apr-06, 12:50 AM
philosphy, that is modern philosophy, does not provide any answers. Its only purpose (in my world view) so far as science is concerned is to help formulate what questions to ask.
i also have a bit of a problem with this certainty you keep talking of... science never gives you certainty.
so far as the conversation above, where you complain about the use of statistics i absolutley agree with you. i dont think kzb was literally meaning that would be a scientific probabiity mind you.
the problem i get from your case for the study of our solar system for me is, so far as the big question is concerned, it may not actually get us anywhere. Its not finding life that really matters, its finding something we can be sure is a second genesis. It may be you could find life in the solar system that is so different that it is clearly a seperate genesis of life....but theres a pretty good chance it will be inconclussive.
if you find an atmosphere which shows stronge evidence of exo-planet biology, then it is almost certain to be an independent genesis.

Selfsim
2012-Apr-06, 05:38 AM
philosphy, that is modern philosophy, does not provide any answers. Its only purpose (in my world view) so far as science is concerned is to help formulate what questions to ask.I don't see many problems with posing questions from a philosophical basis. Many of great scientific discoveries started out in exactly this way. I personally find no answers in philosophy, either. Curiously, others do, however.

also have a bit of a problem with this certainty you keep talking of... science never gives you certainty. Well, I think that was my point. In this particular case, the more and deeper scientific considerations added to the mix, the less certain the outcomes appear to be when it comes to remote exo-gas inference. The 'certainty' I mention, (in the last paragraph of my post #24), actually comes from the risk assessment of two options .. which has more to do with the business of exploration, (a 'community reality'), than with science. (The returns from local exploration are well known, hence more certain).

If I ask: 'How can I discover life remotely over light-year distances ?', I will find no certainty, because the answer is model dependent, and that model in turn, either depends on data which is absent until exo-life is discovered, or is dependent on the discovered life to be Earth-like, or by some other 'first contact' means.

Its discovery locally, if it exists, is at least, practically feasible. Because we know of ‘habitable zones’ locally, a null finding still adds to knowledge of 'habitability zone' conditions. (Not to mention the spin-off technological benefits directly attributable to the more complex enterprise).

Its discovery (or verification) over light-year distances, is not feasible in practice .. we already know this .. no verifiable progress towards the definition of 'habitable zone' is achievable, because exo-life cannot practically be confirmed following some instance of exo-atmospheric gas detection.

so far as the conversation above, where you complain about the use of statistics i absolutley agree with you. i dont think kzb was literally meaning that would be a scientific probabiity mind you.Being somewhat blunt; "then don't quote meaningless, undemonstrable statistics !" (Please note: I mean this metaphorically .. not personally). Understand the tools one is using, before attempting to use them in a scientific sense, in a science forum.

the problem i get from your case for the study of our solar system for me is, so far as the big question is concerned, it may not actually get us anywhere. Its not finding life that really matters, its finding something we can be sure is a second genesis. It may be you could find life in the solar system that is so different that it is clearly a seperate genesis of life....but theres a pretty good chance it will be inconclussive.There goes that 'chances' word again .. you are presuming an outcome which is undeterminable. The 'chance' is unknown.
The more complex the task, the more intelligence needs to be directly applied to that task. Technologically armed local human examination, is the best method we know for undertaking complex tasks - like exo-life verification.


if you find an atmosphere which shows stronge evidence of exo-planet biology, then it is almost certain to be an independent genesis.Why ?

Regards

eburacum45
2012-Apr-06, 09:52 AM
If a planet the same 'size' as Earth is discovered with an oxygen/nitrogen atmosphere that might mean several things; a waterworld with a deep ocean could have an oxygenated atmosphere, without any life being present. However such a planet would be somewhat less dense than Earth. The temperature is important too; a planet with a surface temperature of +600K would not support any kind of life I can easily imagine.

If we find a planet that is the same temperature, density and mass as the Earth, and one that is not likely to be tidally locked (as most of those 'billions' of Earth-like planets mentioned in the OP are likely to be) then life would be a very likely explanation for the existence of an oxygen rich atmosphere. Without life our oxygen would probably only last about a million years or so before it is absorbed by the crust.

But exact Earth-clones are likely to be very rare; on the other hand life may be commonplace on planets that do not resemble Earth very much at all.

mutleyeng
2012-Apr-06, 11:14 AM
first, sorry, i dont use forums that often and i never worked out how to multi quote.

most of science knowlege is model dependent.
what have you learnt from a null finding? what "habitable zones" do we know of locally...other than on earth?

Its discovery (or verification) over light-year distances, is not feasible in practice .. we already know this .. no verifiable progress towards the definition of 'habitable zone' is achievable, because exo-life cannot practically be confirmed following some instance of exo-atmospheric gas detection.

can you demonstrate to me that this is true? I appreciate we do not currently have the hardware to do analysis of exo planet atmospheric conditions right now, but my approval of the quest is that the ability to do so is not beyond known technology.

Being somewhat blunt; "then don't quote meaningless, undemonstrable statistics !" (Please note: I mean this metaphorically .. not personally). Understand the tools one is using, before attempting to use them in a scientific sense, in a science forum.

i agree to an extent, but this is a forum about science, not a science forum. most of us are lay persons i would guess (sorry to guess, but hey)

There goes that 'chances' word again .. you are presuming an outcome which is undeterminable. The 'chance' is unknown.

yep, thats the frontiers of science for you. we are making hypothosis here, we can only really weigh chances.

The more complex the task, the more intelligence needs to be directly applied to that task. Technologically armed local human examination, is the best method we know for undertaking complex tasks - like exo-life verification.

Why ?


demonstrate to me that you would be able to distinguish two biological lifes as being two seperate genesis.
if you are talking about completely diferent base life forms, the best way to do that is on earth, forget the solar system. The problem you have with an entirely different base life, is how do you look for it?
(addition added) as to why could analysis of exo planet atmosphere give strong indications of life...its because we have models that require only biology to create those indicators. Yes that could be we doont know enough, but you can apply that logic to any field of science...the standard model might be wrong, but for now we assume it is not, mainstream science at least.

eburacum45
2012-Apr-06, 12:03 PM
...demonstrate to me that you would be able to distinguish two biological lifes as being two seperate genesis.

If I may answer this particular question;
Life on Earth can be demonstrated to have evolved from a primordial common ancestor using phylogenetics. See
http://en.wikipedia.org/wiki/Last_universal_ancestor
Any biota originating from another world would not share a common ancestor with Earth-life, unless there had been some sort of genetic transfer between the worlds.

Interstellar genetic transfer could happen naturally, via panspermia (but the chances of such a event happening can be calculated, and are very low indeed) or by deliberate transfer by a hypothetical advanced civilisation. No one knows how likely that is.

mutleyeng
2012-Apr-06, 12:15 PM
im not sure that really answers my question ebura,
i find it hard to conceive how any distinction could be make without a sample of the very earliest incarnation of both.

I am not talking here of interstellar transfer...i agree entirely that is extremely unlikely, which is why my personal opinion is that study of exo planets is the best way open to us to answer that question. That or we just get really lucky by stumbling across phosphorus based life or some such thing.

eburacum45
2012-Apr-06, 12:42 PM
i find it hard to conceive how any distinction could be make without a sample of the very earliest incarnation of both.

Try this article;
The Molecular Clock
http://en.wikipedia.org/wiki/Molecular_clock
Using phylogenetics and protein chemistry it is possible to determine roughly how long ago any two species diverged from each other (with a certain amount of uncertainty, which is also discussed on that page).
A species from another planet would share no ancestors with any species on our world, so this method could not obtain a realistic value for the date of divergence.

mutleyeng
2012-Apr-06, 01:07 PM
sure, but hands up who thinks life on earth began as DNA?
as i said very early on, i dont know much about biology, and i really hope they would be able to demonstrate it as you suggest, but if we do not have early enough samples of primative early earth life, then you are going to need to be able to establish time frames for life that will be really difficult to establish.
To my untrained eye it just seems a minefield of potential unknowns. But i hope i am just being ignorant...more than possible

I think it would be a great deal easier to demonstrate that life on another planet was related, than it would be to demonstrate that it deffinately wasnt.

added:
i dont even really see the conflict here. the study of exo-planets is furthering our knowledge greatly regardless of the life issue.
We knew next to nothing about system formation before we looked at exo planets. Now we still know next to nothing, but a lot more than we did. We have found sytems that we thought were impossible, like planet formation around biary systems.
to study their atmospheres will just as likely add to our knowledge of planetary formation. compared to manned exploration, this is cheap science

eburacum45
2012-Apr-06, 02:59 PM
I think it would be a great deal easier to demonstrate that life on another planet was related, than it would be to demonstrate that it definitely wasn't.If we do demonstrate a relationship between life on another world and life here, that would be a very significant result; but in most, if not all, cases, there would be no relationship. Quite likely there would be very little overlap in biochemistry. Alien life might not use DNA at all, or might express it in an entirely unrelated way.

Of course we couldn't determine any of this without actually getting our hands on actual alien samples. I can't imagine any way to do molecular biochemistry via telescope.

Rhaedas
2012-Apr-06, 03:12 PM
sure, but hands up who thinks life on earth began as DNA?

Nope, it was much simpler than DNA. It's still a new science with lots of questions to answer, but there's plenty of reason to think that life started here on Earth.


as i said very early on, i dont know much about biology, and i really hope they would be able to demonstrate it as you suggest, but if we do not have early enough samples of primative early earth life, then you are going to need to be able to establish time frames for life that will be really difficult to establish.

We have very old fossilized traces of life's activities. Not the organisms themselves, but their processes left marks that are distinguishable from geologic events.


I think it would be a great deal easier to demonstrate that life on another planet was related, than it would be to demonstrate that it deffinately wasnt.

Agreed. A match, just like DNA tests, says a lot. Chances are that even if life elsewhere followed similar steps in growth, it will have distinct differences.


i dont even really see the conflict here. the study of exo-planets is furthering our knowledge greatly regardless of the life issue.
We knew next to nothing about system formation before we looked at exo planets. Now we still know next to nothing, but a lot more than we did. We have found sytems that we thought were impossible, like planet formation around biary systems.
to study their atmospheres will just as likely add to our knowledge of planetary formation. compared to manned exploration, this is cheap science

Any new knowledge, even if it brings new questions, is good knowledge. I'm very encouraged that the Kepler budget was extended. And even if we find some things that are the same, that's good data too. But we probably won't...look at our own solar system. Before we started looking we thought one planet or moon was like another. Every body we visit has uniqueness as well as similarities. It's all good science.

mutleyeng
2012-Apr-06, 03:17 PM
reply to eburas points:
for reason you have already given, you wouldnt need to do it by telescope for exo planets to reasonably conclude it was unrelated.
would it be very sigificant to demonstrate a relationship between life on two worlds?
im sure it qould be interesting...not sure i would have learnt anything fundimental from it. i already know life can survive in space, i aleady know rocks can migrate between planets.


added,
i do acknowledge you may learn a great deal about lifes development from two sperate planet, but related life.when i question if i would learn anything fundimental from it, i am meaning cosmolgical. i conceed it may have great value to biology

eburacum45
2012-Apr-06, 03:34 PM
Well, i wouldn't be that surprised if life on Mars (or Europa, or Titan) turned out to be distantly related to Earth Life. If it was, that wouldn't really tell us much about life in other systems.

On the other hand, if life in two widely separated solar systems turned out to be related, I'd favour deliberate (or accidental) dispersal by some advanced civilisation at some time in the past. Natural interstellar panspermia is so unlikely that the artificial hypothesis would start to look very favourable by comparison.

mutleyeng
2012-Apr-06, 04:08 PM
Nope, it was much simpler than DNA. It's still a new science with lots of questions to answer, but there's plenty of reason to think that life started here on Earth.



We have very old fossilized traces of life's activities. Not the organisms themselves, but their processes left marks that are distinguishable from geologic event.

.

any suggested reading material to clue me up better on this?
i am really unclear on just how much is known (hypothesis) about very early life. i know rna is often spoken of, but what i am interested in is how we could trace that through to dna life. also in what is known about the transition from organic chemestry to biology.
also interested in anything discussing why our life is tied to earth origins.
im quite happy to acknowlege what i know may be very mis guided...like i say, im just a lay person.

Rhaedas
2012-Apr-06, 04:57 PM
Abiogenesis is the term you're looking for, and I'm no expert either on it, as there's several schools of thought on what might have happened. However, a good start as always is Wikipedia, http://en.wikipedia.org/wiki/Origin_of_life. Specifically down to "Current Models". One name mentioned on there is Jack Szostak, and there's a good video on Youtube about his ideas of simple organic replicators. http://www.youtube.com/watch?v=U6QYDdgP9eg

And I'm sure there's a few real expert here that can add more, and/or critique what's on those links.

mutleyeng
2012-Apr-06, 05:36 PM
thanks for the link.
yes, ive googled abiogenesis a good number of times.....there is so little on it its frustrating.
the problem i guess i have is this subject engages me from a cosmological perspective rather than a biological one, so it is fascinating to find out just how an astrobiologist might go about trying to distinguish different trees of life with so little data of life when abiogenesis may have happened.
what you said of the biochemical signitures in our oldest rocks is interesting, but the big question is, are they early enough i guess

Rhaedas
2012-Apr-06, 05:44 PM
http://www.sciencedaily.com/releases/2011/08/110821205241.htm

Here's a link to the story on the ancient bacteria found in Australia. Dated 3.4 billions years old, but the really important thing is that these were still complex organisms compared to very early life. So if they were around only a billions years after the Earth first formed, then that narrows the time period that life could have started. It might have been an explosion much like the Precambian, where there was nothing, and then everywhere very quickly (geologically speaking).

mutleyeng
2012-Apr-06, 06:00 PM
thats great thanks,
ive just been googling astrobiology and finally they are starting to come out from under their rocks and talk about what they are up to.
will have a read of the story you linked. dosnt it make you wonder though, that billion year gap from formation to known life is the same billion yr period that Mars is believed to have been warm and wet

swampyankee
2012-Apr-06, 07:12 PM
any suggested reading material to clue me up better on this?
i am really unclear on just how much is known (hypothesis) about very early life. i know rna is often spoken of, but what i am interested in is how we could trace that through to dna life. also in what is known about the transition from organic chemestry to biology.
also interested in anything discussing why our life is tied to earth origins.
im quite happy to acknowlege what i know may be very mis guided...like i say, im just a lay person.

You could start here (http://www.talkorigins.org/), at the Talk Origins site.

Colin Robinson
2012-Apr-07, 04:00 AM
That matters a lot to me. Intelligent life will talk
with us and tell us about all the worlds they know,
and all the ideas they know.

Why should they?

After all, there are highly intelligent earthlings who argue that it would be a serious mistake to send out messages revealing our existence to alien civilizations whose technology and intentions are unknown to us. Why wouldn't aliens reason the same way?

The possibility does exist that their methods of observation are so advanced that they know all about our technology, and have concluded that we are much too primitive to pose any threat. But even if they know what technology we have today, how could they know what technology we'll have tomorrow?

Jeff Root
2012-Apr-07, 04:52 AM
That matters a lot to me. Intelligent life will talk
with us and tell us about all the worlds they know,
and all the ideas they know.
Why should they?
Because they want to.

If they didn't want to, they wouldn't have contacted us,
and we wouldn't know they existed. The only intelligent
extraterrestrials we can discover are those who want to
talk with others.

What are you doing here?



After all, there are highly intelligent earthlings who argue
that it would be a serious mistake to send out messages
revealing our existence to alien civilizations whose
technology and intentions are unknown to us. Why
wouldn't aliens reason the same way?
They might, for a while. That could get boring after a
few million years, though, don't you think? Never talking
to anyone because you are afraid of what you imagine
they might do to you if they knew you existed? Maybe
even just a few thousand years. Or a few hundred.



The possibility does exist that their methods of observation
are so advanced that they know all about our technology, ...
That is possible only if they currently have observers in
our Solar System.



... and have concluded that we are much too primitive to
pose any threat.
That is already certain. There is no way we could pose a
threat to any civilization capable of communicating with us.



But even if they know what technology we have today, how
could they know what technology we'll have tomorrow?
They have been around for millions of years. They have
the ability to communicate with us, even though we have
only just recently learned how it can be done, and have
yet to do it. They must have had the ability for most of
the lifetime of their civilization. Millions of years. They
must have used that ability, or they would have lost it.
So they have learned from thousands of other civilizations
with a cumulative experience of billions of years.

They know what to expect.

-- Jeff, in Minneapolis

Selfsim
2012-Apr-07, 06:07 AM
what have you learnt from a null finding? what "habitable zones" do we know of locally...other than on earth?A null finding in a 'Habitable Zone', would tell us for instance, that maybe our habitability criteria require modification. Or say, depending on the habitat of a non-discovery, there may be some obvious reason for the non-finding of exo-'life', which we can also add to the definition of where to spend less time looking within those 'Habitable Zones'.

Some local habitable zones have already been mentioned by others .. Europa, Mars, Enceladus, Titan, etc.



Its discovery (or verification) over light-year distances, is not feasible in practice .. we already know this .. no verifiable progress towards the definition of 'habitable zone' is achievable, because exo-life cannot practically be confirmed following some instance of exo-atmospheric gas detection.

can you demonstrate to me that this is true? I appreciate we do not currently have the hardware to do analysis of exo planet atmospheric conditions right now, but my approval of the quest is that the ability to do so is not beyond known technology.
The presence or absence of a technology is not what I see as being a big issue. There are also physical limits these technologies are up against, which seem to be easily passed off as 'present technology' limits. Technologies are also constrained by Physical Laws. There are also hard limits outside of which, any such technology is unable to function. The generalised idea that such limits can be removed by human design, innovation, resource and sheer will, is not a hard and fast Law of nature. There seems to be some kind of generalised idealistic belief, that humans can always go on doing this. There are shades of grey in this argument, so I would not accept a generalised assertion in this regard, without specifics.

Demonstrating what I say is true: Inferring exo-life from the presence of atmospheric gases is still by inference only. I am referring to verification of exo-life, which requires that an exo-life specimen be modelled. In order to do that, we have to have examined in detail, the 'metabolic processes' (or optical reflection properties of) en-masse exo-life instances. This simply cannot be done, if we have never discovered a single exo-life instance, nor if we have no hard data from anywhere else about other than earth-life 'metabolism', (nor exo-life optical reflective properties). This may seem extreme .. but I remind you of the magnitude of the issues surrounding a claim of: 'exo-life discovered' !



There goes that 'chances' word again .. you are presuming an outcome which is undeterminable. The 'chance' is unknown.yep, thats the frontiers of science for you. we are making hypothosis here, we can only really weigh chances.Well, others seem to only be exploring the posited concept of: 'Exo-life existing, in what we presently call a 'Habitable Zone' '.

I choose to explore a less biased supposition from the outset .. and it results in a different set of priorities, which are panning out to be be a major resource allocation issue. I feel this is a more immediate crisis requiring confrontation, than exploring the niceties of a posited intellectual concept.



Why ?demonstrate to me that you would be able to distinguish two biological lifes as being two seperate genesis.Is that an answer .. or another question ? :)

if you are talking about completely diferent base life forms, the best way to do that is on earth, forget the solar system. The problem you have with an entirely different base life, is how do you look for it?.. Goes with pursuing the posited concept that 'exo-life exists'. That question is for others to answer. :)

(addition added) as to why could analysis of exo planet atmosphere give strong indications of life...its because we have models that require only biology to create those indicators. Yes that could be we doont know enough, but you can apply that logic to any field of science...the standard model might be wrong, but for now we assume it is not, mainstream science at least.A common misconception. 'Life' is already well defined. 'Exo-life' seems to be used in the sense that it is a variant of 'Life' and yet, we cannot define (or constrain) what it is, purely from the theory or known Laws of Physics or Chemistry. (As an aside: Biology on the other hand, has always been an empirical lab-based science). This characteristic, (amongst others), is actually supporting evidence that non-deterministic behaviours might be at cause the emergence of life. Such concepts are commonly accepted as 'mainstream' in the Biological Sciences. Astronomers and Cosmologists are yet to fully bridge both domains so as to achieve sufficient 'critical mass' of thinking, and depth of expertise in these concepts. Its only in the very early stages of the field's evolution and I think we're seeing the outputs of those very early stages. There's a long way to go, and much patience will be required to acquire the necessary data.

My view is that we need to take meaningful steps in acquiring that data .. over endlessly posting more and more unending hypotheticals.

Regards

Colin Robinson
2012-Apr-07, 06:32 AM
That is already certain. There is no way we could pose a
threat to any civilization capable of communicating with us. They have been around for millions of years.

I know the argument -- another technological civilization is unlikely to be at the exact same age as ours, so it will be either much older or much younger, and it couldn't be much younger if it is able to communicate via radio, therefore it is almost certain to be much older...

But... Is it necessarily the case that a vastly older technological civilization will have vastly superior technology?

I know it's often assumed that once technological progress reaches a certain point, it will keep getting better and better, faster and faster. However, I don't see how we can be sure either that it will happen that way on Earth, or that it will have happened that way on other worlds.

Maybe there are worlds where technology advances to a certain stage, and then plateaus -- i.e. it reaches a certain level, then stays much the same for century after century, millenium after millenium?

In that case, their civilization could be vastly older than ours without being vastly more technically advanced. So maybe we could pose a threat to them after all…

Colin Robinson
2012-Apr-07, 07:21 AM
demonstrate to me that you would be able to distinguish two biological lifes as being two seperate genesis.
if you are talking about completely diferent base life forms, the best way to do that is on earth, forget the solar system. The problem you have with an entirely different base life, is how do you look for it?

Life elsewhere in the solar system might be different enough to imply a separate beginning, without being completely different. One definition of life is, IIRC, "a chemical system capable of darwinian evolution". So how do you look for such a chemical system? Well, you can look for places in the solar system where complex chemical activity seems to be going on, and then you try to find out as much as possible about the specifics of that chemistry. You don't search only for proteins and nucleic acids, but you do look for systems of catalysts and for polymers capable of holding and passing on information...

mutleyeng
2012-Apr-07, 09:15 AM
a chemical system capable of darwinian evolution is a pretty poor definition in my opinion. i can see quite easily other adaptive pressures on microbial life not falling ito that definition at all.
@selfism,
i underlined "known" for a reason. there is certainly speculation that there are habital zones within the solar system based on the analysis of very limited criteria. therefore you are speculating too.
i do agree with you that we have our individual choices of priorities. You have one, i have another.
So far you havnt managed to give specifics as to why yours should be the concentrated priority.
You would need to provide me with some specifics as to why exo planet atmospheric analysis in any way will be limited by laws of physics. The methodology is well known, the ability to do it already exists in some specific conditions.
The concept is not science fiction and does not require the bending of any physical laws-so far as i am aware.

your last paragraph was interesting, but i cant help feeling that is a matter for biologists within their own field

swampyankee
2012-Apr-07, 11:08 AM
People are speculating about alternatives to water as a solvent for life, including ammonia, various hydrocarbons, liquid nitrogen, supercritical carbon dioxide, and molten salts. Each will have its own habitable zone, and some of them would probably consider life at liquid water temperatures (which span from about 273 K to about 647 K) as impossible.

Selfsim
2012-Apr-07, 11:38 AM
@selfism,
i underlined "known" for a reason. there is certainly speculation that there are habital zones within the solar system based on the analysis of very limited criteria. therefore you are speculating too.Nup ... I'm not using my own speculative classifications. I'm using these ones. (http://phl.upr.edu/projects/habitable-exoplanets-catalog/methods) The rankings of confirmed and unconfirmed exo-planet surface habitability is here. (http://phl.upr.edu/projects/habitable-exoplanets-catalog/list_hab) (They're pretty comprehensive too, given what's presently known, if you ask me).

i do agree with you that we have our individual choices of priorities. You have one, i have another.
So far you havnt managed to give specifics as to why yours should be the concentrated priority.
You would need to provide me with some specifics as to why exo planet atmospheric analysis in any way will be limited by laws of physics. The methodology is well known, the ability to do it already exists in some specific conditions.
The concept is not science fiction and does not require the bending of any physical laws-so far as i am aware.I don't think we're on the same wavelength here ... detection of a remote exo-atmosphere is not the major issue. Concluding that exo-life exists, purely because of atmospheric composition, is. (I've tried saying this in many different ways throughout this thread ... I don't know how else to say it) ...
We can cite correlations between the two until we're blue in the face, but until we can actually confirm that certain proportions of certain exo-gases (eg: O2) can ONLY be sustained by some critical mass of known exo-life metabolism, the presence of these gases, will only ever enable inferences of exo-life 'possibilities'. Frankly, given the diversity space of 'possible' natural exo-planetary processes, it wouldn't surprise me in the least that over time, we will discover way more O2 renewal/sustaining processes than just earth-like life metabolism, (for instance). To me, this is such a myopic perspective, inference drawn from it about Earth-like exo-life 'possibilities', leaves me completely cold.

The physical constraints which limit the technology, appear in trying to reach exo-planets light-years away, to confirm the correlations between specific exo-gas measurements, and the presence of exo-life on the exo-body, possessing those gases. This is simply, not feasible from a practical perspective ! Our only choice from what I can see, is to try to look for exo-life locally, in order to add any credibility whatsoever, to this method.


your last paragraph was interesting, but i cant help feeling that is a matter for biologists within their own fieldChuckle, chuckle .... I passed this comment in another thread: "For some strange reason, the field of Astrobiology stands alone in science as having the sole purpose of justifying the belief that its subject matter exists !"
:)
Regards

Selfsim
2012-Apr-07, 11:53 AM
People are speculating about alternatives to water as a solvent for life, including ammonia, various hydrocarbons, liquid nitrogen, supercritical carbon dioxide, and molten salts. Each will have its own habitable zone, and some of them would probably consider life at liquid water temperatures (which span from about 273 K to about 647 K) as impossible.Hi swampyankee;
See ... this is exactly what I'm on about when it comes to rampant speculation !
There is seemingly no end to the possibilities !

How does any of this speculation help in trying to pin down a practical cohesive strategy ?

I have read almost the entire history of human civilisation in this forum to explain 'the possibilities' when it comes to exo-life speculation .. and it leads to, where/what, exactly ??

Practical considerations limit the possibility space and will lead to incremental steps towards the ultimate goal.
Speculation just seems to lead to sci-fi stories, (and royalites for their authors) !

Regards

Colin Robinson
2012-Apr-07, 11:56 AM
a chemical system capable of darwinian evolution is a pretty poor definition in my opinion. i can see quite easily other adaptive pressures on microbial life not falling ito that definition at all.

You may have a valid point there, but you haven't expressed it coherently. Would you care to rephrase?

Colin Robinson
2012-Apr-07, 12:07 PM
The physical constraints which limit the technology, appear in trying to reach exo-planets light-years away, to confirm the correlations between specific exo-gas measurements, and the presence of exo-life on the exo-body, possessing those gases. This is simply, not feasible from a practical perspective ! Our only choice from what I can see, is to try to look for exo-life locally, in order to add any credibility whatsoever, to this method.

What do you mean by "locally"? Do mean "within this solar system"? Or "here on Earth"?

Jeff Root
2012-Apr-07, 12:40 PM
There is no way we could pose a threat to any civilization
capable of communicating with us.
...

They have been around for millions of years.
I know the argument -- another technological civilization is
unlikely to be at the exact same age as ours, so it will be
either much older or much younger, and it couldn't be much
younger if it is able to communicate via radio, therefore it is
almost certain to be much older...

But... Is it necessarily the case that a vastly older technological
civilization will have vastly superior technology?
No, and they don't need to have vastly superior technology.

Given that they are at least several light-years away, as they
almost certainly are, no attack we could make could reach
them in less than thousands of years, and the probability of
such an attack doing significant damage on its target would
be vanishingly small, even if they raise no defense against it.
But thousands of years of lead time should be enough to
develop an adequate defense. And they'll already know
how such attacks or potential attacks had been handled
by others, anyhow.



I know it's often assumed that once technological progress
reaches a certain point, it will keep getting better and better,
faster and faster. However, I don't see how we can be sure
either that it will happen that way on Earth, or that it will
have happened that way on other worlds.
I agree with that completely. However, if they are able to
communicate with us, they will have already gained the
knowledge of many other civilizations, so they will have
plenty of ideas-- many of them well-tested-- of how to
deal with bellicose or wantonly destructive civilizations.
If they can't deal with an enemy on their own, they have
friends who will help them. That's an advantage of being
connected.



Maybe there are worlds where technology advances to a
certain stage, and then plateaus -- i.e. it reaches a certain
level, then stays much the same for century after century,
millenium after millenium?

In that case, their civilization could be vastly older than
ours without being vastly more technically advanced.
So maybe we could pose a threat to them after all…
No, we will not know they exist unless they communicate
with us. If they have the ability to communicate with us,
they will have communicated with others, and will have
gained their knowledge of how to deal with sociopaths.

-- Jeff, in Minneapolis

mutleyeng
2012-Apr-07, 12:45 PM
You may have a valid point there, but you haven't expressed it coherently. Would you care to rephrase?

sorry, im not great at coherently.
The theory of evolution has moved on some way from origin of species. Darwinian evolution suggests adaptation for survival benefits. On an exo world the pressure may come from enviroment, like radiation- something more akin to Lamarkism perhaps

MaDeR
2012-Apr-07, 03:02 PM
that local exploration of our Solar System has resulted in scientific and sociological benefits way beyond most human and scientific value measures. In comparison with: 'exo-atmospheric-gas-detection-and-analysis-over-light-year-distances', its returns on investment, can at least be demonstrated to be certain.
This is very, very, very wrong. By exploring exoplanets and discovering what is similiar and what is different about them, we can get to know more about our solar system and Earth itself.
If you value solar system exploration at all, then you must value exploration of everything outside it, too.

Selfsim
2012-Apr-07, 10:56 PM
This is very, very, very wrong. By exploring exoplanets and discovering what is similiar and what is different about them, we can get to know more about our solar system and Earth itself.
If you value solar system exploration at all, then you must value exploration of everything outside it, too.Well hello there, MaDeR ! Nice to meet you !

So I should make it clear that the point being made here pertains only to the making of progress in the exo-life discovery goal. Surveying exo-atmospheres in support of acquiring knowledge about exo-planet diversities and chemistries, is a separate issue … and one I'm happy to acknowledge has exploratory and technological benefits.

The comparison between, and subsequent prioritisation of strategies, is being made as a way of separating out the recent Astrobiological emphasis, which on its own, cannot be practically demonstrated, due to (i) a lack of capability of meaningfully interpreting measurements, once they are obtained and; (ii) I suspect, more fundamentally, because the initial premise behind Astrobiology is biased in the direction of: 'exo-life existing' in the first place. Which is Ok for launching an avenue of enquiry .. but it in doing so, it shouldn't lose track of the huge array of other possibilities and value propositions, nor should its supporters.

There are significant plans evolving which are being driven solely by Astrobiological research goals which are having impacts on local Solar System exploration projects. When this happens, one invariably compares the scientific outcomes of both approaches, in the light of exo-life detection. I am simply saying that the foreseeable scientific benefits of local exploration in the quest for learning about exo-life (if it exists), outweigh those which have a significant interpretive database lacking. The way of building that database, is by local exploration.

I don't understand why this is so difficult to get across ? It is a fairly obvious point, and I have even seen a Fraser Cain/Exo-Planetary Scientist interview, also make a similar point (although it was unintentional) … so even our media guys now understand this !!

Regards

swampyankee
2012-Apr-08, 01:10 AM
Hi swampyankee;
See ... this is exactly what I'm on about when it comes to rampant speculation !
There is seemingly no end to the possibilities !

How does any of this speculation help in trying to pin down a practical cohesive strategy ?

I have read almost the entire history of human civilisation in this forum to explain 'the possibilities' when it comes to exo-life speculation .. and it leads to, where/what, exactly ??

Practical considerations limit the possibility space and will lead to incremental steps towards the ultimate goal.
Speculation just seems to lead to sci-fi stories, (and royalites for their authors) !

Regards

I think trying to search where we think vaguely Earth-like life (carbon based, using water as a solvent, at a temperature between about 273 and 373 K, etc) may exist is the only rational starting point. The logic for this is that we've got a better chance of recognizing this kind of life than a life-form living in the methane/ethane lakes of Titan. I'm not entirely sure that on-the-spot human explorers would recognize alien life before it literally bit them on the nose.

Colin Robinson
2012-Apr-08, 02:12 AM
Hi swampyankee;
See ... this is exactly what I'm on about when it comes to rampant speculation !
There is seemingly no end to the possibilities !

How does any of this speculation help in trying to pin down a practical cohesive strategy ?

I have read almost the entire history of human civilisation in this forum to explain 'the possibilities' when it comes to exo-life speculation .. and it leads to, where/what, exactly ??

Let me give you one example of where "speculation" can lead to.

The 1952 Miller-Urey experiment, applied an energy source to a hydrogen-rich mixture of gases, dissolved the results in water, and demonstrated formation of compounds including amino acids.

This classic piece of lab work tested the hypothesis put forward 28 years earlier by Alexander Oparin and J.B.S. Haldane, that life on Earth could have developed from an ancient atmosphere that was hydrogen-rich, rather than oxygen-rich.

When Oparin and Haldane put forward that hypothesis, they had no way of testing it. They were speculating. And they may have been quite wrong, about the make-up of the atmosphere of ancient Earth.

But the bottom line is...

Disciplined speculation can and does stimulate history-making empirical research.

neilzero
2012-Apr-08, 02:14 AM
Two stars pass within a few AU of each other perhaps monthly somewhere in our galaxy, so advanced beings can transfer between solar systems almost as easily humans can travel to Titan or the big moon of Neptune. Admittedly this likely has not happened to our solar system yet, but at least a few inhabited planets likely started habitation in this way. Neil

Colin Robinson
2012-Apr-08, 02:41 AM
I think trying to search where we think vaguely Earth-like life (carbon based, using water as a solvent, at a temperature between about 273 and 373 K, etc) may exist is the only rational starting point. The logic for this is that we've got a better chance of recognizing this kind of life than a life-form living in the methane/ethane lakes of Titan. I'm not entirely sure that on-the-spot human explorers would recognize alien life before it literally bit them on the nose.

Titan's lakes differ in composition from Earth's lakes. All the same, they are recognizable as lakes. Alien life may differ in composition from Earth life, but if it has mouths to bite us with, it will be recognizable as life.

Selfsim
2012-Apr-08, 07:20 AM
Let me give you one example of where "speculation" can lead to.

The 1952 Miller-Urey experiment, applied an energy source to a hydrogen-rich mixture of gases, dissolved the results in water, and demonstrated formation of compounds including amino acids.

This classic piece of lab work tested the hypothesis put forward 28 years earlier by Alexander Oparin and J.B.S. Haldane, that life on Earth could have developed from an ancient atmosphere that was hydrogen-rich, rather than oxygen-rich.

When Oparin and Haldane put forward that hypothesis, they had no way of testing it. They were speculating. And they may have been quite wrong, about the make-up of the atmosphere of ancient Earth.

But the bottom line is...

Disciplined speculation can and does stimulate history-making empirical research.G'Day Colin;

I need to answer your question from several posts ago ... when I say 'local', I am thinking primarily of Solar System exploration, but I see no particular reason to exclude lab-based biological research, or extremophile research (on Earth, Earth Orbit, etc), either. Basically, whatever can be shown to result in some tangible incremental contribution to the end goal is what I'm on about.

Thus, addressing your point above .. sure .. disciplined speculation by scientists living in the real-world, is a tried and tested way of evolving thinking. There are many other examples of this throughout scientific history.

So what does this have to do with a speculative undertaking which can only lead to inference vs an undertaking which has a chance of producing verifiable evidence of directly correlated data ?

Regards

Colin Robinson
2012-Apr-08, 08:46 AM
G'Day Colin; I need to answer your question from several posts ago ... when I say 'local', I am thinking primarily of Solar System exploration, but I see no particular reason to exclude lab-based biological research, or extremophile research (on Earth, Earth Orbit, etc), either. Basically, whatever can be shown to result in some tangible incremental contribution to the end goal is what I'm on about.

Thank you for explaining what you mean by "local".


Thus, addressing your point above .. sure .. disciplined speculation by scientists living in the real-world, is a tried and tested way of evolving thinking. There are many other examples of this throughout scientific history.

So what does this have to do with a speculative undertaking which can only lead to inference vs an undertaking which has a chance of producing verifiable evidence of directly correlated data ?

That depends which speculative undertaking you have in mind. I agree with you that the question of life on extra-solar planets is likely to remain unanswered for a long time. On the other hand, if answers are ever going to be found, I'm inclined to think speculation will be part of the process that gets us to that stage.

Re local research... when swampyankee mentioned ideas about life based on a solvent other than water,


People are speculating about alternatives to water as a solvent for life, including ammonia, various hydrocarbons, liquid nitrogen, supercritical carbon dioxide, and molten salts. Each will have its own habitable zone, and some of them would probably consider life at liquid water temperatures (which span from about 273 K to about 647 K) as impossible.

you said


this is exactly what I'm on about when it comes to rampant speculation !

Yet we know already that within our own solar system there is at least one world with large amounts of one class (at least) of liquid other than water.

I'm talking the lakes of liquid methane/ethane on Titan, because their existence is established. However, other solvents mentioned by swampyankee may exist within our solar system too. E.g. According to the astrobiologist William Bains subsurface liquid nitrogen is considered possible for Neptune's moon Triton.

Thus, if life based on liquid methane or liquid nitrogen is considered theoretically possible, surely this says something about what we can look for locally, and where we can look for it?

Selfsim
2012-Apr-08, 10:30 AM
Colin;

If you object to my usage of the term 'rampant' in describing a particular BAUT behaviour, that's ok .. 'twasn't in reference to the topic of disciplined scientific speculation anyway. My post #63 clarified the more important point, and I agree, that disciplined speculation is a valuable part of science.

As far as the chemical solvent variants mentioned by swampyankee occurring within our own solar system goes, I'd have to request links to appropriate peer-reviewed papers and studies, (rather than going by heresay), before commenting further. Swampy's words pointed out that these ideas were speculative. At the highest level however, notice how speculation has the effect of diverging the present water-based Habitable Zone search space strategy? Disciplined scientific speculation coming from Astrobiology, I thought, targetted a convergence effect ... interesting. (Perhaps this is just part of the 'early-days-yet' toing and froing phenomenon ?)

Anyway, if these variants have substance behind them, and demonstrate appropriate rigor and discipline, then I can at least, see that investigating such HZs within our solar system, at least has a chance of being capable of contributing to an interpretive database of evidence which correlates planetary atmospheric compositions with exo-life findings, (or non-findings, as the case may be).

Regards

mutleyeng
2012-Apr-08, 10:41 AM
theres the problem with a concentrated approach when you (science) are at the limits of knowledge.
Ive heard very learned people say that nitrogen base is impossible.
If you go to titan and there is no life found, have you learnt that methane cannot be a solvent of life? of course not. you have just learnt that there is no life on titan.
compare this issue to theoretical physics... should there be a concerted effort on string theory? or is it better to have as many avenues of research as can be accomodated.
I dont have a problem with selfisms argument as where the best empirical answers would come from, or indeed that the study of our system would likely expand our knowledge of biology regardless.
what i want to know is, has abiogenesis happened in another star system. I dont expect to have concrete empirical confirmation of that, but i could expect to have very strong indications (if it exists). It may come from biology within our solar system, it may come from exo planet study. Lets have them both please.
I think its more the concerted effort in one direction that bothers me.

Selfsim
2012-Apr-08, 11:17 AM
I think its more the concerted effort in one direction that bothers me.Agreed ... (in an ideal world).

Perhaps I should revise my assertion to read:

"Spectroscopically sourced exo-planetary atmospheric gas analysis, used as a method for inferring the presence or absence of exo-life, at light year distances, is a fundamentally flawed strategy unless local exploration also proceeds simultaneously ?"

:)

Regards

mutleyeng
2012-Apr-08, 11:49 AM
I wouldnt have a problem with that. Its always going to be about degrees of confidence. the more data you have from any source, the better the interpretation

Colin Robinson
2012-Apr-09, 01:47 AM
As far as the chemical solvent variants mentioned by swampyankee occurring within our own solar system goes, I'd have to request links to appropriate peer-reviewed papers and studies, (rather than going by heresay), before commenting further.

Re Neptune's moon Triton, and possibility of life using liquid nitrogen as a solvent, see William Bains in the peer-reviewed journal Astrobiology (http://www.liebertpub.com/overview/astrobiology/99/), Vol 4, page 137 - 167

I don't think you can read this actual article without paying for the privilege, unless you know a library that has the journal. However, its author, William Bains has also written a less formal article about the same topic (http://www.williambains.co.uk/astrobiology/life.html), which can be read free online.

Re Existence of methane/ethane lakes on Titan
see E.R.Stofan et al "The lakes of Titan" in Nature 445, 61-64 (4 January 2007) (http://www.nature.com/nature/journal/v445/n7123/abs/nature05438.html)

The abstract states: "Here we provide definitive evidence for the presence of lakes on the surface of Titan".

Regarding the overall question of life in non-water solvents, see chapter 6 of the report by the US National Research Council subcommittee on The Limits of Organic Life in Planetary Systems (http://www.nap.edu/openbook.php?record_id=11919&page=69)



Swampy's words pointed out that these ideas were speculative. At the highest level however, notice how speculation has the effect of diverging the present water-based Habitable Zone search space strategy? Disciplined scientific speculation coming from Astrobiology, I thought, targetted a convergence effect ... interesting. (Perhaps this is just part of the 'early-days-yet' toing and froing phenomenon ?)

Yes, if what you mean by "convergence effect" is an effort to narrow the search, I think that has been happening. It's obviously unfeasible to try to look everywhere -- to turn over every rock in the solar system, or even every rock on Mars, for example, to see if anything is crawling about underneath. So some astrobiologists came up with the the idea of following the water -- since all known life has liquid water in its cytoplasm, look for other places in the solar system (or beyond) that may have liquid water now, or may have had it in the past. But other astrobiologists thought that you narrow the search too much if you don't consider the possibility of fluids other than water as solvents for life. It is, as you say, a toing and froing thing...

MaDeR
2012-Apr-12, 03:59 PM
So I should make it clear that the point being made here pertains only to the making of progress in the exo-life discovery goal. (...)
If I understand it right, you have problem with interpreting results of exo-atmosphere measurements in light of extraterrestial life, because it is next to impossible to prove that unstable atmospheres/strange properties/whatever it is indeed caused by life, not some exotic non-biological chemistry. Am I right?

Selfsim
2012-Apr-13, 07:18 AM
If I understand it right, you have problem with interpreting results of exo-atmosphere measurements in light of extraterrestial life, because it is next to impossible to prove that unstable atmospheres/strange properties/whatever it is indeed caused by life, not some exotic non-biological chemistry. Am I right?Ok ... I don't have any 'problems'.

The issue, on the other hand, is that inanimate matter is distinguished over life, by a lack of very specific functions.
If these functions are possessed by something, then that 'something', is then classified as living.
In the case of 'unintelligent life', these functions are unable to be remotely diagnosed.
They can be locally tested, however.
Examining reflected light remotely, leads to inference, as a means for determining 'life'.
Inference and deduction determinations, are based on statistical significance.
Statistical significance requires information about parent distributions.
We have no such information in the case of exo-life.

Localised testing over light-year distances, in order to gather this information, is not feasible.

Regards

kzb
2012-Apr-13, 03:34 PM
Selfsim wrote:
Localised testing over light-year distances, in order to gather this information, is not feasible.

I think you give up too easily!

Like it or not, this is inevitably the next stage. Inevitably there are going to be mass debates over what it all means. And I still think that if a planet is observed to have similar atmosphere and light curves to Earth, that will mean something.

Jeff Root
2012-Apr-13, 05:30 PM
I think Selfism has a point, that spectroscopic analysis of the
atmospheres of distant planets will not be clear and obvious
in its indications of the presence of life, but essentially I reject
the gist of it. Lots and lots of things are determined by
circumstantial evidence. This will just be another. If it looks
like a duck, and acts like a duck, and sounds like a duck, then
chances will be pretty good that it is a duck. The more certain
you want to be about it, the more carefully and completely you
will examine it. Maybe we will find lots of planets that look and
sound a lot like they have life, but none that look and sound so
much like they have life that we can reasonably feel confident
that they really do have life. So what. We'll worry about that
situation if and when we run into it.

-- Jeff, in Minneapolis

Selfsim
2012-Apr-13, 10:43 PM
I think Selfism has a point, that spectroscopic analysis of the
atmospheres of distant planets will not be clear and obvious
in its indications of the presence of life, but essentially I reject
the gist of it. Lots and lots of things are determined by
circumstantial evidence. This will just be another. If it looks
like a duck, and acts like a duck, and sounds like a duck, then
chances will be pretty good that it is a duck. The more certain
you want to be about it, the more carefully and completely you
will examine it. I think you'll find that the real quest driving the whole exo-life enquiry, is the question about a second genesis. Remote spectroscopic analysis (or spectropolarimetry), will also not resolve this deeper question.
Exploration of the surface will. This is not feasible, if the sample is at light-year distances.


Maybe we will find lots of planets that look and
sound a lot like they have life, but none that look and sound so
much like they have life that we can reasonably feel confident
that they really do have life. So what. We'll worry about that
situation if and when we run into it.You mean Mars, eh ?

Bring on Curiosity !

Regards

Selfsim
2012-Apr-13, 11:04 PM
Localised testing over light-year distances, in order to gather this information, is not feasible.

I think you give up too easily!Your opinion is noted and respected, but does not addresss the timeframe from which my statement was framed (ie: in the present).

The future is just as unknown as whether exo-life exists or not, (ie: the actual subject matter, which my statement is addressing).


I think you give up too easily!

Like it or not, this is inevitably the next stage. Inevitably there are going to be mass debates over what it all means. And I still think that if a planet is observed to have similar atmosphere and light curves to Earth, that will mean something.Humans are meaning-adding machines !

I'm sure the meaning we add to such an observation, will also be describable in statistical uncertainty terms. Whether amateurs ever bother to understand what this actually means, is another question.

This is also where I can see that the tenacity you call for, (ie: 'not giving up too easily'), once applied, might result in a productive conversation. Applying tenacity directly to what is inherently uncertain, (courtesy of nature), on the other hand, leads to dogma.

Regards

Paul Wally
2012-Apr-20, 12:54 AM
Examining reflected light remotely, leads to inference, as a means for determining 'life'.

Regards

I agree that one shouldn't jump to conclusions from limited evidence, but if life seems to be the only or more likely explanation of a planet's atmospheric composition it makes sense to at least entertain the hypothesis that there's life. If you're saying don't jump to conclusions about life, then I agree, but if you are saying we shouldn't do these remote measurements of planetary atmospheres because it doesn't conclusively prove that there's life, then I strongly disagree. Much can be learned from such observations by correlating atmospheric composition with the conditions in the solar system where the planet is located. We would then have a better idea of the kinds of solar systems where life may possibly exist.

Jeff Root
2012-Apr-20, 07:55 AM
It's clear to me that he's saying something in between:
We should do all the remote observation we can, but it
will never be good enough to determine whether what
we observe is due to life.

-- Jeff, in Minneapolis

Jeff Root
2012-Apr-20, 08:26 AM
I might as well reply to this as long as I'm here.




I think Selfism has a point, that spectroscopic analysis of the
atmospheres of distant planets will not be clear and obvious
in its indications of the presence of life, but essentially I reject
the gist of it. Lots and lots of things are determined by
circumstantial evidence. This will just be another. If it looks
like a duck, and acts like a duck, and sounds like a duck, then
chances will be pretty good that it is a duck. The more certain
you want to be about it, the more carefully and completely you
will examine it.
I think you'll find that the real quest driving the whole exo-life
enquiry, is the question about a second genesis.
I've been interested in the subject for at least fifty years.
For me, the question of how often life arises has always
been a subset of the question of where life can be found.
That also seems to be true for the people I know personally
who have a degree in astrobiology or who work on SETI.
The question of how, where, when, how quickly and how
often life arises is very interesting and very important to
me, but it isn't what motivates me to be interested more
generally in discovering and learning about extraterrestrial
life. If follows from my more general interest.



Remote spectroscopic analysis (or spectropolarimetry),
will also not resolve this deeper question.
There is no good reason why it shouldn't. It depends on
how carefully we look and what shows up when we do.



Exploration of the surface will. This is not feasible, if the
sample is at light-year distances.
That's true in the short term and medium term. If there
is good spectroscopic evidence for life on some relatively
nearby planets, though, we will eventually visit at least
some of them to learn more.




Maybe we will find lots of planets that look and sound a
lot like they have life, but none that look and sound so
much like they have life that we can reasonably feel
confident that they really do have life. So what. We'll
worry about that situation if and when we run into it.
You mean Mars, eh ?
You know I didn't.

-- Jeff, in Minneapolis

Selfsim
2012-Apr-24, 09:42 PM
I agree that one shouldn't jump to conclusions from limited evidence, but if life seems to be the only or more likely explanation of a planet's atmospheric composition it makes sense to at least entertain the hypothesis that there's life.I question the 'sense' in entertaining such a hypothesis if there can be no definitive resolution by means of verification. If an exo-atmosphere is light years distant, there can be no such resolution.
To continue with a hypothesis which is neither verifiable nor falsifiable by practical means, seems destined to become an obsession.

… I gotta call it like I see it (in this particular case) .. apologies for eliminating areas of grey in what I'm saying, but I really do think some folk have lost sight of practicality constraints. No matter how intense one's dream might be, some things simply aren't feasible. Retrieveing verification evidence over light-year distances is one of 'em.


If you're saying don't jump to conclusions about life, then I agree, but if you are saying we shouldn't do these remote measurements of planetary atmospheres because it doesn't conclusively prove that there's life, then I strongly disagree. Much can be learned from such observations by correlating atmospheric composition with the conditions in the solar system where the planet is located. We would then have a better idea of the kinds of solar systems where life may possibly exist.Ok .. so we live in a non-ideal world, where resouces are constrained. If there exists other options/tests/experiments which can be demonstrated to make tangible returns on the sole basis of exo-life exploration, which can be demonstrated to be practically verifiable and falsifiable, I'd have to prefer those alternatives.

I don't have a problem acknowledging the spin-off benefits (eg: technological etc), derived from pursuing a dream, but these can also be obtained by pursuing more practical options ..

Regards

Selfsim
2012-Apr-24, 10:35 PM
It's clear to me that he's saying something in between:
We should do all the remote observation we can, but it
will never be good enough to determine whether what
we observe is due to life. .. Even if we found remotely, (at present-day telescopic resolution scales), what seemed to be an exact duplicate of Earth, there is still no reason to assume that exo-planet will have our type of life, no life, some variant of it, or had some variant of it, which became non-viable, or left the planet, etc, etc …

The means for enabling the extrapolation from Earth's case history, is limited by the laws of physics, chemistry, and randomness, at certain scale levels. Whilst these Laws might be ubiquitous throughout the observable universe, and would thus influence the outcome of life emergence (and subsequent evolutionary processes), the outcome(s) of their complex interactions, can render the outcomes completely unpredictable at some scale levels, and we know this specifically because of the known complexity associated with life.

If we cite Earth-life as our starting point of evidence for life, then we should include the entirety of what we know about it, and Earth's geophysical environment (at multiple scale levels) ... not just the bits which satisfy a particular variant of a speculative exo-life hypothesis. Randomness still plays a large role in it all, and certain processes can be 'tipped' at certain times. This 'tipping' can easily make or break the outcome of steady-state life/no-life. And we know this, for certain. Knowing this for certain, vastly increases the possibility space, and makes the possibility of exo-life emergence on a duplicate of Earth, a lot less certain.

Remote detection of possibly biogenic exo-gases, as a means of inferring the possible presence of exo-life, erodes optimism of exo-life (once again), to near meaninglessness, because of this vastly expanded possibility space.

Regards

Paul Wally
2012-Apr-25, 12:57 AM
I question the 'sense' in entertaining such a hypothesis if there can be no definitive resolution by means of verification. If an exo-atmosphere is light years distant, there can be no such resolution.

At this stage I think the aim is not as you say "definitive resolution by means of verification", but rather to use the data that we can get to build a tentative model
that could for instance help us estimate the prevalence of life in the galaxy. A model could also predict currently unforeseen new evidence not originally used in building it.



To continue with a hypothesis which is neither verifiable nor falsifiable by practical means, seems destined to become an obsession.

A hypothesis can also be tested by comparing its logical consequences with what is practically observable. For instance we might find that a planet supporting life according to our theory orbits a star with certain properties that cannot support life on such a planet. That would be an example of falsification due to contradictory evidence in terms of the theory.


… I gotta call it like I see it (in this particular case) .. apologies for eliminating areas of grey in what I'm saying, but I really do think some folk have lost sight of practicality constraints. No matter how intense one's dream might be, some things simply aren't feasible. Retrieveing verification evidence over light-year distances is one of 'em.

It's only a practicality issue if you actually want to find conclusive evidence of extrasolar life, but as I said the point is to build a model that might be useful in yet unforeseen ways.


Ok .. so we live in a non-ideal world, where resouces are constrained. If there exists other options/tests/experiments which can be demonstrated to make tangible returns on the sole basis of exo-life exploration, which can be demonstrated to be practically verifiable and falsifiable, I'd have to prefer those alternatives.

I don't know how far we are from actually detecting extrasolar planetary atmospheres, but I can imagine it being like a Kepler type project. It doesn't seem that far fetched though.


I don't have a problem acknowledging the spin-off benefits (eg: technological etc), derived from pursuing a dream, but these can also be obtained by pursuing more practical options ..

The possibility exists that even after Mars, Europa and Titan have been thoroughly explored we won't have any exolife to study in detail. So the planetary exploration program is probably not the most economic way to get an idea of the prevalence of life in the galaxy at large.

At the moment I think the best way to go about is to build computer models of, say solar system formation and planetary formation from Kepler type missions and then to combine such models with a theory of abiogenesis using data acquired from e.g chemical experiments and from whatever else we may know about the evolution of life here on Earth. I believe that understanding the general principles (not just contingent data) of abiogenesis is the key to solving the problem of the probability of life in general.

Selfsim
2012-Apr-25, 03:02 AM
"To develop a model of Astrobiology, or not … that is the question" ….

What is the true purpose of such a model ?

If I was serious about finding exo-life, and I have the choice of either:

i) going and looking for it, or;
ii) developing a speculative, practically unverifiable model about it,

What would I do ?

My 2 cents worth: (i) above. :)

Regards

Footnote:
As an attempt to contribute some factual data to this thread (beyond opinions), as far as our present remote exo-life bio-sign detection capability goes, a recently released (Nov 2011) (http://arxiv.org/abs/1104.0570) paper claims confirmed detection of a strong 3.3 micron feature, (corresponding to the methane v3 branch), in the atmosphere of HD 189733b (a hot Jupiter ~63 Lyrs distant). (Done by the Spex spectrograph at the NASA Infrared Telescope Facility, atop Mauna Kea). There are several other of these projects presently underway, or under consideration. Regards

iquestor
2012-Apr-25, 10:58 AM
it wasnt too long ago it was thought to be impossible to detect small rocky planets, yet here we are at the verge of finding many of them.

I beleive spectroscopy of distant planetary atmospheres could one day provide evidence beyond a reasonable doubt that there is life. Take a look at the TED Talk done br Dr Garik Isrealian.

I agree absolute proof would require contact or at least a visual.

but I don't agree with the idea that "we can't prove it through spectroscopy, so why bother at all?" attitude -- finding convincing evidence of life elsewhere will fuel technology to one day get us there.

Paul Wally
2012-Apr-25, 04:33 PM
i) going and looking for it, or;
ii) developing a speculative, practically unverifiable model about it,

What would I do ?

My 2 cents worth: (i) above. :)



i) and ii) are not two mutually exclusive options as you seem to think. If you going to look for something it helps to form an idea of where and how to look for it. Having a model helps in this regard, otherwise you'll have to look everywhere, and that's not very practical is it?



As an attempt to contribute some factual data to this thread (beyond opinions), as far as our present remote exo-life bio-sign detection capability goes, a recently released (Nov 2011) (http://arxiv.org/abs/1104.0570) paper claims confirmed detection of a strong 3.3 micron feature, (corresponding to the methane v3 branch), in the atmosphere of HD 189733b (a hot Jupiter ~63 Lyrs distant). (Done by the Spex spectrograph at the NASA Infrared Telescope Facility, atop Mauna Kea). There are several other of these projects presently underway, or under consideration.

So what do they do with this data? Perhaps scientists look at data like this and together with other data formulate models.


We confirm the previously reported strong emission at ~3.3 microns and, by assuming a 5% vibrational temperature excess for methane, we show that non-LTE emission from the methane nu3 branch is a physically plausible source of this emission. We consider two possible energy sources that could power non-LTE emission and additional modelling is needed to obtain a detailed understanding of the physics of the emission mechanism.


Science is not just about data collection. There's always an element of theorizing to explain stuff. And a theory can be wrong and scientists know this.

Selfsim
2012-Apr-25, 10:30 PM
i) and ii) are not two mutually exclusive options as you seem to thing. If you going to look for something it helps to form an idea of where and how to look for it. Having a model helps in this regard, otherwise you'll have to look everywhere, and that's not very practical is it?The exclusivity arises when one considers the funding priorities and its impact on local exploration. (http://blogs.discovermagazine.com/badastronomy/2012/02/13/white-house-asks-for-brutal-planetary-nasa-budget-cuts/)

(I get that such a model is intended to guide the search, specifically by narrowing the Kepler confirmed findings).

As I outlined earlier on in this thread, the issue I'm raising is limited to the exo-life justification component of remote exo-atmospheric gas analysis projects:

So I should make it clear that the point being made here pertains only to the making of progress in the exo-life discovery goal.

The reference 'database' for interpreting such remote measurements, is dependent on confirmed (verified) causality between exo-life and exo-gases. There is presently only one instance to draw from (Earth-life/Earth atmosphere). Direct ET communication, or a random chance local discovery of exo-life, are presently our only means for taking this data beyond an instance of one. Interpretation of remote exo-gas measurements, is dependent on data gathered through local exploration.

Without this missing data, as you say, interpretation will be by means of inference only. Which is no different to what we already have. No progress on exo-life determination will have been made.

Some folk are content to live with inference as a primary means for determining the existence of exo-life. Extraordinary scientific claims call for extraordinary scientific evidence, and this will be missing until other instances of exo-life are verified. There is a limit to what can be inferred from remote measurements over light-year distances.

So what do they do with this data? Perhaps scientists look at data like this and together with other data formulate models.We already have a standard model for Earth-based life. The quest for exo-life is to verify that model. We are at the next phase of the process, so we should be taking steps which directly support the next phases of achieving that goal.

Science is not just about data collection. There's always an element of theorizing to explain stuff. And a theory can be wrong and scientists know this.You generalise back to 'Science'. We need to distinguish exactly what the hunt for exo-life is about, and distinguish it from astrophysical science … because it is fundamentally different, due to vastly greater complexity of what we're looking for, and the targetted scale level.

Regards

Paul Wally
2012-Apr-26, 01:14 AM
The exclusivity arises when one considers the funding priorities and its impact on local exploration. (http://blogs.discovermagazine.com/badastronomy/2012/02/13/white-house-asks-for-brutal-planetary-nasa-budget-cuts/)

You're mixing up the issue of funding with that of choosing the best research methodology. By the looks of it, it does seem that local planetary exploration requires much more resources than exoplanet observatories, but then again with planetary exploration there is a broad range of scientific objections like just learning more about planets in general. As I said it's entirely possible that we find no life on any of the other planets in our solar system.


(I get that such a model is intended to guide the search, specifically by narrowing the Kepler confirmed findings).

As I outlined earlier on in this thread, the issue I'm raising is limited to the exo-life justification component of remote exo-atmospheric gas analysis projects:

"Exo-life justification" is where my issue lies. Why are you focused on justification? If Exo-life is eventually discovered will you then be surprised? Since we already
know that it's possible the issue is not to justify its existence but rather to find out how it is possible. So for me it's largely a theoretical problem of how the laws of nature make the emergence of life possible in the universe at large. Given that this is the problem statement, any empirical research must be directed at finding clues that would help solve this theoretical problem, rather directing it at justifying the existence of exo-life.



The reference 'database' for interpreting such remote measurements, is dependent on confirmed (verified) causality between exo-life and exo-gases. There is presently only one instance to draw from (Earth-life/Earth atmosphere). Direct ET communication, or a random chance local discovery of exo-life, are presently our only means for taking this data beyond an instance of one. Interpretation of remote exo-gas measurements, is dependent on data gathered through local exploration.

The Earth is not an instance,sample or datapoint, it's more like a whole planet where life has emerged somewhere in this galaxy. Indeed, if we could explain how life emerged here we can explain how it can emerge anywhere else. At the moment we haven't yet solved the theoretical problem of how life emerges.



Without this missing data, as you say, interpretation will be by means of inference only. Which is no different to what we already have. No progress on exo-life determination will have been made.

Again, you're focussed on exo-life justification.


Some folk are content to live with inference as a primary means for determining the existence of exo-life. Extraordinary scientific claims call for extraordinary scientific evidence, and this will be missing until other instances of exo-life are verified. There is a limit to what can be inferred from remote measurements over light-year distances.
We already have a standard model for Earth-based life. The quest for exo-life is to verify that model. We are at the next phase of the process, so we should be taking steps which directly support the next phases of achieving that goal.

Do you really think the existence of exo-life is an extraordinary scientific claim? I think the quest for exo-life is more about learning more about it and the emergence of life in general than about justification of its existence.



You generalise back to 'Science'. We need to distinguish exactly what the hunt for exo-life is about, and distinguish it from astrophysical science … because it is fundamentally different, due to vastly greater complexity of what we're looking for, and the targetted scale level.

Exobiology is about the study of life on other planets, but since we're not likely to find any samples any time soon, the approach should be to do the most we can with the data we can find. By getting as much as possible information on other solar systems we can get an idea of how common the conditions for the existence of life as we understand it is.Then a theory could be formulated linking the process of solar system formation with the process of the formation of life as we understand it.

Selfsim
2012-Apr-27, 07:14 AM
As I said it's entirely possible that we find no life on any of the other planets in our solar system.Because precedent based empirical life tests exist, and must be applied locally, a null conclusion is practically feasible.
The same cannot be said for remote testing over light-year distances.
A null finding locally would be a big step forward in the hunt for exo-life.


"Exo-life justification" is where my issue lies. Why are you focused on justification? If Exo-life is eventually discovered will you then be surprised? Since we already
know that it's possible the issue is not to justify its existence but rather to find out how it is possible. So for me it's largely a theoretical problem of how the laws of nature make the emergence of life possible in the universe at large. Given that this is the problem statement, any empirical research must be directed at finding clues that would help solve this theoretical problem, rather directing it at justifying the existence of exo-life.
With respect, I don't think we're on the same wavelength just yet ..
The justification of which I speak, is in reference to projects whose goal is remote spectroscopic/telescopic/spectropolarimetry of exo-planet atmospheric 'bio'-gases. The astrobiological elements of these projects, target development of speculative models, which can only be interpreted via inference.

Even if an Earth-like planet is found with an atmosphere of O2, CH4, Nitrogen, CO2 and H2O, the conclusion can still only be inferred, and there is no feasible way to verify life on that planet (or otherwise).

It is feasible to verify exo-life with local exploration projects in habitable zones, however .. and yet these projects


Exobiology is about the study of life on other planets, but since we're not likely to find any samples any time soon, the approach should be to do the most we can with the data we can find. By getting as much as possible information on other solar systems we can get an idea of how common the conditions for the existence of life as we understand it is.Then a theory could be formulated linking the process of solar system formation with the process of the formation of life as we understand it.The field of Astrobiology stands alone in science as having the sole purpose of justifying the belief that its subject matter exists.

{My underline}: We have no idea about when we might find 'samples' … about the only definitive statement than can be justifiably made, is that if we don't make the attempt, we'll never retrieve any 'samples' of exo-life.

Regards

Paul Wally
2012-Apr-27, 02:17 PM
A null finding locally would be a big step forward in the hunt for exo-life.


Maybe .. maybe not. I think it depends on the kinds of conditions at the site where we don't find life. Then some kind of inference will have to be drawn from that null observation ... but since you have a problem with drawing inferences how is it going to be a big step forward for you?



With respect, I don't think we're on the same wavelength just yet ..
The justification of which I speak, is in reference to projects whose goal is remote spectroscopic/telescopic/spectropolarimetry of exo-planet atmospheric 'bio'-gases. The astrobiological elements of these projects, target development of speculative models, which can only be interpreted via inference.

I don't know what to make of this. Do you think that the projects are unjustified or the inferences drawn from the empirical results of these projects? If your issue is with the latter, you're welcome to present your own interpretation or possible explanations.



Even if an Earth-like planet is found with an atmosphere of O2, CH4, Nitrogen, CO2 and H2O, the conclusion can still only be inferred, and there is no feasible way to verify life on that planet (or otherwise).

Discovery of such a planet would be quite significant. Even if we cannot directly observe the cause of these gasses the problem remains to explain how they could arise. For example oxygen is a gas that must be dynamically sustained in some way on a terrestrial planet because it tends to combine with other elements on the surface.



The field of Astrobiology stands alone in science as having the sole purpose of justifying the belief that its subject matter exists.


I don't think that is true. Exobiologists already except that their subject matter exists and don't try to justify it. They're just trying to learn what they can about it from the very limited evidence available.

By the way, the very term exobiology is very geocentric, it suggests two fields of biology terrestrial and extra-terrestrial. In reality there should be only one field of universal biology inclusive of all lifeforms. Earth biology is an instance of universal biology.

Selfsim
2012-Apr-28, 07:15 AM
Maybe .. maybe not. I think it depends on the kinds of conditions at the site where we don't find life. Then some kind of inference will have to be drawn from that null observation ... but since you have a problem with drawing inferences how is it going to be a big step forward for you? Ok ... I don't have any problems .. and I don't seek any big steps forward.
The issue on the other hand, is that a null result of a directly applied life test, contributes to furthering knowledge of 'habitable zone' definitions.

I don't know what to make of this. Do you think that the projects are unjustified or the inferences drawn from the empirical results of these projects? If your issue is with the latter, you're welcome to present your own interpretation or possible explanations.Ok ... I don't have any issues.
In comparison with locally applied life-tests which have been demonstrated innumerable times over on Earth-life samples, (and thus constitute a well established, vast historical repository of verified results), remote exo-gas detection pales into virtual insignificance, when it comes to firmness of conclusions drawn. Remote spectrographic (etc) results are dependent on model assumptions. Direct LR metabolic/chirality/C12/C13 isotope ratio/C3/C4 fixing/habitat characterisation/microscopic inspection/specific life molecule testing is not feasible over light-year distances. Such direct tests, far exceed the resolution of the measurement of some remotely detected exo-atmospheric gas which may well be present for some reason other than life presence. Remote spectrographic detection's exo-life interpretive database cannot be shown to be applicable to a particular exo-planet/moon etc, until at least another similar correlated life instance/exo-atmosphere is discovered and confirmed.

I'm starting to seriously wonder why this is such a problem to understand ?


Discovery of such a planet would be quite significant. Even if we cannot directly observe the cause of these gasses the problem remains to explain how they could arise. For example oxygen is a gas that must be dynamically sustained in some way on a terrestrial planet because it tends to combine with other elements on the surface. Well that's one explanation of a dynamically sustainable mechanism .. and it is entirely Earth-centric. Whether or not 'evidence' of this mechanism is always solely indicative of the presence of life, is unknown.


I don't think that is true. Exobiologists already except that their subject matter exists and don't try to justify it. They're just trying to learn what they can about it from the very limited evidence available.I'm sorry, Paul .. that statement requires some serious rethinking ... I'll leave you to it.


By the way, the very term exobiology is very geocentric, it suggests two fields of biology terrestrial and extra-terrestrial. In reality there should be only one field of universal biology inclusive of all lifeforms. Earth biology is an instance of universal biology.We have a standard life/genetic code model. Whether this is universal or not, is what is being tested.

Regards

Colin Robinson
2012-Apr-29, 12:11 AM
The field of Astrobiology stands alone in science as having the sole purpose of justifying the belief that its subject matter exists.

This sort of joke goes back at least to 1964. It appeared in George Gaylord Simpson's article "The Non-prevalence of Humanoids" (Science, Vol 143, 21 Feb 1964), where he explained in detail why he thought searching for life beyond Earth would be futile.

I read thru his article in hard copy in an academic library not long ago. You can also read the first page free on-line via http://www.sciencemag.org/content/143/3608/769 but you do have to pay for the privilege of downloading the full article.

Simpson's argument was not that he considered life beyond Earth unlikely. He argued that in practice it was not likely to be found by humans in the foreseeable future because:

1. It was improbable that evolution on a different world would result in a species sufficiently human-like for radio SETI to give a positive result.
2. He thought this solar system probably did not contain habitable environments beyond Earth for any sort of life.
3. He thought that exo-planets probably existed, but that the limitations of our technology would prevent us from detecting them for the foreseeable future.

Well, he was wrong about detection of exoplanets, in any case. Whether he was right about the solar system remains to be established.

As for the point about unlikeliness of radio-users evolving on another world, it may be a valid argument against radio SETI projects; but it's hardly an argument against astrobiology as such.

Selfsim
2012-Apr-29, 06:10 AM
The field of Astrobiology stands alone in science as having the sole purpose of justifying the belief that its subject matter exists.Yep, Colin .. I'm willing to confess plagiarism .. and, frankly I'm not really too fussed about debating whether he was right, or not. Does this really matter in the end ?

I think the point he makes in this prose is pretty valid, however.

I mean, presently, it seems that Astrobiology provides commentary about where life might be found, and under what conditions. Implicit in this commentary, is the affirmation that exo-life exists .. which is fair enough for exploring the optimistic hypothesis, (even though the optimistic hypothesis is not falsifiable in practice, and thus, interestingly, the pessimistic case is unlikely to accumulate supporting evidence at the same rate, if at all, as a direct result of this). Ie: the investigation seems very lopsided.

So, the 'subject matter' ie: 'exo-life', really is being implicitly justified by means of the accumulation of 'Evidence for exo-life', (as Jeff Root has made clear for us) .. like it or not. Further, I'd imagine that if the field of Astrobiology did not exist, then there would probably be little/no evidence accumulating in support of the pro exo-life hypothesis.

The conclusion that exo-life exists being a belief, is pretty-well inescapable, as there is clearly no evidence that it does exist.

That Astrobiology makes no overt attempts to justify the fundamentals of the hypothesis, almost excludes it from 'classical' science and yet, it is not portrayed this way publically. I've seen Chris McKay (for eg) openly admitting this in interviews. The reason cited for not following the traditional scientific process, is simply that it is not possible to move forward with investigating the hypothesis, by taking the traditional 'classical' approach. The point is fair enough.

Nonetheless, I do find that the subject matter is being implicitly justified, covertly, through accumulation of evidence for the exo-life hypothesis.

Gaylord-Simpson's words are simply straight-talk and serve as a reminder that Astrobiology really is disconnected from the scientific process, at least in terms of its fundamental tenets.

Regards

Colin Robinson
2012-Apr-29, 10:05 AM
Yep, Colin .. I'm willing to confess plagiarism .. and, frankly I'm not really too fussed about debating whether he was right, or not. Does this really matter in the end ?

Does it matter that certain of Simpson's ideas have been falsified?

I think it matters, in the sense that it can help us understand what falsification means in scientific history.


I mean, presently, it seems that Astrobiology provides commentary about where life might be found, and under what conditions. Implicit in this commentary, is the affirmation that exo-life exists .. which is fair enough for exploring the optimistic hypothesis, (even though the optimistic hypothesis is not falsifiable in practice, and thus, interestingly, the pessimistic case is unlikely to accumulate supporting evidence at the same rate, if at all, as a direct result of this). Ie: the investigation seems very lopsided.

You contrast the optimistic hypothesis, that exo-life exists, with the pessimistic case. But why think in terms of just two hypotheses? After all, Simpson's paper is optimistic, in the sense that he thought exo-life likely did exist. However, he was very pessimistic about the chances of human beings ever being able to observe or study it.

And what about the Rare Earth Hypothesis, which suggests active multicellular life is very rare, while microbial life may be much more common? Would you call that optimistic or pessimistic? It might seem like bad news to a SETI enthusiast, but good news if you happen to be a microbiologist...

Perhaps it would make more sense to speak of a range of hypotheses that have been developed about how common or rare is life in the universe, and about the feasibility or otherwise of finding examples of it beyond our home planet.

Many hypotheses (both optimistic and pessimistic) have suggested, and many have been falsified... That is how science moves forward.

For example, back in 1903 Alfred Russel Wallace put forward the idea that life in the Solar System is only possible in what is called today the Goldilocks zone. He also suggested that life is only possible very near the centre of the Galaxy... The Goldilocks zone hypothesis has not been falsified yet. On the other hand, the galaxy-centre hypothesis was falsified rather thoroughly quite a long time ago.


That Astrobiology makes no overt attempts to justify the fundamentals of the hypothesis, almost excludes it from 'classical' science and yet, it is not portrayed this way publically. I've seen Chris McKay (for eg) openly admitting this in interviews. The reason cited for not following the traditional scientific process, is simply that it is not possible to move forward with investigating the hypothesis, by taking the traditional 'classical' approach. The point is fair enough.

Exactly what point was Chris McKay making? Was he saying that, in order to move forward, scientists who study stars and planets sometimes develop hypotheses on the basis of less evidence that would be used by scientists studying things here on Earth?

If so I'd agree with him.

For instance, back in 1868 Jules Janssen and Norman Lockyer noticed some odd, unexpected lines in the solar spectrum during an eclipse. Norman Lockyer put forward the hypothesis that the lines were the signature of a hitherto unknown element. He even gave it a name, based on the Greek word for Sun.

Had any scientist before ever postulated a new element without a laboratory specimen, either of the element itself, or one of its compounds??

Norman Lockyer's hypothesis turned out to be right, though. Its name is Helium.

Selfsim
2012-Apr-30, 07:07 AM
Does it matter that certain of Simpson's ideas have been falsified?

I think it matters, in the sense that it can help us understand what falsification means in scientific history.Why dwell on this one example ? .. (There are plenty of better falsification examples). I'm also dubious about your usage of the term 'falsification' as it pertains to speculative ideas, also.
Also, I have no idea at what time in history he made his exo-planet detection 'prediction' comment. He died in 1984, and the first detection wasn't until 1992, 8 years after his death ... and at a time just prior to major astronomical technological advances which were surely not foreseeable by a paleontologist .. who was not of a technological background.

Your term' foreseeable future' is subjective, and thus doesn't serve too well as a criterion for making it a textbook 'falsification' case study, especially around that particular era.

At the end of the day, it was all just opinion. I personally find debating opinions, to be a quite low-value exercise.


You contrast the optimistic hypothesis, that exo-life exists, with the pessimistic case. But why think in terms of just two hypotheses? After all, Simpson's paper is optimistic, in the sense that he thought exo-life likely did exist. However, he was very pessimistic about the chances of human beings ever being able to observe or study it.Hair-splitting (??) The only feature distinguishing optimism I can see here, was his opinion that exo-life existed. Everyone's got an opinion … and they don't make a difference to the physical reality at this scale.
Whether anyone can ever observe or study exo-life, (if it exists), is anyone's guess .. depends on whether the sample is local or remote .. amongst many other issues.


And what about the Rare Earth Hypothesis, which suggests active multicellular life is very rare, while microbial life may be much more common? Would you call that optimistic or pessimistic? It might seem like bad news to a SETI enthusiast, but good news if you happen to be a microbiologist…Once again … its all just opinion … opinions don't make a difference to physical reality at these scales.
Also, 'enthusiasts' should take a leaf from the pages of professionals. Professionals doing real science don't really care about the results in advance. They care more about performing good science. 'Good news or bad news', is more about how science is conducted, rather than being about whether their opinions turn out to be right or not !
Another dimension on this comes from Simpson himself:

"I don't think that evolution is supremely important because it is my specialty; it is my specialty because I think it is supremely important."


Perhaps it would make more sense to speak of a range of hypotheses that have been developed about how common or rare is life in the universe, and about the feasibility or otherwise of finding examples of it beyond our home planet.

Many hypotheses (both optimistic and pessimistic) have suggested, and many have been falsified... That is how science moves forward.Science moves forward on the basis of independently verifiable, repeatable test results. Perception is subject to opinions. Opinions change .. so do the perceptions. Physical reality is independent of perceptions and opinions.


For example, back in 1903 Alfred Russel Wallace put forward the idea that life in the Solar System is only possible in what is called today the Goldilocks zone. He also suggested that life is only possible very near the centre of the Galaxy... The Goldilocks zone hypothesis has not been falsified yet. On the other hand, the galaxy-centre hypothesis was falsified rather thoroughly quite a long time ago.I'm dubious about your usage of the term 'falsified' here. 'Unlikely', might seem to be a more appropriate term (??)


Exactly what point was Chris McKay making? Was he saying that, in order to move forward, scientists who study stars and planets sometimes develop hypotheses on the basis of less evidence that would be used by scientists studying things here on Earth?

If so I'd agree with him. Actually, he wasn't saying anything about 'moving forward'. In fact the point he was making is that Astrobiologists are mostly wrong about many things. He said that the net effect of being wrong so often, is that they get used to accepting just about anything anyone comes up with. The 'filters' (my word) for ascertaining veracity of anything in Astrobiology have to be dropped, which makes the field more 'open and receptive' to ideas than the classical sciences. He went on to say he thought this was good for newcomers, as they get the sense that they can speak about their new ideas, without fearing the 'mighty wrath' of accountability (my words).
(This is pathetic, if you ask me .. and it seems that Simpson thought that also).


For instance, back in 1868 Jules Janssen and Norman Lockyer noticed some odd, unexpected lines in the solar spectrum during an eclipse. Norman Lockyer put forward the hypothesis that the lines were the signature of a hitherto unknown element. He even gave it a name, based on the Greek word for Sun.

Had any scientist before ever postulated a new element without a laboratory specimen, either of the element itself, or one of its compounds??

Norman Lockyer's hypothesis turned out to be right, though. Its name is Helium.Yes but this hypothesis was formed on the basis of a huge amount of existing evidence and independently verifiable, repeatable lab experiments. That a particular element may not be known on Earth, in this context, is not a huge leap of faith. The sub-atomic physics he was drawing from, and extrapolating from, was fundamentally deterministic and predictable.
Life on the other hand, is complex by nature. Its functions are not purely deterministic … if it was, there'd be a cure for every disease and ailment known .. and the cure would work exactly the same way, in every case.
This is the fundamental differentiator at a biological level, as to why exo-life cannot be predicted.
… And yet so many seem to 'speculate' that it can be ! Beats me why this is done when there is abundant evidence against doing so ..

Regards

Selfsim
2012-Apr-30, 08:22 AM
The Chris McKay interview is on Youtube here. (http://www.youtube.com/watch?v=xlIj-BtYWn4)

Its about 45 mins in length. His comment comes in at about the 29:50 mark, and I should point out that he's actually referring to 'Planetary Science' when he makes it ... (not Astrobiology) .. apologies for my error .. I was going by memory in my previous posts.

Regards

Colin Robinson
2012-May-01, 02:19 AM
The Chris McKay interview is on Youtube here. (http://www.youtube.com/watch?v=xlIj-BtYWn4)

Its about 45 mins in length. His comment comes in at about the 29:50 mark, and I should point out that he's actually referring to 'Planetary Science' when he makes it ... (not Astrobiology) .. apologies for my error .. I was going by memory in my previous posts.

Thank you for supplying that reference. I've just been playing what he says around that 29:50 mark, about planetary scientists like himself often being dead wrong.

The example he gives is an interesting one: they expected Titan's surface to be largely or completely covered by liquid hydrocarbons, and therefore designed the Huygens lander for a splashdown rather than a landing on a solid surface...

For those of us (including myself) who are not planetary scientists, it's important to remember that they were right to predict liquid hydrocarbons on the surface of Titan. They were just wrong about how much.

Very large lakes in the polar regions, but no global ocean...

As you wrote in your earlier posting...


Professionals doing real science don't really care about the results in advance. They care more about performing good science. 'Good news or bad news', is more about how science is conducted, rather than being about whether their opinions turn out to be right or not !

Perhaps that's the point Chris McKay was making. When Huygens didn't land on an ocean, people like Chris did not greatly care that their theoretical model of Titan was wrong. They were pleased that Huygens had succeeded in landing and sending back data for them to study.


Science moves forward on the basis of independently verifiable, repeatable test results.

Yes, "test" is the word. They develop hypotheses, and design repeatable experiments to test them.

Paul Wally
2012-May-01, 05:45 AM
I mean, presently, it seems that Astrobiology provides commentary about where life might be found, and under what conditions.

"Might be found" indicates hypothesis, i.e. it's not conclusive.


Implicit in this commentary, is the affirmation that exo-life exists .. which is fair enough for exploring the optimistic hypothesis, (even though the optimistic hypothesis is not falsifiable in practice, and thus, interestingly, the pessimistic case is unlikely to accumulate supporting evidence at the same rate, if at all, as a direct result of this). Ie: the investigation seems very lopsided.

What is an "optimistic hypothesis"? An hypothesis needs only to be consistent and testable ... I don't see where optimism and pessimism fits into this picture. Anyway, the testable hypothesis should be something more complex than simply existence or non-existence of life at a particular location. The hypothesis contains the kinds of processes occurring in the remote biosphere producing observable phenomena. Such a more detailed theory would be falsified if contradictions arise between the observable phenomena as interpreted by the theory.



So, the 'subject matter' ie: 'exo-life', really is being implicitly justified by means of the accumulation of 'Evidence for exo-life', (as Jeff Root has made clear for us) .. like it or not.

No ... "exo-life" is not justified by evidence, it is merely supported or corroborated by evidence. There's a huge difference.


Further, I'd imagine that if the field of Astrobiology did not exist, then there would probably be little/no evidence accumulating in support of the pro exo-life hypothesis.

Obviously, a field must exist for evidence to be systematically accumulated in that particular field.



The conclusion that exo-life exists being a belief, is pretty-well inescapable, as there is clearly no evidence that it does exist.

"Exo-life" is neither a conclusion nor a belief, it's a postulate. A postulate is prior to evidence, so whether there is or is not evidence is irrelevant.



That Astrobiology makes no overt attempts to justify the fundamentals of the hypothesis, almost excludes it from 'classical' science and yet, it is not portrayed this way publically. I've seen Chris McKay (for eg) openly admitting this in interviews. The reason cited for not following the traditional scientific process, is simply that it is not possible to move forward with investigating the hypothesis, by taking the traditional 'classical' approach. The point is fair enough.



Nonetheless, I do find that the subject matter is being implicitly justified, covertly, through accumulation of evidence for the exo-life hypothesis.

What you're saying doesn't make logical sense. While something is still a hypothesis it is not justified. It can only be justified when there is conclusive evidence. Any hypothesis, in any science is by definition not justified. It is illogical to require that an hypothesis be justified before it is justified.



Gaylord-Simpson's words are simply straight-talk and serve as a reminder that Astrobiology really is disconnected from the scientific process, at least in terms of its fundamental tenets.


I see no fundamental difference between astrobiology and the rest of science. As long as it has testable logical consequences it's very much like theoretical physics with its theoretical postulates like neutrinos, anti-matter, quarks, Higgs boson, magnetic monopoles, strings etc. Some of these are confirmed but some are not... very much like exo-life.

Selfsim
2012-May-02, 06:48 AM
I mean, presently, it seems that Astrobiology provides commentary about where life might be found, and under what conditions.
"Might be found" indicates hypothesis, i.e. it's not conclusive. Yep .. its certainly not conclusive .. the 'justification term refers to the way the so-called 'evidence' is used in justifying the exo-life postulate (ie: "Evidence for exo-life"). This is separate from justifying exo-life's existence in the physical universe. None-the-less, in the light of there being no direct evidence in support of exo-life per se, the perception of it becomes real in the community. I call this reality by consensus and it is peculiar to communities of humans (some also call it reality-thru-politics' :) )


What is an "optimistic hypothesis"? An hypothesis needs only to be consistent and testable ... I don't see where optimism and pessimism fits into this picture. I've used the term 'optimistic' in the sense of referring to the 'optimistic' outlook, which in this case would be that exo-life exists. The pessimistic outlook would be that exo-life does not exist. I'm not too hung up on the words though .. but these particular ones convey the sentiment frequently expressed by those who seem to spend lots of time thinking about exo-life matters .. (and talking it into existence).


Anyway, the testable hypothesis should be something more complex than simply existence or non-existence of life at a particular location. The hypothesis contains the kinds of processes occurring in the remote biosphere producing observable phenomena. Such a more detailed theory would be falsified if contradictions arise between the observable phenomena as interpreted by the theory. So somehow we've swapped from a 'hypothesis' to a 'theory' in the same paragraph ..?...
I'd also prefer to go with a reworded version of what you wrote .. as follows:
"The hypothesis might contain the kinds of processes which might occur in a postulated remote biosphere, which may produce observable phenomena consistent with Earth-life biogenic processes. The observation of such phenomena, also does not rule out the possibility that these could also be produce by non-biogenic processes, not included in the initial hypothesis postulates."


No ... "exo-life" is not justified by evidence, it is merely supported or corroborated by evidence. There's a huge difference.Agreed ! Although other posters in this forum practising reality by consensus, might not agree with this.


Obviously, a field must exist for evidence to be systematically accumulated in that particular field.Data exists regardless of whether a 'field' of study exists or not. Why does it become 'evidence' because the field exists, I wonder ?


"Exo-life" is neither a conclusion nor a belief, it's a postulate. A postulate is prior to evidence, so whether there is or is not evidence is irrelevant.Well if there is no evidence then who cares whether we label it a 'postulate' or a 'belief' ... call it a 'thought' or an 'idea' .. I don't care ... but if there is no evidence, then its existence in the physical universe is indeterminate. 'Evidence' is not my word for it anyway. It came from others in this forum, which is why I'm using it.


What you're saying doesn't make logical sense. While something is still a hypothesis it is not justified. It can only be justified when there is conclusive evidence. Any hypothesis, in any science is by definition not justified. It is illogical to require that an hypothesis be justified before it is justified.Hopefully the distinctions of reality-by-consensus, and physical reality will add some clarity to what I'm on about (??) I agree with what your saying from a scientific perspective. There are two levels I'm addressing here simultaneously (ie: consensus reality and scientific (physical) reality).

I see no fundamental difference between astrobiology and the rest of science. As long as it has testable logical consequences it's very much like theoretical physics with its theoretical postulates like neutrinos, anti-matter, quarks, Higgs boson, magnetic monopoles, strings etc. Some of these are confirmed but some are not... very much like exo-life.Fine ... and I absolutely disagree with drawing parallels between astrobiology and the theoretical constructs you mention. In many cases, the above postulations are a logical consequence of direct observations and measurements. This is not so for exo-life postulations. Earth life exists, is independently verifiable, and does not require the existence of exo-life. The presence of certain exo-gases also does not necessarily require the presence of exo-life.

Earth-life encompasses a much wider range of non-linearly interacting systems, which makes the physics of it fundamentally different from sub-atomic particle behaviours, and we know it. Life is based on macro and micro complex adaptive processes, (and I realise you are very much aware of complex systems and what distinguishes them from deterministic Physical models). The sum of the whole, is not the sum of its parts (unlike particle physics).

The hypothetical particle models you mention lead to practical outcomes and practical, feasible tests, (with the exception of strings .. I'll get back to that). Where the hypothetical 'exo-life' model is applied to exo-planets/moons at light-year distances, such a test is not practically feasible.

Strings are supported in rigorous mathematical theoretical 'postdictions' of readily observable phenomena (eg: Newtonian and Maxwellian physics). The supporting theory has a high degree of internal consistency which facilitates specific qualitative descriptions of measurables. It explains observable phenomena like some condensate behaviours. It 'synthesises' quantum gravity, and the other fundamental forces. It provides theoretical descriptions of Entropy conditions applicable to Event Horizons, which is so far, not achievable in other theories.

Exo-life hypotheses have no such consistency, nor exclusive support for observed phenomena in either pre-, or post-diction capacities. Exo-life hypotheses' primary function (other than sentimental value) is to test whether our Earth-life models are ubiquitous and 'standard', wherever Earth-like conditions prevail elsewhere in the universe. In that sense, the test function is not practically executable in most of the target environments it is hypothesised to exist in, (exo-planets/moons, at light-year distances). They may be executable locally, however.

Regards

Paul Wally
2012-May-02, 02:38 PM
Yep .. its certainly not conclusive .. the 'justification term refers to the way the so-called 'evidence' is used in justifying the exo-life postulate (ie: "Evidence for exo-life"). This is separate from justifying exo-life's existence in the physical universe. None-the-less, in the light of there being no direct evidence in support of exo-life per se, the perception of it becomes real in the community. I call this reality by consensus and it is peculiar to communities of humans (some also call it reality-thru-politics' :) )

If the issue is about public perception then I understand your point, but within the scientific community (if there is such a thing) there cannot be such a "reality consensus" it goes against the very critical nature of scientific discourse.



I've used the term 'optimistic' in the sense of referring to the 'optimistic' outlook, which in this case would be that exo-life exists. The pessimistic outlook would be that exo-life does not exist. I'm not too hung up on the words though .. but these particular ones convey the sentiment frequently expressed by those who seem to spend lots of time thinking about exo-life matters .. (and talking it into existence).

But I think you assume that one has to be certain of the actual physical existence of something in order to talk about it. It's useful to lay the conceptual groundwork even before any evidence is found.


So somehow we've swapped from a 'hypothesis' to a 'theory' in the same paragraph ..?...
I'd also prefer to go with a reworded version of what you wrote .. as follows:
"The hypothesis might contain the kinds of processes which might occur in a postulated remote biosphere, which may produce observable phenomena consistent with Earth-life biogenic processes. The observation of such phenomena, also does not rule out the possibility that these could also be produce by non-biogenic processes, not included in the initial hypothesis postulates."

I used the word "theory" just to accentuate that it's more complex than a singular proposition. Yes, you can reword as you did, but that is just to make sure there is no misunderstanding of the meaning of the word "hypothesis"; that it is tentative and that there are possible alternatives.



Data exists regardless of whether a 'field' of study exists or not. Why does it become 'evidence' because the field exists, I wonder ?

I'm not sure I understand your point. Would Rutherford have built his instrument that lead to his discovery of the atomic nucleus if the field of physics didn't exist?


Well if there is no evidence then who cares whether we label it a 'postulate' or a 'belief' ... call it a 'thought' or an 'idea' .. I don't care ... but if there is no evidence, then its existence in the physical universe is indeterminate. 'Evidence' is not my word for it anyway. It came from others in this forum, which is why I'm using it.

If it's a postulate then it's possible that it exists but there's no evidence that it does, but when there is evidence then it is a fact. It's important to care about the difference between postulates and facts. The existence of things in the universe is what it is. It's completely independent of what we humans currently take as evidence. Evidence depends on existence not the other way around. So, if there exist billions of inhabited planets in the galaxy then they exist right now as we speak, independently of whether we have evidence or not. The question is then what the best approach is to follow, given only two logical possibilities:
1) Exo-life exists or
2) exo-life doesn't exist.
Which mistake would you rather make? :)


Fine ... and I absolutely disagree with drawing parallels between astrobiology and the theoretical constructs you mention. In many cases, the above postulations are a logical consequence of direct observations and measurements.

How do you draw logical consequences from observations and measurements? You can observe the sun rising every morning but cannot logically deduce from that data that the sun will rise tomorrow. We can make logical deductions from theory yes, e.g. a theory of angular momentum applied to a spinning earth.


This is not so for exo-life postulations. Earth life exists, is independently verifiable, and does not require the existence of exo-life. The presence of certain exo-gases also does not necessarily require the presence of exo-life.

While this is all true, it is just stating some obvious facts. It's not scientifically interesting because it doesn't make any testable predictions. To postulate something that might be wrong is more interesting than simple stating the obvious facts. I would rather say that there are universal kinds of processes in this universe that made Earth life possible and therfore it also makes exo-life possible. Interesting questions emerge: What is the nature of these processes? What are the possible variations if Earth life is but a single instance? Are there any tell-tale signs of life elsewhere that are currently observable?


Earth-life encompasses a much wider range of non-linearly interacting systems, which makes the physics of it fundamentally different from sub-atomic particle behaviours, and we know it. Life is based on macro and micro complex adaptive processes, (and I realise you are very much aware of complex systems and what distinguishes them from deterministic Physical models). The sum of the whole, is not the sum of its parts (unlike particle physics).

Yes, the particular contents and mathematical tools are different for different fields of science, but I was talking about the general methodology of science that is the same: That of proposing hypotheses and testing it.


The hypothetical particle models you mention lead to practical outcomes and practical, feasible tests, (with the exception of strings .. I'll get back to that).

What about the atomic theory? For a long time atoms were just speculation, then it became only a working hypothesis in 19th Century chemistry. More tangible evidence of the existence of atoms only emerged in the early 20th century.


Where the hypothetical 'exo-life' model is applied to exo-planets/moons at light-year distances, such a test is not practically feasible.

A model could make practically observable predictions and we could design our instruments to look for the right things. It's the same with physics, postulated particles can have observable effects even though we cannot observe these particles directly, but we design our instruments to be able to observe the macroscopic effects the theory predicts and therefore to test the theory.



Strings are supported in rigorous mathematical theoretical 'postdictions' of readily observable phenomena (eg: Newtonian and Maxwellian physics). The supporting theory has a high degree of internal consistency which facilitates specific qualitative descriptions of measurables. It explains observable phenomena like some condensate behaviours. It 'synthesises' quantum gravity, and the other fundamental forces. It provides theoretical descriptions of Entropy conditions applicable to Event Horizons, which is so far, not achievable in other theories.

Now what is needed is exactly the biological analogue of such a theory of everything. A theory is needed that 'postdicts' Earth-life and predicts all other variations of life in the universe.




Exo-life hypotheses have no such consistency, nor exclusive support for observed phenomena in either pre-, or post-diction capacities. Exo-life hypotheses' primary function (other than sentimental value) is to test whether our Earth-life models are ubiquitous and 'standard', wherever Earth-like conditions prevail elsewhere in the universe. In that sense, the test function is not practically executable in most of the target environments it is hypothesised to exist in, (exo-planets/moons, at light-year distances). They may be executable locally, however.

I cannot speak about exo-life hypotheses in general, I'm sure there's a wide variety of interesting ideas out there, including the possibility of non-carbon based life-forms. Each hypothesis will have to be treated individually in terms of consistency and testable consequences, and this includes consequences that may be observable currently or in the near future. I don't think you can dismiss these possibilities beforehand. You cannot know beforehand what we will or will not discover, even over light year distances.

Selfsim
2012-May-04, 05:58 AM
But I think you assume that one has to be certain of the actual physical existence of something in order to talk about it. It's useful to lay the conceptual groundwork even before any evidence is found.Definition and constraining the possibilities of what one is thinking about is necessary ... if this is what you mean by 'conceptual groundwork' then I agree. Sometimes this is difficult to find around this forum...

I used the word "theory" just to accentuate that it's more complex than a singular proposition. Yes, you can reword as you did, but that is just to make sure there is no misunderstanding of the meaning of the word "hypothesis"; that it is tentative and that there are possible alternatives.Sure. A theory provides an explanation .. which is likely to be more complex, less tentative, and has several firm bases either in other theory, or observation, or both. The quantitative side also kicks into theory.

I'm not sure I understand your point. Would Rutherford have built his instrument that lead to his discovery of the atomic nucleus if the field of physics didn't exist?Well, it would seem that he arrived at the Rutherford model after a series of Geiger-Marsden experiments, aimed at probing the structure of the atom, which ultimately changed the view of the day from the 'plum-pudding model' of the atom, to a nucleus based model. All this was a direct result of the high deflection of alpha particles observed in these experiments. What role does preconceived dogma play in any of that ?
The man was experimenting and going from there. His opinions were trivial considerations. He was after the reality of how materials behaved .. irrespective of what 'the field' of Physics had to say about atoms.

The model was developed gradually from the data. That differs from searching specifically for another instance of something which already exists. The two areas are not the same by any comparison I can envisage.


If it's a postulate then it's possible that it exists but there's no evidence that it does, but when there is evidence then it is a fact. It's important to care about the difference between postulates and facts. The existence of things in the universe is what it is. It's completely independent of what we humans currently take as evidence. Evidence depends on existence not the other way around. So, if there exist billions of inhabited planets in the galaxy then they exist right now as we speak, independently of whether we have evidence or not. The question is then what the best approach is to follow, given only two logical possibilities:
1) Exo-life exists or:
2) exo-life doesn't exist.
Which mistake would you rather make? :) [/colour] Whilst I broadly agree with the gist of the first part of what you say, there is another 'logical possibility' (your term), which is so often overlooked in these discussions ... and it happens to be the only supportable option .. ie:
3) It is unknown​ whether exo-life exists, or not ! (Ie: indeterminate).

Why is this so frequently disregarded ? Following this 'logical possibility' can yield very practical results, and results in way less biased ventures.


How do you draw logical consequences from observations and measurements? You can observe the sun rising every morning but cannot logically deduce from that data that the sun will rise tomorrow. We can make logical deductions from theory yes, e.g. a theory of angular momentum applied to a spinning earth. Deductions ... yes. Deductions are not inferences. All exo-life hypotheses I've encountered are dependent on inference ... not deduction. The distinction being that with inference, the belief in the truth of the premise is necessary .. whereas in deduction, the generalised statement (or Physical Laws) come first, and are used to 'deduce' (or predict) the specific case in question via established theory .. no belief needs to be held as truth, because the Laws are based in physically verifiable evidence .. (as opposed to some wild idea).


While this is all true, it is just stating some obvious facts. It's not scientifically interesting because it doesn't make any testable predictions. To postulate something that might be wrong is more interesting than simple stating the obvious facts. I would rather say that there are universal kinds of processes in this universe that made Earth life possible and therfore it also makes exo-life possible. Interesting questions emerge: What is the nature of these processes? What are the possible variations if Earth life is but a single instance? Are there any tell-tale signs of life elsewhere that are currently observable?Whilst you may not find this approach 'scientifically interesting', it is the honest, (ie: non-belief based), approach ... ie: acknowledge the facts and then see what can be done. What I'm saying is that the mere act of local exploration is what will build real knowledge about exo-life. I've used James Cook's expeditions to look for a non-existent (at the time) hypothesised Northwest Passage and the hypothesised 'Great Southern Continent' as examples. The hypotheses (or theories) of the day were irrelevant. In fact, he falsified all of them. The act of exploration was the only factor which made the difference.
Its the same as looking for an instance of exo-life, based on the Earth-life model. Looking for so called 'possible biogenic exo-gases' results in inference based conclusions only. Travelling feasible distances, and looking at the appropriate scale level, is the only way to find out ! Even if exo-life isn't present where we can look, then at least we can eliminate that specific habitat and ponder why it wasn't present there. My point is that if we're serious about looking for exo-life ... then take meaningful steps that result in firm conclusions .. rather than ones which are only capable of inference based conclusions, which still end up being about 'my' opinion vs 'your' opinion. (Figuratively speaking .. not personally speaking, that is).


Yes, the particular contents and mathematical tools are different for different fields of science, but I was talking about the general methodology of science that is the same: That of proposing hypotheses and testing it. And exo-life tests are not practically feasible over light-year distances.
So, in effect, such a hypothesis is not practically testable.
Why should Astrobiology get away with generating impractical, resource intensive, unfeasible tests, whereas other areas of science cannot ?

What about the atomic theory? For a long time atoms were just speculation, then it became only a working hypothesis in 19th Century chemistry. More tangible evidence of the existence of atoms only emerged in the early 20th century.The evidence emerged because testing resulted in verifiable observational data which led to the nuclear based model. The hypothesis you mention became obsolete in an instant. The hypothesis added no value to the process .. as a matter of fact, it might as well have been a bed-side story for all it ended up being worth !
Exo-biology tests over light year distances is not practically feasible and therefore leads to nothing more than opinion-based inference. Nothing can be resolved. How does this support scientific progress in the hunt for hypothesised exo-life?

A model could make practically observable predictions and we could design our instruments to look for the right things. It's the same with physics, postulated particles can have observable effects even though we cannot observe these particles directly, but we design our instruments to be able to observe the macroscopic effects the theory predicts and therefore to test the theory.We already have a 'life' theory. The hunt for Earth-like exo-biology is the test for the universality of that theory. The test is not practically feasible for remotely testing for exo-biology, over light year distances.

Now what is needed is exactly the biological analogue of such a theory of everything. A theory is needed that 'postdicts' Earth-life and predicts all other variations of life in the universe.If it is needed, then why not pursue meaningful avenues .. rather than ones which we already know, cannot progress the quest ?
We already have a 'life' theory. Finding exo-biology allows for the execution of that universality test .. this is not practically feasible over light year distances, nor via inference based conclusions on the presence/absence of exo-gases.

I cannot speak about exo-life hypotheses in general, I'm sure there's a wide variety of interesting ideas out there, including the possibility of non-carbon based life-forms. Each hypothesis will have to be treated individually in terms of consistency and testable consequences, and this includes consequences that may be observable currently or in the near future. I don't think you can dismiss these possibilities beforehand. You cannot know beforehand what we will or will not discover, even over light year distances.If the laws of physics have to be violated it can be dismissed on a theoretical basis. If the practicality of executing the tests is not feasible, then the best one can 'hope' for is more opinion-based debate. Opinion based debates never resolve science issues.

Regards

Colin Robinson
2012-May-04, 09:45 AM
What I'm saying is that the mere act of local exploration is what will build real knowledge about exo-life. I've used James Cook's expeditions to look for a non-existent (at the time) hypothesised Northwest Passage and the hypothesised 'Great Southern Continent' as examples. The hypotheses (or theories) of the day were irrelevant. In fact, he falsified all of them.

Yes, he falsified those hypotheses. But no, they were not irrelevant. The hypotheses you've mentioned raised questions which the explorer set out to answer, and did answer.

I recommend you have a look at Karl Popper's studies of the scientific method, such as his book Conjectures and Refutations.

If a hypothesis raises questions that stimulate research, then it has contributed something to science even if it does get falsified.

Maybe that is why a serious planetary scientist (and astrobiologist) like Chris McKay is not ashamed to say that the ideas of planetary scientists have often been quite wrong.


Travelling feasible distances, and looking at the appropriate scale level, is the only way to find out ! Even if exo-life isn't present where we can look, then at least we can eliminate that specific habitat and ponder why it wasn't present there.

I agree with you that examining possible habitats in the Solar System will be scientifically fruitful, even if it leads to the conclusion that a certain location is not a habitat.

But to do this at all, we'll need hypotheses about which places in the Solar System might be habitats, how organisms there might function, and how would you find them if they were there...

That's why we need people like Chris McKay...

Selfsim
2012-May-04, 10:20 AM
Yes, he falsified those hypotheses. But no, they were not irrelevant. The hypotheses you've mentioned raised questions which the explorer set out to answer, and did answer.Nonsense ... Cook was despatched by the Admirality to observe the transit of Venus and to see what other lands he could claim for the King. The Northwest Passage expedition was also motivated by the potential for commercial gain. The act of exploration was the means for achieving these goals, and its rewards were more than familiar to the Admirality. It had nothing to do with the geographers' hypotheses !
The postulated geographical hypotheses were regarded by the Admiralty (and Cook) as laughible .. Cook despised them, because to him, they lied by producing ridiculously inaccurate maps causing unnecessary death and suffering for seafarers.


I recommend you have a look at Karl Popper's studies of the scientific method, such as his book Conjectures and Refutations.

If a hypothesis raises questions that stimulate research, then it has contributed something to science even if it does get falsified.Cook's falsification (via detailed recorded observations) was co-incidental and after the fact. 'Twas historians and academics who declared the falsification ... not Cook nor the Admiralty.


Maybe that is why a serious planetary scientist (and astrobiologist) like Chris McKay is not ashamed to say that the ideas of planetary scientists have often been quite wrong.... or maybe McKay is just a poor scientist who doesn't realise he's being motivated by fantasies of Star Trek and political lobbying, rather than doing productive science which leads to tangible results?


I agree with you that examining possible habitats in the Solar System will be scientifically fruitful, even if it leads to the conclusion that a certain location is not a habitat.

But to do this at all, we'll need hypotheses about which places in the Solar System might be habitats, how organisms there might function, and how would you find them if they were there...

That's why we need people like Chris McKay...We don't need McKay to do that ! Its been going on for centuries before he turned up !
The local research in the extremes of Earth environments didn't require McKay to lift a finger !
This glorification of McKay is beginning to teeter on the edge of pseudoscientific behaviour !

Colin Robinson
2012-May-04, 11:25 AM
Nonsense ... Cook was despatched by the Admirality to observe the transit of Venus and to see what other lands he could claim for the King. The Northwest Passage expedition was also motivated by the potential for commercial gain. The act of exploration was the means for achieving these goals, and its rewards were more than familiar to the Admirality. It had nothing to do with the geographers' hypotheses !

In your posting immediately before this one you wrote of "James Cook's expeditions to look for a non-existent (at the time) hypothesised Northwest Passage and the hypothesised 'Great Southern Continent' ". Now again you use the expression "Northwest Passage expedition". And then you tell us it "had nothing to do" with the hypothesis of a Northwest Passage...

Where is the nonsense?


... or maybe McKay is just a poor scientist who doesn't realise he's being motivated by fantasies of Star Trek and political lobbying, rather than doing productive science which leads to tangible results?

Do you have empirical evidence to back your hypothesis that McKay is a poor scientist?

Paul Wally
2012-May-04, 05:14 PM
Definition and constraining the possibilities of what one is thinking about is necessary ...
Why limit your thinking? Thinking about something and thinking that it's true are two different things.


Well, it would seem that he arrived at the Rutherford model after a series of Geiger-Marsden experiments, aimed at probing the structure of the atom, which ultimately changed the view of the day from the 'plum-pudding model' of the atom, to a nucleus based model. All this was a direct result of the high deflection of alpha particles observed in these experiments. What role does preconceived dogma play in any of that ?
The man was experimenting and going from there. His opinions were trivial considerations. He was after the reality of how materials behaved .. irrespective of what 'the field' of Physics had to say about atoms.

You were talking about "existence" of a field. If the field of physics didn't exist how is a complex experiment requiring complex instrumentation even possible in a conceptual vacuum. Rutherford was surprised by his finding, how could he have been surprised if he didn't have some pre-conceived idea that was then falsified? "Conjectures and refutations", that's the process.



Whilst I broadly agree with the gist of the first part of what you say, there is another 'logical possibility' (your term), which is so often overlooked in these discussions ... and it happens to be the only supportable option .. ie:
3) It is unknown​ whether exo-life exists, or not ! (Ie: indeterminate).
Why is this so frequently disregarded ? Following this 'logical possibility' can yield very practical results, and results in way less biased ventures.


In reality there is only two possibilities, what we know or don't know is not a possibility in the reality out there, it's only in our minds. "We don't know" doesn't exist out there. Reality is not agnostic, it is one way or the other, right now, as we speak. And this whole thing about "biased ventures" just represents a misunderstanding of what it means to hypothesize. If it's not conclusive how can it possibly be biased? This kind of thinking of "biased ventures" seems more applicable to the kinds of statistical methods used in the social and economic sciences; there must be a representative sample space etc etc. Anyway, statistics at best will only give you a phenomenological theory rather than a comprehensive theory based on fundamental and universally applicable principles.



Deductions ... yes. Deductions are not inferences. All exo-life hypotheses I've encountered are dependent on inference ... not deduction. The distinction being that with inference, the belief in the truth of the premise is necessary .. whereas in deduction, the generalised statement (or Physical Laws) come first, and are used to 'deduce' (or predict) the specific case in question via established theory .. no belief needs to be held as truth, because the Laws are based in physically verifiable evidence .. (as opposed to some wild idea).

Deduction is the most rigorous form of inference. It is purely logical inference from a premise, irrespective of empirical truth value of the premise. Other forms of inference are inductive inference (generalization from a set of instances) and abductive inference (going from empirical data to an explanation of that empirical data). It is the latter kind of inference that I find most applicable to theoretical progress in both physics and exobiology.


Whilst you may not find this approach 'scientifically interesting', it is the honest, (ie: non-belief based), approach ... ie: acknowledge the facts and then see what can be done. What I'm saying is that the mere act of local exploration is what will build real knowledge about exo-life. I've used James Cook's expeditions to look for a non-existent (at the time) hypothesised Northwest Passage and the hypothesised 'Great Southern Continent' as examples. The hypotheses (or theories) of the day were irrelevant. In fact, he falsified all of them. The act of exploration was the only factor which made the difference.

It is equally honest and non-belief based to qualify one's ideas as hypothetical ... but we have been over this numerous times and we're going around in circles. Your example of Jimmy Cook has no application to the issue of exo-life. Since the existence of a hypothetical north-west passage, Australia and New Zealand are completely contingent matters there is no conceivable general theory with which their existence or non-existence could have been predicted. It is quite a different situation with exo-life; it is conceivable that there is theory by which the existence of life under certain conditions could be deduced.


Its the same as looking for an instance of exo-life, based on the Earth-life model. Looking for so called 'possible biogenic exo-gases' results in inference based conclusions only. Travelling feasible distances, and looking at the appropriate scale level, is the only way to find out ! Even if exo-life isn't present where we can look, then at least we can eliminate that specific habitat and ponder why it wasn't present there. My point is that if we're serious about looking for exo-life ... then take meaningful steps that result in firm conclusions .. rather than ones which are only capable of inference based conclusions, which still end up being about 'my' opinion vs 'your' opinion. (Figuratively speaking .. not personally speaking, that is).

You keep on wanting either firm conclusions or nothing. I think I've made my point clear on "conclusions" numerous times.


And exo-life tests are not practically feasible over light-year distances.

This point I also addressed a few times. You cannot know this a priori.


So, in effect, such a hypothesis is not practically testable.

You don't know this.


Why should Astrobiology get away with generating impractical, resource intensive, unfeasible tests, whereas other areas of science cannot ?

The resource issue I addressed also. At the moment local planetary exploration is much more resource intensive, not that I have anything against local exploration.


The evidence emerged because testing resulted in verifiable observational data which led to the nuclear based model. The hypothesis you mention became obsolete in an instant. The hypothesis added no value to the process .. as a matter of fact, it might as well have been a bed-side story for all it ended up being worth !
Exo-biology tests over light year distances is not practically feasible and therefore leads to nothing more than opinion-based inference. Nothing can be resolved. How does this support scientific progress in the hunt for hypothesised exo-life?

These are your opinions.


If it is needed, then why not pursue meaningful avenues .. rather than ones which we already know, cannot progress the quest ?
We already have a 'life' theory. Finding exo-biology allows for the execution of that universality test .. this is not practically feasible over light year distances, nor via inference based conclusions on the presence/absence of exo-gases.
If the laws of physics have to be violated it can be dismissed on a theoretical basis. If the practicality of executing the tests is not feasible, then the best one can 'hope' for is more opinion-based debate. Opinion based debates never resolve science issues.

... and more opinions.

Selfsim
2012-May-04, 10:10 PM
Paul;

Although this discussion may to have given you the impression that I outright reject hypothesisation in the scientific process, I have already agreed, (elsewhere - in the past), that I recognise and fully acknowledge the role it plays in guiding scientific thinking and modelling. I do not find these views to be shared by other across this forum, however.

My issue lies in over-emphasing the reality of hypotheses with the view to directly acting upon them. Prioritising a hypothesis based venture and depleting resources away from non-hypotheses based science projects is a growing issue thesedays, (IMO).

I find over-emphasis on the importance of hypotheses is exactly what is happening in this forum (IMO) .. this being by way of multiple restatement almost to the point of excess. Hypotheses are best handled by those who originate them, and by those empowered within scientific communities, to able to support, reject or moderate them.

Lobbying in support of scientifically unsupportable hypotheses, to the extent they become reality-by-consensus in the mind of the public, (IMO), is directly at odds with the principles of science … (ie: in-so-far as science being our best tool for distinguishing reality from delusion). This is at the core of my opposition.

You say I have expressed opinions (in the latter comments on your previous post). I would agree they are indeed opinions (although historically supportable). This is exactly where opinion based hypotheses lead, and why debating opinions, in my view, is a waste of time.

I'd like to suggest we move on, and discuss more productive matters where the potential for learning and knowledge acquisition abounds, eh ?

Best Regards

Colin Robinson
2012-May-05, 10:58 PM
The model was developed gradually from the data. That differs from searching specifically for another instance of something which already exists. The two areas are not the same by any comparison I can envisage.

Yes. To look for life on other worlds is to search for another instance of something which is already known to exist.

Not comparable to the way atomic physics developed? Maybe not...

But what about the scientists who worked on the question of exo-planets, before the existence of exo-planets was definitely established?

Weren't they "searching specifically for another instance" of a sun with planets?

Selfsim
2012-May-06, 05:44 AM
Yes. To look for life on other worlds is to search for another instance of something which is already known to exist.

Not comparable to the way atomic physics developed? Maybe not...

But what about the scientists who worked on the question of exo-planets, before the existence of exo-planets was definitely established?

Weren't they "searching specifically for another instance" of a sun with planets?Well, if those scientists were unsuccessful .. (and they were) … then they were clearly barking up the wrong tree ... right up until the first exo-planet discovery !

As it turns out, in fact, the first exo-planet was discovered (http://www.nature.com/nature/journal/v355/n6356/abs/355145a0.html)purely by chance, and was a direct result of observing a millisecond Pulsar in 1992, (PSR 1257+12), with the intention of making precise timing measurements of the pulses ! The Pulsar was found to not even be associated with a companion stellar object !

In other words, the act of exploration, (as opposed to a deliberate, preconceived search for a 'sun with planets'), was the cause of the discovery. Ie: random chance, (pure luck), combined with the deliberate act of exploration within practical capabilities, in this case, resulted in a totally unexpected exo-planet discovery !

Centuries of dreaming of finding a 'sun with planets' was just that … a dream … nothing more.

I assert that in cases like this, acting upon a dream, with the belief in mind that the capability will materialise because of that belief, is just plain naivity. The bulk of the effort in creating the enabling technologies leading to subsequent exo-planet discoveries, eventually came about for a whole pile of other unrelated reasons.

What came after the first discovery might be a better example of your point (?) But I'd say after the first discovery, the quest became to find how many are out there. After the first few discoveries, the 'how many' question, (for me), rapidly disappeared again … back into the 'noise' ...

Regards

Colin Robinson
2012-May-06, 07:56 AM
Well, if those scientists were unsuccessful .. (and they were) … then they were clearly barking up the wrong tree ... right up until the first exo-planet discovery !

They were raising a question which they were not able to answer conclusively.


As it turns out, in fact, the first exo-planet was discovered (http://www.nature.com/nature/journal/v355/n6356/abs/355145a0.html)purely by chance, and was a direct result of observing a millisecond Pulsar in 1992, (PSR 1257+12), with the intention of making precise timing measurements of the pulses !

Yes, and the people who timed the pulses concluded that they had found exoplanets, and the scientific community agreed.

Could that have happened if the question of exo-planets had not previously been a topic of discussion among scientists?


Centuries of dreaming of finding a 'sun with planets' was just that … a dream … nothing more.

A dream that came true in an unexpected way.


I assert that in cases like this, acting upon a dream, with the belief in mind that the capability will materialise because of that belief, is just plain naivity. The bulk of the effort in creating the enabling technologies leading to subsequent exo-planet discoveries, eventually came about for a whole pile of other unrelated reasons.

I'd agree that the capabilities don't develop only because scientists formulate questions whose answers they yearn to find.

There usually are "unrelated reasons" for scientific advances, like rocket technology being developed for military purposes, and afterwards being used to study the solar system and to launch space telescopes...

So, to raise a scientific question insistently is not a sufficient condition for an answer to arrive... Then why do scientists raise questions which cannot be immediately answered?

Raising a question cannot guarantee an answer. But without the question, would the answer ever come?

swampyankee
2012-May-06, 04:12 PM
QM has its, ahem, less than scientific "theories," such as the many-universes hypothesis. Currently, the evidence supporting string theory is not much better than that for non-terrestrial life.

The questions that astrobiology purports to investigate -- "how did life originate?" and "could it originate someplace else?" -- are both sensible, scientifically acceptable questions, albeit ones which cannot be currently answered. In this regard, they are really no different than questions like "what happens inside a black hole?"

Paul Wally
2012-May-06, 04:18 PM
But what about the scientists who worked on the question of exo-planets, before the existence of exo-planets was definitely established?



This is a very good question. Answering it could shed some light on the scientific process. I would add some further questions:
1) Did these scientists work on theoretical aspects of exoplanet detection methods which later contributed to actual exo-planet detection?
2) Did they actually attempt to detect exoplanets?
3) If the answers are yes to 1) and 2) then we should ask why they failed to detect exo-planets. Were there perhaps technological limitations at the time?

I think the problems with exo-planets and exo-life detection are mainly technological, i.e. to develop the technological means to detect them. The scientific issues are to learn more about these things, but the question of whether these things exist or not is really not the big question. It is not as if the scientists were surprised then by the discovery of exo-planets, as in: "Wow!, I didn't know that's possible. So exo-planets do exist after all? Gee! That's really paradigm changing!". The same applies to exo-life. All our efforts should go into developing the scientific theories, methods and technologies that would increase our chances of detecting exo-life, instead of getting stuck on the question of whether it exists or not.

Selfsim
2012-May-06, 10:25 PM
So, to raise a scientific question insistently is not a sufficient condition for an answer to arrive... Then why do scientists raise questions which cannot be immediately answered? errr … because that's what humans do .. and why the checks and balances in the scientific process, were developed in so far as to redirect such thoughts and efforts, back into the real universe, and out of delusional thinking.


Raising a question cannot guarantee an answer. But without the question, would the answer ever come?Who is challenging the raising of scientific queries ?
Certainly not me ! As I stated previously:

the issue lies in over-emphasing the reality of hypotheses with the view to directly acting upon them. Prioritising a hypothesis based venture and depleting resources away from non-hypotheses based science projects is a growing issue thesedays, ..Dedicating major resources to pursuing an inference whose assumptions are taken as reality, is a flaw in rationale. Science has a long history of trying to dispel the dogma established by using this approach.

When it can be demonstrated that other competing projects can return results, at least capable of constraining the possibility-space, (ie: actively demonstrate correlations between measured HZs and the presence/absence of exo-life), these project should take priority.

Regards

Selfsim
2012-May-07, 07:03 AM
I think the problems with exo-planets and exo-life detection are mainly technological, i.e. to develop the technological means to detect them. The scientific issues are to learn more about these things, but the question of whether these things exist or not is really not the big question. It is not as if the scientists were surprised then by the discovery of exo-planets, as in: "Wow!, I didn't know that's possible. So exo-planets do exist after all? Gee! That's really paradigm changing!". The same applies to exo-life. All our efforts should go into developing the scientific theories, methods and technologies that would increase our chances of detecting exo-life, instead of getting stuck on the question of whether it exists or not.So why execute projects which we know are incapable (in practice) of answering the question (ie: unfeasible in practice).. when we have others which are capable (in practice) of answering the question (ie: feasible) ?

Clearly, there is a case to be accounted for, as far as the existence of exo-life, (even if your view is, that there is none) .. for example, why has NASA gone out of its way to declare that the MSL/Curiosity is mission is specifically not for the sole purpose of detecting life ? Why does Claudio Maccone encourage political 'trickery' in the SETI camp (http://www.bautforum.com/showthread.php/131758-Galactic-net?p=2014239#post2014239) by advising SETI folk to leverage the successful Cosmology stream, in order to move exo-life investigation forwards ?


Whether these things exist or not is really not the big question …
{snip} …
All our efforts should go into developing the scientific theories, methods and technologies that would increase our chances of detecting exo-life, instead of getting stuck on the question of whether it exists or not.
If this is the case, why does Chris McKay openly state (http://www.youtube.com/watch?v=xlIj-BtYWn4) that: "the generalisation of the phenomenon of life is 'hard' because we only have one instance of life to draw from, and that this is a case where the science will only advance by going out and looking, and we really need to be driven by the data" (~9:56 min mark) … and that: "we can't even replicate our own life … we are far from being able to synthesise our own life in the laboratory … we are way, way too early in our understanding of life to rule anything out, or anything in" .. "we're lost" (~11:47mins).

If all this is the case, then exactly why is the existence or not, of 'these things' (ie: exo-life), not a big question ? (It certainly seems that McKay thinks it is). If its as hard as he says, then why not do as he says … ie: go out and look for it, by generating the data which leads to answers ... as opposed to making attempts at constructing a 'hard'-to-construct theory ?

Technology 'Problems':
Why does Marc Kaufman also argue the same point, (http://www.bautforum.com/showthread.php/130417-How-Would-Humans-Respond-to-First-Contact-from-an-Alien-World?p=2005536#post2005536)that the technology is absent for detecting exo-life and yet, it is widely known that the remote exo-gas sensing technology (over lyr distances), already exists ? (http://www.bautforum.com/showthread.php/130142-billions-of-potentially-habitable-planets?p=2011281#post2011281) It would seem that its practical application over light-year distances, in terms of expecting to be able to draw conclusions from the results, is where the problems set in, and these 'problems' arise specifically because of a lack of past instance reference data to support any correlations which might be observed.. ie: not technology limitations at all .. just plain old missing data !

Why is it reported that the target exo-species detection technologies (http://www.bautforum.com/showthread.php/128566-Biochip-for-Mars-Life-Detection) have already been tested, and demonstrated to be effective in detecting life ?

Are LR, racemic and chirality tests, also unsupported in technology ?

Regards

Paul Wally
2012-May-07, 01:04 PM
So why execute projects which we know are incapable (in practice) of answering the question (ie: unfeasible in practice).. when we have others which are capable (in practice) of answering the question (ie: feasible) ?

Which projects are incapable of answering what question? I'm sure there are some projects (yet to be developed) capable of answering some questions, but I don't think you can predict what projects will be developed, and how technology would develop and what we may possibly discover. It's seems more that you want to block the process even before it has started.


Clearly, there is a case to be accounted for, as far as the existence of exo-life, (even if your view is, that there is none) .. for example, why has NASA gone out of its way to declare that the MSL/Curiosity is mission is specifically not for the sole purpose of detecting life ?

Is that so? Perhaps it's for the simple logical reason that if there is no life to detect the mission will at least be useful for other purposes also.


Why does Claudio Maccone encourage political 'trickery' in the SETI camp (http://www.bautforum.com/showthread.php/131758-Galactic-net?p=2014239#post2014239) by advising SETI folk to leverage the successful Cosmology stream, in order to move exo-life investigation forwards ?

Now why do you have to drag politics and other people's opinions into a discussion of purely logical and physical possibilities?



If all this is the case, then exactly why is the existence or not, of 'these things' (ie: exo-life), not a big question ? (It certainly seems that McKay thinks it is). If its as hard as he says, then why not do as he says … ie: go out and look for it, by generating the data which leads to answers ... as opposed to making attempts at constructing a 'hard'-to-construct theory ?

There's nothing wrong with attempting to construct any theory. Now it seems not only do you not want empirical research relating to extra-solar life, you also don't want theoretical progress.

Colin Robinson
2012-May-10, 01:27 AM
for example, why has NASA gone out of its way to declare that the MSL/Curiosity is mission is specifically not for the sole purpose of detecting life ?
Is that so? Perhaps it's for the simple logical reason that if there is no life to detect the mission will at least be useful for other purposes also.

There is a detailed "horse's mouth" explanation of the mission's scientific aims at MSL Science Corner: Science Goals (http://msl-scicorner.jpl.nasa.gov/ScienceGoals/). As explained there, they are not looking directly for organisms, but they are looking for complex organic compounds. This is something that has not been attempted since the Viking mission, except by the British mission Beagle 2 which didn't land successfully.

An excerpt from the NASA page:


MSL is not a life detection mission and is not designed to detect extant vital processes that would betray present-day microbial metabolism. Nor does it have the ability to image microorganisms or their fossil equivalents. MSL does have, however, the capability to detect complex organic molecules in rocks and soils. If present, these might be of biological origin, but could also reflect the influx of carbonaceous meteorites… MSL will also be able to evaluate the concentration and isotopic composition of potentially biogenic atmospheric gases such as methane, which has recently been detected in the modern atmosphere.

Selfsim
2012-May-10, 07:30 AM
Which projects are incapable of answering what question? I'm sure there are some projects (yet to be developed) capable of answering some questions, but I don't think you can predict what projects will be developed, and how technology would develop and what we may possibly discover. It's seems more that you want to block the process even before it has started.See the two new threads I started:

i) ESA EChO Exo-Gas Mission (http://www.bautforum.com/showthread.php/132268-ESA-EChO-Exo-Gas-Mission?p=2016191#post2016191) - This thread describes a proposal for an orbital exo-gas detection telescope. I assert that if this project were to go ahead in isolation, (hypothetically), the data returned by it, would be so unconstrained, (only in as far as exo-life detection progress), any exo-life conclusions it might make, would be highly questionable. It is critically dependent on data from local exploration of other Solar System HZs and/or exo-life exploration conclusions.

ii) Exo-Oceans Not Detectable ? (http://www.bautforum.com/showthread.php/132256-Exo-Oceans-Not-Detectable) - I think its fair enough to regard the paper in this thread as highlighting present limitations, (which admittedly, may well be overcome further down the track). However, it serves as a pertinent reminder about the present limitations of specular reflectometry and its inaccuracies, when it comes to detecting 'waterworlds' (still a NASA high priority Astrobiological target environment).

Regards

Paul Wally
2012-May-10, 09:14 PM
See the two new threads I started:

i) ESA EChO Exo-Gas Mission (http://www.bautforum.com/showthread.php/132268-ESA-EChO-Exo-Gas-Mission?p=2016191#post2016191) - This thread describes a proposal for an orbital exo-gas detection telescope. I assert that if this project were to go ahead in isolation, (hypothetically), the data returned by it, would be so unconstrained, (only in as far as exo-life detection progress), any exo-life conclusions it might make, would be highly questionable. It is critically dependent on data from local exploration of other Solar System HZs and/or exo-life exploration conclusions.

It's good to hear that ESA is planning such a mission. Just to get data from exo-planet atmospheric composition would be valuable in itself. I mean, it should at least tell us whether some earth-like physical conditions are common in universe. The conclusions that can be drawn from the data, I think, depends on the broader research process which may not necessarily include a simultaneous "local exploration" mission.



ii) Exo-Oceans Not Detectable ? (http://www.bautforum.com/showthread.php/132256-Exo-Oceans-Not-Detectable) - I think its fair enough to regard the paper in this thread as highlighting present limitations, (which admittedly, may well be overcome further down the track). However, it serves as a pertinent reminder about the present limitations of specular reflectometry and its inaccuracies, when it comes to detecting 'waterworlds' (still a NASA high priority Astrobiological target environment).


Sure, there are limitations. Things are certainly developing faster than I expected, people went from talking about hot Jupiter's, to Neptunes, to super Earth's, to Earth sized planets and 'waterworlds' in a very short period of time. May I ask why you put waterworld in inverted commas? You think it's nonsense? :)

Selfsim
2012-May-10, 11:45 PM
It's good to hear that ESA is planning such a mission. Just to get data from exo-planet atmospheric composition would be valuable in itself. I mean, it should at least tell us whether some earth-like physical conditions are common in universe.How does making such a finding, necessarily result in the conclusion of "common in the universe" ?
Is drawing conclusions about frequency distributions statistically valid for a parent population of the size of the observable universe ? How so ?


The conclusions that can be drawn from the data, I think, depends on the broader research process which may not necessarily include a simultaneous "local exploration" mission.Local exploration and localised bio-testing is the only means by which verification can be practically achieved. (Apart from direct ET contact, caused by a random chance discovery).


Sure, there are limitations. Things are certainly developing faster than I expected, people went from talking about hot Jupiter's, to Neptunes, to super Earth's, to Earth sized planets and 'waterworlds' in a very short period of time. May I ask why you put waterworld in inverted commas? You think it's nonsense? :)No .. in this case, my thoughts don't effect the physical reality.
For me, the term 'waterworld' anthropomorphises the reality … which would be a lump of rock and water.
The term 'world' includes countries, people, societies, institutions and other natural features. Until there is evidence of such things, the application of such a term is premature, and unjustifiably prescriptive.

(Nonetheless, others here seem to take some solace in the use of the term).

Regards

Paul Wally
2012-May-11, 01:28 AM
How does making such a finding, necessarily result in the conclusion of "common in the universe" ?
Is drawing conclusions about frequency distributions statistically valid for a parent population of the size of the observable universe ? How so ?

It surely doesn't look as if we are located in a particularly special corner of the universe. If you have evidence that general conditions where the local group of stars are located are especially different from elsewhere in the galaxy and that our galaxy is especially different from the other galaxies in the universe then please present it. My main point, however, is that the data will have scientific value even if we cannot conclude the existence of life from it. You seem to think that if we cannot conclude the existence of exo-life from such a mission we shouldn't even bother doing it in the first place. Any information is better than nothing.



No .. in this case, my thoughts don't effect the physical reality.
For me, the term 'waterworld' anthropomorphises the reality … which would be a lump of rock and water.
The term 'world' includes countries, people, societies, institutions and other natural features. Until there is evidence of such things, the application of such a term is premature, and unjustifiably prescriptive.

(Nonetheless, others here seem to take some solace in the use of the term).



I don't think the intended meaning of the term "waterworld" is that it must be populated, but simply that it is a planet covered with water. Do you have possible reasons why planets covered with water couldn't exist or why they would be unlikely?

Selfsim
2012-May-11, 04:11 AM
How does making such a finding, necessarily result in the conclusion of "common in the universe" ?


It surely doesn't look as if we are located in a particularly special corner of the universe. If you have evidence that general conditions where the local group of stars are located are especially different from elsewhere in the galaxy and that our galaxy is especially different from the other galaxies in the universe then please present it.The Cosmological Principle can be formally stated (from Wiki):

'Viewed on a sufficiently large scale, the properties of the Universe are the same for all observers.' This amounts to the strongly philosophical statement that the part of the Universe which we can see is a fair sample, and that the same physical laws apply throughout.
So, there is nothing in that, which states that the properties of two particular planets, when viewed at the scale level of Earth's oceans, which formed under the same Laws of Physics/Chemistry, will exhibit the same physical characteristics at that scale.
As a matter of fact, (as a sample), of the ~180 (??) moons/planets/dwarf planet rocky bodies in our Solar System, to the best of my knowledge, no two are identical at the scale of the oceans of Earth, nor are there any such bodies having liquid oceans which resemble Earth's (chemically, volumes, etc). And such a sample also doesn't rule out oceans of water on exo-'waterworlds' .. Inferences drawn either way, on these bases at these scales, are meaningless.

All this happens without the need for invoking anything 'special' about our location in the galaxy (or universe).

If it was all so formulaic, then we could predict the appearance of liquid oceans .. and we can't. Thus, for the same reasons, we cannot predict the distribution, and thence, the 'likelihood', of exo-'waterworlds'.


My main point, however, is that the data will have scientific value even if we cannot conclude the existence of life from it. You seem to think that if we cannot conclude the existence of exo-life from such a mission we shouldn't even bother doing it in the first place. Any information is better than nothing.(Re: the underlined bit): That is not what I think .. I have repeated my views on this so many times, all I can conclude is that there is some kind of impediment preventing my message from getting through .. I expressed candidly, where I was coming from in post #104. (http://www.bautforum.com/showthread.php/130142-billions-of-potentially-habitable-planets?p=2014475#post2014475)


The term 'world' includes countries, people, societies, institutions and other natural features.
I don't think the intended meaning of the term "waterworld" is that it must be populated, but simply that it is a planet covered with water. … The definition came from the Merriam-Webster dictionary. (http://www.google.com.au/#hl=en&output=search&sclient=psy-ab&q=definition+world&oq=definition+world&aq=f&aqi=g4&aql=&gs_l=hp.3..0l4.2872.5204.0.5572.16.15.0.1.1.1.340. 3169.0j10j4j1.15.0...0.0.6aCpxvWJ3II&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=5e48873a38f42348&biw=860&bih=855)


Do you have possible reasons why planets covered with water couldn't exist or why they would be unlikely?Why are you asking me ? The answer to such a question is not relevant from where I stand.

Regards

eburacum45
2012-May-11, 06:44 AM
The argument for waterworlds depends on simulations of planetary formation, which seem to predict that a high proportion of terrestrial planets will have deep, or very deep, coverings of water. I note that the wiki page calls them 'ocean planets'
http://en.wikipedia.org/wiki/Ocean_planet
this was the label given to them by Kuchner and Leger in 2003, and may have been chosen deliberately to avoid the implication that such planets might be inhabited 'worlds'.

In fact it might be difficult or impossible for life to emerge on a deep ocean planet, as there would be no rockpools on the surface where organic chemicals might collect and become concentrated enough to react and interact. A deep ocean planet would be a very dilute environment, or so it seems to me (the same would probably be true of a gas giant).

Colin Robinson
2012-May-11, 09:17 AM
… The definition came from the Merriam-Webster dictionary. (http://www.google.com.au/#hl=en&output=search&sclient=psy-ab&q=definition+world&oq=definition+world&aq=f&aqi=g4&aql=&gs_l=hp.3..0l4.2872.5204.0.5572.16.15.0.1.1.1.340. 3169.0j10j4j1.15.0...0.0.6aCpxvWJ3II&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=5e48873a38f42348&biw=860&bih=855)

Merriam-Webster actually offers a list of different senses of "world" (http://www.merriam-webster.com/dictionary/world), one of which is "14. a celestial body (as a planet)".

Paul Wally
2012-May-11, 01:17 PM
So, there is nothing in that, which states that the properties of two particular planets, when viewed at the scale level of Earth's oceans, which formed under the same Laws of Physics/Chemistry, will exhibit the same physical characteristics at that scale.

That is not what I said.
This is ...

Just to get data from exo-planet atmospheric composition would be valuable in itself. I mean, it should at least tell us whether some earth-like physical conditions are common in universe.

I didn't say it should tell us that some earth-like physical conditions are common. I don't know what it will tell us. That's what scientific instruments are for.


As a matter of fact, (as a sample), of the ~180 (??) moons/planets/dwarf planet rocky bodies in our Solar System, to the best of my knowledge, no two are identical at the scale of the oceans of Earth, nor are there any such bodies having liquid oceans which resemble Earth's (chemically, volumes, etc). And such a sample also doesn't rule out oceans of water on exo-'waterworlds' .. Inferences drawn either way, on these bases at these scales, are meaningless.

I explicitly referred to "local group of stars", not the solar system. If several planets with some Earth-like physical conditions are discovered in the local group of stars why wouldn't that tell us something about the commonality of such conditions in general?


That is not what I think .. I have repeated my views on this so many times, all I can conclude is that there is some kind of impediment preventing my message from getting through .. I expressed candidly, where I was coming from in post #104. (http://www.bautforum.com/showthread.php/130142-billions-of-potentially-habitable-planets?p=2014475#post2014475)

So what is this supposed to mean:

So why execute projects which we know are incapable (in practice) of answering the question (ie: unfeasible in practice).. when we have others which are capable (in practice) of answering the question (ie: feasible) ?



… The definition came from the Merriam-Webster dictionary. (http://www.google.com.au/#hl=en&output=search&sclient=psy-ab&q=definition+world&oq=definition+world&aq=f&aqi=g4&aql=&gs_l=hp.3..0l4.2872.5204.0.5572.16.15.0.1.1.1.340. 3169.0j10j4j1.15.0...0.0.6aCpxvWJ3II&pbx=1&bav=on.2,or.r_gc.r_pw.r_qf.,cf.osb&fp=5e48873a38f42348&biw=860&bih=855)
So what? It's the intended meaning that matters.


Why are you asking me ? The answer to such a question is not relevant from where I stand.

It's relevant, because if you cannot present any possible reason why something wouldn't exist then it's not at all interesting to ask the question: "Does it exist?".

MaDeR
2012-May-12, 09:45 PM
How does making such a finding, necessarily result in the conclusion of "common in the universe" ? Is drawing conclusions about frequency distributions statistically valid for a parent population of the size of the observable universe ? How so ?
I would be very careful in challenging Copernican Principle. Very, very careful*.

In fact, your question is wrong.

It should be asked by me, and it should be "why statistical results from sufficiently large local sample would not be assumed to be applicable to rest of universe?".

*Only known to me exception is lack of known/visible extraterrestial intelligence, and we cannot know if this is really due to our special place in universe or for other (more or less morbid) reasons. Assumption that Copernicam Prinicple would imply such visibility could also be challenged.

Selfsim
2012-May-16, 12:02 AM
It's good to hear that ESA is planning such a mission. Just to get data from exo-planet atmospheric composition would be valuable in itself. I mean, it should at least tell us whether some earth-like physical conditions are common in universe.
How does making such a finding, necessarily result in the conclusion of "common in the universe" ? Is drawing conclusions about frequency distributions statistically valid for a parent population of the size of the observable universe ? How so ?

It surely doesn't look as if we are located in a particularly special corner of the universe. If you have evidence that general conditions where the local group of stars are located are especially different from elsewhere in the galaxy and that our galaxy is especially different from the other galaxies in the universe then please present it.
So, there is nothing in that, which states that the properties of two particular planets, when viewed at the scale level of Earth's oceans, which formed under the same Laws of Physics/Chemistry, will exhibit the same physical characteristics at that scale.
As a matter of fact, (as a sample), of the ~180 (??) moons/planets/dwarf planet rocky bodies in our Solar System, to the best of my knowledge, no two are identical at the scale of the oceans of Earth, nor are there any such bodies having liquid oceans which resemble Earth's (chemically, volumes, etc). And such a sample also doesn't rule out oceans of water on exo-'waterworlds' .. Inferences drawn either way, on these bases at these scales, are meaningless.


All this happens without the need for invoking anything 'special' about our location in the galaxy (or universe).


If it was all so formulaic, then we could predict the appearance of liquid oceans .. and we can't. Thus, for the same reasons, we cannot predict the distribution, and thence, the 'likelihood', of exo-'waterworlds'.

That is not what I said.
This is ...

Just to get data from exo-planet atmospheric composition would be valuable in itself. I mean, it should at least tell us whether some earth-like physical conditions are common in universe.
I didn't say it should tell us that some earth-like physical conditions are common. I don't know what it will tell us. That's what scientific instruments are for.



I explicitly referred to "local group of stars", not the solar system. If several planets with some Earth-like physical conditions are discovered in the local group of stars why wouldn't that tell us something about the commonality of such conditions in general?


I would be very careful in challenging Copernican Principle. Very, very careful*.


In fact, your question is wrong.


It should be asked by me, and it should be "why statistical results from sufficiently large local sample would not be assumed to be applicable to rest of universe?". :silenced: :D :lol:
Errr ... (achem) ... sorry ... there are no wrong questions in science ... there are wrong answers in mathematics, though ...

I agree that the Copernican Principle is indeed being tested with these measurements .. and rightly so ! The Principle would have no validity if it weren't continually put to the test !

The lower scale limit of its applicability in this case, is the issue. The scale Paul was addressing, is vastly different to the scale I am addressing. Both are currently valid viewpoints coming from different perspectives.

Can one rely on the Copernican Principle as a valid basis for concluding the presence or absence of liquid oceans, (essential for 'Earth-like life').. purely because of a planet's relative location and proximity to specific star types? I would have thought the answer was 'no', but direct measurements may make some difference here:

Erubacum pointed out (in another thread):
In most cases I'd expect the presence of a deep ocean to be determined by density calculations; the presence of a shallow or partial ocean would be more difficult to detect. .. which I also have no problems with .. (where such measurement accuracy is possible … and where the usual conclusion terminology: 'consistent with', is duly noted). Inference is also drawn from other measurements in order to form such conclusions .. and precise measurements leading to density figures, are presently still subject to significant uncertainties and other modelling assumptions.

So, let's just say we do conclude via means of indirect measurements and calculations, that there is another 'Earth-like' planet, with 'Earth-like' bodies of liquid water, then the conclusions of its 'commonality', (or its degree of ubiquity), is dependent on just how many planets we had to search, and how many Earth-like planets were found in that sample. How precise we have to be in specifying 'Earth-like' conditions also depends on what the target is. Life emergence may require extremely precise conditions, and so 'Earth-like' might require much greater precision, in order to make conclusions about the emergence and/or presence of exo-life, than for say planetary evolution modelling. This is where localised biological testing comes into play.

At the moment, from the measurement data obtained by Kepler, we are also starting to get an idea of the magnitude of environmental diversity. If we take our our Solar System sample and combine it with the Kepler findings as an indicator of diversity of the measured planet sample group, frankly, the environmental diversity just within that sample looks to be vast. What happens if the frequency of 'Earth-like exo-planets' in precise detail, (ie: the 'commonality' figure), ends up being as rare as our form of life is within the parent population of the DNA permutation space ? In this instance, the conclusion of 'common' would be dubious, regardless of the Corpernican Principle.

The same rationale applies to exo-life distributions. We already know that the possible permutation space for life instances, dwarfs the estimates of the numbers of stars and exo-planets in the observable universe. From the parent population of total permutations, we have only one instance of life on Earth. My point is that as measurements reveal what they do, (in terms of diversity), we need to be prepared to step beyond the comfort zone of the Copernican Principle, and go where the data takes us, rather than force the data to fit with the Principle, based on subjectively biased speculations of exo-life.


*Only known to me exception is lack of known/visible extraterrestial intelligence, and we cannot know if this is really due to our special place in universe or for other (more or less morbid) reasons. Assumption that Copernicam Prinicple would imply such visibility could also be challenged.If you say: "we cannot know", then I'll take that as: "we cannot know" (ie: unknown) ...

What else is out there which 'we cannot know' ?

Paul Wally
2012-May-16, 11:56 AM
At the moment, from the measurement data obtained by Kepler, we are also starting to get an idea of the magnitude of environmental diversity. If we take our our Solar System sample and combine it with the Kepler findings as an indicator of diversity of the measured planet sample group, frankly, the environmental diversity just within that sample looks to be vast. What happens if the frequency of 'Earth-like exo-planets' in precise detail, (ie: the 'commonality' figure), ends up being as rare as our form of life is within the parent population of the DNA permutation space ? In this instance, the conclusion of 'common' would be dubious, regardless of the Corpernican Principle.

If we are to combine our solar system's data with that of Kepler's findings then we can only admit those data that another Kepler (and Earth) would also see, say 20 light years from here. For instance we cannot include the fact that there is life on Earth if we are unable to detect life on exo-planets, and the same applies to all the other kinds of data like water ocean, oxygen atmosphere etc. If we are still unable to detect water oceans on exo-planets, we cannot include the fact that Earth has a water ocean within the sample.

So "some Earth-like conditions" would mean all the conditions here detectable from a distant Earth, say 20 light years away.

Selfsim
2012-May-16, 11:03 PM
If we are to combine our solar system's data with that of Kepler's findings then we can only admit those data that another Kepler (and Earth) would also see, say 20 light years from here. For instance we cannot include the fact that there is life on Earth if we are unable to detect life on exo-planets, and the same applies to all the other kinds of data like water ocean, oxygen atmosphere etc. If we are still unable to detect water oceans on exo-planets, we cannot include the fact that Earth has a water ocean within the sample.

So "some Earth-like conditions" would mean all the conditions here detectable from a distant Earth, say 20 light years away.(My bold)
Now why would you say that ? (Ie: the exclusions ?)
What is it that you're testing, now ?

Paul Wally
2012-May-17, 12:28 PM
(My bold)
Now why would you say that ? (Ie: the exclusions ?)
What is it that you're testing, now ?

What I'm saying is that in order to draw fair comparison between the different solar systems we have to measure them equally. The fact that we are here and not there presents an inherent measurement bias. Only the light years distant detectable data about our own system can be compared to the light year distant detectable data about the other systems. Look for instance at our Jupiter, with an orbital period of almost 12 years. If Jupiter is detected by a distant Kepler then it would take another 12 years to confirm and yet another 12 years before final confirmation of the existence of Jupiter. So as far as our distant Kepler is concerned, Jupiter doesn't exist yet and cannot therefore be included in our confirmed statistical data of the solar systems.

MaDeR
2012-May-17, 08:47 PM
Can one rely on the Copernican Principle as a valid basis for concluding the presence or absence of liquid oceans, (essential for 'Earth-like life').. purely because of a planet's relative location and proximity to specific star types?
Copernican Principle (CP) does not talk about details like this. CP claims that we (and our situation) are nothing usual or exceptional in universe. This is very general claim.
Please note that relative rarity is not same thing as being unusual. Example: is one in milion rare? In human terms, yes. In galaxy terms, it is still rare (one in milion), yet plentiful (about 250 thousand, if one in milion is about stars).

Being "our kind of life appears in one in milion solar systems" would not violate CP, especially if there would be various kind of life taking another one or two in milion from pie.


At the moment, from the measurement data obtained by Kepler, we are also starting to get an idea of the magnitude of environmental diversity.
In light of what I said earlier, diversity would support CP.


My point is that as measurements reveal what they do, (in terms of diversity), we need to be prepared to step beyond the comfort zone of the Copernican Principle, and go where the data takes us, rather than force the data to fit with the Principle, based on subjectively biased speculations of exo-life.
Copernican Principle does not suggest all found exo-life will be exactly same as our kind of life. In fact, I hold opinion that CP supports and expects diversity of life. This means we are not only one life, but also we are not only one kind of life (being only one kind would be in itself special and unusual, coming dangerously close to violating CP).


If you say: "we cannot know", then I'll take that as: "we cannot know" (ie: unknown)
Inferring "we cannot never ever know" from what I said is false assumption.