PDA

View Full Version : EXPOSE-E(d) life in space!



A.DIM
2012-Jun-25, 02:05 PM
Recently there was this news (http://www.esa.int/esaCP/SEM5RNBXH3H_index_0.html) about the ESA's EXPOSE-E experiments aboard the ISS. Again, we find that life is capable of surviving the rigours of space travel ... which supports panspermia hypothesis.

René explains, “These organisms go into a dormant state waiting for better conditions to arrive.”
...
Living organisms surviving in open space supports the idea of ‘panspermia’ – life spreading from one planet to another, or even between solar systems.

It seems possible that organisms could colonise planets by hitching rides on asteroids. ESA is probing this intriguing theory further on future Station missions with different samples.

Exciting, I say!


For further reading, here is a special collection of papers on the EXPOSE-E mission from Astrobiology, Volume 12, Issue 5 (http://online.liebertpub.com/toc/ast/12/5)

Selfsim
2012-Jun-26, 01:13 AM
Exciting, I say!
Hmm … I'm not sure I share that feeling .. to me, Panspermia represents only yet another 'possible' initial condition … which really doesn't progress knowledge about anything much ..(??). Should it ?

Why is it exciting ?

Cheers

A.DIM
2012-Jun-28, 03:47 PM
Hmm … I'm not sure I share that feeling .. to me, Panspermia represents only yet another 'possible' initial condition … which really doesn't progress knowledge about anything much ..(??). Should it ?

Why is it exciting ?

Cheers

Hi Selfsim.

If panspermia is proved you don’t think knowledge will have progressed? Sure, it doesn’t provide answers for abiogenesis hypotheses, but it’s not really meant to, is it? Panspermia is more a description of the evolution and spread of life in the universe, not how, or even where it originated (should it?).

Personally, I find it exciting knowing “primitive” yet extreme life can survive the rigors of space travel, which was thought impossible (by the mainstream) only a couple of decades ago; this bodes well for life being ubiquitous, which is also exciting. Of course when scientific beliefs are falsified, knowledge is gained; this too, is exciting.

In my view there’s little reason to cram the origin of life in the universe into an earth-sized time frame. I mean, how could we ever discover where life originated if we find it is capable of spreading around so? If we don’t insist abiogenesis occurred on Earth, other, perhaps better, hypotheses for the origin of life in the universe could arise.

Cheers!

starcanuck64
2012-Jun-28, 04:36 PM
While panspermia might be possible how probable would it be?

It would take a great deal of energy to first of all achieve solar escape velocity for a life bearing chunk of material then hundreds of thousands or millions of years of transit between star systems to finally impact on the surface of a suitable receiving planet.

Abiogenisis may be a hard process to pin down, but since it obviously exists(or we wouldn't be here) and given constant physical laws it will repeat over and over again in the proper conditions. It's a far more likely candidate for life appearing on earth.

mutleyeng
2012-Jul-04, 03:14 AM
I would see this as not excluding panspermia rather than supporting it.

Im fine with migration of life within a system - but it would take a lot to convince me it could happen on a galactic scale.

I do agree that local abiogenesis seems more likely. but i'm not even sure you can assume abiogenesis would repeat over given constant physical conditions can you? what with chaos and all that jazz

A.DIM
2012-Jul-04, 03:41 PM
While panspermia might be possible how probable would it be?

It would take a great deal of energy to first of all achieve solar escape velocity for a life bearing chunk of material then hundreds of thousands or millions of years of transit between star systems to finally impact on the surface of a suitable receiving planet.

Abiogenisis may be a hard process to pin down, but since it obviously exists(or we wouldn't be here) and given constant physical laws it will repeat over and over again in the proper conditions. It's a far more likely candidate for life appearing on earth.

It’s been a mantra of mine: similar ingredients in similar environments give similar results. I wholeheartedly agree if physics and chemistry are everywhere the same, abiogenesis seems likely to occur anywhere suitable, all the time. But with our sample of one, I don’t think we can say any scenario is “a far more likely candidate” than another. In my opinion, simply “because it is here” is insufficient as a probability argument.

As to lithopanspermia, or interstellar transfer, I must ask: are stellar systems closed systems, cut off from every other star; Likewise with galaxies? We know planetary systems are not closed systems. Stellar encounters and galactic collisions too are taken as factual. Our sun is thought to have been born in a “nursery” amidst other stars, prompted by a supernova. What precludes the possibility that this star had a life bearing planet which was blasted apart by the supernova and then incorporated into our solar system? I don’t know, but I suspect there are ways over the time and distance hurdles of interstellar panspermia.

Here’s an interesting scenario from a few years back: Lithopanspermia in Star Forming Clusters (http://arxiv.org/PS_cache/astro-ph/pdf/0504/0504648v1.pdf).

A.DIM
2012-Jul-04, 03:45 PM
I would see this as not excluding panspermia rather than supporting it.

Im fine with migration of life within a system - but it would take a lot to convince me it could happen on a galactic scale.

I do agree that local abiogenesis seems more likely. but i'm not even sure you can assume abiogenesis would repeat over given constant physical conditions can you? what with chaos and all that jazz

Is “chaos and all that jazz” enough to assume something special or unique in our part of the universe? Or would it be more scientifically conservative to assume there’s nothing special here, that our understanding of chemistry and physics is correct?
Personally, I favor the latter.

mutleyeng
2012-Jul-04, 03:56 PM
I dont see special or unique comes into it - random and unpredictable cause and effect can happen anywhere in the universe.
As far as i was aware, that is part of our understanding of physics and chemistry

Selfsim
2012-Jul-05, 02:36 AM
All real systems in nature are non-linear. This also means they are irreversible.

If real systems are non-linear, then they are free to behave unpredictably, and the results cannot be reversed in order to obtain knowledge of the initial conditions.

There is nothing 'special' about this, unless one chooses to use such a term. The selection of such a term, has no effect on the system's behaviour. Thus, a system's unpredictability, is rather 'routine' and not 'special'.

That being said, is the informational content of modern DNA/RNA 'special' ?
It certainly seems pretty specific ! (Ala Dawkins' 'selfish gene concept). What about its chemical precursors ?


similar ingredients in similar environments give similar results.I think this interpretation would then be a version of what I call the 'Sea Monkey' (http://en.wikipedia.org/wiki/Sea_monkey) perspective … (just add water and presto .!.. life appears). The underlying idea in the paper in A.DIM's OP, would seem to be along these same lines. For me, whilst I find panspermia intriguing as far as life-on-Earth goes, (and it also extends the timespan for the development of DNA/RNA informational complexity), as A.DIM mentions, this really is separable from abiogenesis.

As far as I know, no-one to date, has generated life from elements, inorganic or organic naturally occurring simple compounds. (I'm always interested to see what new developments happen along these lines, however)

Panspermia would thus seem to be yet another speculated interpretation of initial conditions (as far as life-on-Earth goes), and it really doesn't matter what those initial conditions were, they can never be known accurately enough, in order to be able to predict the outcome of a 'replay' of those same events/conditions. Each entry point into subsequent phases of chemical evolution, could also be equally viewed as 'initial conditions' .. which, if sensitively balanced, re-introduces subsequent unpredictability.

So what does all this mean ? Well, its simple … the origins of life are unknown. As is the presence/absence of life elsewhere .. no matter what we dream up and attempt to argue from a a speculative 'likely, probable/plausible' perspective, which in my view is the domain of discussion for the pub, over beer or two ! :)

Regards

R.A.F.
2012-Jul-05, 03:06 AM
Is “chaos and all that jazz” enough to assume something special or unique in our part of the universe?

Of course not...there is nothing special about this portion of the Universe, just as there is nothing special about any other portion of the universe.


Don't you agree?

A.DIM
2012-Jul-05, 01:10 PM
I dont see special or unique comes into it - random and unpredictable cause and effect can happen anywhere in the universe.
As far as i was aware, that is part of our understanding of physics and chemistry

I don't deny random unpredictable events take place but I think it's important to keep The Basic Rules of the Universe (http://www.astrobio.net/debate/2179/the-basic-rules-of-the-universe) in mind "because when you see the processes of how we form stars and planets, they occur the same way throughout the universe. We find very familiar carbon chemistry in space. Some molecules, which have been detected in the interstellar medium or in proto-planetary disks, in particular by radio astronomy or infrared spectroscopy on satellites, including hydrogen cyanide, formaldehyde and ammonia are crucial in modern biochemistry as we know it.
...
So in looking at life as we know it, or as we don’t know it, we have to follow the basic rules of the universe. We have to understand abundances and distribution. The inventory is strikingly similar everywhere. We see ices and macromolecular carbon distributed all over galactic and extra-galactic space."

With this in mind, I find it difficult to think a universe which appears so conducive to life as we know it produced life as we know it through random happenstance. Then again it could be stranger than that, if the Laws of physics vary throughout the universe. (http://www.sciencedaily.com/releases/2010/09/100909004112.htm)

mutleyeng
2012-Jul-05, 02:06 PM
I dont understand why you are suggesting (if this is what you are suggesting) that for a different outcome from the same conditions, it would require different laws of physics.
I would imagine it depends on the susceptibility of a given outcome to the micro random unpredictable that we know exists. That is why i would see the emergence of life could be very different to the forming of a star.
Life may very well be almost inevitable given the right conditions - but so far as i can see right now, it might also be very unlikely given those exact same conditions.

starcanuck64
2012-Jul-05, 09:51 PM
It’s been a mantra of mine: similar ingredients in similar environments give similar results. I wholeheartedly agree if physics and chemistry are everywhere the same, abiogenesis seems likely to occur anywhere suitable, all the time. But with our sample of one, I don’t think we can say any scenario is “a far more likely candidate” than another. In my opinion, simply “because it is here” is insufficient as a probability argument.


I guess life here could be a freak occurance only repeated rarely elsewhere and we're the result of the transmission of that rare event from the source. But the fact that life appeared so early in the life of the planet(it's possible it was in development even before the end of the massive bombardment phase) that tends to indicate a physycal process that will be repeated in favorable conditions. With panspermia you would need a huge amount of biological material broadcast if it's occuring over interstellar distances and if within a system, if you have two planets with favorable conditions then life would probably develope on both. Adding an origin that requires both a catastrophic launching then entry favors the local appearance I think.


As to lithopanspermia, or interstellar transfer, I must ask: are stellar systems closed systems, cut off from every other star; Likewise with galaxies? We know planetary systems are not closed systems. Stellar encounters and galactic collisions too are taken as factual. Our sun is thought to have been born in a “nursery” amidst other stars, prompted by a supernova. What precludes the possibility that this star had a life bearing planet which was blasted apart by the supernova and then incorporated into our solar system? I don’t know, but I suspect there are ways over the time and distance hurdles of interstellar panspermia.

That's a possibility I guess, but I still think probability favours the local solution.

If we are the end result of life already seeded within the stellar cloud then shouldn't there be evidence in leftover material?

R.A.F.
2012-Jul-05, 10:05 PM
...I find it difficult to think a universe which appears so conducive to life as we know it produced life as we know it through random happenstance.

I'm not going to touch this as it will get into religion...suffice it to say there is no evidence for some non-random pattern to the Universe, which is what you seem to be implying.



Then again it could be stranger than that, if the Laws of physics vary throughout the universe. (http://www.sciencedaily.com/releases/2010/09/100909004112.htm)

So you are saying that other portions of the Universe are "special". That would make a good argument if you could prove it. Unfortunately, I don't see how you possibly can.

Selfsim
2012-Jul-06, 12:18 AM
Then again it could be stranger than that, if the Laws of physics vary throughout the universe. (http://www.sciencedaily.com/releases/2010/09/100909004112.htm)There was a very thorough paper written by Takeshi Chiba called:
The Constancy of the Constants of Nature: Updates (http://arxiv.org/pdf/1111.0092v4.pdf), (from Nov through to Dec 2011), providing a good unbiased analysis of the Webb findings (amongst many others). They summarised (at the time) that Webb et al was the only group who found the anisotropy in the fine structure constant (alpha). Others subsequently repeated the observations, and did not find it. An explanation for the dissimilarity of the value for some objects, when observed by different scopes, seems to be the current quest. Explanations that the large identified dipole magnitude originates from 'hidden differences in systematic errors between the VLT and Keck samples' has also been countered by some fairly good reasons.

Another more recent paper was: "Is there correlation between Fine Structure and Dark Energy Cosmic Dipoles?" (http://arxiv.org/pdf/1206.4055v1.pdf) by Mariano and Perivolaropoulos, dated June 20 2012. They have developed a theoretical model that has the potential to predict strong aligned dipoles for the fine structure constant and for dark energy:

In such a model, an off-center observer with respect to the Hubble scale core of a global monopole would naturally observe large aligned dipoles for the fine structure constant and dark energy.So, it seems that the preferred interpretation at the moment, is that there may be some kind of theoretically explainable observation bias, rather than an actual variation in the value of the fine structure constant across the observable universe.

That being said, there is a confirmed fractal pattern for the distribution of galaxy clusters in the SDSS measurements of 2005 … which implies at this scale of matter distribution, there is a self-similar pattern. Such patterns may or may not exist at scales different to this … more data is needed to explore this possibility. Whether the same can be said about the potential distribution of speculated 'exo-life', is entirely dependent on the discovery of other instances … nothing more … as it is not possible to predict another instance, without further data (beyond the single instance of Earth-life).

Regards

Selfsim
2012-Jul-06, 12:30 AM
... if you have two planets with favorable conditions then life would probably develope on both. Hi starcanuck64;

Could you elaborate on the basis of this assertion for us ? (ie: Theoretical or practical).
I am always eager to find a mathematically valid basis for such assertions (within the observable universe).

Speculating that it may 'possibly' develop, is vastly different from a stronger assertion that it is 'probable'.

Regards

starcanuck64
2012-Jul-06, 05:17 PM
Hi starcanuck64;

Could you elaborate on the basis of this assertion for us ? (ie: Theoretical or practical).
I am always eager to find a mathematically valid basis for such assertions (within the observable universe).

Speculating that it may 'possibly' develop, is vastly different from a stronger assertion that it is 'probable'.

Regards

Obviously I don't have any hard facts, we haven't even established how abiogenesis occures.

I'm assuming it's a robust process that takes many generations of sponteneous chemical interactions in the presense of a consistent energy source and most likely some sort of physical structure like a thermal vent or clay bed. It's not likely to be a sudden flash and you have life, but a long chain of events. If you have two planets with similar surface conditions and chemical interactions following similar pathways you should arrive at roughly the same point. I find it improbable for instance that if life developed on Mars then somehow the same process wouldn't occure here. Creating an additional step of biological material launched violently from the surface of Mars to eventually go through another violent re-entry to seed life on Earth just complicates the issue I find.

Of course it could have happened that way, but it seems given the limited knowledge we have now that the more likely explanation is a Earthly origin for life.

mutleyeng
2012-Jul-07, 03:43 AM
I'm assuming it's a robust process....

Thats the nail on the head for me. Much as i want to believe, i cant get past that assumption sitting there spoiling it all

Selfsim
2012-Jul-07, 04:28 AM
All real systems in nature are non-linear. This also means they are irreversible.

If real systems are non-linear, then they are free to behave unpredictably, and the results cannot be reversed in order to obtain knowledge of the initial conditions.

There is nothing 'special' about this, unless one chooses to use such a term. The selection of such a term, has no effect on the system's behaviour. Thus, a system's unpredictability, is rather 'routine' and not 'special'.

... if you have two planets with favorable conditions then life would probably develope on both.

Obviously I don't have any hard facts, …
...
I'm assuming it's a robust process…
...
If you have two planets with similar surface conditions and chemical interactions following similar pathways you should arrive at roughly the same point. I find it improbable for instance that if life developed on Mars then somehow the same process wouldn't occure here ...
Ahh .. all hypothetical 'reasons', eh ?

Mine weren't.

I tend to reserve the use of the term 'probable', to matters having a sound mathematical and scientific bases.

Given the evidence that Mars had 'favourable conditions', (specifically: similar surface conditions and, (seemingly), chemical interactions following similar pathways, etc), how probable would you say it might be that life wouldn't emerge on Mars, (even though it did on Earth)?

Regards

Selfsim
2012-Jul-07, 04:53 AM
I'm assuming it's a robust process….Thats the nail on the head for me. Much as i want to believe, i cant get past that assumption sitting there spoiling it allThere is considerable and mounting evidence that biological systems are in fact, poised at criticality in dynamic phase space.

An interesting paper: "Are Biological Systems Poised at Criticality?" (http://arxiv.org/abs/1012.2242) by Mora and Black, (dated: 2nd June 2011; published in J Stat Phys, 2011) showed that statistical mechanical modelling techniques, when applied to diverse examples such as families of proteins, networks of neurons and flocks of birds, revealed that such biological systems are in fact, poised at a criticality, and are thus easily perturbed into chaotic behaviours.

This aspect suggests that biological systems, at some point over the entire lifetime of their emergence and beyond, (not excluding pre-biotic abiogenesis phases), developed dynamic attributes, which distinguished them from the 'just-add-water-type', static equilibrium chemical models.

Frankly, until someone can replicate life from scratch chemically, this underlying non-explicitly stated static equilibirum chemical model, (commonly implied in Astronomical literature), is pure speculation.

Regards

transreality
2012-Jul-07, 09:37 AM
The EXPOSE study seems concerned with survival of spores etc on relatively short duration space missions, for the purposes of planetary protection.

From this study (http://online.liebertpub.com/doi/pdfplus/10.1089/ast.2011.0738): Survival of Bacillus pumilus Spores for a Prolonged Period of Time in Real Space Conditions

"The results of this study reinforce that solar UV exposure has the most detrimental impact on viability
of highly resistant spores in real space conditions, and that outer space is more detrimental than the martian environment.
Prolonged UV radiation (18 months) in real space conditions completely compromised a population of 10^7
highly UV-resistant B. pumilus spores and left only 19 survivors. The surviving population might be due to any of the
following: a resistant subpopulation of spores; partial protection of spores present in multilayers in small groups; or
shielding in the hiding places provided by small pits, cracks, and scratches present on the aluminum coupons as seen
during this study."

Not very good survivorship for 18 months, so how are they meant to last for 115,000 years. This duration is the shortest known Mars to Earth crossing time by a unpowered object (rock), let alone the billion years required for interstellar panspermia. As I understand it, the spores themselves do not multiply while in space conditions, so the increased radiation resistance of survivors is not relevant to panspermic scenarios. On very long timescales cosmic radiation is more significant; this study mostly focuses on the short term danger of UV.

mutleyeng
2012-Jul-07, 02:51 PM
yes thats how i understood it to be. Wasnt that also the reason why they lightened up a little on the rules for sterilization of landers on Mars?

@Selfsim - just to clarify, i agree

starcanuck64
2012-Jul-07, 06:51 PM
Ahh .. all hypothetical 'reasons', eh ?

Mine weren't.

I tend to reserve the use of the term 'probable', to matters having a sound mathematical and scientific bases.

Given the evidence that Mars had 'favourable conditions', (specifically: similar surface conditions and, (seemingly), chemical interactions following similar pathways, etc), how probable would you say it might be that life wouldn't emerge on Mars, (even though it did on Earth)?

Regards

On the time and distance scales we're refering to how likely is there to be significant differences in the constants that would favor life forming in one place and not another, especially at interplanetary distances?

It's entirely possible for Mars to have developed primitive life and it could still be there in the substrate, what I have a hard time with is putting a lot of importance on a process that requires over complicating the origins of life. We do know it's here is compatable with the Earth environment and has adapted to the many changes over several billions of years.

Does that mean there's no chance it arose somewhere else and was transported here...probably not.

Does that mean it's likely earth life originated on another planet or even star system, also probably not.

Selfsim
2012-Jul-08, 12:47 AM
Given the evidence that Mars had 'favourable conditions', (specifically: similar surface conditions and, (seemingly), chemical interactions following similar pathways, etc), how probable would you say it might be that life wouldn't emerge on Mars, (even though it did on Earth)?On the time and distance scales we're refering to how likely is there to be significant differences in the constants that would favor life forming in one place and not another, especially at interplanetary distances?(The non-answer to my invitation to continue with the speculation is duly noted).

Whilst I'm not sure what 'constants' you're referring to, (I'll take a stab, and assume its the 26 known fundamental dimensionless physical constants ? (http://en.wikipedia.org/wiki/Fundamental_physical_constant#Constants_in_the_sta ndard_model_and_in_cosmology)). Variations of these within our observable universe would not be an issue, as they don't have to be different in order for uniqueness to occur. Diversity also emerges from such uniqueness as well. Negative life resultants 'might' be just as 'likely' as positives, so the point really is moot.


It's entirely possible for Mars to have developed primitive life and it could still be there in the substrate, what I have a hard time with is putting a lot of importance on a process that requires over complicating the origins of life. We do know it's here is compatable with the Earth environment and has adapted to the many changes over several billions of years.I'm intrigued … :)
It seems that the term 'possible' has now crept in, whereas before, 'probable' was being used. I'm wondering what the basis is for shifting from one term to another ?
What do you mean by 'over-complicated' ? Would you say life is not 'complicated' ?


Does that mean there's no chance it arose somewhere else and was transported here...probably not.

Does that mean it's likely earth life originated on another planet or even star system, also probably not.Hmm .. we're back to 'probably' again .. :confused:

Cheers

Selfsim
2012-Jul-08, 09:57 AM
...Not very good survivorship for 18 months, so how are they meant to last for 115,000 years. This duration is the shortest known Mars to Earth crossing time by a unpowered object (rock), let alone the billion years required for interstellar panspermia. Interestingly, the oldest documented dormant seed (http://www.usatoday.com/tech/science/2008-06-12-3360628840_x.htm) to have been germinated and grown into a viable plant, is a date palm recovered from Masada in Israel. According to the article, it was radio carbon dated at about 2,000 years old.

I think this is about the oldest confirmed form of viable dormant life so far known. (??)

A far cry from 115,000 years, eh ?
(Not to mention it also didn't have to endure full exposure to interplanetary space environments, either).

Interesting.

djellison
2012-Jul-08, 06:06 PM
Roughly a 1 in 10^6 survive, even while under the van allen belts.

I wouldn't call that life in space. I'd called it death in space.

JCoyote
2012-Jul-08, 07:57 PM
The low survival rate might not be of significance. Dropping a corpse on a planet that has the right conditions could easily be the start of life there. Life doesn't have to be alive to generate more, different, life.

I would also point out that panspermia allows the possibility that initial conditions for the origin of life need not even be present on a particular planet. For example, if there was a very ideal world for the formation of single-celled life forms, it might not be ideal for multi-cellular life to ever gain a foothold. But spores from one planet land on another and after some time... we see lots of examples of organisms rapidly spreading into new ecosystems. This just takes that idea and broadens the playing field.

The life involved does not need to be recognizable to us either. For example, remains of silicon based life arriving on the planet, where the leftover structures form excellent homes for proteins to start information processing.

But the only real advantage if panspermia proved out would be a long term one; it could mean life we encounter on other planets would share fundamental similarities to us that are otherwise unlikely.

djellison
2012-Jul-08, 10:50 PM
Life doesn't have to be alive to generate more, different, life.

Do you have any evidence for this?

Noclevername
2012-Jul-09, 12:16 AM
The low survival rate might not be of significance. Dropping a corpse on a planet that has the right conditions could easily be the start of life there. Life doesn't have to be alive to generate more, different, life.

Pan-dead-ia?

Selfsim
2012-Jul-09, 02:11 AM
Life doesn't have to be alive to generate more, different, life.
Do you have any evidence for this?

Pan-dead-ia?Dormancy, surely, must be a factor in this gem (??) (Depending on the definition of 'alive/dead', that is).
If so, the evidence for the longevity of a viable dormant organism, would have to be along the lines of my post #25 .. ~ 2,000 years ?
I don't know how long DNA/RNA as an intact molecule can survive, (so as to preserve the necessary information - a few thousand years, under 'habitable' conditions ?), but it would be difficult to imagine how nature could pull off a re-animation process, without there being, (or having been), a complete second abiogenesis, or without intelligent intervention. There's no evidence of that in 'downtown life central' (ie: Earth).

JCoyote's post #27 highlights just how unconstrained some speculation can get ! Does science progress in this way ?

Noclevername
2012-Jul-09, 02:26 AM
At last, we have an explanation for the spread of zombies across the galaxy! ;)

(I forgot to take my meds, can't you tell?)

R.A.F.
2012-Jul-09, 02:33 AM
At last, we have an explanation for the spread of zombies across the galaxy! ;)

(I forgot to take my meds, can't you tell?)



...and here I thought they were just "kicking in". :)

R.A.F.
2012-Jul-09, 02:45 AM
This just takes that idea and broadens the playing field.

In other words, extending the speculation beyond what any evidence actually indicates.

R.A.F.
2012-Jul-09, 03:00 AM
At last, we have an explanation for the spread of zombies across the galaxy! ;)

They are already in Seattle. (http://www.youtube.com/watch?v=5IBhyPywO-E):D





On a side note...at 1:47, 2:40, and 3:15 of the above video, you will find My Son, the zombie being "interviewed".

As you can imagine, I am very proud.

A.DIM
2012-Jul-09, 12:29 PM
...
So what does all this mean ? Well, its simple … the origins of life are unknown. As is the presence/absence of life elsewhere .. no matter what we dream up and attempt to argue from a a speculative 'likely, probable/plausible' perspective, which in my view is the domain of discussion for the pub, over beer or two ! :)

Regards

Hi.
Perhaps we can petition the administration here upon the impending merger that the Life in Space sub forum be renamed “The Pub.” :D
Then again, as I said above, panspermia isn’t really meant to answer the question of abiogenesis. We’ll likely never have answers to where, when and maybe even how life originated, but life’s ability to survive in space, or on Mars, moons, comets etc., is no longer as “unlikely, improbable/implausible” as was thought only a few decades ago. I dare say that if ESA et al are doing science which pertains to panspermia hypotheses it’s rather at the forefront of astrobiology and space science.

A.DIM
2012-Jul-09, 12:33 PM
I dont understand why you are suggesting (if this is what you are suggesting) that for a different outcome from the same conditions, it would require different laws of physics.

No, I'm suggesting this. What I’ve said is I think there’s more reason to assume similar outcomes from similar ingredients in similar environments than happenstance one-off occurrences.


I would imagine it depends on the susceptibility of a given outcome to the micro random unpredictable that we know exists. That is why i would see the emergence of life could be very different to the forming of a star.

I’m not sure I understand your first sentence here (is it a sentence?). What is an example of “the micro random unpredictable that we know exists?”


Life may very well be almost inevitable given the right conditions - but so far as i can see right now, it might also be very unlikely given those exact same conditions.

I understand your perspective; it’s what we have with a sample of one.

A.DIM
2012-Jul-09, 12:54 PM
If we are the end result of life already seeded within the stellar cloud then shouldn't there be evidence in leftover material?

Great question, and I would think so.
What evidence should we expect to see? "Prebiotic" organic compounds and complex molecules? Microfossils and bacterial spores? Interstellar dust particles which match the spectra for dried frozen bacteria? :D

Noclevername
2012-Jul-09, 02:23 PM
What evidence should we expect to see?


Life. In space.

The other things are not evidence of life in space, only indicators that life is made of commonly available materials and tends to get into grounded meteorites.

R.A.F.
2012-Jul-09, 04:03 PM
...panspermia isn’t really meant to answer the question of abiogenesis.

You do have some "question" in your mind where the "answer" is panspermia.


...or to put it another way, what question do you think panspermia answers?. If you could tell us that, perhaps it would help us better understand your reasoning.

R.A.F.
2012-Jul-09, 04:07 PM
I find it difficult to think a universe which appears so conducive to life as we know it produced life as we know it through random happenstance.

Going back I noticed this. From a "sample" of one, how did you arrive at the conclusion bolded above?

starcanuck64
2012-Jul-09, 04:27 PM
(The non-answer to my invitation to continue with the speculation is duly noted).

I'm going with the information we have so far which is one sample, it's a little difficult to do statistical analysis on that basis.


Whilst I'm not sure what 'constants' you're referring to, (I'll take a stab, and assume its the 26 known fundamental dimensionless physical constants ? (http://en.wikipedia.org/wiki/Fundamental_physical_constant#Constants_in_the_sta ndard_model_and_in_cosmology)). Variations of these within our observable universe would not be an issue, as they don't have to be different in order for uniqueness to occur. Diversity also emerges from such uniqueness as well. Negative life resultants 'might' be just as 'likely' as positives, so the point really is moot.

I was refering to possible variations in constants that you posted on earlier.


I'm intrigued … :)
It seems that the term 'possible' has now crept in, whereas before, 'probable' was being used. I'm wondering what the basis is for shifting from one term to another ?
What do you mean by 'over-complicated' ? Would you say life is not 'complicated' ?

Hmm .. we're back to 'probably' again .. :confused:

Cheers

Once again, unless I missed the momentus occassion of life being discovered on Mars, we're still just talking about a sample size of one and the use of probably and possibly is appropriate IMO.

And yes life is very complicated as is the issue of determining how it originated when we can't say with certainty the conditions present on the early Earth or the possible pathways that resulted in lifeless organic compounds becoming self-sustaining life.

Panspermia takes that uncertainty one step further is all I'm saying.

edit- I didn't notice R.A.F. making the point about sample size when I wrote my post.

starcanuck64
2012-Jul-09, 04:51 PM
Great question, and I would think so.
What evidence should we expect to see? "Prebiotic" organic compounds and complex molecules? Microfossils and bacterial spores? Interstellar dust particles which match the spectra for dried frozen bacteria? :D

Prebiotic and complex molecules can be produced by non-biological processes, it would need to be a fossil of bacteria or whatever was present.

djellison
2012-Jul-09, 04:58 PM
What evidence should we expect to see? "Prebiotic" organic compounds and complex molecules?

How is that evidence of life?

R.A.F.
2012-Jul-09, 05:38 PM
I didn't notice R.A.F. making the point about sample size when I wrote my post.

No worries...I actually like the way you phrased it better than the way I phrased it. :)

A.DIM
2012-Jul-09, 10:51 PM
The EXPOSE study seems concerned with survival of spores etc on relatively short duration space missions, for the purposes of planetary protection.

From this study (http://online.liebertpub.com/doi/pdfplus/10.1089/ast.2011.0738): Survival of Bacillus pumilus Spores for a Prolonged Period of Time in Real Space Conditions

"The results of this study reinforce that solar UV exposure has the most detrimental impact on viability
of highly resistant spores in real space conditions, and that outer space is more detrimental than the martian environment.
Prolonged UV radiation (18 months) in real space conditions completely compromised a population of 10^7
highly UV-resistant B. pumilus spores and left only 19 survivors. The surviving population might be due to any of the
following: a resistant subpopulation of spores; partial protection of spores present in multilayers in small groups; or
shielding in the hiding places provided by small pits, cracks, and scratches present on the aluminum coupons as seen
during this study."

Not very good survivorship for 18 months, so how are they meant to last for 115,000 years. This duration is the shortest known Mars to Earth crossing time by a unpowered object (rock), let alone the billion years required for interstellar panspermia. As I understand it, the spores themselves do not multiply while in space conditions, so the increased radiation resistance of survivors is not relevant to panspermic scenarios. On very long timescales cosmic radiation is more significant; this study mostly focuses on the short term danger of UV.

Obviously I take a more optimistic view of life's ability to survive space conditions, as well as the results of this work. Most interesting in this study, to me, was that "After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10–40% survivability, whereas a survival rate of 85–100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions."

This would suggest that, if adequately shielded, life can survive. Which is essentially what they say in conclusion:

"Spores managed to survive under dark conditions as well as in the middle and bottom layers of the exposure tray protected from UV. We also observed that spores exposed to space and simulated martian conditions have elevated levels of proteins responsible for resistance traits. A subpopulation of spores may possess enhanced protective machinery and may survive under extreme space conditions. Given our results, we hypothesize that spores sheltered under spacecraft structures, as well as a mutant subpopulation, can survive during space travel. This study provides new insights into the principal limits of life and its adaptation to environmental extremes on Earth or other planets. The research has implications for the evolution and distribution of life."

It's clear we're only now beginning to realize how resistant and adaptable microbes and bacteria are. I think the more we learn the less chance we have of "planetary protection."

A.DIM
2012-Jul-09, 11:04 PM
Prebiotic and complex molecules can be produced by non-biological processes, it would need to be a fossil of bacteria or whatever was present.

Indeed, only last year we discussed a discovery that complex organics previously thought to only come from other life are made by directly by stars. Interestingly the chemcial signatures in the study resemble coal and petroleum, which in fact, are remnants of ancient life.
Good thing, I guess, stars do it naturally...
:)

A.DIM
2012-Jul-09, 11:06 PM
How is that evidence of life?

I suppose it isn't.

JCoyote
2012-Jul-10, 01:04 AM
I think my statement was a bit misunderstood.

On the timescales we are talking about, simply dropping the leftover protein and nucleic acid goo of some earth specimens... which could be many millions of years more complex than anything in the soup it lands in... could be an initiating factor for life.

It is not an irrational or unscientific concept. Even very badly damaged remains of life, are still far closer to life than the basic chemistry of many worlds. Structure more complex than extant chemistry would not be surprising to create a "seeding" effect as proteins twist and impact surrounding amino acids, even if millions of years are required. A few million years closer, is still closer. And the odds of finding unexpected genetic similarities would also remain higher (though hardly guaranteed).

djellison
2012-Jul-10, 01:10 AM
Even very badly damaged remains of life, are still far closer to life than the basic chemistry of many worlds. Structure more complex than extant chemistry would not be surprising to create a "seeding" effect as proteins twist and impact surrounding amino acids, even if millions of years are required. A few million years closer, is still closer. And the odds of finding unexpected genetic similarities would also remain higher (though hardly guaranteed).

Do you have any evidence for this? Any studies that dead life can bring something to the mix regarding biogenesis that a billion years of prebiotic ooze can not?
?

Noclevername
2012-Jul-10, 01:12 AM
Even very badly damaged remains of life, are still far closer to life than the basic chemistry of many worlds.

(bold mine)

Considering that besides Earth, we have only a sketchy idea of the major chemistry of terrestrial planets in our own solar system, I'm not sure about this statement.

JCoyote
2012-Jul-10, 01:35 AM
(bold mine)

Considering that besides Earth, we have only a sketchy idea of the major chemistry of terrestrial planets in our own solar system, I'm not sure about this statement.

I'll grant that, but so far all attempts to find things as complex as proteins on any other planet we have encountered have been inconclusive at best. As it stands... the math says it's uncommon. And unless you assume that the congealing planetary nebula intrinsically give rise to complex molecules... which by the way I would say is conjecture far wilder... then yes the starting chemistries of planets lack the complexity. But it does arise. Naturally. The only question is does it spread, and do leftovers make an impact on other planets in the process? Extra complexity is extra complexity added into a system and I'd have a hard time imagining it not making an impact over time, especially down at the chemical level.

Selfsim
2012-Jul-10, 01:36 AM
It is not an irrational or unscientific concept. Even very badly damaged remains of life, are still far closer to life than the basic chemistry of many worlds. I'm having a hard time seeing anything scientific about any of this (??) :confused:

What does 'closer to life' mean, if we cannot predict how life emerges ?

Speculation ! (Or more like science-fiction !)

Selfsim
2012-Jul-10, 01:47 AM
I'll grant that, but so far all attempts to find things as complex as proteins on any other planet we have encountered have been inconclusive at best. As it stands... the math says it's uncommon. What 'math' ?

… Extra complexity is extra complexity added into a system and I'd have a hard time imagining it not making an impact over time, especially down at the chemical level.How can you assess the impact of 'extra complexity' on a process which is not known ?

Noclevername
2012-Jul-10, 01:47 AM
I'll grant that, but so far all attempts to find things as complex as proteins on any other planet we have encountered have been inconclusive at best. As it stands... the math says it's uncommon. And unless you assume that the congealing planetary nebula intrinsically give rise to complex molecules... which by the way I would say is conjecture far wilder... then yes the starting chemistries of planets lack the complexity. But it does arise. Naturally. The only question is does it spread, and do leftovers make an impact on other planets in the process? Extra complexity is extra complexity added into a system and I'd have a hard time imagining it not making an impact over time, especially down at the chemical level.


Just a note: Planetary nebulae are not associated with the formation of planets, they are emitted by certain dying stars. The term you want is Protoplanetary Disk (http://en.wikipedia.org/wiki/Protoplanetary_disk), which according to Wikipedia:


Relation to abiogenesis:

Based on recent computer model studies, the complex organic molecules necessary for life may have formed in the protoplanetary disk of dust grains surrounding the Sun before the formation of the Earth. According to the computer studies, this same process may also occur around other stars that acquire planets. (Also see Extraterrestrial organic molecules).


EDIT: Here (http://www.space.com/15089-life-building-blocks-young-sun-dust.html) is the link to that WP statement's reference.

Colin Robinson
2012-Jul-10, 02:25 AM
There is considerable and mounting evidence that biological systems are in fact, poised at criticality in dynamic phase space.

An interesting paper: "Are Biological Systems Poised at Criticality?" (http://arxiv.org/abs/1012.2242) by Mora and Black, (dated: 2nd June 2011; published in J Stat Phys, 2011) showed that statistical mechanical modelling techniques, when applied to diverse examples such as families of proteins, networks of neurons and flocks of birds, revealed that such biological systems are in fact, poised at a criticality, and are thus easily perturbed into chaotic behaviours.

According to Wikipedia:"Self-organized criticality... is considered one of the mechanism by which complexity arises in nature". (WP Self-organized criticality (http://en.wikipedia.org/wiki/Self-organized_criticality))


This aspect suggests that biological systems, at some point over the entire lifetime of their emergence and beyond, (not excluding pre-biotic abiogenesis phases), developed dynamic attributes, which distinguished them from the 'just-add-water-type', static equilibrium chemical models.

Frankly, until someone can replicate life from scratch chemically, this underlying non-explicitly stated static equilibirum chemical model, (commonly implied in Astronomical literature), is pure speculation.

Can you give an example of the astronomical literature you have in mind, that implies a "static equilibrium chemical model"? Or are you just setting up a straw-man?

transreality
2012-Jul-10, 02:58 AM
Obviously I take a more optimistic view of life's ability to survive space conditions, as well as the results of this work. Most interesting in this study, to me, was that "After 18 months of exposure in the EXPOSE facility of the European Space Agency (ESA) on EuTEF under dark space conditions, SAFR-032 spores showed 10–40% survivability, whereas a survival rate of 85–100% was observed when these spores were kept aboard the ISS under dark simulated martian atmospheric conditions."

This would suggest that, if adequately shielded, life can survive. Which is essentially what they say in conclusion:

"Spores managed to survive under dark conditions as well as in the middle and bottom layers of the exposure tray protected from UV. We also observed that spores exposed to space and simulated martian conditions have elevated levels of proteins responsible for resistance traits. A subpopulation of spores may possess enhanced protective machinery and may survive under extreme space conditions. Given our results, we hypothesize that spores sheltered under spacecraft structures, as well as a mutant subpopulation, can survive during space travel. This study provides new insights into the principal limits of life and its adaptation to environmental extremes on Earth or other planets. The research has implications for the evolution and distribution of life."

It's clear we're only now beginning to realize how resistant and adaptable microbes and bacteria are. I think the more we learn the less chance we have of "planetary protection."

It is clear that 1.5 year of exposure will 'compromise' any exposed spores, but that others that have some form of shielding can survive, the numbers are not large, and the duration is way to short to relevant to panspermia, but yes there are survivors. But they cannot 'adapt' while in space. so the radiation resistance of survivors is not relevant to survivorship in space, though it would be useful if the surviving spores end up landing in a viable environment that has increased radiation compared to their source environment.

This seems to echo the conclusions of other studies, for example: "Survival of Rock-Colonizing Organisms After 1.5 Years in Outer Space", here (http://online.liebertpub.com/doi/pdfplus/10.1089/ast.2011.0736).

"The LIFE experiment has demonstrated that some, but not all, of those most robust microbial communities from extremely
hostile regions on Earth are also partially resistant against the even more hostile environment of outer space. In
this experiment, the following species stood out as the most persistent survivors after 1.5 years in outer space: the black
fungus C. antarcticus (as determined from PMA assay) and the symbiotic X. elegans (as determined from PSII activity)
and its mycobiont (as determined by LIVE/DEAD staining). However, the CFU test did not yield any survivors of C.
antarcticus flight samples that were exposed to the unattenuated solar extraterrestrial spectrum (space 100% insolated)
and less than 10% survivors for the space dark samples. This means that even if the cell membrane seemed
to be intact, as indicated by the PMA test, the cells had lost their ability to grow and divide.

<...>
Although we have demonstrated that some rock-dwelling species are capable of partially withstanding the harsh environment
of outer space, or certain parameters of it, for at least 1.5 years, the data are insufficient for drawing any
consequences for the likelihood of lithopanspermia. The possibility of surviving a much longer journey in space, as
would be required for natural travel from Mars to Earth or vice versa, still remains an open question. This especially
applies to organisms that dwell at the surface of rocks, like the lichen X. elegans, which would be fully exposed to the
lethal spectrum of solar extraterrestrial UV radiation during a hypothetical interplanetary transfer. The only one data point
at an exposure time of 1.5 years, resulting in a viability of 45 – 2.50%, as determined by PSII activity, does not allow any
extrapolation over hundreds, thousands, or even millions of years, as would be required for lithopanspermia (Gladman
et al., 1996)."

The survivability of organisms that have evolved to survive dessication is interesting. Not having internal water means there are less side effects from UV radiation, freezing etc, Another interesting aspect is the role of the symbiont fungus in allowing lichens to continue metabolism in vaccuum. Interesting, and relevant on the timescale of planetary protection from spacecraft, but not necessarily to panspermia.

Selfsim
2012-Jul-10, 04:10 AM
Can you give an example of the astronomical literature you have in mind, that implies a "static equilibrium chemical model"? Or are you just setting up a straw-man?Well, I seem to be in exactly the right place for a few straw men ... so what the heck !!??
(Hmm … I was wondering where you and Mr Wally were, Colin. :) )

Admittedly, my above language may have been somewhat 'loose' .. but hey … is there anything 'tight' in this thread ? :)

Cheers

Selfsim
2012-Jul-10, 04:34 AM
According to Wikipedia:"Self-organized criticality... is considered one of the mechanism by which complexity arises in nature". (WP Self-organized criticality (http://en.wikipedia.org/wiki/Self-organized_criticality)) So .. (??)
Not sure what your point is here .. can you elaborate ?

Selfsim
2012-Jul-10, 10:09 AM
here is considerable and mounting evidence that biological systems are in fact, poised at criticality in dynamic phase space.

An interesting paper: "Are Biological Systems Poised at Criticality?" (http://arxiv.org/abs/1012.2242) by Mora and Black, (dated: 2nd June 2011; published in J Stat Phys, 2011) showed that statistical mechanical modelling techniques, when applied to diverse examples such as families of proteins, networks of neurons and flocks of birds, revealed that such biological systems are in fact, poised at a criticality, and are thus easily perturbed into chaotic behaviours.According to Wikipedia:"Self-organized criticality... is considered one of the mechanism by which complexity arises in nature". (WP Self-organized criticality (http://en.wikipedia.org/wiki/Self-organized_criticality))
...

Can you give an example of the astronomical literature you have in mind, that implies a "static equilibrium chemical model"? Or are you just setting up a straw-man?Ok, so I haven't ever really given a proper answer to this question ... so here goes an attempt ...
Where I'm coming from is that traditional (classical) science usually concentrates on the steady state behaviour of systems, ie: the equilibrium position. The initial conditions are almost always assumed irrelevant, since the equilibrium state is independent of starting point - all starting positions end up with the same behaviour (e.g. a chemical reaction always settles at the same balance of constituents; a planetary orbit follows the same path, regardless of initial location). The transients, (caused by perturbations), are usually discarded in these studies, by allowing time for the system to settle down ... (or even worse ... completely ignored by the application of renormalisation techniques). In most cases also, the system to be studied is defined as being isolated from outside interference (either physically or conceptually) - thus actually excluding any perturbation effects from being considered. (Ok .. stay calm A.DIM et al ... :) ).

In non-equilibrium systems however, it is the transients that are the actual behaviour - the steady state is now irrelevant. Many Complex Systems never settle to a fixed state. There is evidence, (such as outlined in the paper I posted), that evolving biological systems are an example of one such system. In general these systems are subject to constant perturbation, which drives bursts of transient behaviour. Perturbations and transients are closely coupled in endless feedback loops.

At the moment, I can't think of a reason that abiogenesis phases should be excluded from such a perspective because if abiogenesis was subject to the environment, (amongst other non-linear influences), then perturbations almost certainly abounded over geological (or even astronomical) timescales.

Also, in general, it cannot be necessarily said that a major perturbation will have the larger effect, and a minor one only a small effect. The knock-on effect of any perturbation of a critical system can vary from zero to infinite - and there is an inherent fractal unpredictability in its behaviour. (The butterfly effect ... sensitivity to initial conditions, remains paramount).

Regards

Colin Robinson
2012-Jul-12, 09:50 AM
...At the moment, I can't think of a reason that abiogenesis phases should be excluded from such a perspective because if abiogenesis was subject to the environment, (amongst other non-linear influences), then perturbations almost certainly abounded over geological (or even astronomical) timescales.

Also, in general, it cannot be necessarily said that a major perturbation will have the larger effect, and a minor one only a small effect. The knock-on effect of any perturbation of a critical system can vary from zero to infinite - and there is an inherent fractal unpredictability in its behaviour. (The butterfly effect ... sensitivity to initial conditions, remains paramount).

The "butterfly effect" refers to meteorology, if I remember correctly... Phenomena like thunderstorms may be chaotic, and (in a sense) unpredictable, but they happen here on Earth, and on other planets as well. I think it was the Venera program that demonstrated existence of lightning on Venus.

Complex systems are a complex topic, no doubt. And life is the most complex of systems, and there is lot we still don't understand about how it got started, and how it has developed to where we are now. But what element in the theories of complexity would lead us to expect less of it on other worlds than here?

Selfsim
2012-Jul-12, 11:02 PM
The "butterfly effect" refers to meteorology, if I remember correctly... Phenomena like thunderstorms may be chaotic, and (in a sense) unpredictable, but they happen here on Earth, and on other planets as well. I think it was the Venera program that demonstrated existence of lightning on Venus.The butterfly effect was a lesson for Physics. The literal interpretation you make, is missing the main point to be learned.

Before it was discovered in physics, the 'universal' assumption was that physics is deterministic and therefore the mathematics one uses in physics, should always give a predictable result. This was clearly falsified when the differential equations used in describing weather forecasts, demonstrated extreme sensitivity to initial conditions and prevented prediction. That is the butterfly effect.

Until Lorenz, no Physicist realized that such unpredictable behaviour would show up in a phase space that was relevant to physics, and that it was generated by such a simple and physically motivated differential equation.

In your lightning example, no-one could predict from atmospherical physical theory, that lighting would occur on Venus, Jupiter etc - at all ! 'Twas entirely up to empirical science (direct probe observations), to make this discovery. That it actually did occur, is irrelevant when one could not predict it from constrained theory in the first place.

There is no reason to assume that the same would not apply in the case of the belief about extra(exo)-terrestrial life. There is nothing science can say which validates any belief based on speculative 'predictions'.


Complex systems are a complex topic, no doubt. And life is the most complex of systems, and there is lot we still don't understand about how it got started, and how it has developed to where we are now. But what element in the theories of complexity would lead us to expect less of it on other worlds than here?… That it is a complex system in theory, which includes chaotic behaviours and the reality that comes with them ie: unpredictability !

It doesn't matter what anyone conjures up, the reality is that the presence/absence of it elsewhere, is entirely unpredictable. Everything implying that life might have emerged elsewhere, is nothing more than wild imaginings, and nothing better than sci-fi. This is not merely my opinion ...(!!)… this is a consequence of the lack of empirical evidence from which prediction must be based.

Such beliefs are tantamount to outright denial of the known general behaviours of the broader class of physical systems, which accurately characterise biology !!
'Believers' should explain why life, (and its origins), should be specifically excluded from these !!??

R.A.F.
2012-Jul-12, 11:27 PM
There is nothing science can say which validates any belief based on speculative 'predictions'.

I like that phrase...it would make a good sig.

Selfsim
2012-Jul-12, 11:36 PM
I like that phrase...it would make a good sig.Gee, R.A.F.;
Its sooo hard to get such a simple message across !
My head has brick imprints all over it ! :)

Cheers

Colin Robinson
2012-Jul-14, 11:03 AM
It doesn't matter what anyone conjures up, the reality is that the presence/absence of it elsewhere, is entirely unpredictable. Everything implying that life might have emerged elsewhere, is nothing more than wild imaginings, and nothing better than sci-fi.

???

How can it be "wild imaginings" to say that life even might have emerged elsewhere, if (as you say) the reality of its presence/absence is "entirely unpredictable"?

Logically speaking, if you deny that something might have emerged, you are implying that its emergence is impossible. You are predicting its absence.

MaDeR
2012-Jul-14, 11:44 AM
unpredictability !
It doesn't matter what anyone conjures up, the reality is that the presence/absence of it elsewhere, is entirely unpredictable. Everything implying that life might have emerged elsewhere, is nothing more than wild imaginings, and nothing better than sci-fi.
Unpredictableness (if this word does not exists, it should!) do not have anything with chances of occurence. You find life impossible to happen elsewhere just because it is unpredictable? Somehow you are sure it does not exist despite its unpredictability. Logical error.

There are systems that are unpredictable, yet they create themself by every opportunity. Weather is unpredictable, yet every planet with any amount of atmosphere will have weather. Planet configuration emerging from protoplanet disk is unpredictable, yet almost always planets will happen (not happening require unusual circumstances, for example nearby very massive star that would blast away disk before anything could form).

So no, you cannot deny possibility of existence of system just because this system have property "unpredictable", be it weather, planet formation or exolife.

Selfsim
2012-Jul-14, 10:12 PM
??? How can it be "wild imaginings" to say that life even might have emerged elsewhere, if (as you say) the reality of its presence/absence is "entirely unpredictable"?If you accept that the reality of unpredictability, (for sound scientific reasons), then the statement: "it might have emerged elsewhere", is a speculative prediction. Speculation is generated by human imagination (imaginings), which by no means, has to be reflected in reality. (For example: most of science is counterintuitive, which interestingly, demonstrates how limited our imaginations really are, and also demonstrates the non-reality upon which it is based).
Anything unconstrained may be 'possible' ... but we know this is not how nature works .. there are always constraints and tradeoffs. Unconstrained speculation therefore, can easily lead one one astray from reality.


Logically speaking, if you deny that something might have emerged, you are implying that its emergence is impossible. You are predicting its absence.Sure ... but I am not denying anything. 'Unknown' is a valid state ... it doesn't need qualification by statements of what might or might not, be 'possible'. Sometimes when arguing from the 'unknown' perspective, it looks as if one is denying the speculative case for 'exo-life exists'. To balance this out, sometimes it also looks like one is denying the speculative case for 'exo-life doesn't exist'. At other times, one can appear to be supporting both cases.

But it only looks that way.

This is why the 'unknown' perspective is appropriate .. because it allows for any case variants of either of the 'exists' or 'doesn't exist', considerations.

Another aspect to this is that there is:

i) what we know;
ii) what we know we don't know;
iii) what we don't know that we don't know.

Making speculative statements about what might be possible, comes at the cost of making assumptions about what we don't know (ie: items (ii) and (iii)). Once these assumptions are formed, it is very difficult to back-track and undo them, when and if, falsifying evidence is found. This can even lead to scientific paradoxes, especially if the assumptions cease to be present in the discussion. I find the assumptions underpinning the 'exo-life exists' arguments made in this forum, to be largely absent. (Note: I'm not necessarily saying you necessarily do this, either … but I do reserve the right to call anyone on it, if I see it being done).

I assert that making assumptions and logical arguments about what we know is unknown, is ultimately self-defeating. It detracts from making unbiased observations of the unknown if and when it appears, (caused by the act of exploration).

Regards

Selfsim
2012-Jul-14, 11:30 PM
Unpredictableness (if this word does not exists, it should!) do not have anything with chances of occurence. You find life impossible to happen elsewhere just because it is unpredictable? Somehow you are sure it does not exist despite its unpredictability. Logical error.Nope .. see my last post #66.
Theory is our only insight into what may be presently unobserved. Theories make predictions. If there is no empirical data that allows the formation of a speculative conclusion, then there can be no construction of a premise. If there is no premise, then there can be no theory and therefore no prediction. When this happens there is not much which can be said. So be it.

When you use the phrase 'chances of occurrence' you are speaking statistically, and you should be able to derive the 'chances of occurrence' you speak of. Please proceed .. I'm eager to see it done. Making statements about 'chances of occurrence' is a statement of prediction .. eg: "the event has not yet occurred, but the chances of it occurring in the future are 'x' chances out of 'y' random trials". This is a scientifically based, mathematical definition. If you are not speaking scientifically or mathematically, then please use some other language to distinguish the basis from which you are speaking.


There are systems that are unpredictable, yet they create themself by every opportunity. Weather is unpredictable, yet every planet with any amount of atmosphere will have weather. Planet configuration emerging from protoplanet disk is unpredictable, yet almost always planets will happen (not happening require unusual circumstances, for example nearby very massive star that would blast away disk before anything could form).Note that you can assert the planetary atmospheric/protoplanetary disk statements as 'real', because of the vast amount of evidence underpinning the real causes, and their effects.

Where is the same evidence for exo-life ?
Absent, eh ?

I do not see any correlation between planetary atmospheric/protoplanetary disks, and the emergence of exo-life. Life as we know it, exists at vastly different scales, (many orders of magnitude smaller), and has sensitivities at vastly different scales, and is way more complex than the examples you cite. It is subject to vastly different influences. It has entirely different and more complex behaviours. What is the relevance of your analogy ?


So no, you cannot deny possibility of existence of system just because this system have property "unpredictable", be it weather, planet formation or exolife.Once again, I am not denying the existence of such a generalised system. If a complex system is defined, parts of it at certain scales and points in time, can possess degrees of freedom which can move it from stability to instability, especially when perturbed. Such behaviour will result in unpredictability at certain scales. Because of this, the emergence of viable life is not a simple 'given', and it will remain that way until we have another example of non-terrestrial emergence. Until we have such data, its occurrence elsewhere cannot be predicted from theory.

Colin Robinson
2012-Jul-15, 12:52 AM
If you accept that the reality of unpredictability, (for sound scientific reasons), then the statement: "it might have emerged elsewhere", is a speculative prediction....I assert that making assumptions and logical arguments about what we know is unknown, is ultimately self-defeating. It detracts from making unbiased observations of the unknown if and when it appears, (caused by the act of exploration).

Is it an instance of "logical arguments about what we know is unknown", to suggest that ancient Earth might have been uniquely affected by some cosmic equivalent of a butterfly wing-flap, in just such a way that life got started here but nowhere else?

MaDeR
2012-Jul-15, 09:21 AM
I do not see any correlation between planetary atmospheric/protoplanetary disks, and the emergence of exo-life. (...) What is the relevance of your analogy ?
All of my examples have property "unpredictable". You were trying to dismiss existence of system just because it have this property - and only this property was entirely enough.
You cannot dismiss system called "exolife" because of this property only and ignore existence of other systems with this property.


It doesn't matter what anyone conjures up, the reality is that the presence/absence of it elsewhere, is entirely unpredictable. Everything implying that life might have emerged elsewhere, is nothing more than wild imaginings, and nothing better than sci-fi.
This older quote shows clearly that you claimed having "unpredictable" property is enough to deny existence of system. You unintentionally made generalization, but you meant to apply it to exolife only. Sorry, but denying possibility of exolife will need something more specific than merely having "unpredictable" property. It is not enough.

Selfsim
2012-Jul-15, 11:33 PM
MaDeR;

In principle, I accept the generalised point you make, although it was not applicable to where I was coming from. (Admittedly, I didn't explicitly state exactly where I was originally coming from, however).

Have you considered what the outcome would be in the case where parts of the emergence process itself, are subject to complex chaotic behaviours ? Try predicting a viable life outcome from such a process …

This would not necessarily be a basis for dismissing other 'possibilities', and is not presented for such purposes. Consideration of such a case however, broadens one's focus from a deterministically driven model .. (which is the minority case in nature, and one which rarely occurs in biological systems).

KABOOM
2012-Jul-16, 02:15 PM
MaDeR;

In principle, I accept the generalised point you make, although it was not applicable to where I was coming from. (Admittedly, I didn't explicitly state exactly where I was originally coming from, however).

Have you considered what the outcome would be in the case where parts of the emergence process itself, are subject to complex chaotic behaviours ? Try predicting a viable life outcome from such a process …

This would not necessarily be a basis for dismissing other 'possibilities', and is not presented for such purposes. Consideration of such a case however, broadens one's focus from a deterministically driven model .. (which is the minority case in nature, and one which rarely occurs in biological systems).

I think that too much emphasis is being given to the need for "predictability" whence the "proper ingredients" and "condtions" for abiogenesis are present. In fact, one can opine (and either side of this points is only that, an opinion) that to the exent that "unpredictability" is a facet of pre-biotic complex organic chemisty that such a property may well indeed increase (rather than decrease) the possibility of abiogenesis eventually materializing and taking afoot in a given location.

Most chemical reactions happens quickly. To the extent that a given location has the right ingredients and conditions, the duration of such conditions would be typically measured on a cosmic timescale (tens of millions of years). So subject all of the individual occurences of pre-biotic organic chemical reactions, presumably occuring at various locations within a given exo-planet, to "chaos" with regards to phase changes and results. Yes, the ability to "predict" any individual outcome would be impossible (similar to predicting when or where lightning would strike in the atmosphere in Venus). However, this system would have billions and billions of individual chemical reactions amongst these "proper ingredients", many of which would occur under slightly different conditions. So while we can never predict when and where lightning will strike, we can assert with high confidence that over the next 1 year lightning is likely to strike in a visible manner when observed from my lounge chair on my back deck. Weather may be a simpler process than abiogenesis but that does not mean that with enough data similar overall predictions can't be made with increased levels of confidence over time.

MaDeR
2012-Jul-16, 09:38 PM
In principle, I accept the generalised point you make,
Then you must think up something else than "unpredictability". I do not think you will have easy time thinking up something that life posses, other systems (that have no problem with existence in large numbers) doesn't and thus you could claim that having ithis property for some reason will restrict life to Earth only.

In fact, I think your cursade against exolife is doomed even before it began. In other threads you try to preemptively dismiss potential future discoveries of certain spectra from certain planets. I am sorry if it is too personal, but I do not understand this kind of thought. You clearly think there is no extraterrestial life, yet you think (fear?) there will be many discoveries of planets that will be similar to Earth (down to similar spectra indicating atmospheric imbalance unexplainable with known purely abiological mechanisms). This is illogical for me.

If I thought there is no exolife, I would predict no life signatures. No biological traces. Just dead husks, sterile planets, gray rocks, empty spectra. Not something that pretends to have life, but obviously it cannot be it cannot be proven to be exolife.


Try predicting a viable life outcome from such a process …
I do not have to predict if today will be raining methane on Titan to prove claim that Titan have weather. In other words, requirement to predict some particular "viable life" is red heering and it is not needed to prove that some kind of exolife exists.