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Doodler
2012-Jan-31, 01:32 PM
http://space.msnbc.msn.com/_news/2012/01/30/10274347-if-et-exists-hes-avoiding-us-cosmic-number-crunchers-say#comments


Considering that these are the signatures of life that we'd look for, provided we had a proper target to study, is it possible we're under some kind of quarantine?

ravens_cry
2012-Jan-31, 03:18 PM
Unfortunately, there is so many unknowns that there is no certainty of this.
It might make a nice science fiction story, but we really have no idea what the odds are of anything like technological civilization as we have right now, let alone something that can undertake casual interstellar travel.
We only have one known example of the former, us, and none of the latter, and you can't do odds with only a single specimen let alone zero.

Extrasolar
2012-Jan-31, 06:29 PM
I think that there has to be an actual motivation before we leave our solar system and explore to the degree that this article is saying. Mainly, alterations in the star of a system. How many G stars have gone to their red giant phase? K stars live longer (dont they?) and F stars don't live long enough for a humans to have developed and left the solar system. The only logical place that provides a need to expand out are stars reaching the end of their main sequence. I don't know enough about star classes so please correct me if I'm wrong.

Colin Robinson
2012-Jan-31, 11:53 PM
http://space.msnbc.msn.com/_news/2012/01/30/10274347-if-et-exists-hes-avoiding-us-cosmic-number-crunchers-say#comments


Considering that these are the signatures of life that we'd look for, provided we had a proper target to study, is it possible we're under some kind of quarantine?

Yes, it is possible. That is known as the Zoo Hypothesis.

http://www.daviddarling.info/encyclopedia/Z/zoohypoth.html

However, I was not very impressed by Thomas Hair's argument that advanced extraterrestrials would know there is life on Earth because they would have detected our chlorofluorocarbons (CFCs).

The things is, humans only started experimenting with CFCs in the late 19th century. If the nearest advanced extraterrestrials are more than about 50 light years away, they simply have not had time to detect the CFCs and get a message to Earth congratulating or criticizing us humans for synthesizing them. Not unless you assume they have faster-than-light technology.

Elukka
2012-Feb-01, 12:03 AM
Another possibility that pops to mind is that they could know there's life on Earth from taking a cursory look at it, but haven't investigated further, perhaps because they've already seen millions of outwardly similar planets. Or maybe they have figured out there is indeed a technological civilization here but don't really care either way. They could be curious to meet us, or they could be not, in which case we're probably not terribly relevant to an interstellar civilization as of now.

astromark
2012-Feb-01, 08:40 PM
According to the 'Drake' equation there might be as many as 50,000 life forms of some intelligence across this Galaxy.

and that being so does not suggest we will ever find it., or any traces of it..

Time and distance are the enemy's we can not beat. That we should and must keep looking is also real.

Mark @ 39' 55", 52.92 South.

ravens_cry
2012-Feb-01, 09:45 PM
We really don't have enough information to really use the Drake equation except as a tool for knowing what we need to know to know.
Maybe intelligent life even close to as we know it is only one to the galaxy or even one to observable universe.
I am not saying we shouldn't keep looking, I would love to find another Mind, another perspective, another set of characters in the Story, but the Drake equation isn't much use as of yet for any real knowing.

Extrasolar
2012-Feb-01, 11:16 PM
We really don't have enough information to really use the Drake equation except as a tool for knowing what we need to know to know.
Maybe intelligent life even close to as we know it is only one to the galaxy or even one to observable universe.
I am not saying we shouldn't keep looking, I would love to find another Mind, another perspective, another set of characters in the Story, but the Drake equation isn't much use as of yet for any real knowing.

Or even one to the observable or unobservable universe or multiverses. If we were the only ones within the observable Universe however, and if the average number of stars in the 200 billion galaxies have 200 billion stars, that would be a .000000000000000000000025% of all stars produce life. And the same would have to have been said about planets outside of our solar system before any others were discovered.

(and before we knew of other galaxies, the chances must have been considerably better per total number of stars at 0.000000000005%)

ravens_cry
2012-Feb-02, 02:39 AM
Wow, them numbers are so small they're big, if you know what I mean. Unfortunately, we really don't know enough to really say if those are unlikely odds or not, which, incidentally, was my point.

Extrasolar
2012-Feb-02, 03:27 AM
Wow, them numbers are so small they're big, if you know what I mean. Unfortunately, we really don't know enough to really say if those are unlikely odds or not, which, incidentally, was my point.

Agreed. And it doesn't really matter how many of the variables are known for the Drake equation if only one isn't. I wonder what it would take to know all the variables. A complete and accurate survey of all known factors in a large percentage of the galaxy from the center to the edge I guess. So .... never? Even then it would only be the same thing it is now. An extrapolation applied to a mostly unknown.

Middenrat
2012-Feb-02, 04:26 AM
Even with the inherent uncertainty of any outcome applying the Drake formula, astromark yet makes a valid point for me. After all I'm sure he is informed of recent Kepler findings and will have used conservative factors for the other variables which produce a (human scale) large number which still won't be enough to prevent contemporary civilizations from being any more than ships passing in the night. i.e. the 'quarantine zone' is space/time itself.

Colin Robinson
2012-Feb-02, 10:06 AM
Even with the inherent uncertainty of any outcome applying the Drake formula, astromark yet makes a valid point for me. After all I'm sure he is informed of recent Kepler findings and will have used conservative factors for the other variables which produce a (human scale) large number which still won't be enough to prevent contemporary civilizations from being any more than ships passing in the night. i.e. the 'quarantine zone' is space/time itself.

As well as space/time distance, another factor to consider is biological/cultural/technological distance.

Is it possible there are life-forms in the galaxy at least as complex and adaptable as humans, who however are not heavily into 20th century human technologies like analog radio, nor 21st century human techno-fashions like digital tv and the internet?

Is it possible they would consider relativity and the quantum theory as primitive superstitions, or kindergarten-obvious, or irrelevant?

astromark
2012-Feb-02, 07:37 PM
It looks to me as we all have grasped the truth of finding 'Other' life forms continues to ramp up.

With the known numbers constantly being adjusted up. So to the chances...

Which remain at practicably zero.

... But I love the curve ball idea that maybe we are their descendants... and NO. That idea is unsupported., but fun.

ravens_cry
2012-Feb-03, 06:19 AM
Maybe their craft crashlanded a few billion years ago and the only things that survived were some bacteria-like organisms. This evolved and became us and the rest of life on Earth in due time.
No evidence for that either, but at least its' consistent with the genetic relationships all life on Earth shares.
Here's something I wonder, how long do you think till we can start doing spectroscopic studies on extrasolar terrestrial planets? If there's life Jim that's somewhat as we know it, the indicators in their atmospheres would be huge clues.

Colin Robinson
2012-Feb-03, 07:49 PM
Maybe their craft crashlanded a few billion years ago and the only things that survived were some bacteria-like organisms. This evolved and became us and the rest of life on Earth in due time.
No evidence for that either, but at least its' consistent with the genetic relationships all life on Earth shares.
Here's something I wonder, how long do you think till we can start doing spectroscopic studies on extrasolar terrestrial planets? If there's life Jim that's somewhat as we know it, the indicators in their atmospheres would be huge clues.

I'd expect that spectroscopic studies on extrasolar terrestrial planets will start to be done soon, if it hasn't happened already. I've heard of work being done on the atmospheric composition of exoplanets, though I think they were Jupiters or Neptunes rather than terrestrial worlds. It may be dependent on the planet passing directly between us and its sun, which not all extrasolar planets do.

Compared to radio SETI, studies of atmospheres could potentially detect a much greater range of life-forms. Here on Earth, only one species produces radio, it has done so for only a tiny fraction of its history, and people like Hawkings warn us not to produce too much radio in case someone is listening... On the other hand, all living things on Earth carry out metabolism, and affect the composition of the atmosphere...

One complication... there is a theory that some of the chemistries we call metabolism may predate "life as we know it". It has been shown that many of the steps in the reductive Krebs cycle (also called the reverse Krebs cycle) can be done with the help of mineral catalysts rather than enzymes.

http://astrobio.net/exclusive/3359/shallow-origins

The reductive Krebs cycle uses carboxylic acids to absorb H2 and CO2 and produce more carboxylic acids.

Such "prebiotic metabolism", as it has been called, looks like very good news for the probability of life getting started on other worlds with suitable conditions. It makes the origin of life seem less like a lottery win...

On the other hand, it complicates the scientific task of distinguishing between life and non-life. If we humans detect metabolism-like chemistries happening in another world's atmosphere, we will have to consider the possibility that it may not be life as such.

Selfsim
2012-Feb-03, 11:59 PM
If we humans detect metabolism-like chemistries happening in another world's atmosphere, we will have to consider the possibility that it may not be life as such.
The thing which really bugs me, is the plausible argument that the strategy of remotely detecting exo-atmospheric gases is actually counter-productive towards the search for exo-life.

It diminishes resources targeted at accumulating hard data, needed to model the relationships between habitable environments and the presence/absence of exo-life.

These models need way more empirical data targetted at constraining uncertainties. This can only be achieved by confirmed correlations of the presence or absence of exo-life instances, in a given habitable zone, or possibly, the confirmed lab-synthesis of life from abiogenic origins. (Leaving aside for the moment: ET announcements, or SETI intelligence detection, that is). The former of these, is not feasible over distances in the order of light-years. The latter is exclusive of remote exo-atmospheric gas detection.

The conclusion being that giving priority to the remote detection of exo-atmospheric gas strategies, supports an objective other than a scientific commitment which targets specifically, exo-life discovery.

Regards

eburacum45
2012-Feb-04, 11:17 AM
Detecting exogases is vital for developing a theory of astrobiology. We need to know what environments are out there, and how many planets have exotic components in their atmosphere.

Oxygen is a good biomarker; if a planet has oxygen and a rocky surface, it is quite likely to have life, as oxygen is too reactive to remain in an atmosphere without being constantly renewed. But other exotic components might also be biomarkers; if we see a planet with a lot of chlorine in the atmosphere, that too is highly reactive, and would probably all disappear unless it was constantly replenished by biological action. But this would not be a biology we are familiar with.

There may be many different types of biochemistry on different worlds, and the end products might be detectable even if the mechanism that put them there remains unknown.

Zo0tie
2012-Feb-04, 08:15 PM
http://space.msnbc.msn.com/_news/2012/01/30/10274347-if-et-exists-hes-avoiding-us-cosmic-number-crunchers-say#comments


Considering that these are the signatures of life that we'd look for, provided we had a proper target to study, is it possible we're under some kind of quarantine?

I've concluded a different reason we aren't being contacted. Because of the enormous cost, energy, material and time to travel between stars or even to send a message and get one back it is likely(certain) that technological civilization goes through one of two final stages.

1- Continue to expend resources at an exponentiating rate until environmental, political, resource collapse reduces the people to a primitive subsistence level or extinction.

2- Virtual reality advances so far that 'exploring' the universe in a game setting that is indistinguishable from reality becomes the choice of the entire civilization. In virtuality FTL is possible and the gritty reality of bordom, frustration, and horrendous risk of REAL space travel disappears. The cost of virtual space travel drops to near zero and you can choose the parameters of the universe you explore. Alien encounters would be everywhere from psychic dragons to Solaris oceans. Sure it's fake, but creative gamers can add all sorts of surprises to keep the players happy for life, while plugged into their Matrix style cocoons with visions of Total Recall dancing in their heads. Only a handful of scientists would continue to explore the real universe with orbital telescopes and robot space probes. Their discoveries would be used to add new features to the virtual reality universes to keep things interesting.

I'm not sure which fate will be ours. Sadly I suspect it will be 1 but it may be a combination of 1 and 2.

Solfe
2012-Feb-04, 09:27 PM
If you like science fiction, David Brin has an interesting short story called the Crystal Spheres where solar systems are literally surrounded by spheres to keep intelligent life in. Alistair Reynolds has a different mechanism for isolation which is just as interesting.

I think it is terribly unlikely that we are quarantined. We aren't driven or creative enough to launch an interstellar mission. However, I could could a rational for a quarantine if a culture was doing dangerous/annoying things to get to other stars. Think of ships with incredibly large reactors, dazzling pusher lasers or tons of antimatter. That would be fearsome to see.

Ara Pacis
2012-Feb-04, 11:36 PM
Virtual reality advances so far that 'exploring' the universe in a game setting that is indistinguishable from reality becomes the choice of the entire civilization. In virtuality FTL is possible and the gritty reality of bordom, frustration, and horrendous risk of REAL space travel disappears. The cost of virtual space travel drops to near zero and you can choose the parameters of the universe you explore. Alien encounters would be everywhere from psychic dragons to Solaris oceans. Sure it's fake, but creative gamers can add all sorts of surprises to keep the players happy for life, while plugged into their Matrix style cocoons with visions of Total Recall dancing in their heads. Only a handful of scientists would continue to explore the real universe with orbital telescopes and robot space probes. Their discoveries would be used to add new features to the virtual reality universes to keep things interesting.

There's a theory that this has already happened. Perhaps that's a good thing, for maybe we're in cryosleep on our way to another star system and when we "die" we're actually waking up.

Colin Robinson
2012-Feb-05, 01:53 AM
The thing which really bugs me, is the plausible argument that the strategy of remotely detecting exo-atmospheric gases is actually counter-productive towards the search for exo-life. It diminishes resources targeted at accumulating hard data, needed to model the relationships between habitable environments and the presence/absence of exo-life. These models need way more empirical data targetted at constraining uncertainties. This can only be achieved by confirmed correlations of the presence or absence of exo-life instances, in a given habitable zone, or possibly, the confirmed lab-synthesis of life from abiogenic origins.

I don't see this as an either-or question.

If we humans really want to know about life in the universe -- how rare or common it may be, what range of forms it can take -- then we need to study exo-planets and their atmospheres.

We also need to continue developing theoretical models and laboratory simulations of abiogenesis, to try to establish whether it is a high-probability or low-probability event, and whether it could result in biochemistries unlike the biochemistry which has emerged here on Earth.

And we also need to continue exploring this Solar System, especially the locations where life is plausible, such as Mars and Titan.

Colin Robinson
2012-Feb-05, 02:49 AM
Detecting exogases is vital for developing a theory of astrobiology. We need to know what environments are out there, and how many planets have exotic components in their atmosphere.

Oxygen is a good biomarker; if a planet has oxygen and a rocky surface, it is quite likely to have life, as oxygen is too reactive to remain in an atmosphere without being constantly renewed. But other exotic components might also be biomarkers; if we see a planet with a lot of chlorine in the atmosphere, that too is highly reactive, and would probably all disappear unless it was constantly replenished by biological action. But this would not be a biology we are familiar with.

There may be many different types of biochemistry on different worlds, and the end products might be detectable even if the mechanism that put them there remains unknown.

As long as the mechanism that puts them there remains unknown, how can we know whether it is a biological mechanism or a non-biological one? Even if we think a biological mechanism is "quite likely"…

That is one reason I think it is important to explore worlds within the reach of current space-probes, such as Mars and Titan. Find out where the atmosphere of Mars gets its methane from. Find out what happens to ethane and acetylene on Titan -- is there a process that breaks down these compounds, if so, what sort of process?

It may not be biology at all -- certainly not the sort of biology we are familiar with. But at least it is possible, with current technology, to send a robot lander and have a look.

Selfsim
2012-Feb-05, 06:00 AM
Detecting exogases is vital for developing a theory of astrobiology. We need to know what environments are out there, and how many planets have exotic components in their atmosphere.Well, its an interesting dilemma actually ... Which is more 'vital' ..?.. developing a theory to explain a phenomenon which has not been observed .. or actively pursuing the phenomenon to justify theory development ?

Is it a theory which is being pursued … or a hypothesis ?
If its a theory, then does looking at exo-gases support verification … or falsification ?
I can see how local exploration leads incrementally towards verification.

Fascinating !!


Oxygen is a good biomarker; if a planet has oxygen and a rocky surface, it is quite likely to have life, as oxygen is too reactive to remain in an atmosphere without being constantly renewed. Oxygen is a good biomarker on Earth. If a planet has oxygen and a rocky surface, it may, or may not have life. Oxygen is a reactive element and on Earth, it remains in the atmosphere by being constantly renewed.

Undiscovered exo-planetary processes may well be possible for renewing atmospheric oxygen, and may also not necessarily be related, in the slightest, to the presence of exo-life.

Oxygen is an element which can exist in many forms .. volumes have been found in space, and elsewhere.

What does it mean if it is discovered on an exo-planet if the interpretation model has no empirical basis ?


But other exotic components might also be biomarkers; if we see a planet with a lot of chlorine in the atmosphere, that too is highly reactive, and would probably all disappear unless it was constantly replenished by biological action. But this would not be a biology we are familiar with.Free atmospheric chlorine could also be replenished by undiscovered exo-planetary processes.
What does its remote detection tell us when the interpretation model has no empirical basis ?


There may be many different types of biochemistry on different worlds, and the end products might be detectable even if the mechanism that put them there remains unknown.There may be many different instances of metabolic efficiencies distributed amongst different worlds … including some that don't produce any remotely detectable by-products over the distances involved.
How can we possibly relate exotic exo-gases to lifeforms which have never been modelled?

We need to recognise the vast diversity of exo-environments already uncovered, and broaden our thinking in recognition of that data. As it pertains to the quest to discover exo-life, we need to commensurately recognise the impacts of that environmental diversity and revise our Earth-centric views of the exo-biology/geological relationship. Until we retrieve hard data from our immediate local environments, we have not reduced any of that uncertainty space. Retrieving more exo-planetary data, no matter how numerous, does not reduce that uncertainty, either.

Reducing uncertainty is the objective in the search for exo-life. Remote atmospheric detection over light-year distances, cannot directly reduce that uncertainty. If it is competing with limited resources, which can be shown to be capable of reducing that uncertainty, which would you choose ?

Regards

Colin Robinson
2012-Feb-05, 08:05 PM
Returning to the question in the OP...


Considering that these are the signatures of life that we'd look for, provided we had a proper target to study, is it possible we're under some kind of quarantine?

Is it plausible that a more advanced civilization would choose to observe us earthlings without making themselves known to us?

There are several reasons they might adopt such a policy. One is altruism -- they may consider contact would be detrimental to us. Another, more self-interested motive might be this...

A highly intelligent species would value information. Perhaps they value an inhabited planet like Earth as a source of new information. If so, an important question for them would be: What policy will result in Earth being most productive of new information? A policy of discrete observation, without contact, might be their answer to that question.

Speculation? Yes of course it is. As are all the other resolutions of the Fermi-Hart paradox…

Zo0tie
2012-Feb-06, 02:26 AM
There's a theory that this has already happened. Perhaps that's a good thing, for maybe we're in cryosleep on our way to another star system and when we "die" we're actually waking up.

If this is virtual reality then I'd really like to meet the sadist who designed the system. With a blunt instrument in my hand to show him my approval. No, as bizarre as it can be I'm pretty sure this is reality.

Gomar
2012-Feb-08, 05:44 PM
Maybe their craft crashlanded a few billion years ago and the only things that survived were some bacteria-like organisms. This evolved and became us and the rest of life on Earth in due time.

Or Maybe an alien monolith landed on Earth 50,000 years ago and planted intelligence into man-apes. One of them picked up a bone to defend his tribe's water pond from other man-apes. Then he threw the bone in the air... and bam humans have nukes and space
ships flying in space.
Or maybe God was an alien colonist who planted his people on Earth... Adam&Eve.
Or maybe intelligence is so unlikely humans are the most advanced species in the universe.

ravens_cry
2012-Feb-08, 06:53 PM
Who knows?
If the future is the undiscovered country, the past is the undiscoverable country. From the fragments of years gone by, we piece together our theories and hypotheses.
My quoted comment was meant in response to astromarks "we're alien descendent" comment and meant in the same light, not provable or even something I personally think is true, but an idea to consider, an interesting thought.

Colin Robinson
2012-Feb-08, 09:54 PM
Who knows?
If the future is the undiscovered country, the past is the undiscoverable country. From the fragments of years gone by, we piece together our theories and hypotheses.
My quoted comment was meant in response to astromarks "we're alien descendent" comment and meant in the same light, not provable or even something I personally think is true, but an idea to consider, an interesting thought.

The idea of life being spread by means of space craft, sometimes called "directed panspermia", does have some serious literature. One scientist who discussed it as a possibility was Francis Crick, co-discoverer of the DNA code.

ravens_cry
2012-Feb-08, 10:15 PM
The idea of life being spread by means of space craft, sometimes called "directed panspermia", does have some serious literature. One scientist who discussed it as a possibility was Francis Crick, co-discoverer of the DNA code.
Well, this idea wasn't so much "directed" as " microscopic survivor goes native." though I have heard of that as well, both as a serious discussion and as a basis for science fiction.

Colin Robinson
2012-Feb-08, 11:59 PM
Or Maybe an alien monolith landed on Earth 50,000 years ago and planted intelligence into man-apes. One of them picked up a bone to defend his tribe's water pond from other man-apes. Then he threw the bone in the air... and bam humans have nukes and space
ships flying in space.
Or maybe God was an alien colonist who planted his people on Earth... Adam&Eve.

If the first man and woman on Earth came from elsewhere in the universe, why would human DNA have so much in common with the DNA of other terrestrial biota, especially mammals and primates? Unless the space craft that brought them here brought all the other species as well... and fossils into the bargain??

The other scenario, from the film 2001, at least doesn't have this problem. Arthur C. Clarke did know something about science, and wanted to create science fiction not fantasy. Although there is no convincing evidence that extraterrestrials stimulated human technologies back in the stone age, neither is there an obvious scientific argument to rule it out.


Or maybe intelligence is so unlikely humans are the most advanced species in the universe.

Or maybe there are very complex life-forms on other worlds, but they are so different from us (and from each other) that terms like "intelligence" and "advanced" are hardly applicable?

eburacum45
2012-Feb-09, 12:38 AM
Oxygen is a good biomarker on Earth. If a planet has oxygen and a rocky surface, it may, or may not have life. Oxygen is a reactive element and on Earth, it remains in the atmosphere by being constantly renewed.

Undiscovered exo-planetary processes may well be possible for renewing atmospheric oxygen, and may also not necessarily be related, in the slightest, to the presence of exo-life.

Oxygen is an element which can exist in many forms .. volumes have been found in space, and elsewhere.

What does it mean if it is discovered on an exo-planet if the interpretation model has no empirical basis ?
To be honest, if oxygen is discovered in the atmosphere of an exoplanet, my first thought isn't 'Aha- life!' it is 'Aha- photodissociation of water'. On a planet coverd in water oxygen would be produced by the effect of light on water vapour. Hydrogen would then be lost by Jeans escape.

But on Earth this process is slower than the rate of absorption of oxygen by the crust, so without photosynthesis the oxygen produced by photodissociation would be minimal.

Waterworlds, and icy worlds like Europa, could quite likely have oxygen atmospheres. In fact O2 is present on many of the icy moons of the Solar system.

According to A. Leger a better biomarker would be ozone.
see
http://arxiv.org/ftp/astro-ph/papers/0308/0308324.pdf

The only way to have a significant amount of O3 in the atmosphere spectrum is that O2 is produced at low altitude, eg by biological photosynthesis...There may be abiotic mechanisms to produce and retain O3 , but its detection in an exoplanetary atmosphere is likely to be an encouraging sign.

Extrasolar
2012-Feb-09, 12:39 AM
Or maybe there are very complex life-forms on other worlds, but they are so different from us (and from each other) that terms like "intelligence" and "advanced" are hardly applicable?

While I understand the idea of there being lifeforms so different from us that we fail to recognize it in the first place, a measure of intelligence or advancement that is similar to ours or similar to what we have been (simple tool makers) would be obvious. Mathematics is universal, and evidence of its use would be intelligence.

Colin Robinson
2012-Feb-09, 12:40 AM
Well, this idea wasn't so much "directed" as " microscopic survivor goes native." though I have heard of that as well, both as a serious discussion and as a basis for science fiction.

True. Not so much "directed panspermia" as "accidental panspermia", a scenario discussed by the astrophysicist Thomas Gold.

Colin Robinson
2012-Feb-09, 01:20 AM
While I understand the idea of there being lifeforms so different from us that we fail to recognize it in the first place,

True, humans might conceivably mistake an unfamiliar life-form for a mineral. This is a somewhat different scenario that what I had in mind though.


a measure of intelligence or advancement that is similar to ours or similar to what we have been (simple tool makers) would be obvious.

I'd agree that their intelligence might be obvious, if they did stuff that was obviously similar to what we do today, or to what we did in the stone age.

But consider a scenario like this...

Astronomers detect an exoplanet that looks promising for life. An interstellar space probe is sent to have a look. The probe arrives, sends back pictures of what are obviously motile living things – an abundant species, though an unfamiliar one – the creatures resemble vertebrates in certain respects, but other things about them are more like insects, molluscs or cnidarians. The probe also finds and photographs structures which the creatures have made, and in which they live: weird structures, but impressively large and stable.

The question arises: Are these structures the equivalent of humans' cities? Or are they more comparable to termite mounds? Or to the great underwater structures created here on Earth by the coral polyp?

How would you go about answering such questions?


Mathematics is universal, and evidence of its use would be intelligence.

What would qualify as "evidence of its use"?

An alien organism that could construct a regular hexagon might be no more (or less) "intelligent" that a honey bee.

Extrasolar
2012-Feb-09, 01:33 AM
True, humans might conceivably mistake an unfamiliar life-form for a mineral. This is a somewhat different scenario that what I had in mind though.



I'd agree that their intelligence might be obvious, if they did stuff that was obviously similar to what we do today, or to what we did in the stone age.

But consider a scenario like this...

Astronomers detect an exoplanet that looks promising for life. An interstellar space probe is sent to have a look. The probe arrives, sends back pictures of what are obviously motile living things – an abundant species, though an unfamiliar one – the creatures resemble vertebrates in certain respects, but other things about them are more like insects, molluscs or cnidarians. The probe also finds and photographs structures which the creatures have made, and in which they live: weird structures, but impressively large and stable.

The question arises: Are these structures the equivalent of humans' cities? Or are they more comparable to termite mounds? Or to the great underwater structures created here on Earth by the coral polyp?

How would you go about answering such questions?


Ah, yes, if the scenario is limited by information from a probe, then I can totally see that we could miss all kinds of things, including a possible knowledge of mathematics. (They could be under-dwellers that barely make a scene on the surface or a billion other scenarios). However, lets say the probe indeed finds a planet with life on it, and we go there. In that situation, I believe it would be fairly easy to tell. Complex structures require math, even if we found them beneath the ground of a mostly barren planet. A civilization would have to be very paranoid to deliberately make their society look like they don't know or use math when they really do.


What would qualify as "evidence of its use"?

An alien organism that could construct a regular hexagon might be no more (or less) "intelligent" that a honey bee.

Indeed, but it is measurable.

Colin Robinson
2012-Feb-09, 02:29 AM
Ah, yes, if the scenario is limited by information from a probe, then I can totally see that we could miss all kinds of things, including a possible knowledge of mathematics. (They could be under-dwellers that barely make a scene on the surface or a billion other scenarios). However, lets say the probe indeed finds a planet with life on it, and we go there. In that situation, I believe it would be fairly easy to tell. Complex structures require math, even if we found them beneath the ground of a mostly barren planet.

What if we landed on a planet, observed a range of complex structures, whose design would require mathematical knowledge...

but then we did some archeology, and found that the builders of these structures had been doing the same sort of thing for hundreds of thousands of years, with no apparent change or innovation...?

Selfsim
2012-Feb-09, 02:56 AM
What if we can't travel to any such planet, as this is beyond our range of our transit and communications technologies ?

Which happens to be real-world reality (as opposed to Sci-fi conjecture).

Regards

Colin Robinson
2012-Feb-09, 03:39 AM
What if we can't travel to any such planet, as this is beyond our range of our transit and communications technologies ?

Then we ought to keep an open mind about what may or may not be out there.


Which happens to be real-world reality (as opposed to Sci-fi conjecture).

The OP of this thread refers to the fact that we haven't yet received any message from intelligent extra-terrestrials. This bit of negative evidence is consistent with many possibilities. All of which will remain conjectures till we know which is right.

Extrasolar
2012-Feb-09, 04:02 AM
What if we landed on a planet, observed a range of complex structures, whose design would require mathematical knowledge...

but then we did some archeology, and found that the builders of these structures had been doing the same sort of thing for hundreds of thousands of years, with no apparent change or innovation...?

Then I would say the definition of intelligence would be applicable.

The assertion being made is:



Or maybe there are very complex life-forms on other worlds, but they are so different from us (and from each other) that terms like "intelligence" and "advanced" are hardly applicable?

I don't want to debate special scenarios, I'll only say we can only know as much as our machines tell us, and if we had some good enough to visit a civilization, then we would determine intelligence or not. It would always be applicable.

Colin Robinson
2012-Feb-09, 11:06 AM
Then I would say the definition of intelligence would be applicable.

The assertion being made is:

I didn't make an assertion. I asked a question. To which you replied:


Mathematics is universal, and evidence of its use would be intelligence.

If so, could the concept of SETI (Search for Extraterrestrial Intelligence) be equally well expressed as SETM (Search for Extraterrestrial Mathematicians)?

Extrasolar
2012-Feb-09, 11:49 AM
I didn't make an assertion. I asked a question. To which you replied:



If so, could the concept of SETI (Search for Extraterrestrial Intelligence) be equally well expressed as SETM (Search for Extraterrestrial Mathematicians)?

Right, the question you asked, not the assertion you made. I would say yes to the SETI question.

ravens_cry
2012-Feb-09, 01:51 PM
Ah, yes, if the scenario is limited by information from a probe, then I can totally see that we could miss all kinds of things, including a possible knowledge of mathematics. (They could be under-dwellers that barely make a scene on the surface or a billion other scenarios). However, lets say the probe indeed finds a planet with life on it, and we go there. In that situation, I believe it would be fairly easy to tell. Complex structures require math, even if we found them beneath the ground of a mostly barren planet. A civilization would have to be very paranoid to deliberately make their society look like they don't know or use math when they really do.

Or they could be like termites,honey bees and ants on a larger scale, their individual efforts working together on some instinctual level to create what we would call "structures".
They could be using mathematics, they just might not be aware of it.

True. Not so much "directed panspermia" as "accidental panspermia", a scenario discussed by the astrophysicist Thomas Gold.
I believe there was a thread wondering if we have been doing just that with some of our probes and landers.
To be honest, my response was meant in as a humbling of the grandiose "we might be descendants of people from the sky"! to "we might be the the descendants of quasi-intestinal flora!"
Still yes, it is something to think about and I am sure many good thoughts have been thought.

Colin Robinson
2012-Feb-09, 11:22 PM
I believe there was a thread wondering if we have been doing just that with some of our probes and landers. To be honest, my response was meant in as a humbling of the grandiose "we might be descendants of people from the sky"! to "we might be the the descendants of quasi-intestinal flora!" Still yes, it is something to think about and I am sure many good thoughts have been thought.

Our human grandiosity can benefit from a little humbling, I think.

Perhaps an even more humbling hypothesis about how life came to Earth is the "metabolism-first" one.

As if it wasn't enough to be told that our ancestors were apes, and before that reptiles, fish, microbes...

Now comes the rumor of a not-yet-living quasi-ancestor who was a cycle of mineral-catalysed chemical reactions – a bunch of carboxylic acids, four to six carbon atoms long, quietly consuming carbon dioxide and hydrogen, and excreting vinegar.

Githyanki
2012-Feb-11, 03:51 PM
I think there's more to consider about alien life than math alone. Probably the assumption that all intelligent life turns out like us and wants to conquer the universe.

cosmocrazy
2012-Feb-11, 05:08 PM
According to the 'Drake' equation there might be as many as 50,000 life forms of some intelligence across this Galaxy.

and that being so does not suggest we will ever find it., or any traces of it..

Time and distance are the enemy's we can not beat. That we should and must keep looking is also real.

Mark @ 39' 55", 52.92 South.

Absolutely!

But, this is based on what we (humans) are not capable of.
Time and distance may be experienced differently by alien species. By this I mean, what we may consider a long time or a far distance might not be the same for ET.
All we have to go on is our own experience of life here on Earth. We only assume that life out there is no more resiliant as life here on Earth.

What if there exists an alien species that live much much longer than what we experience. What if they are able to live in much more hostile enviroments? What if they can with stand more enviromental extremes or are much better at repairing/healing than us? What if when they reproduce, genetically they pass on directly all their learned information and experiences so that the next generation automatically gaines a wealth of knowledge, experience and understanding? what if they have access to unimaginable amounts of energy? What if they are capable of crossing interstella distances with what seems like ease to them? What if they are capable of travelling near light speeds? What if they can somehow warp spacetime like gravity, able to manipulate it at will?...

Ok these variables all sound very sci-fi, but they are not impossible or should I say they cannot yet be proved either way.

I believe the chances of us being the only intelligent life in the universe is near on impossible. Simply because there are so many stars in the universe that will have so many planets orbiting them. But I cannot see how it would ever be possible for them or us to make contact unless one or more of those sci-fi variables I mentioned were possible.

So for now all we can do is keep looking and wait.

Ara Pacis
2012-Feb-11, 06:34 PM
I suspect that humans are the only intelligent and potentially spacefaring creatures in the galaxy, and possibly beyond. There may be intelligent species on other worlds, as there are on earth, but they may not have the physical ability to travel off-world or even use tools in anything more than a rudimentary fashion.

If there were, we'd probably be able to tell if we saw them in person. While it's not impossible for different species to experience time at different speeds, I don't think it's probable that there would be extreme variations. After all, chemistry, thermodynamics and radiation act on molecular biology in their own frames of reference that limit how fast or slow information can be transmitted. Maybe they might be mistaken for trees but not rocks, ignoring camouflage.

Colin Robinson
2012-Feb-11, 09:23 PM
I think there's more to consider about alien life than math alone.

Yes, I think there is a lot more.


Probably the assumption that all intelligent life turns out like us

Yes. If we are looking for beings like ourselves, why not just look in the mirror?


and wants to conquer the universe.

If they really are like us, they are very good at making movies about themselves conquering the universe…

Colin Robinson
2012-Feb-11, 10:03 PM
If there were, we'd probably be able to tell if we saw them in person. While it's not impossible for different species to experience time at different speeds, I don't think it's probable that there would be extreme variations. After all, chemistry, thermodynamics and radiation act on molecular biology in their own frames of reference that limit how fast or slow information can be transmitted. Maybe they might be mistaken for trees but not rocks, ignoring camouflage.

You think that (apart from camouflage) a living thing could never be mistaken for a non-living object?

What about corals? Some have shapes like trees, but others can look very like rocks. As far as I know, this has nothing to do with camouflage, it is the way they use calcium carbonate for stability.

Selfsim
2012-Feb-11, 11:13 PM
You think that (apart from camouflage) a living thing could never be mistaken for a non-living object?

What about corals? Some have shapes like trees, but others can look very like rocks. As far as I know, this has nothing to do with camouflage, it is the way they use calcium carbonate for stability.
The real question is what are the odds for misdiagnosis by using remote sensing technologies, over light-year distances ?
How does this compare with diagnosis performed onsite, by human beings armed with life detecting laboratory equipment ?

Regards

Colin Robinson
2012-Feb-12, 01:27 AM
The real question is what are the odds for misdiagnosis by using remote sensing technologies, over light-year distances ?

Interesting question...

If ET astronomers detected O2 and organic compounds being produced in Earth's atmosphere at or near the surface, would they said: "Eureka, photosynthesis!"

Or would they said: "Hmm, very interesting chemistry. Must be some sort of catalyst involved here..."


How does this compare with diagnosis performed onsite, by human beings armed with life detecting laboratory equipment ?

... or even a robot lander, which could not only test for complex molecules, but could also take photos of microscopic structures?

Selfsim
2012-Feb-12, 02:58 AM
Interesting question...

If ET astronomers detected O2 and organic compounds being produced in Earth's atmosphere at or near the surface, would they said: "Eureka, photosynthesis!"

Or would they said: "Hmm, very interesting chemistry. Must be some sort of catalyst involved here…"
Well, I took the time to read through the paper eburacum45 linked in post #31 (thanks eburacum45 .. much appreciated :) ). As he mentions, A. Leger seems to think O3 is a better litmus test than O2. Beats me why … Leger still seems to be assuming photosynthesised O2 is the supply chain source, so I'm not sure what the difference is, except O3 would be at higher altitudes, unable to be interfered with by hypothesised ground-hugging reactive H, OH and HO2, and hence, perhaps easier to detect. (Many, many, many hidden assumptions, glossing over many, many, many hidden variables here).

In the overall scheme of a truly vast exo search-space, of vast physical environment diversity, for something we have trouble remotely diagnosing, even on Earth, (ie: 'life'), I still find it difficult to understand the seemingly unswerving fixation of looking for Earth-like life, and metabolic by-products over vast interstellar distances. Other than by circumstances of pure lack of exo-life instance data, for which a strategy for overcoming it by searching locally, would seem to be the priority, I find building search strategies on top of such a myopic perspective, to be limiting in the extreme, and ultimately no better, … no .. I mean … actually worse than, the good 'ol coin-toss approach applied to existing Kepler-like data, filtered by scientific intuition.


... or even a robot lander, which could not only test for complex molecules, but could also take photos of microscopic structures?… and then be unable to return this valuable data .. because of the vast distances which cannot be feasibly bridged by present-day communications technologies ..??..
… Which kind of answers my question about misdiagnosis by using remote sensing technologies, over light-year distances … the answer seems to be, from a practical perspective .. 100%.

Regards

Ara Pacis
2012-Feb-12, 06:52 AM
You think that (apart from camouflage) a living thing could never be mistaken for a non-living object?

What about corals? Some have shapes like trees, but others can look very like rocks. As far as I know, this has nothing to do with camouflage, it is the way they use calcium carbonate for stability.

And how intelligent are coral?

Colin Robinson
2012-Feb-12, 07:13 AM
Well, I took the time to read through the paper eburacum45 linked in post #31 (thanks eburacum45 .. much appreciated :) ). As he mentions, A. Leger seems to think O3 is a better litmus test than O2. Beats me why … Leger still seems to be assuming photosynthesised O2 is the supply chain source, so I'm not sure what the difference is, except O3 would be at higher altitudes, unable to be interfered with by hypothesised ground-hugging reactive H, OH and HO2, and hence, perhaps easier to detect.

Leger's point, if I understand it correctly, isn't that the reactive H, OH, and HO2 are ground-hugging exactly. Rather that in photosynthesis they don't get produced, or at least don't accumulate, as happens in straightforward photolysis of H2O.

The difference is this: Both photolysis and photosynthesis involve breaking up the water molecule into oxygen and hydrogen, but in photosynthesis, the hydrogen is then combined with CO2 to produce organic compounds such as sugars. Leaving the oxygen free to form ozone...

So if you detect O3 in the atmosphere of a water-rich planet, you may conclude that not only is water being dissociated, but there is something going on to consume the resulting hydrogen, e.g. by combining it with CO2.

So far so good... but what if hydrogen and CO2 can be combined by some process not involving a living organism? Such as a reductive Krebs cycle involving carboxylic acids and mineral catalysts instead of enzymes?

Which is something recent lab work suggest can indeed happen... I mentioned this finding in an earlier posting, but here it is again for your convenience.

http://astrobio.net/exclusive/3359/shallow-origins


Other than by circumstances of pure lack of exo-life instance data, for which a strategy for overcoming it by searching locally, would seem to be the priority,

If you count the worlds of this solar system as "local", then yes, I agree -- we are most likely to find unambiguous exo-life data by searching with robot missions to Mars, Europa, Enceladus and Titan.

I find Titan especially attractive, because we already know there are complex chemical reactions there, and life can be viewed as a subset of complex chemistry…

Colin Robinson
2012-Feb-12, 07:26 AM
And how intelligent are coral?

I concede they may not be geniuses. Still, they are probably smarter than the average tree. Coral polyps don't have brains as such, but do have nerve nets, which trees do not have.

This seems relevant because in your last post you suggested that intelligent aliens might possibly be mistaken for trees...

eburacum45
2012-Feb-12, 07:31 AM
I can imagine an extraterrestrial lifeform that secretes complex nerve-like structures into its substrate so that numerous individual polyp-like organisms can be connected neurally into a single responsive organism; eventually such creatures could become intelligent (assuming suitable evolutionary pressure).

I call this imaginary species Brain-coral (the hyphen is there to differentiate it from the somewhat less responsive examples found on our world).

One day in the far future our descendants may face the challenge of communicating with thinking coral reefs. Or something else equally as unexpected and outside our experience.

Ara Pacis
2012-Feb-12, 08:19 AM
I concede they may not be geniuses. Still, they are probably smarter than the average tree. Coral polyps don't have brains as such, but do have nerve nets, which trees do not have.

This seems relevant because in your last post you suggested that intelligent aliens might possibly be mistaken for trees...only insofar as I think the concept is merely improbable instead of impossible with regard to intelligences experiencing time at different rates. Something that experiences time slowly might be slow moving and mistaken for what we consider flora. That a dumb such organism on earth or another planet might exist seems plausible, that a smart such organism might exist seems unlikely, and that we would remotely detect its intelligence without detailed longitudinal analysis and vivisection seems even less likely.

Selfsim
2012-Feb-12, 09:30 AM
So far so good... but what if hydrogen and CO2 can be combined by some process not involving a living organism? Such as a reductive Krebs cycle involving carboxylic acids and mineral catalysts instead of enzymes?

Which is something recent lab work suggest can indeed happen... I mentioned this finding in an earlier posting, but here it is again for your convenience.

http://astrobio.net/exclusive/3359/shallow-origins
Thanks for the link (again) .. much appreciated .. and interesting.
And this is just one example of such a process ... how many other ones could one dream up from amongst a selection of vast environmental diversity ? (Please .. a purely rhetorical question .. :) )

If you count the worlds of this solar system as "local", then yes, I agree -- we are most likely to find unambiguous exo-life data by searching with robot missions to Mars, Europa, Enceladus and Titan.

I find Titan especially attractive, because we already know there are complex chemical reactions there, and life can be viewed as a subset of complex chemistry…Yep .. that's kind of what I'm talkin' 'bout .. except, IMHO, robotics are best, only for rudimentary data gathering. Even within our own system, the risk of losing one, 'locally', is far from insignificant. However, if we lose track of the priority of finding evidence 'locally', the quest to solicit light-year distant sensed data alone, cannot possibly progress knowledge of exo-life distributions (if it exists at all).

Unless robotically sensed 'local life' is glaringly obvious .. declaration of exo-life without human contact, is also difficult to envisage.

Regards

Solfe
2012-Feb-13, 12:54 AM
I think there's more to consider about alien life than math alone. Probably the assumption that all intelligent life turns out like us and wants to conquer the universe.

I would settle for conquering the tri-state area. :)

Gomar
2012-Feb-13, 05:05 AM
Or maybe there are very complex life-forms on other worlds, but they are so different from us (and from each other) that terms like "intelligence" and "advanced" are hardly applicable?

If any species has gone beyond making fire, stone tools, and living in caves to develop math and writing,
building pyramids, then electricity, then TV and radio, then skyscrapers, then airplanes, then computers,
then space flight, then flying to other planets and galaxies... then they are intelligent, and _very_ advanced, no matter how they look.

If 1+1=2 could be understood by any alien species, whether beavers, penguins, or dolphins on any planet then they are intelligent.

Colin Robinson
2012-Feb-13, 11:05 AM
If any species has gone beyond making fire, stone tools, and living in caves to develop math and writing,
building pyramids, then electricity, then TV and radio, then skyscrapers, then airplanes, then computers,
then space flight, then flying to other planets and galaxies... then they are intelligent, and _very_ advanced, no matter how they look.

You are saying that if their bodies are different from ours, but their technologies are the same, then they are intelligent... But how likely is it that their technologies really would be the same?


If 1+1=2 could be understood by any alien species, whether beavers, penguins, or dolphins on any planet then they are intelligent.

We express mathematical concepts by means of symbols: either sounds or written characters. What if we encounter a complex life form which uses symbols we can't understand, and neither can they understand our symbols? How would we know whether they do or don't have a concept corresponding to "1 + 1 = 2" ?

Ara Pacis
2012-Feb-13, 07:17 PM
You are saying that if their bodies are different from ours, but their technologies are the same, then they are intelligent... But how likely is it that their technologies really would be the same?



We express mathematical concepts by means of symbols: either sounds or written characters. What if we encounter a complex life form which uses symbols we can't understand, and neither can they understand our symbols? How would we know whether they do or don't have a concept corresponding to "1 + 1 = 2" ?

Physics, gravity and chemistry do not change.

Colin Robinson
2012-Feb-13, 08:56 PM
Physics, gravity and chemistry do not change.

It's true that Newton showed that the same laws of gravity describe planetary orbits and falling rocks. And since the invention of spectroscopy, it's been understood that the chemical elements in stars are the same as those on Earth.

As I understand it, this is basically why Ronald Bracewell thought advanced inhabitants of different worlds would have enough in common to make radio sets and use them to form what he called a Galactic Club.

Is Bracewell's conclusion a valid one?

Does the universal character of gravity, chemistry etc mean that tree-like intelligent beings would be likely to send us radio messages, inviting us to join a scientific discussion with them?

Or suggesting a friendly exchange of specimens for vivisection?

Ara Pacis
2012-Feb-14, 10:20 AM
Does the universal character of gravity, chemistry etc mean that tree-like intelligent beings would be likely to send us radio messages, inviting us to join a scientific discussion with them?Not if they can't manipulate matter or energy in a technologically timely manner.

JCoyote
2012-Feb-18, 07:57 PM
Although it seems less likely, I could easily see species existing with high intelligence but not having the drive to create technology. The development of technology of significant level may be more unique to us than we'd think.

Although intelligent trees seem unlikely... evolution does seem to reduce intelligence with reductions in mobility. Their are species on earth that have an active and mobile life phase and then have an immobile and unintelligent phase.

It would not be surprising to find out that mobility-strategists in evolution are almost the only organisms that ever grow any sort of intelligence.

However some highly adaptive organisms... say something almost like a shape-shifter... could develop very high levels of intelligence, but because it would be channeled into adapting themselves to their environment, you might not see significant technological development. Even among human cultures, the perceived need for technological improvement is relatively new.

Ara Pacis
2012-Feb-20, 08:58 PM
Although it seems less likely, I could easily see species existing with high intelligence but not having the drive to create technology. The development of technology of significant level may be more unique to us than we'd think.

Although intelligent trees seem unlikely... evolution does seem to reduce intelligence with reductions in mobility. Their are species on earth that have an active and mobile life phase and then have an immobile and unintelligent phase.

It would not be surprising to find out that mobility-strategists in evolution are almost the only organisms that ever grow any sort of intelligence. That's what I'm suggesting.


However some highly adaptive organisms... say something almost like a shape-shifter... could develop very high levels of intelligence, but because it would be channeled into adapting themselves to their environment, you might not see significant technological development. Even among human cultures, the perceived need for technological improvement is relatively new.You may be right about the shapeshifter and intelligence if we take cephalopods as examples.

Not sure about Humanity though, we and our antecedents have been using technology (tools & techniques) for millions of years.

nikkoo
2012-Jun-04, 05:44 AM
If this is virtual reality then I'd really like to meet the sadist who designed the system. With a blunt instrument in my hand to show him my approval