NASA: We'll find signs of alien life by 2025

[Greg Bernhardt]

I'm getting some popcorn!
http://www.huffingtonpost.com/2015/04/08/nasa-alien-life_n_7023134.html

"I think we're going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years," NASA chief scientist Ellen Stofan said Tuesday during a panel event on water in the universe.

"We know where to look. We know how to look," Stofan added. "In most cases we have the technology, and we're on a path to implementing it. And so I think we're definitely on the road."

Others at the panel agreed.

 

[Matternot]

There's bound to be microbes on some other planet out there... and finding them would only be the start! The real science begins when probes are sent to the planet to study their life forms!

 

[Greg Bernhardt]

There's bound to be microbes on some other planet out there... and finding them would only be the start! The real science begins when probes are sent to the planet to study their life forms!

I watched the "Europa Project" on Netflix last night. SciFi, but still fun to watch and dream.

 

[Almeisan]

If life is inevitable when there is liquid water, mankind (maybe not NASA) will find it in 20 years.

But, what if life is not common? Some things only happen once, even in near-infinitely large universes.

 

[rootone]

I don't think anyone said the liquid water makes life inevitable, but it certainly seems to be prerequisite for all life on Earth, so it probably is elsewhere.
Since we now have discovered exoplanets which have a good chance of liguid water, this does increase the liklyhood of life being discovered.
However we don't have any certainty of how life begins once water is present, it could still be the case that some other conditions are necessary, and those other conditions might be a lot more rare than the presence of water.

 

[Ophiolite]

"I think we're going to have strong indications of life beyond Earth within a decade, and I think we're going to have definitive evidence within 20 to 30 years," NASA chief scientist Ellen Stofan said Tuesday during a panel event on water in the universe.

The statement is a reasonable one if, and only if, life is reasonably common in our part of the universe. The emergence of life is probably complex and we have only speculative notions as to the probability of each step in that complex process. Until we have expanded our knowledge of life beyond a sample size of one, such speculations are interesting, but barely constitute science.

 

[Ygggdrasil]

We have found meteorites from Mars on Earth, so it's reasonable to think there might be meteorites from Earth on Mars and other bodies in the solar system. Thus, it's possible that material ejected from Earth could have seeded life throughout the solar system. While I would be extremely surprised to find evidence of an independent emergence of life elsewhere in the solar system, I would not be as surprised to find evidence of Earth-like microbial life in areas where there is water (e.g. on Europa).

 

[Astudious]

We have found meteorites from Mars on Earth, so it's reasonable to think there might be meteorites from Earth on Mars and other bodies in the solar system. Thus, it's possible that material ejected from Earth could have seeded life throughout the solar system. While I would be extremely surprised to find evidence of an independent emergence of life elsewhere in the solar system, I would not be as surprised to find evidence of Earth-like microbial life in areas where there is water (e.g. on Europa).

But how many such locations in the solar system could have sustained life, had microbes from Earth ended up on them?

As for independent emergence of life, we cannot really speculate as to how improbable it is because life is a currently an unexplained emergent phenomenon to us... it could well be that life is truly a freak singular occurrence and the chances are miniscule of that repeating anywhere else in the universe, we won't know until we understand the biochemistry better (at least, I think...)

 

[russ_watters]

I've long believed that life beyond Earth would be proven scientifically within my lifetime. The problem I see is that it may not convince the general public, who wants to see little green men, not a spectrograph indicating an atomsphere that was probably created by microbial life.

As for independent emergence of life, we cannot really speculate as to how improbable it is because life is a currently an unexplained emergent phenomenon to us...

I think you are overstating it. Abiogenesis is heavily studied and while it is difficult to prove exactly what happened, there is good lab evidence of the likely general phenomena.

 

[Almeisan]

I don't think there is good evidence. We can't even get steps of abiogenesis to happen even in controlled lab experiments.

 

[Ophiolite]

I think you are overstating it. Abiogenesis is heavily studied and while it is difficult to prove exactly what happened, there is good lab evidence of the likely general phenomena.

Please provide citations supporting this assertion. We have fragments of processes that may or may not be part of the complete abiogenesis sequence. (Miller-Urey type experiments, or self forming lipid vesicles are examples.) They offer plausible partial pathways, but there is nothing like a cohesive, demonstrable route from non-life to life. I am completely with Almeisan on this one.

I have little doubt that we shall eventually determine, in great detail, how life arose, but we are presently very distant from that achievement.

 

[CalcNerd]

Well the Drake equation certainly took a big jump up in numbers as it used to rely upon one planet per ten stars.

Admittedly, it is hard to imagine planets (much less planets with life) in binary star systems (and a large percentage of stars are in binary systems).

I am prejudiced into thinking intelligent life will be carbon based with an H20 requirement. However, basic rudimentary life could be based upon other liquids as well. Its just that many of these types of life forms may not be able to survive or evolve much past micro-organisms. In fact our Earth had only micro-organisms for the first couple of billion years as well.

Intelligent life of any measurable intelligence is only a very recent phenomena.

 

[Almeisan]

Well, the Drake equation is basically obselete at the moment because life on other planets is not a question of astronomy/planetary physics.
It is a question of biochemistry and biology.

We might set up a new Drake equation, but in most steps of abiogeneisis we know the odds are zero in our labs, giving lab experiment timescales.

 

[CalcNerd]

Well, I also believe that dolphins could certainly evolve and surpass us (maybe even already have) in intellegence. However, without any means to affect their environment ie make tools, fire, metallurgy, history via the printed page etc. they will be forever constrained to the oceans. They could not develop any technical civilization and therefore not make themselves known nor travel anywhere off the globe.

If our Earth had no protruding land mass so to speak, dolphins would be at the top of the evolutionary ladder and remain at their technological level for eons ie Zero technology. Similar creatures on other worlds could never really make themselves known nor travel off of their planets either.

 

[russ_watters]

Please provide citations supporting this assertion. We have fragments of processes that may or may not be part of the complete abiogenesis sequence. (Miller-Urey type experiments, or self forming lipid vesicles are examples.) They offer plausible partial pathways, but there is nothing like a cohesive, demonstrable route from non-life to life. I am completely with Almeisan on this one.

Please reread carefully what I said: I think you actually did agree with me. I didn't claim we have a cohesive, demonstrable route from non-life to life, I said we have good lab evidence of the "likely general phenomena". "General phenomena" sounds an awful lot like "plausible partial pathways" to me. I purposely put several qualifiers in the post.

This is a big subject, but an example of the "general phenomean" studied in the lab is:

The Miller–Urey experiment and similar experiments demonstrated that most amino acids, basic chemicals of life, can be synthesized from inorganic compounds in conditions intended to be similar to early Earth. Several mechanisms have been investigated, including lightning and radiation. Other approaches ("metabolism first" hypotheses) focus on understanding how catalysis in chemical systems in the early Earth might have provided the precursor molecules necessary for self-replication.[11] Complex organic molecules have been found in the solar system and in interstellar space, and these molecules may have provided starting material for the development of life on Earth.

http://en.wikipedia.org/wiki/Abiogenesis

Anyway, I don't want to drag this off track - I don't think this is critical to the thread.

 

[DaveC426913]

We have found meteorites from Mars on Earth, so it's reasonable to think there might be meteorites from Earth on Mars and other bodies in the solar system. Thus, it's possible that material ejected from Earth could have seeded life throughout the solar system. While I would be extremely surprised to find evidence of an independent emergence of life elsewhere in the solar system, I would not be as surprised to find evidence of Earth-like microbial life in areas where there is water (e.g. on Europa).

Well, I see a logistical problem here.

We think Mars suffered an impact spectacular enough to create the Hellas Basin on one side, the Tharsis Bulge on the opposite and split it like a gutted fish along the Valles Marineris. The poor planet practically burst like a balloon! So certainly energy to spare to fling rocks around the solar system.

But you're talking about an impact occurring after the creation of life. I'm just not sure that Earth has suffered sufficient insult recently enough to make this plausible.

 

[Chronos]

Life sprang up on Earth almost as soon as it became habitable - like a billion years after it formed. I think life is virtually inevitable anywhere else under similar circumstances. Complex life? - that may be an exophytic horse of a different color.

 

[Almeisan]

We have no idea how abiogenesis happened. Did it happen in a pond or tidepool? Did it happen in the deepsea near a smoker? We have no clue.
We think we need lightning or heat, or metabolism of reduced substsances, and now radiation is suggested as well. Basically, we have no idea which energy, if not metabolism, is the original driving force.
We think it started with RNA or something very similar, and that is logical, but we have no experimental data to show this is how it must happen. We have no clue what needs to happen first. Maybe vesicles are needed first.

We know that through several ways it is possible to make amino acids, make RNA, make vesicles. But we know that can happpen through controlled experiments.All we know is that it happened and that it is not chemically impossible. We have no clue about the probability, except that it happened fast after conditions on Earth made life possible (or so we are told by geologists).
And every time the issue is raised, the 60 year old Urey-Miller experiment is invoked. We struggle to deliberately make synthetic life de novo when we can do so much in both biochemistry and molecular biology.

 

[mfb]

Mars -> Earth meteorites are much easier than the opposite direction - a lower escape velocity and no atmosphere for most of the time.

Life sprang up on Earth almost as soon as it became habitable - like a billion years after it formed. I think life is virtually inevitable anywhere else under similar circumstances. Complex life? - that may be an exophytic horse of a different color.

The Earth won't be able to support complex life for much longer than another billion years. If life would have evolved a billion years later, it might never have reached a species that can discuss this topic. The early evolution of life could have been necessary for our existence, so I would not take that as strong evidence for a likely evolution of life.

I've long believed that life beyond Earth would be proven scientifically within my lifetime.

I'm really looking forward to that. Atmospheric gas compositions are fine.
I don't share Stofan's optimism, however, as long as we don't know how frequent life is and how often it leaves detectable traces.

 

[rollingstein]

Umm...isn't there a little bit of a conflict of interest here?

It's like Schwinn or Trek telling investors that bike ridership numbers are surely going to explode.

 

[PWiz]

I would be particularly surprised if life is not discovered on some other planet by the time I'm a grandad, since nucleosynthesis goes hand in hand with abiogenesis so well. At least we will then be able to find an answer to the Fermi Paradox (which puzzles my mind to an immeasurable extent).

 

[PWiz]

I just found a very interesting article published in the MIT Technology Review that suggests why it would be disastrous if we were to discover remains of any life on Mars or on nearby planets: http://www.technologyreview.com/article/409936/where-are-they/

I think it offers an interesting perspective on this topic, and deserves some consideration.

 

[Monsterboy]

I watched the "Europa Project" on Netflix last night. SciFi, but still fun to watch and dream.

Have you watched "Darwin IV " ? [YOUTUBE]

 

[Almeisan]

I just found a very interesting article published in the MIT Technology Review that suggests why it would be disastrous if we were to discover remains of any life on Mars or on nearby planets: http://www.technologyreview.com/article/409936/where-are-they/

I think it offers an interesting perspective on this topic, and deserves some consideration.

I think this is a good article. I had come to this conclusion myself, though I don't remember if it is commonly put exactly like in the article when Fermi Paradox is discussed, or if it indeed was my own conclusion.

I must say that I believe this idea also fuels my skepticism of life being common and intelligence being inevitable.

Also, it seems much more convincing that biochemistry or evolution is a common theme, and 'Great Filter' than something societal of psychological about civilizations. One would think the latter would have extreme diversity. I don't see evolutionary convergence in the nature or psychology of intelligent civilizations.

 

[PWiz]

I think this is a good article. I had come to this conclusion myself, though I don't remember if it is commonly put exactly like in the article when Fermi Paradox is discussed, or if it indeed was my own conclusion.

I must say that I believe this idea also fuels my skepticism of life being common and intelligence being inevitable.

Also, it seems much more convincing that biochemistry or evolution is a common theme, and 'Great Filter' than something societal of psychological about civilizations. One would think the latter would have extreme diversity. I don't see evolutionary convergence in the nature or psychology of intelligent civilizations.

This seems especially convincing when one thinks that the habitable epoch occurred just a few million years after the big bang, and that there has been AMPLE time for at least a few thousand species of organisms - taking the lowest of estimated values possible - to form out of uncountable potential chances, and the Earth can most definitely not be the only place to support life (it's almost been 13.87 billion years now - is it fair to say we are the only ones?). Yet there is no trace of extraterrestrial organisms around us (or so we think). Maybe their presence is very well regulated by some "intergalactic organization," maybe we are in a remote rural corner of the galaxy, or maybe we are too irrelevant at this point to be bothered with. But that's enough speculation. Whatever the case might be, we would certainly benefit from the knowledge that self-destruction could be a very probable fate for humanity if countermeasures are not enforced in time.

 

[Chronos]

One worrisome aspect of the 'Great Filter' concept is the destructive potential of ready access to exotic technology. One 'martyr' might be all it takes to end a sufficiently advanced civilization. Even a civilization that merely suffers technological 'recession' might be doomed to repeat the same mistake in perpetuity. What might human civilization look like if nukes the size of a cell phone were easily constructed? - not to mention the kind of technology that might become available in the future. It does not appear altruism is a trait that evolves in lock step with technology on this planet.

 

[DaveC426913]

Umm...isn't there a little bit of a conflict of interest here?

It's like Schwinn or Trek telling investors that bike ridership numbers are surely going to explode.

How is that a conflict of interest? Everyone has the right to flog their own livelihood.

 

[RaulTheUCSCSlug]

It is interesting to see the start of the long long journey that this will start, but sad that I firmly believe that we won't be sending out any probes any time soon.

 

[PWiz]

One worrisome aspect of the 'Great Filter' concept is the destructive potential of ready access to exotic technology. One 'martyr' might be all it takes to end a sufficiently advanced civilization. Even a civilization that merely suffers technological 'recession' might be doomed to repeat the same mistake in perpetuity. What might human civilization look like if nukes the size of a cell phone were easily constructed? - not to mention the kind of technology that might become available in the future. It does not appear altruism is a trait that evolves in lock step with technology on this planet.

I disagree. I think the 'Great Filter' is something more than just self-destruction because of deadly technology. If formation of life itself or the progress from prokaryotes to eukaryotes is not the Great Filter (i.e. formation of complex organisms is common throughout the universe), then you'd expect at least a few civilizations to have escaped the fate of self-destruction and become dominant in the galaxy. Yes, many might have pulled the curtains on their own show, but some would have survived out of chance. It also seems very improbable that advanced organisms would constrict themselves to their planet of origin. Looking all around, we see that life has a tendency to spread out, and colonization would only increase the survival chances of a civilization.

No, there is something more to the filter, something more sinister...

 

[Monsterboy]

Well, I also believe that dolphins could certainly evolve and surpass us (maybe even already have) in intellegence. However, without any means to affect their environment ie make tools, fire, metallurgy, history via the printed page etc. they will be forever constrained to the oceans. They could not develop any technical civilization and therefore not make themselves known nor travel anywhere off the globe.

If our Earth had no protruding land mass so to speak, dolphins would be at the top of the evolutionary ladder and remain at their technological level for eons ie Zero technology. Similar creatures on other worlds could never really make themselves known nor travel off of their planets either.

Hmmm ...i don't think so
If any species gets intelligent enough to recognize the need of tools to increase their chances of survival and make their work easier ,they will try to build tools by whatever means that are available ,after being subjected to natural selection ,they will eventually evolve body parts that will help them build better and better tools ,you think all our hominid ancestors and those before them had such flexible thumbs like ours? No.

 

[Jimster41]

Man, what a time to be alive... If they do.

I read this guy Chaisson (Harvard, Tufts) and his proposal is that complexification, is driven by the expansion of the universe and the laws of thermodynamics (toward nucleosynthesis and abiogenesis?) His writing left me with a sense that complex emergent replicating systems are probably ubiquitous. The physics is aimed at them. I believe we will find it in our solar system. I'd bet a sixer on it. In fact someday I think we'll look back and be embarrassed we thought we were remotely rare, or at least that the biochemistry of life was rare. We'll realize we are just mobile and chatty, for garden variety replicating slime.

The problem is distance. Distance is possibly the punchline to a very cruel joke.

 

[PWiz]

Man, what a time to be alive... If they do.

I read this guy Chaisson (Harvard, Tufts) and his proposal is that complexification, is driven by the expansion of the universe and the laws of thermodynamics (toward nucleosynthesis and abiogenesis?) His writing left me with a sense that complex emergent replicating systems are probably ubiquitous. The physics is aimed at them. I believe we will find it in our solar system. I'd bet a sixer on it. In fact someday I think we'll look back and be embarrassed we thought we were remotely rare, or at least that the biochemistry of life was rare. We'll realize we are just mobile and chatty, for garden variety replicating slime.

The problem is distance. Distance is possibly the punchline to a very cruel joke.

You do realize that if we find life not as complex as humans, it would spell danger for us, right?

 

[Jimster41]

Yeah, I think I buy that. It would probably be nice if we could spot them before they spot us...

 

[PWiz]

Erm, that's not exactly my point . Did you read the article in post #22?

 

[Monsterboy]

http://www.universetoday.com/113153/is-our-solar-system-weird/

Other stellar systems don’t seem to have the division of small rocky planets closer to the star and larger gas planets farther away. In fact, large Jupiter-type planets are generally found close to the star. This makes our solar system rather unusual.

Computer simulations of early planetary formation shows that large planets tend to move inward toward their star as they form, due to its interaction with the material of the protoplanetary disk. This would imply that large planets are often close to the star, which is what we observe. Large planets in our own system are unusually distant from the Sun because of a gravitational dance between Jupiter and Saturn that happened when our Solar System was young.

According to this article and a documentary i saw on discovery ,if we want to find life supporting planets in other star systems ,we need to find a weird solar system just like like our own where the gas giant (in our case Jupiter) is not too close to the sun indicating that it did not gobble up all the matter meant for inner rocky planets during the early days of the formation of solar system and allowed 2 or 3 rocky planets to exist between itself and it's star.

Without Saturn's intervention Jupiter might have gobbled up all the matter meant for inner planets i.e mercury,venus,earth and Mars would not exist ! This happens to be the case with most of the solar systems that we have spotted i.e a large gas giant orbiting close to it's star.

The movie "Avatar" offered an alternative theory of life evolving on a moon orbiting a gas giant.

 

[PWiz]

http://www.universetoday.com/113153/is-our-solar-system-weird/
According to this article and a documentary i saw on discovery ,if we want to find life supporting planets in other star systems ,we need to find a weird solar system just like like our own where the gas giant (in our case Jupiter) is not too close to the sun indicating that it did not gobble up all the matter meant for inner rocky planets during the early days of the formation of solar system and allowed 2 or 3 rocky planets to exist between itself and it's star.

Without Saturn's intervention Jupiter might have gobbled up all the matter meant for inner planets i.e mercury,venus,earth and Mars would not exist ! This happens to be the case with most of the solar system that we have spotted i.e a large gas giant orbiting close to it's star.

The movie "Avatar" offered an alternative theory of life evolving on a moon orbiting a gas giant right.

There's some evidence of life evolving in interstellar gas clouds under the presence of strong e.m. radiation. The asymmetric presence of amino acids on Earth (the left handed "bias") is also predicted to occur in these gas clouds when circularly polarized ultraviolet radiation is absorbed by different degrees by the chiral amino acids. Right handed amino acids have a higher peak absorbance for UV light, causing a greater proportion of them to be degraded by photolysis. However, for this enantioselectivity to occur, the band of polarized radiation must be small. Nevertheless, this mechanism provides some ground to assume that life doesn't necessarily need to begin on a rocky planet.

 

[Jimster41]

Just went back and read it. I've read just about everything by Alistair Reynolds. Some chilling (but also beautiful) stuff. In one (I can't remember which), humanoid life itself is considered a plague and a race of "Inhibitors" has set traps for it all over the place. We think they are pretty, and curious.

If everyone thinks it's better that we hide out, okay. But that seems existentially problematic also. For my part, I do like to think that the evolutionary principles of cooperation and symbiosis are also likely to propagate. Maybe that's Pollyanna, on the other hand fear is a defense mechanism, important surely, but also a potential barrier to thought and action.

 

[mfb]

You do realize that if we find life not as complex as humans, it would spell danger for us, right?

That is a very strong statement. It lowers our estimate of the probability that we will ever colonize the galaxy - especially if that life is quite complex (so it took more steps). It does not mean we would be doomed - there could be many inhabitated planetary systems if interstellar colonization turns out to be too difficult.

@Monsterboy: I don't see where they get that conclusion from, but the fact that they do not seem to account for observation bias indicates a poor quality of the article. Most gas giants we know are close to the star - simply because they are much easier to detect there. Finding a hot Jupiter is quite easy, finding a true Jupiter-analog is very hard (there are just a few stars where we would have found a planet like Jupiter). All those rocky Kepler planets could have gas giants further away.

 

[PWiz]

@mfb If complex life is discovered, it will be proof that the formation and evolution of life to complex levels is not uncommon (if we are able to find it in just another decade, then that means life was in close proximity to us, and considering the size of the observable universe, I would attribute this to a very high 'life' density). This would suggest that some very strong factor has prevented all such species formed in the past from evolving and reaching the level of development that would enable them to colonize the galaxy (we don't see them here right now), and since we're talking about a timescale were a million years amount to a sneeze, this is tantamount to saying that humans too must go through the same rigorous barrier, and there is no reason to assume we will succeed where most probably thousands have failed.

 

[mfb]

I know that argument, there is no need to repeat it. "Staying within the planetary system forever" is one sort of "fail to colonize the galaxy" - but certainly not the worst way to fail.

And this filter does not have to exist - we could be the first to start colonizing. The likelihood of that depends on several parameters that are poorly known.

 

[PWiz]

I know that argument, there is no need to repeat it. "Staying within the planetary system forever" is one sort of "fail to colonize the galaxy" - but certainly not the worst way to fail.

And this filter does not have to exist - we could be the first to start colonizing. The likelihood of that depends on several parameters that are poorly known.

Are you saying that was no habitable epoch? That in 13.8 billion years we are the only species to have come this far? A failure at galactic colonization of one specied can only delay the inevitable success of some other species. Five thousand years ago we were living in caves, and today we have GPS satellites out in space. I'm not entirely convinced by your argument.

 

[mfb]

Are you saying that was no habitable epoch?

No. But it certainly did not start a few million years after the big bang - long before the first stars formed, and even longer before the concentration of heavier elements from supernovae was sufficient to create planets like earth? A few billion years could be more realistic.

That in 13.8 billion years we are the only species to have come this far?

Let's say "within our galaxy". Well, can you rule it out?

Five thousand years ago we were living in caves, and today we have GPS satellites out in space.

And in five thousand years we could have extrasolar colonies. Finding other species capable of radio transmissions would indeed make this very unlikely, finding some photosynthesis happening somewhere does not.

 

[PWiz]

And in five thousand years we could have extrasolar colonies.

Exactly. Following your chain of reasoning/speculation that we could be one of the first intelligent species in the universe, I would say that it's very likely many other intelligent organisms formed in our galaxy around the same time. From such a large sample space, there would be so many who would have evolved to our current stage a few (hundred) thousand years before us (and that's not a lot on cosmological timescales). If 5 thousand years can make so much of a difference in development, then shouldn't there be a swarm of species beating us by leaps and bounds in technology? Even interstellar travel should be a piece of cake for them. This again doesn't answer why we don't see extraterrestrials all around us.

 

[mfb]

I would say that it's very likely many other intelligent organisms formed in our galaxy around the same time.

That looks like pure speculation to me.

Even interstellar travel should be a piece of cake for them.

And that as well.

 

[Monsterboy]

I don't see where they get that conclusion from, but the fact that they do not seem to account for observation bias indicates a poor quality of the article. Most gas giants we know are close to the star - simply because they are much easier to detect there. Finding a hot Jupiter is quite easy, finding a true Jupiter-analog is very hard (there are just a few stars where we would have found a planet like Jupiter). All those rocky Kepler planets could have gas giants further away.

So ,even if we come across a solar system exactly identical to ours which 10 or 20 light years away ,we will not able to detect either the Earth-analog or the Jupiter-analog ?

If gas giants as big as Jupiter can't be found because they are a little far away from their star ,then how did we find kepler planets or super Earth's ? these are quite small compared to the gas giants right? and they not very close to their star either.

 

[PWiz]

@mfb Us being the first and only intelligent organisms to develop in the galaxy does not seem very probable either. Where are you getting at?

On 4 November 2013, astronomers reported, based on Kepler space mission data, that there could be as many as 40 billion Earth-sizedplanets orbiting in the habitable zonesof Sun-like stars and red dwarfs in the Milky Way,[4][5] 11 billion of which may be orbiting Sun-like stars.[6] The nearest such planet could be 12 light-years away, according to the scientists.[4][5]

Doesn't seem far from speculation. I mean only one planet with intelligent life in 40 billion?
And is it fair to rule out what can and cannot be achieved in thousands of years when we don't know what the next century might hold for us? In the early 1800s, scientists would laugh at you if you talked about sending a man-made object on Mars. I think the only thing about the future which we should be sure of is not to be sure about anything.

 

[rootone]

The fact remains though, that although Earth-like planets in a Sun-like solar system and within 100 ly seems a reasonable prospect,
and some such planets could provide a habitable environment, we have not yet discovered any sign of life, let alone intelligent life.
To me this implies that having the right conditions for life to survive, does not imply that life inevitably must arise.
There has to be some particularly rare circumstance which allows for a crucial step in abiogenesis to occur.
Hand-wavey guess here - that rare circumstance is whatever it takes to produce a simple self replicating molecule, and sufficient resources in the environment for the replication to actually occur.

 

[Astudious]

@mfb If complex life is discovered, it will be proof that the formation and evolution of life to complex levels is not uncommon (if we are able to find it in just another decade, then that means life was in close proximity to us, and considering the size of the observable universe, I would attribute this to a very high 'life' density). This would suggest that some very strong factor has prevented all such species formed in the past from evolving and reaching the level of development that would enable them to colonize the galaxy (we don't see them here right now), and since we're talking about a timescale were a million years amount to a sneeze, this is tantamount to saying that humans too must go through the same rigorous barrier, and there is no reason to assume we will succeed where most probably thousands have failed.

Clever argument but the flaw, as I see it, is that humanity has almost certainly passed this barrier way behind.

If the fruition of life is common (or at least reasonably probable) then we can suppose it likely that the emergence of complex and (ultimately) intelligent and advanced life is itself highly uncommon, simply by observing the number of species which fail to make it to any kind of high degree of complexity. Then the extraordinary event that has occurred to place us in front of our computers today is not abiogenesis on Earth (which we have suggested here, is not that extraordinary) but rather that we developed from the simplistic biochemical machines that barely constitute "life" into the evolved emergent, highly-complex products we are. The barriers to this occurring are (in my opinion almost certainly) in the first steps of complex growth; once complex physiology/biology gets well underway, evolution takes over and from there a highly-intelligent species seems almost certain to arise.

Therefore, finding life less complex than humans is just a sign that the really-rare event on Earth is the formation of highly-complex life here.

If we were to find traces of several civilizations as complex as ours that failed to make it further, that would corroborate your point. But think about how unlikely that is!

I myself am, by the way, not of the opinion that complex growth of life is truly the extraordinary step but rather than abiogenesis is itself (but this is fairly unsubstantiated by scientific standards of evidence, just speculation).

 

[Astudious]

I know that argument, there is no need to repeat it. "Staying within the planetary system forever" is one sort of "fail to colonize the galaxy" - but certainly not the worst way to fail.

Interesting. Population growth could cause serious problems at that point, and it doesn't seem as far off into the future necessarily as being able to travel to and easily colonize other solar systems. May this will be the end of the human race?!

Somehow, I find it unconvincing that other lifeforms were stopped at the same place. :P

 

[PWiz]

@rootone I think drawing any conclusions at this stage would be premature considering the fact that we haven't even fully explored the Martian surface yet, let alone any other planet in the solar system. My entire argument is based on "if NASA finds life by 2025."
@Astudious Evolution is like a wheel on top of a very tall hill. It's difficult to get the wheel rolling, but once it does, it will definitely lead to more complex organisms over time (even though it's random). One of the "hiccups" to the evolution of intelligent species like us (other than the formation of primordial life itself) is the transition from unicellular prokaryotes to multicellular eukaryotes (if I remember correctly, it nearly took a billion years for this transition to occur, and life on Earth itself is just about 3.5 billion years old; the longer the transition period, the greater the probability that the transition was unlikely and rare). I guess I should clarify: by discovering complex organisms, I mean discovering a "composite" organism - a collective group of structures (cells) in which the chemistry of life occurs, functionally related to each other, but fundamentally distinct (or something along those lines; you get the idea). Now that would be proof that formation of life to that level of complexity is not rare, and we have extremely few likely candidates left for "The Great Filter" which would stop the wheel from rolling towards levels of intelligence comparable to humans, since we don't have any other period of evolutionary stagnation worth mentioning on this timescale. It would be a sign that the filter is ahead of us intead, and that wouldn't be a very pretty scenario.