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

[mheslep]

Life sprang up on Earth almost as soon as it became habitable - like a billion years after it formed.

But how common is a habitable planet? Stable star, small habitable zone from the star, water, big moon to stabilize rotation orientation, outer gas giants to collect space junk, outside of galaxy to avoid super energetic phenomenon. Who's to say these conditions can not be less than one in a hundred million stars, i.e. once per galaxy, perhaps once per universe.

 

[mfb]

Stable star, small planet in the habitable zone, in the right distance from the galactic center: that's still in range of a billion. We'll learn more about gas giants in the next 10 years, and hopefully more about water as well. Moon-sized moons are ... tricky.

 

[mheslep]

"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.

Not precursors, but life itself? Sounds hopelessly arrogant to make such a prediction.

 

[Chronos]

A planet virtually identical to Earth [same 'big' moon, iron core, water, gas giant buddies, etc.] could be exceedingly rare - possibly on the order of 1 per galaxy, although I view this as probably a bit pessimistic based on the principle of mediocrity.

 

[Snerdguy]

Please give a source for that claim.
Life on Earth has been around for 1/3 of the age of the universe, and did not end yet. I would not call this "very short".

"Life is inevitable." has been said by many people in many ways for quite some time now. But here is one detailed explanation:
https://www.quantamagazine.org/20140122-a-new-physics-theory-of-life/

Life on Earth has come and gone and come back again a few times but for a few simple organisms. It's still not that long relevant to the age of the universe. I suppose it will always be a subjective observation though.

 

[mfb]

But here is one detailed explanation:

See the article:

His idea, detailed in a recent paper and further elaborated in a talk he is delivering at universities around the world, has sparked controversy among his colleagues, who see it as either tenuous or a potential breakthrough, or both.
[...]
"Jeremy’s ideas are interesting and potentially promising, but at this point are extremely speculative, especially as applied to life phenomena"

... and so on.

Life on Earth has come and gone and come back again a few times but for a few simple organisms.

There is no evidence of multiple independent events where life emerged from non-living things. All known life on Earth has a common origin. To our knowledge it was never "gone", although it had some hard times in between.

 

[Jimster41]

I think the playah is right. But I'm looking forward to learning what the new part is, because these ideas have been around a good long time. I encountered them 15 years ago in Prigogine, Chassion, Dawkins, Schroedinger, and others.

Some others...
http://arxiv.org/abs/0907.0042
http://www.earth-syst-dynam.net/2/37/2011/esd-2-37-2011.html

 

[Torbjorn_L]

I guess this discussion is mostly over, but since I am intensely interested in astrobiology I will make some quick notes.

- NASA's intent.
NASA, together with astronomers, are pushing for a new generation of large telescopes, here space telescopes. The observational constraint is that if life is likely, they can observe it soon. If not, they can start to constrain its likelihood from above.

- Search for life.
Besides the search for inhabited planets in the radiative habitable zone, we will eventually need to investigate many or most of our system's tidal habitable zones (ice moons). Because a) they constitute the perhaps largest type of biosphere volume, and because b) we can't observe a frequency of biosignatures elsewhere.

- Likelihood for life.

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

Until we have expanded our knowledge of life beyond a sample size of one, such speculations are interesting, but barely constitute science.

Nothing happens 'only once' in a sufficiently large universe, because the permutations among a finite number of particles in a finite observable universe is finite, see e.g. Tegmark.

But that isn't interesting, because we are restricting severely as in everyday life, "if that hadn't happen I wouldn't have ...".

What is relevant here is that emergence of life is a result of a process. And processes that result on the order of one ( zero, one, a few) events would be very finetuned.

The statistics of emergence do constitute science (and shows that emergence is a process; but see also below). See e.g. Lineweaver on how to do statistics here. Loosely, the rapid emergence we observe allows us to claim that the process is likely on at least the order of ~ 10 %/billion years.- Fermi's Question and the Hart-Tipler Conjecture
When we read "Fermi's Paradox" we see the result of a political process. Fermi asked the question "where are they" and answered that space travel and habitability cartography is difficult. (Which they are.)

[ http://www.universetoday.com/119735/beyond-fermis-paradox-ii-questioning-the-hart-tipler-conjecture/ ]

- Emergence of life.

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

They offer plausible partial pathways, but there is nothing like a cohesive, demonstrable route from non-life to life.

We have no idea how abiogenesis happened. ... We struggle to deliberately make synthetic life de novo when we can do so much in both biochemistry and molecular biology.

Cosmologists have not demonstrated how to make a universe within a lifetime in a lab. Yet we study the emergence of the universe.

Evolutionists have not demonstrated how to make whales within the lifetime in a lab. Yet we study the emergence of whales from land living ancestors.

So what do we know, and what do we need to test?

- We know that there are a number of trait homologies between geophysical systems of Hadean and modern cells. So we know the generic phylogenetic tree as much as we know other generic trees of similar complexity. (We also know emergence is a result of a process, first growth of the geophysical systems that it happened in, then evolution after self-replicators emerged.)

- There were also obvious constraints that were in tension with those observations. But whether you adhere to the "pure" RNA world (RNA protocells) of Szostak et al or the "dirty" RNA world (RNA vents) of Russell et al, the last 5 roadblocks I know of fell in the last year. (I have a referenced write up, but it is too long for a PF comment.)

- What remains is to test the two main pathways sufficiently.* This has been ongoing for, oh, a decade now, and it seems astrobiologists expect it will take a few more decades. I'm frankly surprised that people persist in claiming that there are observational problems.

*Meanwhile, if you want to do research strategy, the bottom-up pathway of Szostak is as simple as possible while the top-down pathway of Russell is as complex as the phylogeny constraints makes it. Ironically, or rather consequentially, that translates to the largest prior for Szostak but the largest posterior for Russell. So if I was into betting...

 

[Torbjorn_L]

Also, re thermodynamics of England, I would rather look at Russell, Pascal and Pross here. Especially the former group that are ore empirically based, and locate some problems of the latter two. (They claim that a photophile "soup" is necessary for emergence of replication. That is likely wrong, as any PCR reaction - if it can use metal atoms - can tell us.)

But, yes, emergence of life is a thermodynamic opportunity as a terrestrial planet cools. It extends the conversion of CO2 into CH4 into lower temperatures, maximizing entropy production if it happens.

 

[Jimster41]

@Torbjorn_L I would be interested in links to the research you mention.

It sounds like you are coming from the biology side. There is a thread discussing the plausibility of the physics (thermodynamics of emergence, complexity) over in the cosmology forum (where some might argue it is out of place). As I mention in that thread this seems to be a particularly cross disciplinary topic. To my thinking the synthesis it proposes between the basic physics of matter and energy, and the "life sciences" is one of its explanatory strengths.

https://www.physicsforums.com/threads/why-are-there-heat-engines.809331/page-2#post-5082768

 

[mfb]

What is relevant here is that emergence of life is a result of a process. And processes that result on the order of one ( zero, one, a few) events would be very finetuned.

That "one" does not have to be an absolute number. "One per galaxy", "one per size of the observable universe" or even "one per 10¹⁰ times the volume of the observable universe" are perfectly in agreement with observations. If the universe has infinite size, you don't get a lower limit at all - no matter how unlikely life is it would emerge somewhere, and then ask how likely that was.

Loosely, the rapid emergence we observe allows us to claim that the process is likely on at least the order of ~ 10 %/billion years.

If life would have appeared a billion years later, we would not exist to ask how likely life is. If you require intelligent life to evolve (which you should in those kind of arguments), life on Earth did not start surprisingly early.

 

[GoMario]

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...

You are so damn right. I absolutely agree with you. Everybody in here assumes that humans are the final step in evolution. I disagree. Human Intelligence is but one step on the evolutionary scale. I don't know how many steps there are but for me at least, humanity is not the final step. Not by a long shot. Just think a bit about this. Do you understand the repercussion thereof? I pondered for years about this. 2/3 of the material in the universe is completely unknown to us. We call it 'dark matter'. Intelligence is such a powerfull concept. Natural evolution might very well be about Intelligence. Given enough intelligence one can change matter in a much more complex and powerfull way then gravity can. The invention of a 'brain' more intelligent then the inventors, will be the last invention of everything and everybody in our world as we know it! And I think, humanity is closing in on this feat. And even more: I think that this step is an unavoidable one! Every civilization has to encounter it. After that, civilization as we know it ceases to exist. This is a very common step for all civilizations all over the entire universe. This explains soooo many things and paradoxes including space travel by aliens and absence of extra terrestrial radio signals on their part. But it also says something about us and our future. For example: The year 2200 as we know it, will never come. The Startrek movie will remain just that - a movie. For ever.

 

[mfb]

And even more: I think that this step is an unavoidable one! Every civilization has to encounter it. After that, civilization as we know it ceases to exist.

There are civilizations that went extinct without inventing something more intelligent. The whole human species could have gone extinct in the past if things had been a bit different.
Also, where are those more intelligent things?

 

[Jimster41]

That "one" does not have to be an absolute number. "One per galaxy", "one per size of the observable universe" or even "one per 10¹⁰ times the volume of the observable universe" are perfectly in agreement with observations. If the universe has infinite size, you don't get a lower limit at all - no matter how unlikely life is it would emerge somewhere, and then ask how likely that was.
If life would have appeared a billion years later, we would not exist to ask how likely life is. If you require intelligent life to evolve (which you should in those kind of arguments), life on Earth did not start surprisingly early.

No doubt, we presently have nothing but thundering silence.
I think the incremental encouragement that the theory of life as "just another complex dissipative system" provides is that it places the mechanism by which life occurs... right in the middle of the action, as an expected result of the second law - which is, fundamentally everywhere, rather than as an anomaly - the improbable outcome of some improbable process to begin with. It's small comfort, but an improvement No? And it doesn't have to prove there are aliens, to provide that incremental encouragement, It just has to prove the process that created us is... not rare.

 

[Chronos]

It's not a huge stretch to imagine our galaxy could already be colonized by synthetic, self replicating organisms [i.e., nanobots] - which could be insanely robust and utilize almost any available resource in almost any conceivable environment. Would they offer an endless supply of facilities, resources, and transport, or a risk of developing 'enlightened self interest' over time? Would a biologic sentient deploy a technology with a potentially insurmountable competitive advantages over any biologic it encountered [including those of its home world]? I suspect humans would be unable to resist the temptation. Perhaps the saving grace is interstellar space is too hostile for even superbugs to endure for long periods of time. Perhaps there is some logic behind NASA's use of contamination protocols.

 

[Jimster41]

Sci if book I read (I have looked for it twice now) that has stuck with me, though I can't recall the title, portrayed Earth as invaded from within its own biosphere by a blight of alternative physical chemistry, akin to prions, but affecting everything. The only weapon was cold. We lost and had to watch from Mars as eventually, from the now hostile raw material, an entirely new flora and fauna emerged. Kindof "ice nine"-ish. The unanswered question was whether it was something we created...

 

[GoMario]

There are civilizations that went extinct without inventing something more intelligent. The whole human species could have gone extinct in the past if things had been a bit different.
Also, where are those more intelligent things?

Yes, some civilizations might go extint along the evolution ladder but the majority make it to the end stage. Yes you are right, the human species could have gone extint if 'things were a bit different'. But it did not EXACTLY because things are not 'a bit different' ! If the basic laws and ratios among sub atomic particles in the universe were just a bit different, the entire universe as we know it, would have not existed. As for your last question ~ if you ask that than you did not grasp the idea. You do not understand the concept. But I don't blame you. Took me years to get around it. I do not expect anybody to 'digest it' in mere minutes. I will try to help you with 'down to earth' analogies. And the best one is to imagine the next stage as "God like" . Intelligence will be sort of like God is (for the believers). Infinitely powerfull, everything, everywhere at every time. That happens because the rules of the world as we know it, brake down! "Those more intelligent things" are not part of 'this world' anymore! It is the end for 'our world'. It is a new beginning for theirs. A totally new world with new laws (where intelligence rules) . The ascension to this new world is happening to all civilizations, all over the Galaxy/Universum. We (any civilization for that matter), advance technologicaly in an exponential way (more or less). Exponential functions/graphs, are notoriously difficult to recognise as such until the very end. Until the curve 'shoots up'. And humanity is nearing the flexion point of the graph. Another 100 years perhaps? If not our children, our grandchildren might live to see the day.

 

[mfb]

Yes, some civilizations might go extint along the evolution ladder but the majority make it to the end stage.

There is no evidence for that.

But it did not EXACTLY because things are not 'a bit different' !

We just see selection bias. If we would be extinct we could not discuss here. That does not mean the evolution of similar species elsewhere would be necessary.

You do not understand the concept.

I don't think you are able to judge that based on my posts.
I do not understand the concept of making claims without references, observations or logic backing them up in any way.

 

[GoMario]

There is no evidence for that.
We just see selection bias. If we would be extinct we could not discuss here. That does not mean the evolution of similar species elsewhere would be necessary.
I don't think you are able to judge that based on my posts.
I do not understand the concept of making claims without references, observations or logic backing them up in any way.

The absence of evidence is the evidence. Well, the logic is there but one needs Intelligence to see it. Never mind. You still think 'in the box'.

 

[D H]

Yes, some civilizations might go extint along the evolution ladder but the majority make it to the end stage.

You don't know that. That is pure conjecture on your part.

Even extrapolating from a sample size of one (humanity), you can't say that. Look back at humanity's past. Most civilizations have lasted but a few hundred years and then they collapsed. Some were reborn, some multiple times, only to collapse, again and again. A couple of examples: Two thousand years before the Portuguese rounded Africa, the Phoenicians did the same. Where is Phoenicia today?

Fifty years before the Portuguese rounded Africa, the huge Chinese treasure fleet, led by junks that dwarfed any and all European ships of the time, were sailing all over the western Pacific and Indian Oceans. Then court intrigue and philosophy struck. In less than one hundred years, China had turned inward, so very inward that it became a capital offense to own or work on a junk with more than two masts.

There are lots and lots of examples of human civilizations that rose and fell.

Using a different sample size of one (the Earth), you still can't say that. A number of species has developed near-intelligence. Only one has developed the capability to escape the Earth, to communicate with nearby beings from other planets (if they exist). Our species is the only one that hasn't gotten caught in a Filter of some sort or the other, and we don't know if there are more Filters to come.What we do know is that we appear to be alone (so far). Is this lack of evidence evidence of lack? Not yet, but if lack of evidence is all we see for decades to come, it will be evidence of lack. Right now, we don't know, one way or the other.

 

[D H]

Given that this thread has degenerated into base speculation, I am closing it for now.