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

[mfb]

Life is inevitable. [...]The environmental conditions and chemical reactions that bring about life happen frequently

Please give a source for that claim.

But, the period of time this planet supports life is going to be very short in comparison to galactic time.

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".

 

[Jimster41]

In my post 67, Chaisson, from Harvard Smithsonian Center for Astrophysics, who I believe was intimately involved with SETI - (in fact the paper referenced there was related to a talk he gave to SETI researchers) I'm pretty sure would agree that the physical conditions that drive the formation of complex biological systems are a direct result of the expansion of the universe and the 2nd Law, and as inevitable. It is the premise of much of his writing - and is outlined in the reference paper There are references in the paper that are likely relevant.

 

[Jimster41]

Here's figure from the paper, with caption:Figure 1 – Energy rate densities for a wide spectrum of systems observed throughout Nature display a clear trend across ∼14 billion years as simple primordial matter changed into increasingly intricate, complex systems. The solid black curve implies an exponential rise in system complexity as cultural evolution (steepest slope at upper right) acts faster than biological evolution (moderate slope in middle part of curve), which in turn surpasses physical evolution (smallest slope at lower left). The shaded area includes a huge ensemble of energy rate densities as many varied types of complex systems continued changing and complexifying since their origin; the several dotted black curves delineate notable evolutionary paths traversed by the major systems labeled. The energy-rate-density values and historical dates plotted here are estimates for specific systems along the evolutionary path from big bang to humankind, namely, our galaxy, star, planet, life, and society, as compiled in the bubble inserts (Chaisson 2014b). Similar graphs likely pertain to extraterrestrial life-forms, as all complex systems fundamentally hark back to the early Radiation Era, evolve throughout the Matter Era, and potentially enter the Life Era (left to right across top).

 

[mfb]

That does not look like mainstream science.

 

[Jimster41]

@mfb I'm genuinely interested that you would say that. But I'd be appreciate a more specific justification of that claim.

http://en.wikipedia.org/wiki/Eric_ChaissonIf projecting Evolution through "Society" is discomforting... I recommend this one:

https://www.amazon.com/dp/0262600692/?tag=pfamazon01-20

A link to more info about Prof Jablonka. I'm only about halfway through that one. It's quite dense. But very good.

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

 

[mfb]

@mfb I'm genuinely interested that you would say that. But I'd be interested in a more specific justification of that claim.

Which claim?
"Person A says X" means at least one person says X, but it does not make that idea mainstream.

You can make log-scale plots of everything, that does not mean there would be some deeper connection between the plotted curves. And it certainly does not mean all those curves would have to exist at all.
US funding of science correlates with deaths from hanging, strangulation and suffocation
Divorce rates are linked to margarine consumption?
Age of Miss America is linked to Murders by steam, hot vapours and hot objects?

Also, the plot is a completely arbitrary selection with questionable values. Supernovae do not fit in at all, stars are not represented accurately there, and various other objects would have curves that do not follow the plotted pattern at all.

 

[Jimster41]

Just in case you didn't drill through...

I just want to be clear. This is not mainstream...?

Eric Chaisson
From Wikipedia, the free encyclopedia

[...] (removed by mfb, see below)

 

[mfb]

Please do not copy Wikipedia articles like that, that violates copyright. I removed the 1:1 copy.
Mainstream researchers can hold views that are not shared by the majority. That does not mean those views have to be wrong, but it is good to be skeptical (and if the opinion is not mainstream, that's exactly what is happening).

 

[Jimster41]

Sorry for plagiarizing wiki.

 

[Almeisan]

Ugh, this went ugly.

Mainstream opinion is historically known to be wrong a lot of the time.
Disregarding science because it does not look 'mainstream' is wrong. Any new discovery is not going to be mainstream when it is first discovered/proposed.
Apparently that guy is a 'mainstream scientist', the work discussed is in his field, it is not like he is publishing in something he wasn't trained.
If his crazy idea is 'wrong', and most cracy ideas are, it should be pointed out in a scientific debate. Crazy ideas proposed by trained scientists putting out thorough new ideas being examined closely by peers is how science moves forward. If tomorrow everyone stopped proposing new ideas, science is dead.

And wikipedia articles are not copyrighted. All you need to do is put a link to wikipedia and indicate any changes you made.

 

[Jimster41]

Ugh, this went ugly.

Mainstream opinion is historically known to be wrong a lot of the time.
Disregarding science because it does not look 'mainstream' is wrong. Any new discovery is not going to be mainstream when it is first discovered/proposed.
Apparently that guy is a 'mainstream scientist', the work discussed is in his field, it is not like he is publishing in something he wasn't trained.
If his crazy idea is 'wrong', and most cracy ideas are, it should be pointed out in a scientific debate. Crazy ideas proposed by trained scientists putting out thorough new ideas being examined closely by peers is how science moves forward. If tomorrow everyone stopped proposing new ideas, science is dead.

I appreciate the job the moderators are trying to do. I can understand that PF has a pretty tough problem in trying to provide a stable lucid source of reference for participants, like me who are coming from all angles, bringing confusion, and being confusing. A conservative perspective is reasonable. And I'll own up to the fact I have been influenced by the writings of this guy (no-one to blame but myself). I've come to realize how much recently, largely due to conversations I've had here, and so I'm revisiting my understanding from as many angles as I can find. Frankly, I had sort of assumed his ideas were widely accepted. So I have to be open to the realization that may not be true.

That said, I like the way you put it... and so far his thinking seems particularly "right" in my travels... partly because it is so gestalt. And as I am reading his second book... I am finding it even more, interesting, and frankly, lucid. One thing I like about him, he's not afraid to ponder and talk about the squishy side of things, biology, history, society, culture etc. In other words he's a cross-disciplinarian , which is refreshing. Surely an understanding of the world must be consistent with their complex "facticity", if not explanatory.

 

[D H]

That does not look like mainstream science.

Just in case you didn't drill through...

I just want to be clear. This is not mainstream...?

Eric Chaisson
From Wikipedia, the free encyclopedia

mfb was a bit waffly in writing "That does not look like mainstream science". I'll be less waffly: That is not mainstream science.

Just because someone has a PhD does not make what they write mainstream science. Just because they get that writing published in a peer-reviewed journal does not make what they write mainstream science.

There oftentimes are large lags in science between when a concept is first introduced, then refined, and finally accepted as "mainstream". I'll use a specific example, dark matter, to illustrate. Jan Oort and Fritz Zwicky first puzzled over what appeared to be a missing mass problem in the 1930s. Vera Rubin used much better instrumentation in the 1960s and 1970s to show that there was indeed a missing mass problem. The concept of dark matter didn't become mainstream until the mid 1980s or so. A number of people have proposed various solutions regarding what dark matter actually is. While the concept of dark matter most certainly is mainstream science, not one of those proposed solutions is mainstream science.

 

[Jimster41]

I'm good with that Sir. Makes perfect sense.

Is there a policy here I may have missed regarding discussing non-mainstream science. Seriously. I didn't read all the FAQs and rules...

 

[Evo]

I'm good with that Sir. Makes perfect sense.

Is there a policy here I may have missed regarding discussing non-mainstream science. Seriously. I didn't read all the FAQs and rules...

It's at the beginning of our rules.

• We wish to discuss mainstream science.That means only topics that can be found in textbooks or that have been published in reputable journals.

https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/

 

[Jimster41]

I can imagine that the first paper which was based on a talk Chaisson gave to the founders of SETI, arguably doesn't qualify

How about this one... that describes in more detail the derivation of the plot.
https://www.cfa.harvard.edu/~ejchaisson/reprints/unifying_concept_for_astrobio.pdf

A unifying concept for astrobiology
E.J. Chaisson Wright Center, Tufts University, 4 Colby Street, Medford, MA 02155, USA e-mail : eric.chaisson@tufts.edu

Abstract: Evolution, broadly construed, has become a powerful unifying concept in much of science – not only in the biological evolution of plants and animals, but also in the physical evolution of stars and planets, and the cultural evolution of society and its many varied products. This paper (1) explores the bulk structure and functioning of open, non-equilibrium, thermodynamic systems relevant to the interdisciplinary field of astrobiology, (2) places the astrobiological landscape into an even larger, cosmological context, (3) defines life, complexity and evolution writ large, (4) claims that life depends ultimately on the expansion of the Universe and the flow of energy derived therefrom and (5) proposes a quantitative metric to characterize the rise of complexity throughout all of natural history. That metric is neither information nor negentropy, for these inveterate yet qualitative terms cannot be quantified, nor even defined, to everyone’s satisfaction in today’s scientific community. Rather, the newly proposed metric is normalized energy flow, a revision of a long-cherished term – energy – that is physically intuitive, well defined and readily measurable. All ordered systems – from rocky planets and shining stars, to buzzing bees and redwood trees – can be best judged empirically and uniformly by gauging the amount of energy acquired, stored and expressed by those systems. Appeals to anthropism are unnecessary to appreciate the impressive hierarchy of the cosmic evolutionary narrative, including a technological civilization that now embraces an energetic agenda designed to better understand, and perhaps to unify, all the natural sciences. Received 10 June 2003, accepted 24 June 2003Is the "International Journal of Astrobiology" Reputable...?

http://journals.cambridge.org/action/displayJournal?jid=IJA

 

[Evo]

The Journal has been declining since 2011, it's impact factor has dropped to 0.826.

 

[D H]

This is a bit out of order response; I want to address this first remark before I delve into the body of the discussion.

And wikipedia articles are not copyrighted. All you need to do is put a link to wikipedia and indicate any changes you made.

Wikipedia articles most certainly are copyrighted. From http://en.wikipedia.org/wiki/Wikipedia:Copyrights, "The text of Wikipedia is copyrighted (automatically, under the Berne Convention) by Wikipedia editors and contributors and is formally licensed to the public under one or several liberal licenses. "

PF doesn't comply with those licenses. For one thing, we serve ads. For another, when we find some unapproved PF mirror site, we don't approve. In fact, we strongly disapprove.

Our general response to anything that looks remotely like a copyright infringement is to apply surgery. That includes material from wikipedia.

Mainstream opinion is historically known to be wrong a lot of the time.
Disregarding science because it does not look 'mainstream' is wrong. Any new discovery is not going to be mainstream when it is first discovered/proposed.

PhysicsForums primary focus is mainstream science. That's who we are. We've tried, multiple times, to allow and even encourage speculative discussions. The general consensus was that we need a personal theory forum like we need a computer virus. See https://www.physicsforums.com/threa...y-forum-like-we-need-a-computer-virus.765736/.

There are plenty of sites on the internet that take alternate views. You are free to participate in them. You are free to participate both here and at those other sites. All we ask is that you obey our rules at our site, and don't insist we be just like those other sites.

Is there a policy here I may have missed regarding discussing non-mainstream science. Seriously. I didn't read all the FAQs and rules...

You can find the rules in a number of places. At the top right of every PF window, there's a link to "Terms and Rules" under INFO. At the bottom, you can click on ABOUT. Our ABOUT page contains a link to "Terms and Rules", and also other useful information. Finally, at the very bottom, there's a "Terms and Rules" button. We try to make it easy.
Now, back to the main subject.

I've come to realize how much recently, largely due to conversations I've had here, and so I'm revisiting my understanding from as many angles as I can find. Frankly, I had sort of assumed his ideas were widely accepted. So I have to be open to the realization that may not be true.

I would venture that very little of astrobiology has made its way to "mainstream science". Yet. There's too much extrapolating from a sample size of one from within another sample size of one. Only one of the eight planets appears to bear life, and of that life, only one species has developed the capability to escape the planet. There is so much we don't know (yet). What science does know is that what it thought it knew about planet formation 25 years ago has been turned topsy-turvy, and regarding life beyond the the, science knows that it's currently clueless. Most astrobiologists take the "we are clueless" perspective -- and they want to get out of that category.

Saying that "we'll find signs of alien life by 2025" is a bit of an aggressive claim given that cluelessness. Should they look? Absolutely. Will they find something by 2025? Who knows.

 

[mfb]

Mainstream opinion is historically known to be wrong a lot of the time.

Still much less frequent than non-mainstream options.

Disregarding science because it does not look 'mainstream' is wrong.

It is wrong if you do science. We do not do science here! We discuss science. See the forum rules.

And wikipedia articles are not copyrighted.

They are, they are published under the Creative Commons Attribution-ShareAlike 3.0 Unported License and (usually) the GNU Free Documentation License. See Wikipedia:Copyright and Wikipedia:Citing Wikipedia for details. Just adding a link to the article somewhere (which was not present) is not sufficient, and incorrect citations frequently lead to various legal issues (mainly for images).

Can we get back to the topic of extraterrestrial life?

Edit: D H was faster (and more detailed).

 

[D H]

@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?

Doesn't seem far from speculation. I mean only one planet with intelligent life in 40 billion?

What makes you so quick to reject the null hypothesis? Everything we've seen so far (which admittedly isn't much) is consistent with the null hypothesis.

 

[PWiz]

What makes you so quick to reject the null hypothesis? Everything we've seen so far (which admittedly isn't much) is consistent with the null hypothesis.

I don't want to drag this too long, so I'll summarize it real quick.

I'm not jumping to any side. It's all "if this happens, then..." etc.
If we don't find life for a long time, the probability of abiogenesis being rare in the universe continues to grow. If we find traces of complex life which existed in the past (in the coming years), then the probability of some "Filter" existing in the universe grows (since its proves abiogenesis is common but complex life progressing to become an intergalactic species is not). If complex life still in existence is found (intelligent extraterrestrials), then the probability of other complex species existing who have not yet come into our contact grows.

Basically, we don't know how abiogenesis works, and we don't have enough evidence to comment on it right now. I'm keeping all my options open and playing in the probability playground, waiting for something to roll my way. And about the null hypothesis, I don't think our sample space is large enough as of yet to dismiss these things, so in other words, the stamp should read "No correlation observed (subject to change)."

 

[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.