Question for people up to date with modern biochemistry: if there were extraterrestrial microbes on Earth right now, with totally unique chemical origins unrelated to proteins, nucleic acids, saccharides, etc., how likely would we be to notice them? And which analytic method would find them first?
Is there a systemic search for this kind of crazy stuff, and where are the review papers for them? I don't know the keywords!
Very, very unlikely like astronomically so. Most microorganisms are so small they're practically transparent so we have to exploit biochemistry to "stain" them - hence why you'll often hear of bacteria classified as either Gram positive or negative, because of the Gram stain. If the biochemistry is unique or even slightly different i.e. right handed chirality, we'd basically have zero of our usual tools at our disposal.
There's already a whole world of terrestrial microbes that we expect or even know for certain to exist but can't culture, let alone stain, which means we can't really study them. We'd (theoretically) eventually notice them on electron microscopy slides though, which is how we know there's many unculturable microbes, but whether we'd recognize them as alien is a completely different matter. The microbial world is very diverse and there's nothing I can think of that'd set something apart as alien since we can analyze the chemistry with an electron microscope.
Not at all familiar with biochemistry but octopuses are aliens on earth with very different evolutionary track having developed ‘brains’ before our ancestors did independently! It’s crazy we don’t study things like cephalopods like we do SETI etc…
I've always found the framework we use to search for extraterrestrial life to be too based on our own experience. It could take countless forms, most of which we could never recognize or understand, and might be present everywhere without us knowing. I'm glad that more of the science community is pushing to broaden our horizons.
In this I’m at least speculating that Titan might be likely to host alien life in its steamy cryotropical environment. I’d love to see NASA sink a submersible in those methane seas and look for cryowhales. (Or more likely cryobacteria but cryowhales would rule.)
I’d expect life there to be wholly biochemically alien, probably based on methane or ammonia as solvents, and probably very metabolically “slow” compared to most life here. We might miss even macroscopic Titan life without time lapse photography.
To any intelligent Titanians we would look like the Balrogs from Lord of the Rings: burning lava monsters with blood of molten water.
Counterpoint: Alien life will probably look very similar to life on earth. If you look at evolution then countless species have evolved into something crab-like: https://www.youtube.com/watch?v=wvfR3XLXPvw Turns out that their form is pretty good for survival. While biology can take on a myriad of forms, the competitive nature of life will weed out a lot of them. And since the rules for biochemistry are the same across the universe similar traits that are beneficial here will probably be beneficial there.
Even further - not only the development of biological life forms on other planets would totally depend on the circumstances on that planet and create unimaginably variable life forms, but also these very different life forms would develop very different cultures and as a result, very different technologies. So even when we look for radio signals, we are looking for something that totally depends on our own technology, which is the product of our own civilization that is in turn the product of our own culture, which is a product of our own biology that was created by the circumstances on our planet.
Question is how does this broadening of horizons actually help with anything? When we are heavily constrained on both our ability to collect data and analyze that data, exploding the search space seems counter-productive.
We need some way of prioritizing the search work and for that purpose looking first for life as we know it makes sense as that is where we are most likely to be able to identify life.
If searching for life as we know it does not produce results then of course it makes sense to broaden the search. But that is more relevant debate for our children than for us.
The thing is, people don't realize this argument fully. If you are to accept that life could take countless forms, most which we could never recognize or begin to understand, then it's quite possible rocks are lifeforms, as we don't recognize them as life now nor understand how they could be living. Since most people seemingly don't like the argument that rocks are living, then this shows that this argument (along with others) is flawed with very definition that they want "life" to have.
It is a fun thought, but chemistry is not infinitely complex. Much like the Fermi paradox, once you start applying real world qualifiers on chemistry of complex life the search space becomes quite small.
I used to think that too. Life could be anything; crystals, pure energy, eddies in the superfluid cores of neutron stars, swimming in seas of metallic hydrogen in Jupiter's core, living clouds floating in Venus' upper atmosphere.
The trouble is that when you start asking yourself about what the fundamental nature of life is, all the fun stuff starts to fall out.
For life to be life, it needs to do work. You need a metabolism. You need to "do stuff". The only way to do work ("work" in the physics sense) is to leverage an energy gradient; you need to have hot/cold, high/low pressure, bright/dark, high/low salt concentrations, high/low energy chemicals, positive/negative charge, etc. And you need to extract work from the differences between them. Therefore, you need to have a physical barrier between your high/low energy states; if you didn't, the system would reach equilibrium without you. So you need a physical barrier, it has to be a solid or liquid: you've eliminated your beings of pure energy, superfluid eddies, living clouds.
It's all well and good to use whatever weird energy gradient you want, but most energy gradients are simply too inconvenient; if you want to get energy, chemistry is ultimately going to be the only one that works. It's fine for plants to break water molecules with relatively high energy photons, but you can't build complicated structures with light. You need chemistry. And for chemistry you need to be in the liquid phase. So you've eliminated your crystal based life.
So everything is chemicals with complex structures in a liquid. It doesn't have to be proteins constructed with amino acids, it doesn't have to be ribosomes constructed from RNA, but you need some sort of 'interesting' chemical. How do you build interesting chemicals? Well you have to use carbon. You have to use carbon, no other element fits the bill. The metals are right out; they only form metallic bonds and ionic bonds which are non-structural. The noble gases are out because they don't do chemistry. The halogens are out because they can form just the one covalent bond. The chalcogens (oxygen, sulfur, etc) are also out for the same reason; with only two covalent bonding points you can form chains and rings, but not a branching structure. Nitrogen is too happy to form a triple bond with itself, producing a gas, so basically all molecules with lots of nitrogen atoms are explosive. Phosphorus is a decent candidate, but its chemistry is very finicky. Carbon is great, because it forms 4 covalent bonds that are not too strong and not too weak. Silicon is ... ok? But it cannot form double bonds, it tends to form weak bonds, and is unstable in most chemistries.
So life has to be carbon based. This puts an upper limit on temperatures, because interesting carbon chemistry breaks down at high temperatures. Venus is out, the depths of Jupiter are out.
So we're looking at other solvents besides water. Methane is a great candidate, and as a result lots of people are clamoring to get a Titan mission going. Ammonia is something people talk about, but it's unlikely to be able to form ponds or oceans on a world; it's probably going to break down into methane and molecular nitrogen, because again, carbon rules. But if we detected a large amount of ammonia in the spectra of a planet that could maintain temperatures consistent with liquid ammonia, you could bet that everyone is going to clamoring to study it in detail.
So what are we looking at? Carbon based life on planets with liquid oceans. Which is basically the same as us. We haven't gotten here because we're biased towards what we're like, we've gotten here by starting from first principals, considered everything, and eliminated the things which are impossible.
The book Solaris by Stanislaw Lem is a really great read, describing something alien that is obviously alive, yet too foreign for humans to comprehend or interact with.
The issue of "if you lose your keys at night, the first place you look is under the lamppost" problem with searching for alien life has bothered me too, since I was about the age of this professor's trip to Hawaii. But unlike her my musing never resulted in anything useful.
I'm so glad someone is thinking about this and that that person sounds like a broad thinker!
Alternatives to the biochemistry of Earth life are hard to imagine. Silicon replacing carbon is one possibility but, as yet, despite silicon being vastly more common than carbon, we know there is no silicon life on Earth. It's just at too much of an inherent disadvantage, if it is even possible. I would bet on panspermia over silicon life.
I'm not sure what the point of this is. In the last 60+ years we've obviously learned a lot and widened our definition of where life on Earth can live (eg subsea volcanic vents, in rocks in Antarctica). We obviously don't know the limits of biochemistry and thus in what environments life can evolve and where it can continue to live where it exists. We're certainly not going to be detecting a world full of microbes from light years away.
What we're primarily interested in is detecting tecnological life. At stellar distances this really means detecting evidence of spacefaring civilization. This means practially the same thing because the gap between initial technology and spacefaring technology is a cosmic blink of an eye.
And those signatures will transcend biochemistry and what type of world you originate on barring some major glaring error in our understanding of physics (eg thermodynamics being violated).
The reason is that life will ultimately come down to energy and mass. Both of these mean there is pressure to expand and to expand is to become visible. You can argue that expansion isn't inevitable in all cases and you might be correct but it doesn't matter. It matters only if all civilizations remain small and/or hidden. And the odds of that go down as the number of civilizations go up.
I am of course talking about Dyson Swarms, a cloud of orbitals around a star. To put this in perspective, a full Dyson Swarm around our Sun would give each of the 8 billion people on EArth living area roughly equivalent in size to Africa and each person would have a million times more energy than the entire of humanity currently uses.
Such megastructures would be very obvious from a great distance too (ie due to the IR signature of dissipating heat). Likewise, there would be no hiding from such a civilization.
> We're certainly not going to be detecting a world full of microbes from light years away.
JWST would be able to detect an oxygen rich atmosphere like ours, which is a sure sign of life. Oxygen rich atmospheres are not a stable equilibrium; without all the plants and plankton on Earth, the oxygen in the atmosphere would all recombine, and Earth would be left with an atmosphere with no oxygen but additional CO2.
Atmospheres can either be CO2 rich or methane rich; they can't have significant amounts of both CO2 and methane. They don't exist in equilibrium; either a planet will preferentially convert CO2 to methane or methane to CO2, and there won't be any left of the other.
There are a handful of other atmospheric biosignatures that JWST can detect. Chemical compositions that are a sure sign of life; chemical signatures that are conclusive or strong indicators that life is present, even if we can't classify or describe it. Classifying exoplanets' atmospheres is a primary mission goal of JWST; it's what it's designed to do, and it's doing it right now.
I think we're quickly moving towards living in a sort of poor man's Dyson sphere. More and more of our communications are being enclosed in optical fibers that leak virtually no radiation. Our free space comms are increasingly designed to operate on diminishing amounts of power, and to be practically indistinguishable from noise. We may be a dark planet by a couple centuries from the invention of radio.
Chemical changes to our atmosphere might be detectable from afar.
Life may not look like us, but it sure seems like it's going to have nucleic acids just like us.
The building blocks are extremely common, they seem to have fairly broad initial conditions, and it seems like they are practically inevitable once those conditions exist.
> it seems like they are practically inevitable once those conditions exist
Given that we have exactly one occurrence of Origin of Life, how did you conclude this? From life originating quickly on Earth once it had cooled enough? That could be explained by the conditions in which life might originate not persisting for very long after a planet forms.
We inadvertently did something similar when we discovered the New World. Didn't work out so well for the natives.
That time was an honest mistake, but maybe we should stop trying to play God for a while. At least until we are advanced enough to create our own universe to experiment with.
I will assume the curmudgeonly pose and offer that humanity will branch out and explore and...realize a deep lonliness when the quantum mechanical accidents that led to "life" on Earth are not quite duplicated anywhere else.
For those who don't know, there's a very significant movement happening within factions of the US government to push disclosure on potential non-human intelligence visiting earth. This 15 minute guide is worth the read https://www.uap.guide
Edit: For those who don't know, the 2022 NDAA was passed that included legislation the protect whistleblowers from disclosing to congress about unacknowledged black projects regarding reverse engineering programs that congress was not privy to. https://douglasjohnson.ghost.io/uap-related-provisions-of-th...
> ESTABLISHMENT.—The Secretary of Defense, acting
through the head of the Office and in consultation with the Director of National Intelligence, shall establish a secure mechanism for authorized reporting of—
(A) any event relating to unidentified anomalous phe- nomena; and (B) any activity or program by a department or agency of the Federal Government or a contractor of such a depart- ment or agency relating to unidentified anomalous phe- nomena, including with respect to material retrieval, mate- rial analysis, reverse engineering, research and develop- ment, detection and tracking, developmental or operational testing, and security protections and enforcement.
> there's a very significant movement happening within factions of the US government to push disclosure on potential non-human intelligence visiting earth.
<yawn> Pushing for disclosure is very different than there being anything to disclose. Get back to me when they actually disclose anything worthy of being attributed to non-human intelligence.
There is zero consensus that there is a "non-human intelligence visiting Earth". There is, one could argue, a phenomenon of some kind, either real or imagined, but nobody seems to know what it is. And yes, I’m familiar with the subject, and I’ve been following it for decades.
Also, I think "disclosure" is somewhat of a misnomer. If people don’t know what it is, there’s nothing to disclose. People have been beating the disclosure drum for years. Nothing really has happened except some people made a bit of money selling people on the idea.
And for all intents and purposes, our world-spanning civilization is much too primitive to even begin to disclose something like this if it were true. 85% of the people on this planet believe in superstitious nonsense. We aren’t ready to accept the existence of aliens on other worlds or parallel universes, let alone accept our own brothers and sisters who have a different skin color.
Given what I’ve seen of humanity, the zoo hypothesis is the best thing we can hope for. We just are incredibly stupid as a species at this time and place. I can’t imagine why any alien would want to have anything to do with us.
> (when they really, really love one another) can mix and meld to form a new organism that can replicate itself in turn
I know it's a bit tongue-in-cheek but I kinda wish they'd go with something more realistic that also explains our perspective, something like "when two organisms feel compelled to have sex". Even in humans it's a big stretch to say that deep love is a prerequisite and I think adds some harmful personification to the natural world
The mention of silicon as a potential carbon replacement is also explored a bit in the movie "Ecolution" from 2001 - the half-life for replication is way short and (spoiler) they use an analog of cyanide to destroy the silicon-based aliens
perihelions|3 years ago
Is there a systemic search for this kind of crazy stuff, and where are the review papers for them? I don't know the keywords!
akiselev|3 years ago
There's already a whole world of terrestrial microbes that we expect or even know for certain to exist but can't culture, let alone stain, which means we can't really study them. We'd (theoretically) eventually notice them on electron microscopy slides though, which is how we know there's many unculturable microbes, but whether we'd recognize them as alien is a completely different matter. The microbial world is very diverse and there's nothing I can think of that'd set something apart as alien since we can analyze the chemistry with an electron microscope.
pciexpgpu|3 years ago
TastyDucks|3 years ago
teaearlgraycold|3 years ago
[0] https://en.wikipedia.org/wiki/Megavirus
antihipocrat|3 years ago
bufferoverflow|3 years ago
Sure, they can still be very interesting from the bio/chemistry point of view. But it's the advanced civilizations that we're really after.
kposehn|3 years ago
api|3 years ago
https://adamierymenko.com/titan/
In this I’m at least speculating that Titan might be likely to host alien life in its steamy cryotropical environment. I’d love to see NASA sink a submersible in those methane seas and look for cryowhales. (Or more likely cryobacteria but cryowhales would rule.)
I’d expect life there to be wholly biochemically alien, probably based on methane or ammonia as solvents, and probably very metabolically “slow” compared to most life here. We might miss even macroscopic Titan life without time lapse photography.
To any intelligent Titanians we would look like the Balrogs from Lord of the Rings: burning lava monsters with blood of molten water.
jcfrei|3 years ago
albert_e|3 years ago
There is also this to consider: limits of our own imagination/ comprehension.
If we are like microbes swimming inside a droplet of water, we won't be able to imagine/ comprehend / detect beings of the scale of say flies.
Our mental abilities may also be limited in similar ways. I think that puts a limit on what we can perceive / detect / understand.
unity1001|3 years ago
zokier|3 years ago
We need some way of prioritizing the search work and for that purpose looking first for life as we know it makes sense as that is where we are most likely to be able to identify life.
If searching for life as we know it does not produce results then of course it makes sense to broaden the search. But that is more relevant debate for our children than for us.
Rury|3 years ago
willis936|3 years ago
https://youtu.be/469chceiiUQ
Life inside of stars does enable different options.
nwallin|3 years ago
The trouble is that when you start asking yourself about what the fundamental nature of life is, all the fun stuff starts to fall out.
For life to be life, it needs to do work. You need a metabolism. You need to "do stuff". The only way to do work ("work" in the physics sense) is to leverage an energy gradient; you need to have hot/cold, high/low pressure, bright/dark, high/low salt concentrations, high/low energy chemicals, positive/negative charge, etc. And you need to extract work from the differences between them. Therefore, you need to have a physical barrier between your high/low energy states; if you didn't, the system would reach equilibrium without you. So you need a physical barrier, it has to be a solid or liquid: you've eliminated your beings of pure energy, superfluid eddies, living clouds.
It's all well and good to use whatever weird energy gradient you want, but most energy gradients are simply too inconvenient; if you want to get energy, chemistry is ultimately going to be the only one that works. It's fine for plants to break water molecules with relatively high energy photons, but you can't build complicated structures with light. You need chemistry. And for chemistry you need to be in the liquid phase. So you've eliminated your crystal based life.
So everything is chemicals with complex structures in a liquid. It doesn't have to be proteins constructed with amino acids, it doesn't have to be ribosomes constructed from RNA, but you need some sort of 'interesting' chemical. How do you build interesting chemicals? Well you have to use carbon. You have to use carbon, no other element fits the bill. The metals are right out; they only form metallic bonds and ionic bonds which are non-structural. The noble gases are out because they don't do chemistry. The halogens are out because they can form just the one covalent bond. The chalcogens (oxygen, sulfur, etc) are also out for the same reason; with only two covalent bonding points you can form chains and rings, but not a branching structure. Nitrogen is too happy to form a triple bond with itself, producing a gas, so basically all molecules with lots of nitrogen atoms are explosive. Phosphorus is a decent candidate, but its chemistry is very finicky. Carbon is great, because it forms 4 covalent bonds that are not too strong and not too weak. Silicon is ... ok? But it cannot form double bonds, it tends to form weak bonds, and is unstable in most chemistries.
So life has to be carbon based. This puts an upper limit on temperatures, because interesting carbon chemistry breaks down at high temperatures. Venus is out, the depths of Jupiter are out.
So we're looking at other solvents besides water. Methane is a great candidate, and as a result lots of people are clamoring to get a Titan mission going. Ammonia is something people talk about, but it's unlikely to be able to form ponds or oceans on a world; it's probably going to break down into methane and molecular nitrogen, because again, carbon rules. But if we detected a large amount of ammonia in the spectra of a planet that could maintain temperatures consistent with liquid ammonia, you could bet that everyone is going to clamoring to study it in detail.
So what are we looking at? Carbon based life on planets with liquid oceans. Which is basically the same as us. We haven't gotten here because we're biased towards what we're like, we've gotten here by starting from first principals, considered everything, and eliminated the things which are impossible.
otabdeveloper4|3 years ago
(In the same way we recognize language vs random noise even if we can't understand it.)
babelfish|3 years ago
gumby|3 years ago
I'm so glad someone is thinking about this and that that person sounds like a broad thinker!
Zigurd|3 years ago
alasdair_|3 years ago
belter|3 years ago
unknown|3 years ago
[deleted]
cletus|3 years ago
What we're primarily interested in is detecting tecnological life. At stellar distances this really means detecting evidence of spacefaring civilization. This means practially the same thing because the gap between initial technology and spacefaring technology is a cosmic blink of an eye.
And those signatures will transcend biochemistry and what type of world you originate on barring some major glaring error in our understanding of physics (eg thermodynamics being violated).
The reason is that life will ultimately come down to energy and mass. Both of these mean there is pressure to expand and to expand is to become visible. You can argue that expansion isn't inevitable in all cases and you might be correct but it doesn't matter. It matters only if all civilizations remain small and/or hidden. And the odds of that go down as the number of civilizations go up.
I am of course talking about Dyson Swarms, a cloud of orbitals around a star. To put this in perspective, a full Dyson Swarm around our Sun would give each of the 8 billion people on EArth living area roughly equivalent in size to Africa and each person would have a million times more energy than the entire of humanity currently uses.
Such megastructures would be very obvious from a great distance too (ie due to the IR signature of dissipating heat). Likewise, there would be no hiding from such a civilization.
nwallin|3 years ago
JWST would be able to detect an oxygen rich atmosphere like ours, which is a sure sign of life. Oxygen rich atmospheres are not a stable equilibrium; without all the plants and plankton on Earth, the oxygen in the atmosphere would all recombine, and Earth would be left with an atmosphere with no oxygen but additional CO2.
Atmospheres can either be CO2 rich or methane rich; they can't have significant amounts of both CO2 and methane. They don't exist in equilibrium; either a planet will preferentially convert CO2 to methane or methane to CO2, and there won't be any left of the other.
There are a handful of other atmospheric biosignatures that JWST can detect. Chemical compositions that are a sure sign of life; chemical signatures that are conclusive or strong indicators that life is present, even if we can't classify or describe it. Classifying exoplanets' atmospheres is a primary mission goal of JWST; it's what it's designed to do, and it's doing it right now.
analog31|3 years ago
Chemical changes to our atmosphere might be detectable from afar.
Zigurd|3 years ago
Changes that are not geological, like Earth's great oxygenation event could be vivid enough to be detectable among exoplanets.
bsder|3 years ago
The building blocks are extremely common, they seem to have fairly broad initial conditions, and it seems like they are practically inevitable once those conditions exist.
pfdietz|3 years ago
Given that we have exactly one occurrence of Origin of Life, how did you conclude this? From life originating quickly on Earth once it had cooled enough? That could be explained by the conditions in which life might originate not persisting for very long after a planet forms.
andsoitis|3 years ago
Is it more effective to search for phenotypical effects of life than life itself?
Do we care about life elsewhere unless it as advanced or more advanced than us?
Even if we could find in “space”, can we find it in “time”?
thanatos519|3 years ago
sph|3 years ago
That time was an honest mistake, but maybe we should stop trying to play God for a while. At least until we are advanced enough to create our own universe to experiment with.
bufferoverflow|3 years ago
ph3414a|3 years ago
smitty1e|3 years ago
Sorry.
swayvil|3 years ago
Many users of hallucinogens report meeting "machine elves".
Maybe we should be looking there.
Jerrrry|3 years ago
i am plenty familiar with them and other characters, and their lessons always seemed terrestrial, subconsciously familiar.
CyberDildonics|3 years ago
likeabbas|3 years ago
Other significant efforts searching for alien life include the Galileo Project by Dr. Avi Loeb of Harvard https://projects.iq.harvard.edu/galileo/home
Edit: For those who don't know, the 2022 NDAA was passed that included legislation the protect whistleblowers from disclosing to congress about unacknowledged black projects regarding reverse engineering programs that congress was not privy to. https://douglasjohnson.ghost.io/uap-related-provisions-of-th...
> ESTABLISHMENT.—The Secretary of Defense, acting through the head of the Office and in consultation with the Director of National Intelligence, shall establish a secure mechanism for authorized reporting of— (A) any event relating to unidentified anomalous phe- nomena; and (B) any activity or program by a department or agency of the Federal Government or a contractor of such a depart- ment or agency relating to unidentified anomalous phe- nomena, including with respect to material retrieval, mate- rial analysis, reverse engineering, research and develop- ment, detection and tracking, developmental or operational testing, and security protections and enforcement.
technothrasher|3 years ago
<yawn> Pushing for disclosure is very different than there being anything to disclose. Get back to me when they actually disclose anything worthy of being attributed to non-human intelligence.
sammalloy|3 years ago
Also, I think "disclosure" is somewhat of a misnomer. If people don’t know what it is, there’s nothing to disclose. People have been beating the disclosure drum for years. Nothing really has happened except some people made a bit of money selling people on the idea.
And for all intents and purposes, our world-spanning civilization is much too primitive to even begin to disclose something like this if it were true. 85% of the people on this planet believe in superstitious nonsense. We aren’t ready to accept the existence of aliens on other worlds or parallel universes, let alone accept our own brothers and sisters who have a different skin color.
Given what I’ve seen of humanity, the zoo hypothesis is the best thing we can hope for. We just are incredibly stupid as a species at this time and place. I can’t imagine why any alien would want to have anything to do with us.
bsder|3 years ago
infradig|3 years ago
belter|3 years ago
unknown|3 years ago
[deleted]
e_i_pi_2|3 years ago
I know it's a bit tongue-in-cheek but I kinda wish they'd go with something more realistic that also explains our perspective, something like "when two organisms feel compelled to have sex". Even in humans it's a big stretch to say that deep love is a prerequisite and I think adds some harmful personification to the natural world
e_i_pi_2|3 years ago
Tagbert|3 years ago