Will we know alien life when we see it?
nautil.us
nautil.us
(I've probably been reading too much sci-fi.)
Alien life does not need to be restricted to matter as we know it; if space itself can give rise to self replicating structures, then it too could be alive.
Beyond that, life could occur in any medium and at any scale (in either space or time).
Even regarding terrestrial life, how long did it take for us to notice microbes (as something other than a curse from god)?
There could even be macroscopic lifeforms moving so quickly that we are unable to see them.
So the answer, as far as I can tell, is really that it depends on the kind of life we're referring too.
And if it's too far outside the human context of understanding or perception, then the answer is no.
So yea, the odds of life evolving to something genetically compatible with humanity when we did might be tiny, but we aren’t the only possible form of intelligent multicellular tool using life and it could have happened +/- a few billion years. Given earth starting 5 billion years ago the odds of some intelligent civilization eventually showing up might actually be fairly high, we just don’t have enough data to know.
Now that said, if we did find alien life, how would your feelings about God change?
Still labeling pre Big Bang as SpaceTimeTime or calling that Space Time and relabeling what we experience as local space time doesn’t really matter here. The point is our Big Bang could be happening infinite times in a multiverse without beginning or end. That’s one possibility where there isn’t anything conscious to point to as a GOD just the same kind of things which make up physical reality.
There’s no mention of a ton of very significant things we now know to be real in any holy book. Why isn’t that stuff enough “proof” they’re “fake”?
I also reject your out-of-hand assertion that whatever one thinks about the world's existence has the same meaning to someone as your mythical being has to you.
How blown would your mind be if I posited to you that what you call "GOD" is the universe? Your holly book says he is everywhere and everything all at once, does it not? That "He is within all of us", and yet we are the universe observing itself. He came about out of nowhere with no trace of origin? We don't know what caused the big bang, it just happened.
If aliens exist, it's because the universe "allowed" it to happen (aka the statistical probability is high enough for it to occur or we would not be alive having this conversation) not some conscious divine being.
Anyway something more interesting you said was the belief that all life came from a single cell. It’s unclear if all life ever to exist on earth had cells or if they evolved later. Also, we can’t tell if life showed up independently fairly frequently but was out competed or just once.
This is somewhat dependent on how life is defined. Prions replicate, but aren’t generally considered alive, yet being fairly simple they should have shown up quite frequently due to random chance. The more complex self replicating matter must be to be considered alive the higher the hurdle for life to have formed randomly but the more likely for simpler self replicating matter to evolve into life. Yet, saying evolution of non living mater results in life seems to twist the meaning around unpleasantly.
PS: Perhaps we should have a new definition between dead matter and living matter which is self catalyzing in the right environment. With viruses or prions siting at the complex side and crystals at the simple end.
Consider it in terms of reactions per second - take the likelyhood of non-formation of replicators (call it 99.999999999% - because it actually does not matter), to the power of the number of reactors, to the power of the number of seconds since the universe began.
The likelyhood that no self-replicators form rapidly plummets to a vanishing value.
Not in a cell, but in porous rock around the hydrothermal vents (at the bottom of the ocean).
Given the exponentialish 'population' growth of chemical soup, coupled with the fact that the very low likelyhood of a localised self-replicator forming, by the time second place came about the game would already be over.
Far more likely is preserved 'mutations' to chemical replicators leading to divergent forms of demi-life.
That’s presumably true, but it means there could have been a very large number of losers not just 1. Aka if extremely primitive life showed up once on earth then it might be a rare event, if it happened 100 trillion times then most planets with the right conditions will have some form of life.
If the spread is too wide then the chance of spatiotemporally cohabiting civilizations of distinct origins will be diminishingly small.
But I don't actually think that the planetary parameters that allow for replication are (in any way) specific to earth.
Also, the fact that you think a being of unfathomable complexity can just be, but everything else needs a source is rather silly.
(The other possibility being infinite regression, which is equally silly.)
A chemical soup and enough porous rocks down at the bottom of the ocean to operate as reactors powering endothermic reactions.
These are spread across the entire surface of the earth.
If, by chance, some set of reactions occur forming molecules (or groups of molecules) that catalyse their own formation, then you have constrained self-replication.
Once you have this - and you only need it once, there's an exponential (s-curve really) boom in the prevalence of the chemicals in question.
Any changes to these molecules that preserve the self-replicating nature of the soup will be preserved to an extent and those changes that improve self-replication will not only be preserved but will begin to outpace the parents.
If, for example, I stick a little hydrogen on the front of a structure it'll develop the ability to trace along ion lines.
A chemical soup that hunts its own food.
Of course, these mutations can lead to divergence - which eventually leads to a pseudo-competition.
Step by step, piece by piece, complexity builds up.
Structures integrate and develop the ability to funnel 'food' to where it needs to go for transformation.
And if it is possible for this to happen, then given enough time and enough distinct reactors, it is not simply possible - it is absolutely inevitable.
Basically, in an emergent adversarial environment running late to the party gets you eaten.
I don't see why this has to be the case. If unlikely conditions are correct for something unlikely to occur, then it's not longer unlikely to occur multiple times.
E.g. if you play around with chemical reactions and you hit the right conditions, it usually happens all over the place, and not just one molecule combining.
If we're willing to expand the definition of life, e.g. to accept some type of self-aware computer as alive, then we'd have to tweak the definition, such as it is, and then we're no longer talking about "life" as we think of the word today.
I guess people often wonder about other biochemistries. As far as I know, from a semester of undergrad astrobiology, we don't currently consider those very likely. Silicate chemistries were speculated for decades, but the chemical dynamics just don't tend to work out. The other main idea was ammonia as solvent, but that'd be hardly exotic, and the current thinking is that biochemistry would be entirely too slow at the temperatures where ammonia is liquid.
The wilder ideas, like high energy chemistries on the surface of neutron stars only ever appear in science fiction. (Excepting the odd paper from the seventies, but that was a strange time.)
Maybe people will accuse me of a lack of imagination, but I think it's telling that these threads are almost always mainly the home of comments shouting the word "quantum" like it means something, or getting their information from Mass Effect.
I do think it's an interesting question whether we'd be able to recognize other types of intelligence, but I am pretty sure we'd be able to recognize other types of life.
(By the way, the article seems to be mostly about whether we'd recognize alien life seen through a telescope, but that hasn't deterred speculation about other kinds of life in the thread.)
Source: I actually studied this in college, for a bit.
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> I am pretty sure we'd be able to recognize other types of life.
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> Source: I actually studied this in college, for a bit.
So, let me summarize. You find the question non-sensical, then you are sure you know the answer, and finally you appeal to authority (your own) to elevate your opinion over those of us mere common-sense mortals.
Sorry, I'd have liked to give more weight to your angle, but you kinda made that hard.
Let me try again: I think our various definitions of life are not the actual definition that most astronomers have in their head. I think the actual definition people believe is "I know it when I see it." Two illustrative examples:
Let's say we find a system of chemical reactions going on somewhere that meets most definitions: self-regulating, initial chemical seeds as a basis for heredity, some chain of triggers that causes it to look like it's responding to a stimulus.... This is isn't far-fetched, reactions like this exist in a lab. I don't think we'd call that thing alive - we don't currently. There would be arguments, but most people would probably agree it's a technicality.
Now let's say we find something totally way out there crazy from a science fiction book, like a naturally occurring "computer" running an alien civilization on it. It doesn't have homeostasis - would we call it alive? Most people probably would.
I guess I am prposing that the prevailing actual definition of life that lives in our heads is probably closer to "would I feel bad about killing it?" By both this and the more technical definition, we'd almost certainly recognize it, at least when studied up close. (But probably not through a telescope.)
Is that more sensible?
> you appeal to authority (your own) to elevate your opinion over those of us mere common-sense mortals.
I mean, I'm actually kind of arguing in favor of a common-sense definition, and it's a comment on the internet, which would take me three times as long to type if I sourced it. I would do that for a blog post, but I don't even know if anyone is going to read this :)
But, in fact, this is all so abstract that I wouldn't know what to cite. I still think having an idea of biochemistries, the energy scales, etc. makes someone in the field more qualified to speculate than completely uninformed internet comments.
Regulated metabolism. Homeostasis. I think that's close to capturing the idea we're after. A self-aware computer still has to store its bits somewhere, and get energy and material to do that, presuming it wants to stay alive. That process might as well be called metabolism. Unless it is just totally alien (heh) physics, there would be some kind of metabolism, and localized regions which create an environment suitable for that metabolism to place. That would, if nothing else, produce heat and unusual compounds.
But then again, I doubt humans would have homeostasis for long without their microflora. How is that different? Isn't a virus just a more extreme case of symbiosis? What about less extreme obligate parasites?
Life defies categorization. At best you can find common markers (in addition to the ones you've mentioned, the traits required for natural selection to occur - i.e. reproduction, variation in trait, and variance in offspring - may also be of interest), but in the end it boils down to the anthropocentric notion of "things like us", which isn't very useful outside earth.
I disagree. The most common definition used by working astrobiologists goes along the line of "chemical system that can self-sustain and can undergo darwinian evolution". Our definition of life is intricately tied with our theories about life's origins, and the counter-examples to that definition are fictional and their premise falls apart on closer examination.
Let's take the self-aware computer you mentioned. How would such a computer come to being, exactly? It could have been built by something that does satisfy the above definition (in which case you could consider the computer not alive, but a biosignature). Or it could have been built through some darwinian process, and you're still firmly within the above definition.
Steve Benner has a nice paper about this. DOI: 10.1089/ast.2010.0524
The article doesn't actually address the problems with the 'evolutionary definition', probably because it would mean trying to chip away at a theory that a lot of people spent a lot of time trying to disprove.
> Alive are the things we say are alive, which is mostly stuff like us: some type of metabolism, growth, response to stimuli. By that definition we would certainly recognize it, at least up close.
What about fire?
Is not also some kind of metabolism also assumed?
> What about fire?
I actually rambled about fire, and then deleted the paragraph because the comment was already all over the place. Fire, to me, is a good example of the "good definition" problem I mentioned. I guess we'd all agree it doesn't respond to stimuli, and a necessary property of having a metabolism would be some kind of homeostasis. It also doesn't undergo evolution.
But rejecting it on those grounds doesn't feel complete. Let's say we find some chemical reaction that does self-regulate. This exists in a lab or computer modeling (e.g. https://doi.org/10.1073/pnas.2022987118). Let's say its properties are determined by some initial chemical markers: a basis for heredity. Would we now call it alive?
I don't think we would. I think our definition of life is "I know it when I see it" and the more formal definitions we've tried on in astrobiology are basically just retrofitted to the examples we know or can think of.
I've often thought if complex extraterrestrial beings were discovered they may not "look" much different than anything found on earth, since the spectrum is so vast on this planet (bacteria, plants, mammals, cephalopods, etc.) - considering the universal confines of physics and locomotion. Isn't there something special about crab/spider anatomy as well and it being very "evolutionarily stable" or something? Cannot recall any papers or information on specifics here at the moment.
Meanwhile, I always laugh watching old Twilight Zone episodes and how they have regular humans playing aliens - they don't even bother to differentiate them as a species (likely because of available technology) but think this can work well in a way.
edit word
Carcinization?
Edit: Kicking myself over the missed opportunity to say "space crabs" or a Zoidberg reference
He talks about why certain things simply make sense. Like how wings evolved six times, why communication via sound is simple and communication via some sort of telepathy is not, and why it makes sense for a large animal to be symmetric. From that he reasons why alien life probably wouldn't look all that different.
"Dammit, Joe's thinking at me again. I'm going to ignore him while I watch TV."
[1] https://eukaryotewritesblog.com/2021/05/02/theres-no-such-th...
Life on another planet might originate from an ancestor that functions dramatically different than the last common ancestor for all life on Earth, and that might have huge implications for what a potential multicellular organism with this evolutionary trajectory would look like (if such life even utilized multicellularity, or cells at all)
Same, but for life. We’re probably only going to find the kind of life that has the characteristics and behaviors that we currently recognize as life, and is in a place we think of pointing our telescopes at, and our telescopes are a fine enough sieve to see.
Knowing something is alive gives us a basis for interacting with it. Saying we found life on Mars isn't important because we found life there. It's important because it challenges or confirms our expectations about so many other things.
It's kind of like shooting hoops. The hoop stays in the same place and we try and throw the ball into it from different angles. Each angle we can throw it in from teaches us something new. If you took that hoop and just decided that you get a point by moving the hoop to the ball instead, what does that actually help us with?
Another way of saying it. If everyone is a superhero, then nobody is.
For a very enlightening, very poetic short story from a little known author, I would encourage sci-fi fans to search for "La porcelaine de l'univers" from Bruno Vizerie.
They built xenobots (biological robots) from frog cells which are not evolutionarily programmed to do tasks which they accomplished. Their research in part deals with emergence of agency at multi-cellular level. And they want to get at the fundamental signatures of what makes some collection of agents into a new single agent at an higher level.
Checkout, https://youtu.be/XheAMrS8Q1c
And a new research paper (inhavent had the time to read yet) on this question of how coherent higher order agents emerge from underlying sub-agents.
https://www.frontiersin.org/articles/10.3389/fpsyg.2019.0268...
Arguably, DNA, RNA, and the proteinome are just the universal membrane's way of making more membrane more efficiently.
Discussing life in terms of Darwinian evolution or chemical complexity seems to miss the point. I’d be happy to consider an AI or a cloud “alive”, even if (like a virus) it requires help to replicate.
How are not information processors ? Do you think computers are not a natural extension of us ?
There is absolutely discussion of life as information processing, for instance Stanislas Dehaene is super interesting but I ve heard conferences in biochemistry explaining why all amino acid would work to code information, but the 4 DNA uses have chemical properties that help persist and clone it better and the like.
For example, this theory sti doesn't answer the question how they came into existence in the first place. It's certainly not obviously better than assuming they suddenly appeared on another planet and then transported to earth..
You may not have heard about it, as the paper describing the experiment was only published 69 years ago.
Space is really fucking empty. Seems less likely than throwing a rock out of a rocket on the way to mars and hitting a random bucket, without looking. Add to that that it would require life having evolved while the universe was younger and different to the only state of the universe that we know to support life.
Is it impossible. No. But at that point the theory has as much explanatory power as creationism, i.e. none.
Not sure what you're getting at WRT amino acids. Amino acids form due to the particular chemistry of carbon (what we call "organic chemistry"[1]), and they do so wherever both energy and the building blocks of amino acids exist. No planet required.
This was shown pretty well by the Miller-Urey experiments[2] as well as the discovery of amino acids in interstellar molecular clouds[0].
So...Amino acids can (and do) form wherever the raw materials and energy exist. That's the "how".
[0] https://physicsworld.com/a/amino-acid-detected-in-space/
[1] https://en.wikipedia.org/wiki/Organic_chemistry
[2] https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment
What we consider life are just mechanisms that are complex enough to feel mysterious, also grow and develop fast enough for us to notice.
I don't think looking for life makes much sense. Looking for intelligence (anything you can communicate with to reach meaningful results, insects are also intelligent, pocket calculators also are and that would be cool if they had emerged without the humans building them) and consciousness (no good definition existing to the date) is what is interesting.
But Boltzmann brains do.
- Planets are sentient
- Alien Robots outlive Aliens
- Photon life makes more sense
- Carbon based life is fragile
Yes, we’re meat sacks that pop when poked — that’s a very conserved trait of life on Earth — but for the most part, especially with a holistic view like at a species level, we’re ridiculously hardy.
That "we can imagine" is doing a lot of the work, there. We humans are pretty limited in experience, operating parameters and yes, imagination. On but one dimension, consider the range of all possible temperatures and how narrow the band in which the lifeforms of which we have knowledge can survive. Consider the same along all other dimensions like radiation, gravity, pressure, particulate density, magnetic field intensity, perhaps others we have not even discovered yet.
Carbon life that we know about is "robust" only considering the relatively narrow ranges on our own planet.
It’s easy to be dismissive, but the reality is that life as we know it is pretty freaking incredible.
...on Earth. Take away something as simple as the magnetic field of the planet and suddenly resilient life narrows down to a couple of bacteria, Archaea, or Tardigrades [0] which still die with enough exposure.
Anything above 120 degrees C will also cook our goose and every other form of life, again short of a few Archaea [1] which still die a few degrees later.
And then there's the most basic of all: water without which some life doesn't die but doesn't exactly "live" either. A handful of spores, spore-like forms, or completely dried forms of bacteria for example can go for eons without water but they're not functioning.
And the higher level and complex the organism (thus possibly easier to recognize as life), the higher the chances one of the "subsystems" is more fragile and its failure kills the organism.
[0] https://en.wikipedia.org/wiki/Radioresistance#Radioresistanc...
Antifragility plays well with this definition: it doesn't describe the state, but the potential and the ability to change. Taking into account the huge populations, and the fact that only a couple individuals must survive hardship in order for life to prevail, I can see the antifragility.
- Intelligent life develops superfast AI
- - then develops even more advanced quantum version of it.
- Life slowly starts augmenting its meatspace with advanced replicable machinery
- Eventually everything starts becoming very predictable so it start absorbing the advanced AI in our minds, which slowly becomes our essence (assuming consciousness is 'computable' ie.. not some penrose-esq orchestrated reduction)
- It then builds a hypercomputer operating at very close to max efficiency and start harvesting all matter/stars to sustain it & migrates to it.
there is another path where just like light currently exists as an EM wave packet we discover other stable forms and migrate to that.
of course this does not means the pervious iterations of life do not continue to exist, just that they become increasingly irrelevant.
Actually a valid theory that angels are just friendly aliens and demons are the bad ones. If they can visit earth they probably have godlike technology.