[HN Gopher] Will we know alien life when we see it?
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Will we know alien life when we see it?
Author : Brajeshwar
Score : 41 points
Date : 2023-01-07 16:24 UTC (6 hours ago)
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| Hani1337 wrote:
| I firmly believe that life on Earth was triggered by spores
| meeting water and developing mycelium networks breaking down
| minerals into nutrients and slowly taking advantage of
| photosynthesis to develop more complex life forms. Spores can
| easily resist the vacuum of space, and pass any form of great
| filter. They do help create enzymes and uptake nutrients, they do
| help break down minerals, they do communicate with entire
| ecosystems, and so much more we barely understand. This would
| mean that fungi are of alien origin.
| yamasanama wrote:
| Is your belief based on any kind of evidence in which case I'd
| love to hear your best arguments, or is it a religios belief
| (like in Jesus) in which case there is not much to discuss?
| polishdude20 wrote:
| Check out some stuff written by Nick Lane. He's got a very well
| thought out theory of how life started.
| rhn_mk1 wrote:
| The interesting implication of panspermia is that is yes, we
| would recognize alien life. I find this optimistic.
| Anthropocentric perhaps? Like a version of living in a slightly
| more sophisticated sci-fi show.
| asdff wrote:
| Thats assuming there is one single common origin for all
| panspermia. There could be multiple events and independent
| lineages. These are not mutually exclusive hypothesis because
| even with panspermia, life would have to originate somewhere
| to be seeded elsewhere.
| dieselgate wrote:
| This is actually a fairly reasonable theory given the
| information we currently have access to - not "spores" per se
| but rather by amino acids entering our atmosphere. Check out
| the "panspermia theory" as well as the "Murchison meteorite", I
| believe there may have been amino acids found on other
| meteorite samples since and perhaps one within the past 5 years
| or so. It's possible though our planet is very "ripe" for
| harboring life and there are multiple avenues through which it
| has evolved over time.
| yamasanama wrote:
| What advantage does this theory have over the more common (?)
| assumption that the amino acids came to existence on earth
| itself? Serious question, I'd like to know.
|
| 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..
| nobody9999 wrote:
| >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..
|
| 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_exper
| iment
| h_r wrote:
| One weak advantage is panspermia allows you to avoid the
| question.
| dieselgate wrote:
| This made me laugh, yes I agree in a way. Maybe some day
| we will discover amino acid constituents on earth or
| another planet and it will fill in more of the blanks.
| It's the definition of chicken and egg though
| nobody9999 wrote:
| Done. https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_e
| xperiment
|
| You may not have heard about it, as the paper describing
| the experiment was only published 69 years ago.
| dieselgate wrote:
| Thanks for the link and for the reminder, did learn about
| this experiment actually in organic chemistry years ago.
| Suppose it's a bit nonsensical to look for amino acid
| "constituents" then. Not a fan of the snark though
| dieselgate wrote:
| I'm not so sure it offers an "advantage" but it's rather
| just something we seem to have evidence for - indeed it
| does not answer any questions rather raising more possibly
| kevin_thibedeau wrote:
| Fungi are eukaryotes. They aren't a nascent life form.
| tylershuster wrote:
| If you accept the existence of angels and demons, you already do.
| someweirdperson wrote:
| Do they fulfill our current definition of life?
| tylershuster wrote:
| Is there consensus on that?
| madspindel wrote:
| Aliens from heaven.
|
| 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.
| wincy wrote:
| I think there was an episode of the Outer Limits like this
| where some scientist made contact via wormhole with aliens
| and they looked suspiciously like demons with the horns and
| everything. The aliens of course said "we have a bad rep but
| we're actually good guys!", then proceeded to do something
| like drain the oceans or boil them for terraforming or
| something apocalyptic after convincing the scientist to let
| them teleport through.
| nobody9999 wrote:
| cf. Childhood's End[0] by Arthur C. Clarke.
|
| [0] https://en.wikipedia.org/wiki/Childhood%27s_End
| [deleted]
| nathias wrote:
| I think artificialness is always distinguishable by other sapient
| creatures, we might miss some of the less complex ones.
| nyfresh wrote:
| Hot take, no explanations:
|
| - Planets are sentient
|
| - Alien Robots outlive Aliens
|
| - Photon life makes more sense
|
| - Carbon based life is fragile
| DesiLurker wrote:
| I actually agree with 'QM/EM based life'. My current thinking
| goes as following..
|
| - 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.
| keithwhor wrote:
| As a hot take I'm not incentivized to respond seriously, but I
| will say that Carbon-based life as we know it on Earth is
| seriously antifragile. We've found life in the most
| inhospitable places we can imagine and the kicker is it's all
| self-replicating and self-healing.
|
| 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.
| rendall wrote:
| > the most inhospitable places _we can imagine_
|
| 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.
| keithwhor wrote:
| The range of all possible temperatures is theoretically
| infinite. Life as we know it -- without protection -- can
| survive at everything from 0K to 386K (113C). As humans we
| have harnessed temperatures in the 100s of millions of
| degrees (fusion) safely and can build machines that
| reliably extend our operating parameters far beyond their
| normal bounds.
|
| It's easy to be dismissive, but the reality is that life as
| we know it is pretty freaking incredible.
| buran77 wrote:
| > We've found life in the most inhospitable places we can
| imagine
|
| ...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#Radioresist
| anc...
|
| [1] https://en.wikipedia.org/wiki/Strain_121
| rhn_mk1 wrote:
| I don't think life can be evaluated as a snapshot in a
| moment of time. Life is a process, and it affects a
| population. I think even the most conservative definitions
| may agree on that.
|
| 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.
| enkid wrote:
| I don't know, a center of a star seems pretty inhospitable,
| and we haven't found life there yet.
| lowbloodsugar wrote:
| Are we getting a lot of telemetry from our "center of sun"
| probe?
| oblak wrote:
| enkid's people have had a remote outpost near the center
| for some time now. They have not reported finding any
| life so far there but can we really trust them after the
| Saturn 3 disaster?
| lowbloodsugar wrote:
| 5 mass extinctions. Arguably heading for another one (us and
| everything else).
| Enginerrrd wrote:
| What do you think is occurring that is likely to end our
| species?
| [deleted]
| rhn_mk1 wrote:
| 5 mass extinctions and it's still going. Seems quite hardy.
| [deleted]
| [deleted]
| dieselgate wrote:
| This was a good write up as it contained criteria and points for
| "defining life", it was nice to have a refresher on the meaning
| of "entropic" life as well.
|
| 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
| dcminter wrote:
| > Isn't there something special about crab/spider anatomy as
| well ...
|
| Carcinization?
|
| https://xkcd.com/2314/
| leplen wrote:
| There's a lot of convergent evolution towards the crab body
| plan, a phenomenon known as Carcinisation.
| (https://en.wikipedia.org/wiki/Carcinisation)
| fbdab103 wrote:
| Who is to say that is a universal phenomenon? May have
| something to do with our level of gravity, life cycle of the
| blastocyst, metabolic requirements from respiration, other
| fauna competition, etc. Which is not to say there is a better
| alternative on the table, but I would hesitate to say that we
| should expect crabs on other planets.
|
| Edit: Kicking myself over the missed opportunity to say
| "space crabs" or a Zoidberg reference
| mr_mitm wrote:
| There was a really cool episode on Mindscape with Arik
| Kershenbaum: https://m.youtube.com/watch?v=QFLrpIslOOk
|
| 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.
| asdff wrote:
| The spectrum on this planet really isn't all that vast. Sure,
| to you looking at an organism's morphology it looks vastly
| different, but so do dog breeds from eachother yet they are all
| dogs. You have a lot in common with all forms of life in terms
| of how your cell biology works, because we all share a common
| ancestor.
|
| 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)
| superb-owl wrote:
| The same is true of trees! They've independently evolved many
| times [1]. Any solar-powered biome will probably have trees.
|
| [1] https://eukaryotewritesblog.com/2021/05/02/theres-no-such-
| th...
| aredox wrote:
| Disappointed to see there is no mention of Lem's Solaris, whose
| devoted large paragraphs to this very question.
|
| 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.
| jl6 wrote:
| Remember when most of the known exoplanets were hot Jupiter-like
| worlds, so it looked for a moment that perhaps those were the
| dominant type of planet, but then it became clear that this type
| of planet was commonly detected just because they were the only
| type of planet our techniques were capable of detecting?
|
| 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.
| polishdude20 wrote:
| At some point, if you stretch the definition of life too far,
| what's the point? Like, what's the point of saying a rock is
| alive? We've got them everywhere, we know they exist everywhere
| but we can't really do anything with that info.
|
| 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.
| pcdoodle wrote:
| We're just thinking with our meat over here...
| t8sr wrote:
| We don't even really have an agreed-upon definition of life, so
| the question is basically non-sensical. 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.
|
| 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.
| troops_h8r wrote:
| >We don't even really have an agreed-upon definition of life,
| so the question is basically non-sensical.
|
| 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?
| retrac wrote:
| > we don't even really have an agreed-upon definition of life
|
| 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.
| yamasanama wrote:
| > We don't even really have an agreed-upon definition of life,
| so the question is basically non-sensical.
|
| ...
|
| > I am pretty sure we'd be able to recognize other types of
| life.
|
| ...
|
| > 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.
| mrlonglong wrote:
| > Cell phones don't randomly fluctuate out of a vacuum," quips
| Walker.
|
| But Boltzmann brains do.
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