[HN Gopher] Doubts grow about the biosignature approach to alien...
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Doubts grow about the biosignature approach to alien-hunting
Author : pseudolus
Score : 67 points
Date : 2024-03-23 11:31 UTC (1 days ago)
(HTM) web link (www.quantamagazine.org)
(TXT) w3m dump (www.quantamagazine.org)
| throwaway63467 wrote:
| Let's just hope it's not the "dark forest" theory that's correct,
| although it would make a lot of sense to me assuming the universe
| is teeming with life.
| TomSwirly wrote:
| The most likely theory is that the universe is much like it
| appears to be and the speed of light is an absolute barrier,
| and that in practice means that interstellar civilizations
| never form, because it's simply far, far too expensive and
| difficult.
|
| If alien civilizations lasted indefinitely, that wouldn't be a
| barrier, but in the one sample of a civilization we have, we
| are consuming our resources and generating waste at an
| exponentially increasing rate, and will crash and burn leaving
| us without the quadrillions of "dollars" it would take to even
| start colonizing the stars.
| fredsmith219 wrote:
| Even in this scenario I would still expect to see Von Neumann
| machines at some point.
| palata wrote:
| You mean a civilization that can produce machines able to
| survive indefinitely in isolation, but that isn't capable
| of surviving itself?
|
| Doesn't sound particularly obvious to me...
| cyberlurker wrote:
| Kurzgesagt has many videos on this topic. In one video, they
| point out we may actually be in the right place at the right
| time and could be one of the first civilizations. This seems
| egocentric at first, but if you consider how chaotic the
| early universe has been and how relatively calm things are in
| the last billion years, it does make sense.
|
| Also, I learned recently that we don't have as much time with
| Earth as I originally thought. We have a few hundred million
| years to figure out how to colonize other planets or live in
| space before Earth becomes radically different and
| potentially unlivable. I imagine most civilizations get
| snuffed out like this.
| pfdietz wrote:
| The past survival of livable conditions on Earth is no
| guarantee they will persist for very long in the future.
| There's observer selection bias to consider. For example,
| the O2 level in the atmosphere could drop below that needed
| to sustain higher life. As I understand it, there's been no
| feedback mechanism identified that stabilizes O2 at current
| levels, so the persistence of adequate oxygen over the last
| 500 million years could just be an unlikely accident.
|
| In the absence of burial of photosynthesized materials
| atmospheric O2 will disappear in a few million years as
| reduced materials are exposed by geological processes and
| then oxidized. So, the time constant for O2 fluctuations is
| rather short.
|
| If and when we spread into the galaxy, we may find many
| planets where livable conditions were snuffed out before
| intelligence could arise. In our own solar system, both
| Mars and Venus may have been more habitable than Earth
| earlier in the history of the solar system, but now are
| forever ruined.
| palata wrote:
| > We have a few hundred million years to figure out how to
| colonize other planets or live in space before Earth
| becomes radically different and potentially unlivable.
|
| Hmm... at the rate we are going, big parts of the Earth (a
| big slice around the Equator) may well become unlivable for
| human beings in a couple of decades.
|
| I get the idea that it won't mean that the Earth will be
| unlivable for all organisms, but from what we know, a
| sufficiently advanced civilization only needs a couple
| hundred years to destroy itself.
| richardw wrote:
| And AI is likely a binary outcome. It's either very good
| for us or not, and it won't take a million years to
| figure out which. We were in caves not long ago.
| bamboozled wrote:
| Very little to no evidence that AI is a "binary outcome".
| richardw wrote:
| Very little to no evidence that continuously increasing
| intelligence will maintain the status quo indefinitely,
| on a scale of at least thousands of years. The odds of us
| not either populating the galaxy or utterly owning
| ourselves are vanishingly small. What is the middle
| ground that you think is likely, and what things have to
| happen for that to be true? Why is it more likely than
| one of the extremes?
|
| It's so interesting that our intuitions are vastly
| different on this. You and I both just can't believe that
| our default case isn't obvious.
|
| I personally think "recency bias" is to blame for the
| "we'll muddle through" case. Life is great and the
| weather is fine, and there are no asteroids or globally
| impacting volcanoes, and we haven't had a civilisational
| collapse in a good while, and nukes didn't kill us, so
| the current state is pretty locked in indefinitely,
| despite massive technological change that we have zero
| chance of predicting the outcomes of.
|
| That's an unstable equilibrium at best. We take over the
| galaxy or die trying.
| palata wrote:
| Well we are pretty capable of predicting, right now, that
| our civilization is very likely to collapse in the next
| few decades because we can't seem to address the
| climate/biodiversity problems (which are consequences of
| the abundance of fossil fuels that will end soon).
|
| > We take over the galaxy or die trying.
|
| Let's first survive on Earth, shall we?
| pfdietz wrote:
| How does loss of biodiversity cause civilization to
| collapse in the next few decades?
| palata wrote:
| Don't worry, the energy and climate problems can each
| independently cause civilization to collapse in the next
| few decades ;-).
|
| But if you don't understand how we need biodiversity to
| survive, I guess try to eat ChatGPT or Starship.
| pfdietz wrote:
| Ah, I didn't think you had a justification for the claim.
| Empty hot air.
| bamboozled wrote:
| Let's try not to find out?
| MrJohz wrote:
| The Kurzgesagt videos on these sorts of topics are
| interesting and entertaining, but they're often _very_
| speculative -- they can rely heavily on unique but unproven
| theories, unprovable philosophical questions, or even just
| interesting sci-fi premises.
|
| They're definitely informative and interesting within a
| given scope of discussion -- it's good to ask interesting
| questions and explore what different answers might look
| like, because it helps us to push the boundaries of our
| mental models of the universe. But some of the videos --
| particularly the ones on Boltzmann brains or solutions to
| the Fermi paradox -- are a lot closer to "here's an
| interesting thought experiment" than "here's something
| that's likely to be the case in our universe".
|
| (Although they're usually very explicit when they do dive
| into this sort of speculative territory, and they also do a
| lot of videos which aren't in this vein at all -- this is
| no slight on Kurzgesagt and the people who enjoy watching
| them!)
| cyberlurker wrote:
| We're essentially talking about the Fermi paradox. I
| think speculation is expected and the channel is upfront
| about their cited research.
|
| Your comment could apply to any one commenting on these
| topics and so I am confused.
| MrJohz wrote:
| Yeah, I didn't want my comment to be a criticism of
| Kuzgesagt - like you say, they're usually very upfront
| when they do their more speculative videos. But I think
| sometimes people see the Kuzgesagt name and are like "oh,
| that's the informative science videos, this must be
| true", whereas a lot of the Fermi paradox stuff is closer
| to speculative fiction in nature than some of their other
| videos.
| gcanyon wrote:
| Here's the Kurzgesagt video on moving the solar system
| through the galaxy:
| https://www.youtube.com/watch?v=v3y8AIEX_dU
|
| I've seen at least one "physicist reacts" video to this
| that tl;dw's to: "seems reasonable, would obviously require
| a lot of technological advancement and work"
| pfdietz wrote:
| Neither FTL travel nor unitary interstellar civilizations are
| necessary for the Fermi argument to bite.
| palata wrote:
| Not sure why you got downvoted :-/.
|
| I am always surprised by how people tend to completely ignore
| the scale of the universe. People get excited by claims to
| "go back to the Moon, then Mars, then who knows?", but the
| truth is that given our current understanding of the world,
| sending humans on another solar system is _theoretically
| impossible_. Just look at those distances: we just can 't,
| period.
|
| Of course, we may discover new fundamental physics that would
| change that. But that's a fundamental problem, not an
| engineering problem. Instead of wasting money and energy on
| the engineering required to send humans to Mars (which is an
| artistic performance at this point), we should pay
| fundamental physicists to attempt to revolutionize our
| understanding of the world (wishing them luck) and spend
| those resources into something that is actually important for
| life: preserving life on Earth.
|
| Right now we as a civilization are failing to survive on
| Earth. It seems reasonable to consider that other
| civilizations may have the same problems.
| nojs wrote:
| It's not theoretically impossible, it's just really hard.
| If we go fast enough, we can even do it within the current
| lifespan of a human (from the perspective of that human).
|
| https://en.m.wikipedia.org/wiki/File:Roundtriptimes.png
| palata wrote:
| Well, it starts with "assuming we had something we don't
| have (i.e. the capability to accelerate at 1G for 100
| years)"...
|
| I meant it's theoretically impossible with the theory
| that we have now. Of course if we make breakthroughs in
| the theory, then the theory will change and it may become
| possible.
|
| But SpaceX going to Mars is not exactly revisiting this
| theory. They are just having fun with the current state
| of the theory, which says that they won't bring humans
| further, period.
| jonahrd wrote:
| I don't mean to be nitpicky, but you specified the
| difference between a theoretical impossibility and an
| engineering impossibility in your parent comment. I
| assume the reply is just referring to the fact that
| technically getting to a star system within the 10s of
| light-years away is an engineering feat, not a break-the-
| known-rules-of-the-universe feat. I don't take it that
| they're actually claiming it's a realistic feat that may
| be accomplished soon.
| palata wrote:
| Sure, I guess I shouldn't have used the word
| "theoretically". My point was that with our current
| knowledge and capabilities, it is completely unrealistic
| to consider it remotely possible to achieve such a thing.
| We are orders of magnitudes more likely to disappear as a
| civilization in the short term than to achieve any kind
| of meaningful space travel.
| ianburrell wrote:
| Continuous acceleration to relativistic speeds is
| impossible without magic. Reasonable drives require
| impossibly enormous amounts of fuel. Antimatter drives
| require impractically enormous amounts of fuel.
|
| Relativistic speeds require too much energy, too much
| reaction mass, and too much fuel. None of the reaction
| drives are good enough. It would only be possible with
| magic reactionless drive, and magic source of power.
| pfdietz wrote:
| Or with beamed propulsion.
| mr_mitm wrote:
| I agree. The only way to colonize other solar systems is
| using some sort of cryogenic technology or generation
| ships. And even then, no one alive will ever witness the
| ship arriving at the destination. Which, to me, raises the
| question why you should even do this. There is no benefit.
| Just for the solace of knowing that there is a chance your
| species might survive the demise of your civilization?
| That's not much considering the immense cost. Civilizations
| that do this must have some strong biological urge or have
| founded a suitable religion that compels them to colonize
| other solar systems.
|
| That's not even considering secondary colonies. The time it
| takes for the passengers of a generation ship to start a
| new civilization and gather the resources to launch another
| generation ship is mind boggling. They have to ensure not
| to lose any knowledge or the will to colonize more solar
| systems. By the time they've done this a few times, it's
| probably not even the same species anymore.
| gcanyon wrote:
| The "time it takes for the passengers of a generation
| ship to start a new civilization and gather the resources
| to launch another generation ship" is minuscule compared
| to the time to make the journey in the first place.
| Here's a Kurzgesagt video that essentially proposes using
| our solar system itself as our "generation ship" and
| getting from one star to the next would take on the order
| of a hundred thousand years, while the time to set up to
| travel that way seems reasonable to create in tens of
| thousands, or even thousands, of years.
|
| https://www.youtube.com/watch?v=v3y8AIEX_dU
| mr_mitm wrote:
| Good point. So unless they freeze themselves, whoever
| arrives might not even be the same species as the ones
| who left.
| TomSwirly wrote:
| I expected to be downvoted! It's a grim idea, that this is
| there is and there isn't some huge prize of "a whole
| galaxy" a thousand years down the line.
|
| I would have resisted it when I was a kid, myself.
|
| About fifteen years ago, I made an attempt to figure out
| how much it would cost to set up a self-sustaining colony
| on Mars. My target was a Mars that could make its own
| pressure suits because terraforming would take centuries
| and making your own pressure suits is a precursor to that.
|
| I realized that you had to essentially re-invent almost
| every industrial process humans have today, from baking to
| smelting steel, because all of them rely on unlimited, free
| air, and large quantities of cheap water.
|
| You need to recreate most of the chemical industry, just to
| create new computer chips, each one of which relies on
| hundreds of chemical compounds available at very very high
| purities and affordable prices.
|
| After a lot of work, I was unable to come up with a figure.
| My best guess was $3 to $30 quadrillion dollars, if it were
| even possible!
|
| And all of that to have a bunch of miserable real estate in
| a cold, dark, arid, lifeless, airless, radioactive desert
| characterized by fine, abrasive, statically charged,
| poisonous dust. Antarctica is nicer in every way - much
| warmer, much brighter, has breathable air, endless
| quantities of water, etc - and yet no one lives there.
| gcanyon wrote:
| If you're trying to calculate "how much it would take"
| for a project that size, it seems silly to try to
| calculate in dollars. What you want to consider is how
| many _people_ it would take: what population would you
| need, with reasonable bootstrapping equipment, to
| establish a self-sustaining colony on Mars?
|
| I'll hand-wave away whether Mars has the necessary
| resources (I suspect it actually doesn't, but that's just
| a guess) so if we assume that Mars has the raw materials
| we need, and is just lacking an atmosphere, then it seems
| likely (just spit-balling here) that a million people
| could get the job done, or to be conservative, ten
| million. For comparison, North Korea has something like
| 25 million -- they're not _as_ isolated as a Mars colony
| would be, but they 're also not organized well.
|
| If we _really_ want to translate that back into dollars,
| it seems unlikely that we should budget over a billion
| dollars per person, but maybe?
| palata wrote:
| > so if we assume that Mars has the raw materials we
| need, and is just lacking an atmosphere, then it seems
| likely (just spit-balling here) that a million people
| could get the job done
|
| Hmm... I don't get how it seems likely that a million
| people could get the job done. I mean really, we are
| destroying the conditions necessary for our survival on
| Earth. It's not like we know how to survive in a place
| (Earth) that just requires us to _change nothing_. Why
| would we be able to survive in a place (Mars) that
| requires us to create _from scratch_ the very conditions
| we can 't seem to maintain on Earth?
| gcanyon wrote:
| I'm not sure I understand your point. I'm not an expert,
| but "conditions necessary for our survival" == about 7
| things in (rough) order of immediacy: 1.
| Breathable air 2. Survivable temperature 3.
| Shelter from solar radiation 4. Drinkable water
| 5. Food 6. Energy to support the previous 5
| 7. Raw materials to support the previous 6
|
| I postulated the 7th item, so let's take the previous 6
| in order: 1. We know how to generate
| breathable air and keep it under pressure. We do this in
| nuclear submarines. 2. We know how to insulate
| habitats. We cope with a roughly equivalent temperature
| at Antarctica. 3. We know how to protect against
| solar radiation. We (somewhat) do this at the ISS, and we
| have plans to do it on lunar base. 4. We know how
| to produce water as long as we have raw materials to work
| with. 5. We can grow food in pretty much any
| environment we ourselves can survive in. 6. We can
| generate power in almost any environment if we have raw
| materials.
|
| We are not "destroying the conditions necessary for our
| survival on Earth." -- we are significantly changing the
| environment on Earth, that is true, but not such that we
| will all die. Has any credible person presented evidence
| for that outcome?
| palata wrote:
| > I'm not sure I understand your point.
|
| I guess my point is that though we _know_ how to make a
| few humans survive in space (with constant support from
| the Earth) and we _may know_ how to make a few humans
| survive on Mars without constant support from the Earth,
| I am not at all convinced that we _know_ how to make
| millions of people survive on Mars.
|
| Take point 6 for instance: power. One of the biggest
| problems we currently have on Earth is that we don't know
| how to replace fossil fuels, and fossil fuels are not
| unlimited. It's currently unsolved, and it will impact
| our lives heavily in the next few decades.
|
| > We are not "destroying the conditions necessary for our
| survival on Earth."
|
| We are, most definitely. Where the air humidity is
| saturated (so take a strip around the Equator), if the
| air temperature goes higher than the skin temperature, we
| can't regulate our own temperature anymore (by sweating).
| So we can't live outside without life support.
|
| If we reach an average increase of 4 degrees, then 1/3 of
| the world population will be located in places where
| humans cannot survive outside without life support. And
| right now we are most definitely going for those 4
| degrees.
|
| Now you may not care because you don't live around the
| Equator, but... imagine a world where 1/3 of the
| population _must_ relocate in order to... regulate their
| body temperature properly. And I am not even talking
| about the impact on agriculture in the rest of the world
| where you can still regulate your body temperature
| (because at some point you need to eat). In such a world,
| if you are lucky enough to be in a livable location in
| terms of temperature, you may just not have food.
| Definitely global instability and wars.
|
| Not everyone will die, but you have to realize that
| everybody will be affected greatly.
| gcanyon wrote:
| It depends on what time scale you're talking about. Here's
| a Kurzgesagt video that describes how to do it over the
| course of millions of years:
| https://www.youtube.com/watch?v=v3y8AIEX_dU
|
| That's a loooong time, obviously, but it's not
| "theoretically impossible"
| palata wrote:
| Sure, but it assumes technology we don't remotely have.
| Maybe I should not have used the word "theoretically"
| here. It's just ridiculous to seriously consider it at
| this point.
|
| It is nice to think about it, of course. But I just don't
| get how people support wasting so many resources into
| sending people to Mars where it's basically useless
| (though exciting, I get it!) and we have much bigger
| problems to solve on Earth (e.g. the survival of our
| species in acceptable conditions).
| gcanyon wrote:
| I think the word you misused is "impossible," not
| "theoretically."
| pfdietz wrote:
| > but the truth is that given our current understanding of
| the world, sending humans on another solar system is
| theoretically impossible. Just look at those distances: we
| just can't, period.
|
| Of course it's theoretically possible. We couldn't do it at
| relativistic speeds, but that's hardly necessary. We could
| even do it with chemical propulsion (especially if the
| Oberth effect were exploited by close solar/stellar flyby).
| Granted, the trip would take a long time, the scale of the
| vehicles would be very large, and the humans who arrived
| would not be the ones who left.
| smallmancontrov wrote:
| Three Body Problem is a lot of fun, but if you are that
| concerned by it you should seek out the broader Fermi Paradox
| dialogue which does not favor this solution, and not just
| because it's unwanted. Isaac Arthur's Fermi Paradox Compendium
| on youtube is probably a good place to start and I'm pretty
| sure his Dark Forest video covers the major points. In any
| case, I have them here too:
|
| If the universe is teeming with alien life, why isn't it here?
| It looks like it will take millions of years to colonize the
| galaxy but the likely variation in emergence/evolutionary
| timelines is some decent fraction of billions of years
| (considerably more than 4 billion years, the starting gun is
| metallicity not the formation of Earth). In particular, if
| there is highly capable space-faring life at Alpha Centauri,
| why haven't they probed their neighboring star system in a
| billion years even though it was completely trivial to do so
| relative to subsequently displayed technological feats?
|
| Also: it's really hard to configure the rules of a Dark Forest
| so that the optimal strategy is "hide" rather than "grow, grow,
| grow -- and hope you grow fast enough by the time it matters,"
| and it's spectacularly hard to make that so universal across
| all aliens that none of them "wins" and colonizes the galaxy
| per the previous paragraph.
|
| Finally, Cixin Liu had to break the speed of light to make his
| story work (and then carefully avoid the implications to #1 and
| #2 above, which both get worse if c is no longer a constraint).
| I am all for doing what it takes to tell the story, and even
| more delighted by his deeper exploration of this concept
| further down the line, but one must remember to adjust the
| likelihoods of it all according to the likelihood of the
| premise, which seems quite low according to our present
| understanding.
| pfdietz wrote:
| This is a nit pick and doesn't change your argument, but
| Alpha Centauri would not have been our neighboring star
| system for a billion years. Stars move relative to each other
| in our stellar neighborhood at about 30 km/s, or one light
| year every 10,000 years.
| smallmancontrov wrote:
| Yep, good reminder! Of course, as you point out, it doesn't
| change the argument because probing (or simply direct
| observation, if they must hide) would still be trivial,
| both at larger distances when we weren't quite neighbors
| and on the shorter timescale when we were. Trivial next to
| mustering an interstellar invasion fleet on the turn of a
| dime, at any rate. Besides, if they were itching for a
| fight then the original "decent fraction of billions of
| years" timeline still applies to the question of "why
| didn't they grow and colonize?"
| NegativeLatency wrote:
| Personally I would rather take the chance of being destroyed
| than destroy other life.
|
| That whole idea is also based on IMO the worst instincts of our
| race.
|
| For all we know making it past the great filter involves
| developing an increased empathy for all life.
| lannisterstark wrote:
| Cixin straight up borrowed this from The Killing Star. You
| should read that. It's also pretty fun but goes 0-100 in
| chapter 1.
| wouldbecouldbe wrote:
| I understand it would be super interesting to find biological
| processes similar to earth like life similar to our light, water
| & dioxide cycle (im sure there's a name for it)
|
| But sometimes it sound like many people think that's the only way
| life can start, yet we have no idea how it really works. Also on
| earth there are organisms in the deep sea that have completely
| different biology. We might find life, even sentient one, in
| places we haven't thought to look.
| Kalium wrote:
| Yes.
|
| You're right. Absolutely, completely correct. There's almost
| certainly other ways life can start. Other processes that can
| result in intelligence. Other paths of technological
| development.
|
| The issue, as I understand is, is that all of those are
| completely unknown. We have absolutely no useful idea of how to
| look for wildly different life in places we haven't thought to
| look.
|
| What we _do_ know with certainty is that Earth 's chemistry can
| result in life. We do know that it can result in intelligence.
| We do know what paths our technological development took. We
| even have some idea what these things might look like from
| afar. All together, we have exactly one data point that lets us
| search for similar data points.
|
| Are there other, different world, with different life? Very
| possibly. We humans are well aware of this. We just don't have
| a way of knowing if we've found anything. So as a matter of
| managing limited resources, there's a tendency to stick to what
| we know can work.
| card_zero wrote:
| It may just be a failure of the imagination, but on the face
| of it the only chemistry that could feasibly make organisms
| is organic chemistry. That's not because it's Earth's
| chemistry, but because carbon is a very useful lego brick.
| This leaves us looking for alternatives beyond chemistry,
| something like Douglas Adams's "sentient shade of blue",
| except imaginable and not nonsense. So your certainty about
| this is ... staunch, let's say.
|
| Inevitable Wikipedia article about this:
|
| https://en.wikipedia.org/wiki/Hypothetical_types_of_biochemi.
| ..
| Kalium wrote:
| I'm doing my best to tell this user that their imagination
| is possibly on to something, but mostly this is a waste of
| energy. I'm exaggerating the realistic possibilities to
| help them feel good about themselves because it makes it
| easier to sneak in the idea that this is not a useful or
| productive line of thought.
|
| The approach of "Smart people have thought of that, there
| are very few chemically useful alternatives" is the kind of
| thing that entrenches a person in their insistence that
| this is just a wide-scale failure of imagination. Witness
| their comment about "earthlike biology perspective". They
| _want_ to believe a wider, weirder universe is possible. As
| a rule, it helps people feel heard to tell them they 're
| right about something.
|
| So yes. I'm going to present it as a staunch certainty that
| something else is possible but currently unknowable,
| invisible, and irrelevant. I'm doing this in the hopes that
| the message gets through that this is not simply
| parochialist arrogance at work, from which they might nobly
| dissent.
| wouldbecouldbe wrote:
| Hi Kalium, I've rarely heard anything more condescending
| and arrogant to be honest.
| fellerts wrote:
| > What we do know with certainty is that Earth's chemistry
| can result in life
|
| We know that Earth's chemistry can _support_ life. Panspermia
| is still a plausible explanation for life on Earth.
| mr_mitm wrote:
| I'm on the more pessimistic side of this argument. Lots of very
| smart people have thought about this, and really the only
| element that is able to form complex molecules besides carbon
| is silicon, and there are good arguments as to why it's a much
| worse basis for life. And if you have carbon-based life forms,
| you will have water and CO2.
|
| In any case, it is just way more likely than any other form and
| makes absolutely the most sense to look for this first.
|
| Sure, you can always say that we don't know what we don't know,
| but the periodic table of elements is finite and complete, and
| we are pretty sure that chemistry doesn't change across the
| universe. I realize I'm fighting an uphill battle in my
| position, because it's hard to prove the non-existence of
| things, so you will always be able to say "whatever, maybe you
| didn't think of _everything_ ", and it's true, but I have a
| hard time seeing how life can be anything but carbon-based. If
| you have more insight besides what resembles a god of the gaps,
| I'd be very interested.
| wouldbecouldbe wrote:
| Yeah that make sense, but still very much earthlike biology
| perspective. I mean almost everyone here also believes in
| digital intelligence at some point.
|
| Are there elements that are more stable under high pressure
| or heat? Or opposite?
| mr_mitm wrote:
| I can buy the argument that there might be "digital life"
| that has been built by carbon-based biological life which
| has since ceased to be.
| wouldbecouldbe wrote:
| Hahah that's just the human scenario played out before
| us, let's be a bit more creative!
| mr_mitm wrote:
| I'm up for it, but since you are the one who proposed we
| could have unimaginable forms of life, and I'm coming up
| short, I'm relying on you (or anyone who holds your
| position) here to be the creative one.
| palata wrote:
| > I mean almost everyone here also believes in digital
| intelligence at some point.
|
| I don't think I do. Or maybe I misunderstand what "digital
| intelligence" means.
| wouldbecouldbe wrote:
| I also don't, but here conciousness is often seen as a
| side effect of statistical analysis
| lo_zamoyski wrote:
| > Yeah that make sense, but still very much earthlike
| biology perspective.
|
| What does that mean? The parent's point was that this isn't
| just a matter of looking for what is already familiar, but
| a matter of through the lens of what affordances the
| elements have and therefore what, in principle, is likely
| or even possible, to the best of our physical/chemical
| knowledge.
|
| There's a rational middle ground between parochialism and
| anything goes.
| chartpath wrote:
| Kind of a tangent but I'm really interested in why statements
| like:
|
| > if you have carbon-based life forms, you will have water
| and CO2.
|
| ..can lead to statements like:
|
| > it is just way more likely than any other form
|
| I totally agree on the observation, but what is fascinating
| to me is why a deductive statement can be considered to
| indicate likelihood in probability. It seems there is a bit
| of abductive reasoning going on behind the scenes which
| neither the deductive logic or inductive probability can
| really capture on their own.
| mr_mitm wrote:
| I don't see that particular statement "leading" to the
| second statement. You quoted very selectively and didn't
| quote the part that is the reason why I believe carbon-
| based to be much more likely, i.e. the fact that silicon is
| such a bad candidate and that no other molecule allows
| complex chemistry. Maybe that helps with your fascination.
| Obviously I skipped all the actual arguments, but they are
| easy to find by the interested reader in standard
| literature.
| lumost wrote:
| Doesn't this depend on the STP of the alien environment? It
| seems plausible that planets that are a few hundred degrees
| warmer might benefit from silicon based life, no?
| kilpikaarna wrote:
| You don't have to look for oxygen etc that are the signs of
| earth-like lifeforms. I have no idea what prohects like this
| look for specifically, but any kind of thermodynamic
| disequilibrium that shows up in the atmospheric makeup of a
| planet is potentially a sign of life. Free oxygen is a very
| good candidate, but not necessarily the only one.
| jajag wrote:
| Assembly theory might eventually provide some useful tools in
| this area
|
| https://en.wikipedia.org/wiki/Assembly_theory
| HarHarVeryFunny wrote:
| Yes - seem a much better, more general, approach.
|
| There was an interesting interview of Lee Cronin on Lex
| Fridman's podcast a while ago.
|
| For anyone unfamiliar, Assembly Theory is based on the idea
| that the more structurally complex something is, such as a
| molecule, the less likely it was created by chance, and the
| more likely it was created by an assembly factory of sorts, one
| type of which is life in it's potentially diverse forms.
| gradus_ad wrote:
| I was never very impressed by assembly "theory" (what are its
| testable predictions?)... If we find a refrigerator floating
| in space I don't need an Assembly Theorist to tell me there's
| some intelligent/intentional process behind it.
|
| Seriously, what is it other than a potent source of pop sci
| clickbait?
| Supermancho wrote:
| > If we find a refrigerator floating in space I don't need
| an Assembly Theorist to tell me there's some
| intelligent/intentional process behind it.
|
| Isn't that the point? What you find obvious about a
| refrigerator is precisely because it's complex in a way
| that you understand.
|
| I mean, the problems with the theory are pretty obvious.
| Anything complex is a matter of how you measure complexity.
| A common earth object is obvious because we can easily
| categorize the complexity and recognize it.
| itissid wrote:
| Would that also throw projects like
| https://en.wikipedia.org/wiki/Large_Interferometer_For_Exopl...
| also into question?
| heroic wrote:
| Question is to people who say if universe is teeming with life,
| then why is it not visible close by: We don't know how large the
| universe is. If say life is "teeming" means it's found every 1M
| Parsec on the size of 10^100M Parsec, wouldn't it be teeming, and
| yet nothing in our vicinity?
|
| I'm being genuinely curious, not dissing on anyone.
| dsq wrote:
| Life every million parsecs means less than one life form per
| galaxy, so hardly teeming.
| ryandrake wrote:
| And it's not just the size of the distance we can see, it's the
| size of the slice of time when we are looking. We've had the
| tools to sorta-kinda detect life signatures for what, 10-20
| years? Maybe we can keep that up for another (at best) 100-1000
| years until we destroy ourselves? The universe is on the order
| of 10^10 years old. Star formation will end ~10^14 years from
| now The last black holes will evaporate ~10^100 years from now.
| So our temporal search window is astronomically small, too.
| yungporko wrote:
| it's also not only a question of distance but also a question
| of time. there could be/have been several alien species that
| would be our next door neighbours but just not at the same time
| as us.
| hnlmorg wrote:
| There's a few problems when hunting for life:
|
| Distances are immense:
|
| 1. Our view of the galaxy is very limited. We know almost
| nothing about our closest neighbouring solar system, let alone
| anything further afield
|
| 2. And because the distances are so far, we are effectively
| seeing those distant events hundreds or thousands of years in
| the past.
|
| 3. Where to look? We cannot search everywhere. We can only hope
| to get lucky that we are searching the right corner of the sky
| at the right time.
|
| Alien life is completely alien:
|
| 4. We can only make assumptions of what to look for. Any
| sufficiently encrypted signal might genuinely appear like white
| noise to us.
|
| They might be so advanced that we simply cannot detect them
|
| 5. Early communication systems on Earth were noisy in that they
| were broadcast 365 degrees. Later systems could be targeted,
| focused in a specific direction. As technology advances, noisy
| classical methods of broadcasting become less common. This in
| turn reduces the amount of noisy any extraterrestrial
| eavesdropper could spot.
|
| And that's assuming they're not intentionally "cloaking"
| themselves. Putting aside Star Trek style fantasy for a moment,
| there is an advantage to remaining hidden. Whether you're a
| predator like a burrowing spider or stealth bomber, or prey
| like bugs that camouflage themselves as plants; being hidden
| gives you a massive tactical advantage.
| derelicta wrote:
| I hope I will grow old enough for one to see a proper
| confirmation of life out there
| pfdietz wrote:
| That would be bad news. I hope we never have proper
| confirmation of independently arisen life out there (or, worse,
| intelligent life out there.) It would imply the Great Filter is
| likely to be ahead of us, so humanity would likely be doomed.
| NegativeLatency wrote:
| You can choose to believe that we'll make it past that event,
| and even do things to help your community and neighborhood in
| that spirit.
| pfdietz wrote:
| If we run into another intelligence it is strong evidence
| we haven't made it past the Great Filter. Sure, you can
| choose to believe the opposite, but that's pure wishful
| thinking.
| api wrote:
| It shows no such thing. The Fermi paradox is fun but it
| explodes into such a massive tree of possibilities that are
| all untestable that it's just that... fun.
|
| It could be that as we explore the universe we find a ton of
| microbes but few or no other nearby complex lifeforms with
| any form of intelligence. This would imply that Earth is a
| special environment for fostering stable complexity, in which
| case the great filter is still behind us.
|
| BTW there are reasons to think Earth might be special: it's
| got this nice magnetic field, a huge moon that reduces
| bombardment, a thick radiation shielding atmosphere, volcanic
| activity enough to replenish that atmosphere and the
| landscape, a reasonably stable climate, is not tide locked to
| its star (as many planets likely are), and orbits a friendly
| star that doesn't throw tantrums and blast us with gamma
| rays. (The sun appears to be a cute fuzzy waggy little puppy
| as stars go.)
|
| We just don't really know.
| az09mugen wrote:
| The most probable candidate for now is Europa with an incoming
| NASA mission [0]. Because within the solar system among the 3
| potential candidates to host life in an ocean under thick ice
| sheet. Maybe we will find traces of old life on Mars. IMHO, the
| only other way to have confirmation is to recieve a "hand-
| crafted radio signal".
|
| [0] : https://europa.nasa.gov/
| TheLoafOfBread wrote:
| Regarding alien life and search for it, I have really big problem
| with concept of Dyson Sphere/Swarm. The moment when human race
| will be able to build such megastructures, it is very likely that
| long time before that fusion generators will be about as common
| as a smart phone and probably with a same size.
|
| Furthermore matter is just condensed energy, so why bother with
| some wonky immobile megastructure when you can just decay your
| everyday trash into pure energy.
| randomname93857 wrote:
| >> Furthermore matter is just condensed energy, so why bother
| with some wonky immobile megastructure when you can just decay
| your everyday trash into pure energy.
|
| True, matter is an energy... however the only known way to
| convert matter into pure energy is to make it annihilate with
| antimatter ( akin to electron-positron). We first have to have
| a good and cheap source of antimatter! And the matter
| annihilation may still generate a lot of particles/matter -
| that may be a waste (or not) depending what you do with that
| further.
|
| A Partial conversion of a matter into energy is also fusion and
| fission reactions, but they are limited by the difference
| between source and end element of reaction here
| https://en.wikipedia.org/wiki/Iron_peak#/media/File:Binding_...
| - e.g. H2 -> He3, That uses only a tiny portion of matter, no
| energy that can be extracted from Fe56 (max), and all its close
| elements are also useless for either fusion or fission energy
| extraction.
| gentleman11 wrote:
| Because there's nothing out there but swarms of paperclip
| optimizer ai drones, converting all the universes mass into
| paperclip fueled war machines for when they encounter a competing
| paperclip swarm
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