[HN Gopher] New evidence suggests giant asteroid impacts created...
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New evidence suggests giant asteroid impacts created Earth's
continents
Author : cheinyeanlim
Score : 68 points
Date : 2022-08-15 13:52 UTC (9 hours ago)
(HTM) web link (singularityhub.com)
(TXT) w3m dump (singularityhub.com)
| ggm wrote:
| If you like speculative fiction, John Brunner wrote very odd
| fiction about mobile and ultimately intelligent plants who come
| into being in a meteor rich planet, from water to land, to
| space..
|
| https://en.wikipedia.org/wiki/The_Crucible_of_Time
| anonAndOn wrote:
| Wasn't it originally "continent" but thanks to tectonics it has
| broken up. Could Theia have gifted us a proto-Pangea?
| wrycoder wrote:
| Yes. The article doesn't even mention "moon".
|
| Current information indicates that most of the Earth's
| lithosphere ended up in the Moon.
|
| BTW, George Gamow wrote about the "birth" of the Moon back in
| the '50s.
| Sharlin wrote:
| I don't think the original configuration of continents is well-
| understood. The continents have drifted together and apart
| again several times in the past 3+ billion years. Pangaea was
| just the most recent supercontinent.
| gus_massa wrote:
| Here is a nice video from the last 1000 million years
| https://bigthink.com/hard-science/plate-tectonics-animation/
| fallingknife wrote:
| The article mentions that other planets don't have continents,
| but isn't that an argument against this hypothesis? The same
| process of asteroid collisions would have happened there too.
| sandworm101 wrote:
| Other planets that we have _so-far detected_. There are no
| doubt countless more planets that out current technology cannot
| detect so easily. It may be that all those with continents are
| small enough that they slip though the detection net. We should
| probably hold off on the comparisons until we are able to
| readily detect earth-sized planets around similarly-sized stars
| to ours. Then we can talk about whether our arrangement is or
| is not rare.
| kurupt213 wrote:
| Some theories say water plays a critical role in crust
| formation. There aren't a lot of local planets with liquid
| water on their surface.
| andrewflnr wrote:
| They gloss over a lot with the term "crustal differentiation".
| This page (intro of a book) explains a bit about how magma gets
| separated into silicate-rich and -poor fractions:
| https://www.sciencedirect.com/topics/earth-and-planetary-sci... .
| lampshades wrote:
| 100 years from now: "New evidence suggests giant asteroid impacts
| DIDN'T create Earths continents"
| hinkley wrote:
| When we actually understand how the moon was created, or when
| we understand the lumpy core of the earth (some people say they
| are the same thing) I suspect we'll know more about the plates.
|
| I would also like to invite some aficionados and scientists to
| spend some time watching olive oil floating on simmering water.
| Lots of weird stuff happens, and if subduction and aduction
| zones aren't cause by plate separation but instead caused it as
| I suspect, then there's probably some food for thought to be
| had in a pot of noodle water.
| hinkley wrote:
| We are on such a Goldilocks planet it isn't even funny. Or life
| is so exquisitely tuned to optimize for earth's conditions it
| isn't even funny. Or both.
|
| We see magnetic fields this strong on gas giants, but not on
| inner planets. I wonder too if we will find that some asteroid
| impacts and the formation of the moon didn't goose up the
| magnetic flux of the core while they were at it. Maybe habitable
| zones only appear on tortured worlds, like earth and some of the
| moons of a Jupiter, because normal planets are just too boring,
| don't have enough building blocks for life.
| cmrdporcupine wrote:
| If we see life as an energetic process (movement of energy
| across membranes) then it makes sense that it happened here on
| a planet with an active tectonic situation and plenty of energy
| differentials -- and yet not so intense that they'd be
| destructive to emergent life.
|
| I like Nick Lane's description of abiogensis as a process born
| in the chemical reactions at early alkaline hydrothermal vents.
| Again, a process that could only happen on a very specific kind
| of planet with active tectonics combined with a (at the time
| acidic) liquid water ocean.
| spaetzleesser wrote:
| "Or life is so exquisitely tuned to optimize for earth's
| conditions"
|
| That's how it works. Life adapts to the conditions it faces or
| it goes extinct.
| idlehand wrote:
| It took billions of years to get to that point, too. Complex
| life only really got going during the Cambrian explosion.
| zardo wrote:
| > Or life is so exquisitely tuned to optimize for earth's
| conditions
|
| It seems that it would have to be. If a planet has had life for
| a large number of generations, that life will have evolved to
| fit the conditions.
| yrgulation wrote:
| > We are on such a Goldilocks planet it isn't even funny.
|
| If we are the only living planet then it is out duty to life on
| this planet to expand outwards.
|
| If not then it is our duty to meet the others.
|
| Life here will eventually die regardless of what we do. We
| should start working on spreading the seeds as far as possible.
| Otherwise we would have lived for nothing as a species.
| MisterBastahrd wrote:
| Why do we have a "duty?"
|
| We haven't even figured out how to be good to each other.
| That's far more important than worrying about how to get a
| civilization on Mars. If most people die, that's a tragedy.
| If everyone dies, that's nature and no real value is lost.
| yrgulation wrote:
| It is our duty because life is programmed to spread. It's
| in the biology of any living thing, ranging from animals to
| plants to microorganisms. Our planet's lifespan and size
| are finite so we have to seek out new venues.
|
| You are right re being good to each other.
|
| Scarcity of resources leads to a lot of bad things. People
| and all life are programmed to compete for resources in
| order to survive. Most wars are caused by the struggle to
| control these resources. And that causes misery to those on
| the losing side.
|
| Near space has endless amounts of everything we need so
| that competition can be more relaxed.
|
| If anything, expanding to space will make life better here
| on earth, by keeping our planet cleaner and safer, and will
| give us the time we need to learn how to move beyond our
| basic instincts. We progressed a lot but we need to do
| more.
|
| Mars shouldn't even be the immediate goal. We should
| harness the energy of our star at its full potential and
| extract nearby resources as first steps. Mars will be a
| byproduct of these two.
|
| Else we are stuck arguing over -isms and tribal wars at
| scale over who owns what part of the planet.
|
| The very fact that we push electrons writing here shows
| that we humans have moved beyond the natural, so simply
| stating that "that's nature and no real value is lost" is
| not in our ... nature.
| seti0Cha wrote:
| I don't know, it seems as though one of the basic
| instincts we've progressed past is our instinct to
| spread. When given the freedom to choose, people
| reproduce at less than a replacement rate. World
| population is still rising, but birth rates are falling
| nearly everywhere as different regions become more
| prosperous. Assuming this continues, where will we find
| the people to spread across the universe? Japan can't
| find people to spread outside of Tokyo.
| yrgulation wrote:
| I am not convinced many people are free to chose,
| particularly in the west. When your life depends on a
| mortgage, ever increasing bills and being in an office at
| least eight hours a day you dont have much of a choice.
| Thats just fancy poverty.
|
| People with actual freedom seem to reproduce beyond
| replacement rates:
|
| https://www.statista.com/statistics/299077/billionaires-
| chil...
|
| https://qz.com/1125805/the-reason-the-richest-women-in-
| the-u...
| LiquidSky wrote:
| >Or life is so exquisitely tuned to optimize for earth's
| conditions it isn't even funny.
|
| Well, of course Earth life is optimized for Earth's
| environment. Otherwise it wouldn't exist.
|
| I bet somewhere out there an intelligent lifeform with
| radically different chemistry and biology is posting on their
| online forums, "It's pretty amazing our planet has exactly the
| liquid argon-cadmium oceans we need to survive, really makes
| you think."
| aaaaaaaaaaab wrote:
| >life is so exquisitely tuned to optimize for Earth's
| conditions
|
| *life on Earth
| colechristensen wrote:
| Probably true, but as a balance for this there are about 100
| billion galaxies in the visible universe each with about a
| hundred billion stars, each with a chance to build up the right
| conditions for live.
|
| That's 10^22 opportunities to get it right. We can't possibly
| be alone.
| thaumaturgy wrote:
| Well, there are a couple of problems with this conclusion.
| One is that it assumes that those 10^22 opportunities are
| evenly distributed in time and space. Another is that we
| might not be alone, but we might also never meet our
| neighbors.
|
| The universe hasn't always been a habitable place. It's been
| hotter and more chaotic; life may have arisen and become
| extinct due to radiation or cosmic-scale collisions a billion
| times on a million worlds over the universe's early history.
| We don't know exactly where the lines are, but we're fairly
| certain at this point that the universe is not static in time
| and it has had a less habitable period and will probably have
| a less habitable period again.
|
| We also don't know what the prospects are for long-term life
| in environments like galactic cores. Of the hundred billion
| galaxies we've observed so far, maybe only the tiniest
| fraction of them are capable of supporting life in the long
| term -- recall, it has taken Earth 4.5 billion years to
| produce us! -- and of those that are capable of supporting
| life, perhaps they can only support life out on their edges.
|
| These amount to some pretty significant polynomials added to
| the Drake Equation, and they can attenuate the result a lot.
|
| But let's imagine the AI swarm, the most popular rebuttal to
| the unforgiving conditions of time and space. Let's imagine
| that one arose a billion years ago, and it happened right
| next door in cosmological terms -- 1000 light years away.
| Let's forgive that we are now 71 light years farther away
| from it than we were when it arose [1], it's fun to mention
| but a rounding error in this imaginary scenario. You still
| have the incredible problem of maintaining a homogeneous
| density of AIs over a rapidly increasing volume! Let's figure
| one lonely AI to a solar system's worth of space in 1000
| light years in every direction -- that works out to 2.6
| _trillion_ little self-sustaining devices! [2] With "only" a
| billion years available to cover that volume, 2,600 new AIs
| have had to come online every single year (on average) and
| somehow teleport to their proper location. On Earth, it's
| easy for us to manufacture 2,600 pieces of complicated
| electronics in a year -- all it takes is the collective
| efforts of millions of people to mine the raw materials,
| refine them, design components, manufacture them, and ship
| all those molecules back and forth across the globe some
| absurd number of times. In space, this is much harder.
|
| And this is, I think, a very generous treatment of the AI
| swarm thought experiment. It assumes that each node has an
| indefinite lifespan, and both communication and travel are
| somehow instantaneous over great distances, and that all of
| the necessary raw materials are always nearby, and that the
| entire thing never goes to war against itself, and that there
| are no cosmological disasters (like a GRB) over that billion
| year span, and that it all happened right next door to us in
| our very own galaxy. This is the _best case scenario_ for an
| extraterrestrial presence in our solar system!
|
| [1]: Approximation of the universe's rate of expansion * 1
| billion years * 1000 light years of distance, https://www.wol
| framalpha.com/input?i=70+km%2Fs%2FMpc+*+1000l...
|
| [2]: Volume of a sphere 1000 ly in radius * astronomical
| units per light year / 100 AU, https://www.wolframalpha.com/i
| nput?i=%284*pi*1000%5E3%29%2F3...
| throwaway4aday wrote:
| > It assumes...
|
| It also assumes a level of technological sophistication not
| too different from our own, depending on advances in AI and
| automation this could feasibly be us in 200 years. We
| hobble ourselves by only considering an alien species to be
| somewhat more advanced than us, it's a forgivable fault
| because we want to keep things realistic but it prevents us
| from asking the harder questions about what would be
| possible in 1,000 years or 1,000,000 years of continued
| technological development. Kardashev dared to dream when he
| proposed his scale. What if we could convert our entire
| solar system including the sun into usable energy? an
| entire galaxy? It's akin to the hunter gatherer asking
| "what if we could harness the power of lightning?" he may
| be very far from that dream becoming a reality but it did
| eventually give way to man's ingenuity. We should ask those
| questions: What if we could control gravity? What if we
| could move faster than light? What if we could create any
| kind of matter or field from scratch out of the raw stuff
| of spacetime? What is beyond space itself and could we ever
| access it? Dreams maybe, for today at least but perhaps not
| forever.
| dogma1138 wrote:
| The observable universe isn't particularly interesting as far
| as looking for life goes, heck anything outside of our
| immediate intra-galactic neighborhood isn't particularly
| interesting because we have no chance in hell of ever
| visiting or communicating with systems more than a few light
| years away.
|
| So how rare are true earth like planets does matter a lot.
| boplicity wrote:
| How much subjective time would it take to visit say, 1/10th
| of those galaxies, if you were traveling at say, 99% of the
| speed of light?
|
| It seems to me that the odds of encountering other life forms
| are vanishingly small, simply because of the scale of the
| universe, combined with the low odds of finding other life
| forms. Sure, it might happen, but we're alone until we're
| not. And we're incredibly likely to remain alone for a very
| long time.
| macrolime wrote:
| If you could travel with constant acceleration you could
| get very far very fast.
|
| Traveling with a 1G acceleration for a 100 years could take
| you to the edge of the universe, though billions of years
| would pass on earth.
|
| https://en.wikipedia.org/wiki/Space_travel_under_constant_a
| c...
| colechristensen wrote:
| How long until a post-human consciousness will have a
| lifespan of a billion years?
|
| If never, why is that not a possible future?
|
| There's two scales you can change, yourself, and the tools
| you use to interact. So how fast can you make a spaceship
| competes with how long you can make your life.
| asdff wrote:
| Post human conciousness on earth has already been around
| for what nearly 4 billion years? Life on earth represents
| a meta organism. It's a human bias to elevate the
| significance of the human species component above that of
| the greater meta organism. Ecology can be studied with
| similar tooling whether the frame of reference is a
| continent or your gut microbiome. If we wanted to, say,
| ship earthbound life to another planet, then lets
| consider the best form of earthbound life to make that
| journey across a hostile environment for an indefinite
| period of time. Chances are its not humans adapted to
| persistent hunting and gathering, but put some microbes
| or spores into a vial wrapped in gold foil, and you
| wouldn't even need a complex generational space ship to
| seed earthbound life across the universe, just a gun
| capable of firing the vial on a vector.
| colechristensen wrote:
| You and I are using different definitions for "post" and
| "conscious", not sure how to move forward with such
| differences.
| [deleted]
| vidanay wrote:
| "Space is big. You just won't believe how vastly, hugely,
| mind-bogglingly big it is. I mean, you may think it's a
| long way down the road to the chemist's, but that's just
| peanuts to space."
| asdff wrote:
| Why do we want contact? Leave these trees of life discrete.
| We deal with terrestrial invasive species enough ravaging
| our ecosystems. Imagine if we let loose some organism that
| is capable of outcompeting all other life on earth? It's
| happened before. The early history of life on earth is an
| assortment of dead ends out competed by the few who emerged
| from the primordial soup that beat the less fit forms for
| finite resources. We've lost a lot of variation along the
| way; we have regulatory processes that are conserved from
| humans to yeast because we all come from a common lineage.
| We are all a small part of the earth planetary meta
| organism. Introducing external life into that system may
| simply lead to quick extinction of that external life at
| the place its been introduced, but the worst possible case
| scenario is that life takes root, is more fit than existing
| forms, and displaces the planetary meta organism we
| currently are components of.
| pfdietz wrote:
| Now justify your implicit assumption that the chance life
| arises on a suitable planet is at least 1 in 10^22.
| colechristensen wrote:
| A root fact of my philosophy is the unrefutable claim that
| I exist, and am alive, so the 1 in 10^22 seems very
| reasonable.
| pfdietz wrote:
| Not 1 in 10^21, or 1 in 10^23? Where exactly is this
| number coming from? You are implicitly assuming a
| probability that life can arise. Don't you think that
| number has to be informed by an actual theory of how life
| arises, not inferred just from your own existence?
|
| And in fact, you can conclude nothing from your own
| existence. Observer selection bias.
| inanutshellus wrote:
| This thread comes across as bickering, and detracts from
| OP's original euphoric "wow" message.
| mbostleman wrote:
| Orthogonal and bickering, but I find it interesting. I
| can keep two thoughts going at once. Sort of.
| ziddoap wrote:
| What an oddly pedantic comment.
|
| 10^21, 10^22 and 10^23... Whichever number, the _point_
| that the parent poster was making doesn 't change at all.
|
| > _You are implicitly assuming a probability that life
| can arise._
|
| What are you suggesting? We're all actually not alive?
| Come on.
| pfdietz wrote:
| No, it's not oddly pedantic. It's more an expression of
| anger, because this sort of argument is common among SETI
| people. It's a very common error: there's lots of
| opportunities for life to arise, therefore life must be
| common in the universe. _And this is utter bullshit_.
| Probability does not work that way!
| haswell wrote:
| > _there 's lots of opportunities for life to arise,
| therefore life must be common in the universe. And this
| is utter bullshit._
|
| Why anger? And will you expand on why this is utter
| bullshit? In what way does probability not work this way?
| You are making strong assertions without expanding on why
| you believe those assertions.
|
| Your assertion also goes against some pretty big names in
| the field; not that big names are automatically
| trustworthy, but they do seem to carry more weight than a
| random HN comment (no offense).
| pfdietz wrote:
| The argument that gets my goat is basically this: "if N
| is large enough, then for any probability p > 0, N p >
| 1." And that's clearly false.
|
| The SETI people making this busted argument are
| implicitly assuming p, the chance that life arises on a
| suitable world, is not "too small". And there is no basis
| for making that assumption.
| johnday wrote:
| On all of the Goldilocks planets we have so far been able
| to image with the resolution needed to determine the
| presence of life, we have determined the presence of
| life.
|
| That is not mathematically rigorous, but it _is_ , from
| the Bayesian perspective, enough to move the needle.
| pfdietz wrote:
| Observer selection bias blows that argument out of the
| water. Ask yourself: if life were extremely rare, what
| would be different here on Earth? Nothing, because life
| has to have started on Earth for us to be here to be
| thinking about it.
| haswell wrote:
| I don't think the common form of argument is that because
| N is large enough, life _must_ exist.
|
| The argument is generally that scale and probability
| _favor_ the existence of intelligent life, assuming Earth
| is not somehow exceptional in the universe.
|
| Assuming Earth is exceptional seems just as problematic.
|
| Welcome to the Fermi paradox.
| pfdietz wrote:
| And for any N, if p is small enough, other life is very
| unlikely to exist.
|
| Why are you holding p fixed and allowing N to increase?
| You are implicitly assuming N is in that regime where N >
| 1/p. That's just assuming p > 1/N, and there's no good
| reason to make that assumption.
| layer8 wrote:
| The point is we don't know either way. Earth may or may not
| be a "Goldilocks" planet.
|
| Also, the numbers above are based on the observable
| universe. We have no idea how big the universe is outside
| that region. It could be infinitely large.
| pfdietz wrote:
| Right. So, the argument "10^22 is a lot so we can't be
| alone" is a non sequitur.
| layer8 wrote:
| I understand it to be a counterargument to the
| "Goldilocks" non-sequitur.
| mrcartmeneses wrote:
| It is at least 1 in 10^22 because we have very strong
| evidence of one habitable planet
|
| Edit: See https://en.m.wikipedia.org/wiki/Earth
| scoopertrooper wrote:
| This earth place sounds preposterous!
|
| I'm supposed to believe the planet's alpha predators
| willing make themselves subservient to smaller, but more
| furry beta predators?
| kabdib wrote:
| Anything goes, when you're made of meat :-)
| nikanj wrote:
| To be fair, we are working very hard on changing it to
| uninhabitable
| pfdietz wrote:
| Why 10^22, and not 10^10, or 10^40, or whatever? The
| number has to come from somewhere. This should be a
| strong clue your logic is defective.
| Apes wrote:
| The chance of a habitable planet happening could just as
| easily be 1 in 10^10000000000000000000000000, and it was
| just a freak occurrence it happened at all. Just because
| something happened once doesn't tell you much about the
| odds of it occurring.
| irrational wrote:
| Undoubtably true, but we may never know for sure since light
| speed limitations means we will never leave our galaxy (and
| probably will never personally travel beyond our solar
| system) and there might not be any other life in our galaxy.
| bouncycastle wrote:
| time slows down as speed increases, so in theory, it may be
| possible, for the traveller to leave? (Although the
| observers would be long gone on the return journey.
| Relativity is a crazy thing)
| xqcgrek2 wrote:
| 1 in 10^22 sounds like a lot but it really isn't when it
| comes to probabilities. It's only about a 10 sigma evidence
| against a null hypothesis.
|
| Put it another away, all it takes is about four one-in-a-
| million chance independent events (or filters) and you're
| left with Earth being the only planet with life in the
| observable universe.
| jcims wrote:
| This is the exact point that I would love to see someone
| really dig into relative to some of the prevailing theories
| of biogenesis. Molecular biology is so mind-bogglingly
| complex that 10^22 planets could disappear into the noise
| floor very quickly.
| colechristensen wrote:
| >Put it another away, all it takes is about four one-in-a-
| million chance independent events (or filters) and you're
| left with Earth being the only planet with life in the
| observable universe.
|
| This presupposes life can only exist on a planet with
| several exact characteristics that we have on Earth. Given
| life on Earth exists quite nearly in every environment that
| exists, it could be expected that despite significant
| filters, there is room for several variations which enable
| life even if quite different.
| cogman10 wrote:
| The real question to me is if intelligent life exists.
|
| If you look at the history of earth, there have been
| several filters that very nearly wiped out intelligent
| life.
|
| Further, we needed a few extinction events just to have a
| world where our intelligent life could reach the point of
| developing science. We wouldn't, for example, have been
| able to thrive in the Jurassic period. There were simply
| far too many predators to keep us from doing anything
| more than hiding in caves and trees.
|
| Then if you look at the evolution of humanity, we very
| nearly went extinct a couple of times. We were estimated
| to have been whittled down to 10000 citizens at one
| point. [1]
|
| Evolution, it seems, doesn't necessarily select for
| intelligence. It selects for better killers and better
| hiders. Being smarter than the predators doesn't
| immediately grant enough benefit. If it did, we'd
| probably not be the only intelligent species to ever
| exist.
|
| [1] https://www.npr.org/sections/krulwich/2012/10/22/1633
| 97584/h...
| macintux wrote:
| This is why I worry about our potential extinction: what
| if we truly are the only beings in the entire universe
| capable of exploring it, and we wipe ourselves out?
|
| What an incredible waste.
| irrational wrote:
| How is that a waste? The universe doesn't exist to be
| explored. It just is. It is not wasted if it is never
| explored.
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