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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 chanc

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.

pfdietz 4y ago
Now justify your implicit assumption that the chance life arises on a suitable planet is at least 1 in 10^22.
- layer8 4y ago
  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 4y ago
    Right. So, the argument "10^22 is a lot so we can't be alone" is a non sequitur.
    - layer8 4y ago
      I understand it to be a counterargument to the “Goldilocks” non-sequitur.
- colechristensen 4y ago
  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 4y ago
    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 4y ago
      This thread comes across as bickering, and detracts from OP's original euphoric "wow" message.
      - mbostleman 4y ago
        Orthogonal and bickering, but I find it interesting. I can keep two thoughts going at once. Sort of.
    - ziddoap 4y ago
      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 4y ago
        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 4y ago
        > 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).
- mrcartmeneses 4y ago
  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 https://en.m.wikipedia.org/wiki/Earth
  - Apes 4y ago
    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.
  - nikanj 4y ago
    To be fair, we are working very hard on changing it to uninhabitable
    - aaaaaaaaaaab 4y ago
      >uninhabitable *for humans
  - scoopertrooper 4y ago
    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 4y ago
      Anything goes, when you're made of meat :-)
      - gcanyon 4y ago
        Wait...are you asking me to believe in thinking meat!?
  - pfdietz 4y ago
    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.
dogma1138 4y ago
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.
xqcgrek2 4y ago
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.
- colechristensen 4y ago
  >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 4y ago
    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/2012/10/22/163397584/how-human-beings-almost-vanished-from-earth-in-70-000-b-c https://www.npr.org/sections/krulwich/2012/10/22/163397584/h...
    - macintux 4y ago
      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.
boplicity 4y ago
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.
- vidanay 4y ago
  “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.”
  - gcanyon 4y ago
    For some reason I'm inspired to write: Time is short. You cannot imagine how vanishingly, briefly, disappointingly short it is. I mean, you might think you have all the time in the world, but to the universe, you're a fraction of a gnat's wingbeat.
- colechristensen 4y ago
  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 4y ago
    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.
thaumaturgy 4y ago
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.wolframalpha.com/input?i=70+km%2Fs%2FMpc+*+1000ly+*+1gy https://www.wolframalpha.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/input?i=%284*pi*1000%5E3%29%2F3+*+63241+%2F+100 https://www.wolframalpha.com/input?i=%284*pi*1000%5E3%29%2F3...
irrational 4y ago
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 4y ago
  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)
  - irrational 4y ago
    Sure, but that only matters when you get up to a fairly high percentage of light speed. We’ve never even approached 1% of light speed. The fastest space craft is NASA’s Parker Solar Probe. It has reached 0.05% of light speed.
    - bouncycastle 4y ago
      These are engineering limitations, not "light speed limitations"
      - irrational 4y ago
        It’s both. Even if we could engineer a drive to go a high percentage of light speed, it still takes forever to get anywhere. Space is really really vast and even light speed is really really slow. FTL travel is the only practical solution, except current physics says it is impossible.
unyttigfjelltol 4y ago
You're just referring to known opportunities. The fun starts with unknown chances and specifically infinities. If time is infinite, anything that can happen eventually will happen, right here. If space extends infinitely beyond the observable universe, anything that can happen is happening somewhere (an infinite number of somewheres) right now. No, people approach this question from a far more skeptical position than they should.
- thaumasiotes 4y ago
  > If time is infinite, anything that can happen eventually will happen This doesn't come close to being true. That just isn't how infinite quantities work. You can have an infinite sequence of numbers that doesn't include 3 at any point.

pfdietz 4y ago

Now justify your implicit assumption that the chance life arises on a suitable planet is at least 1 in 10^22.

layer8 4y ago
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 4y ago
  Right. So, the argument "10^22 is a lot so we can't be alone" is a non sequitur.
  - layer8 4y ago
    I understand it to be a counterargument to the “Goldilocks” non-sequitur.
colechristensen 4y ago
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 4y ago
  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 4y ago
    This thread comes across as bickering, and detracts from OP's original euphoric "wow" message.
    - mbostleman 4y ago
      Orthogonal and bickering, but I find it interesting. I can keep two thoughts going at once. Sort of.
  - ziddoap 4y ago
    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 4y ago
      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 4y ago
        > 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).
mrcartmeneses 4y ago
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 https://en.m.wikipedia.org/wiki/Earth
- Apes 4y ago
  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.
- nikanj 4y ago
  To be fair, we are working very hard on changing it to uninhabitable
  - aaaaaaaaaaab 4y ago
    >uninhabitable *for humans
- scoopertrooper 4y ago
  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 4y ago
    Anything goes, when you're made of meat :-)
    - gcanyon 4y ago
      Wait...are you asking me to believe in thinking meat!?
- pfdietz 4y ago
  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.

dogma1138 4y ago

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.

xqcgrek2 4y ago

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.

colechristensen 4y ago
>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 4y ago
  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/2012/10/22/163397584/how-human-beings-almost-vanished-from-earth-in-70-000-b-c https://www.npr.org/sections/krulwich/2012/10/22/163397584/h...
  - macintux 4y ago
    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.

boplicity 4y ago

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.

vidanay 4y ago
“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.”
- gcanyon 4y ago
  For some reason I'm inspired to write: Time is short. You cannot imagine how vanishingly, briefly, disappointingly short it is. I mean, you might think you have all the time in the world, but to the universe, you're a fraction of a gnat's wingbeat.
colechristensen 4y ago
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 4y ago
  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.

thaumaturgy 4y ago

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.wolframalpha.com/input?i=70+km%2Fs%2FMpc+*+1000ly+*+1gy https://www.wolframalpha.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/input?i=%284*pi*1000%5E3%29%2F3+*+63241+%2F+100 https://www.wolframalpha.com/input?i=%284*pi*1000%5E3%29%2F3...

irrational 4y ago

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 4y ago
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)
- irrational 4y ago
  Sure, but that only matters when you get up to a fairly high percentage of light speed. We’ve never even approached 1% of light speed. The fastest space craft is NASA’s Parker Solar Probe. It has reached 0.05% of light speed.
  - bouncycastle 4y ago
    These are engineering limitations, not "light speed limitations"
    - irrational 4y ago
      It’s both. Even if we could engineer a drive to go a high percentage of light speed, it still takes forever to get anywhere. Space is really really vast and even light speed is really really slow. FTL travel is the only practical solution, except current physics says it is impossible.

unyttigfjelltol 4y ago

You're just referring to known opportunities. The fun starts with unknown chances and specifically infinities. If time is infinite, anything that can happen eventually will happen, right here. If space extends infinitely beyond the observable universe, anything that can happen is happening somewhere (an infinite number of somewheres) right now. No, people approach this question from a far more skeptical position than they should.

thaumasiotes 4y ago
> If time is infinite, anything that can happen eventually will happen This doesn't come close to being true. That just isn't how infinite quantities work. You can have an infinite sequence of numbers that doesn't include 3 at any point.