7 ms·

In Great Silence there is Great Hope (2007) [pdf]

28 points by arethuza 6y ago

deleted 6y ago
[deleted]
mannykannot 6y ago
"If – as I hope is the case – we are the only intelligent species that has ever evolved in our galaxy, and perhaps in the entire observable universe, it does not follow that our survival is not in danger. Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, and very improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space. "But we would have some grounds for hope that all or most of the Great Filter is in our past if Mars is indeed found to be barren." It would not give grounds for that hope; it would merely, and at most, not give grounds for suspecting that the hope is in vain. Bostrom cannot quantify how likely his hope is, and what he is praying for here is to maintain that ignorance - to not learn anything that might help quantify the probability in a direction inconsistent with his hope. This strikes me as contrary to the ideals of philosophy.
- ralphstodomingo 6y ago
  I do not see how you came to that conclusion - nowhere in the piece does he hope or pray to maintain such ignorance.
  - mannykannot 6y ago
    He does not put it that way explicitly, but what he is saying is that he hopes we do not gain knowledge that he would would regard as diminishing the likelihood of his hope for humanity being realized. Note that gaining that knowledge would not actually change humanity's chances for colonizing the galaxy; it would only make that probability more clear to Bostrom.
api 6y ago
I think there are just too many unknowns around topics like the existence of intelligent aliens, etc., to draw any firm conclusions about anything. We don't seem to see conclusive evidence for aliens. Okay, maybe a few anomalous UFOs, but none of that stuff is anywhere near firm enough to conclude anything as significant as aliens. We have lights in the sky and funny radar blips, and those could have many explanations. That doesn't mean there aren't any aliens. It just means if they're around they are not advertising their presence. There are many rational reasons not to do so, some altruistic and some self-interested. An ET studying us might want to avoid contamination just like we do when landing probes on other planets. It might also fear that we'd be hostile, and looking around at how humans behave that would not be an irrational concern. If we did respond with hostility or fear, our ETs might face an awful moral conundrum: risk letting us continue developing to the point where we become a danger to other life (including them), or exterminate us preemptively. Might be best just to not make contact and avoid that situation. What about SETI's great silence? It's pretty meaningless. Radiation diminishes with the square of distance. It would take an incredibly powerful directed radio signal to be detectable even a few light years away, and it would have to have simple modulation to have any chance of being noticed. That means an intentional transmission, and one of incredible power. I don't remember exactly but to reach stars dozens of light years away I recall seeing numbers in the hundreds of gigawatts of radiated signal power. That would be on the order of the entire output of the USA power grid fed into a transmitter array to send e.g. Fibonacci numbers and say "yes we are here." That's unlikely for many reasons: it's expensive, a literal shot in the dark, and potentially dangerous. You don't want to get an answer in the form of a relativistic velocity impactor in a few thousand years. Incidental radiation is just not going to be detected at any range. It's not powerful enough. Not only that but as we evolve toward more advanced and efficient technology we are abandoning powerful transmitters in favor of low power cellular systems with lots of small transmitters or mesh networks. Our transmissions are becoming quite a bit harder to detect over time. You couldn't detect an 802.11 network from the Moon, let alone another solar system. There are just so many unknowns. Nothing firm can be said. If people want to get apocalyptic when reasoning from the Fermi paradox, it says more about their attitude than the universe.
- joe_the_user 6y ago
  What about SETI's great silence? It's pretty meaningless. Radiation diminishes with the square of distance. It would take an incredibly powerful directed radio signal to be detectable even a few light years away, and it would have to have simple modulation to have any chance of being noticed. Absolutely. It's worth highlight that Fermi is saying something like "why societies we don't understand using technologies we don't know of to communicate to us."
stupidcar 6y ago
The idea that the "great filter", if there really is one, remains in our future seems to me to be extremely improbable. The fact is, we already have the ability, just about, to colonise space. That we haven't yet has more to do with economic reasons than technological ones, and it's entirely conceivable that we'll see substantial non-Earth settlements in our lifetime. Now, that isn't to say we won't nuke ourselves get turn into grey goo or something before that happens, but the point is, but we're close enough to it that, even being pessimistic, there's got to be a reasonable chance we'll make it (over 0.01, say). And that's not good enough for a great filter. Any catastrophe that happens so close to the point of becoming a multi-planetary civilisation simply wouldn't catch enough species. There'd be too many who would make it through.
- joe_the_user 6y ago
  The idea that the "great filter", if there really is one, remains in our future seems to me to be extremely improbable. The fact is, we already have the ability, just about, to colonise space. Semi-plausible plans exist to colonize the asteroid belt and there's a plan to send a microscopic probe to the nearest star. Those plans are a far, far cry from any colonization of the stars, any really impact on solar systems other than earth. It's worth that if an earth society existed on every star in the galaxy, none would be able to detect the others - all communication fades to quantum noise before it gets to the nearest star.
  - stupidcar 6y ago
    If you're arguing it may not be possible to colonise space at all, that may be true but isn't germane to this discussion. The idea of Fermi paradox and the "great filter" presupposes that it is possible, and that there is some other, civilisation-ending event that stops it. My argument is that, within the context of a debate that accepts the precepts of the Fermi paradox and great filter, the likelihood of where the great filter can be placed is constrained by probability. Within that context, even a limited colonisation of our own solar system would be sufficient to drastically reduce the likelihood of a single event to wipe out humanity entirely.
joe_the_user 6y ago
There must be some kind of barrier that prevents the rise of intelligent, self-aware, technologically advanced, space-colonizing civilizations. Speculation of this sort is interesting but I think it's important to realize it's extremely hypothetical. It can't help but have many hidden assumption and fail to say many "unknown unknowns". One key unstated assumption is that a interstellar space faring civilization could be achieved through technological advancement in short -or-medium order on earth. That a "sci-fi" world is just around the corner. Our current society has indeed been based on constantly, even exponentially increasing technology. But there's no visible way to sustain that exponential growth to the scale of the stars. Indeed, our society's growth is increasingly, visibly unsustainable and our ability to counter our destructive tendencies isn't making progress. So maybe what has to replace our unsustainable trajectory is a society with no technological progress. You could this as "maybe the 'great filter' lies ahead of us" or maybe you could say the image of both the Fermi Paradox and science fiction is based on a belief that Earth's future has a strong potential, a strong tendency to look like the previous 300 years of the increasingly technological expansion of European capitalist society over the globe. And that belief, for good or ill, may be not at all justified. And the thing is that such "filtering" might imply that a given technological species fails, just that it reaches stability and isn't part of this a stellar colonization effort.
cgrealy 6y ago
If humanity turns out to be the most intelligent thing the galaxy has produced... then the galaxy really needs to do better.
at_a_remove 6y ago
A Great Filter? Just the one? Unaddressed is the scenario wherein multiple filters exist. One or more could be behind us; one or more ahead. And so, not finding life on Mars or Titan or anything nearby would be nothing to celebrate.
- ByteJockey 6y ago
  That's covered on page 6: > Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, andvery improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space.
  - at_a_remove 6y ago
    Oh good, I was wondering if I had missed it. I tend to think of the Drake equation as a series of hurdles, myself. It's unpopular but each level of "advancement" doesn't seem to be a given to me.
joe_the_user 6y ago
Another thing to consider is the Fermi paradox arguments assume something like a steady state universe. However, another hypothetical would be this; suppose life appears many places once the universe gets cool enough and thus whatever life has appeared on earth has been developing at a similar speed to whatever life that exists elsewhere. So it's reasonable to think societies as advanced as us exist but it may not be reasonable to expect societies a whole lot more advanced than us exist. Again, how practical and how time-consuming the hypothetical "colonization of a galaxy" would be is relevant and very hard to answer question.
- marcosdumay 6y ago
  There aren't many reasonable reasons for life not to appear ~2 billion years earlier than we did in our own galaxy.
  - joe_the_user 6y ago
    A) Some level of residual radiation or lack of complex chemicals might have delayed life ~2 billion years. B) Proto-life might indeed have evolved 2 billion earlier than earth and have been brought to earth by asteroids. Which is to say it took ~2 billion years for a primordial soup to become single-celled organisms (with viruses being an intermediate stage). C) If life evolves "everywhere", then the odds are we are "typical life" (axiom of mediocrity), so the odds are for whatever reason life was ~2 billion later than some estimates.
    - deleted 6y ago
      [deleted]
    - Reelin 6y ago
      Dinosaurs existed in the Triassic ~250 Mya. Following multiple extinction events primates showed up something like ~80 Mya. Australopithecus only dates to something like 3 Mya, Homo habilis to only ~2 Mya, and humans to a mere ~0.3 Mya. 250 vs 3 (or even 80) is a huge difference, and it's unreasonable to assume that all planets would experience extinction events at anywhere near the same rates. To put it in terms of your axiom of mediocrity, it looks like the "typical" timeline we followed has a lot of wiggle room so why don't we see anyone else?
ncmncm 6y ago
Any of the following suffices to account for silence. All three could be true. 1. Advanced societies develop controlled fusion energy, and lose interest in terrestrial planets. Future activity occurs in the resource-rich Kuiper belts of their and neighboring stars. (Perhaps the most valuable resource there is low temperature.) Extreme primitives stuck on rocky inner planets have nothing of interest to offer, or to say. Aliens who happen by get no closer than Neptune. 2. Expansionist civilizations soon encounter other expansionist civilizations, and annihilate one another. Remaining civilizations are not expansionist, and therefore do not arrive. Humanity will likely be expansionist unless long communication delays make participating in society too difficult. If not, we will eventually encounter another, and either join it, annihilate it, be annihilated, or both of the latter. Having joined, expansion continues until the next such encounter. 3. Life we would recognize develops only on an inner terrestrial planet with a large moon. A planet otherwise like ours with no large moon develops like Venus, as solar tides nearly halt its rotation, and thence its tectonic processes and magnetic field. Earth-like planets equipped with a large moon could be vanishingly rare.

28 points by arethuza 6y ago

deleted 6y ago

[deleted]

"If – as I hope is the case – we are the only intelligent species that has ever evolved in our galaxy, and perhaps in the entire observable universe, it does not follow that our survival is not in danger. Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, and very improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space. "But we would have some grounds for hope that all or most of the Great Filter is in our past if Mars is indeed found to be barren." It would not give grounds for that hope; it would merely, and at most, not give grounds for suspecting that the hope is in vain. Bostrom cannot quantify how likely his hope is, and what he is praying for here is to maintain that ignorance - to not learn anything that might help quantify the probability in a direction inconsistent with his hope. This strikes me as contrary to the ideals of philosophy.

ralphstodomingo 6y ago
I do not see how you came to that conclusion - nowhere in the piece does he hope or pray to maintain such ignorance.
- mannykannot 6y ago
  He does not put it that way explicitly, but what he is saying is that he hopes we do not gain knowledge that he would would regard as diminishing the likelihood of his hope for humanity being realized. Note that gaining that knowledge would not actually change humanity's chances for colonizing the galaxy; it would only make that probability more clear to Bostrom.

api 6y ago

I think there are just too many unknowns around topics like the existence of intelligent aliens, etc., to draw any firm conclusions about anything. We don't seem to see conclusive evidence for aliens. Okay, maybe a few anomalous UFOs, but none of that stuff is anywhere near firm enough to conclude anything as significant as aliens. We have lights in the sky and funny radar blips, and those could have many explanations. That doesn't mean there aren't any aliens. It just means if they're around they are not advertising their presence. There are many rational reasons not to do so, some altruistic and some self-interested. An ET studying us might want to avoid contamination just like we do when landing probes on other planets. It might also fear that we'd be hostile, and looking around at how humans behave that would not be an irrational concern. If we did respond with hostility or fear, our ETs might face an awful moral conundrum: risk letting us continue developing to the point where we become a danger to other life (including them), or exterminate us preemptively. Might be best just to not make contact and avoid that situation. What about SETI's great silence? It's pretty meaningless. Radiation diminishes with the square of distance. It would take an incredibly powerful directed radio signal to be detectable even a few light years away, and it would have to have simple modulation to have any chance of being noticed. That means an intentional transmission, and one of incredible power. I don't remember exactly but to reach stars dozens of light years away I recall seeing numbers in the hundreds of gigawatts of radiated signal power. That would be on the order of the entire output of the USA power grid fed into a transmitter array to send e.g. Fibonacci numbers and say "yes we are here." That's unlikely for many reasons: it's expensive, a literal shot in the dark, and potentially dangerous. You don't want to get an answer in the form of a relativistic velocity impactor in a few thousand years. Incidental radiation is just not going to be detected at any range. It's not powerful enough. Not only that but as we evolve toward more advanced and efficient technology we are abandoning powerful transmitters in favor of low power cellular systems with lots of small transmitters or mesh networks. Our transmissions are becoming quite a bit harder to detect over time. You couldn't detect an 802.11 network from the Moon, let alone another solar system. There are just so many unknowns. Nothing firm can be said. If people want to get apocalyptic when reasoning from the Fermi paradox, it says more about their attitude than the universe.

joe_the_user 6y ago
What about SETI's great silence? It's pretty meaningless. Radiation diminishes with the square of distance. It would take an incredibly powerful directed radio signal to be detectable even a few light years away, and it would have to have simple modulation to have any chance of being noticed. Absolutely. It's worth highlight that Fermi is saying something like "why societies we don't understand using technologies we don't know of to communicate to us."

stupidcar 6y ago

The idea that the "great filter", if there really is one, remains in our future seems to me to be extremely improbable. The fact is, we already have the ability, just about, to colonise space. That we haven't yet has more to do with economic reasons than technological ones, and it's entirely conceivable that we'll see substantial non-Earth settlements in our lifetime. Now, that isn't to say we won't nuke ourselves get turn into grey goo or something before that happens, but the point is, but we're close enough to it that, even being pessimistic, there's got to be a reasonable chance we'll make it (over 0.01, say). And that's not good enough for a great filter. Any catastrophe that happens so close to the point of becoming a multi-planetary civilisation simply wouldn't catch enough species. There'd be too many who would make it through.

joe_the_user 6y ago
The idea that the "great filter", if there really is one, remains in our future seems to me to be extremely improbable. The fact is, we already have the ability, just about, to colonise space. Semi-plausible plans exist to colonize the asteroid belt and there's a plan to send a microscopic probe to the nearest star. Those plans are a far, far cry from any colonization of the stars, any really impact on solar systems other than earth. It's worth that if an earth society existed on every star in the galaxy, none would be able to detect the others - all communication fades to quantum noise before it gets to the nearest star.
- stupidcar 6y ago
  If you're arguing it may not be possible to colonise space at all, that may be true but isn't germane to this discussion. The idea of Fermi paradox and the "great filter" presupposes that it is possible, and that there is some other, civilisation-ending event that stops it. My argument is that, within the context of a debate that accepts the precepts of the Fermi paradox and great filter, the likelihood of where the great filter can be placed is constrained by probability. Within that context, even a limited colonisation of our own solar system would be sufficient to drastically reduce the likelihood of a single event to wipe out humanity entirely.

joe_the_user 6y ago

There must be some kind of barrier that prevents the rise of intelligent, self-aware, technologically advanced, space-colonizing civilizations. Speculation of this sort is interesting but I think it's important to realize it's extremely hypothetical. It can't help but have many hidden assumption and fail to say many "unknown unknowns". One key unstated assumption is that a interstellar space faring civilization could be achieved through technological advancement in short -or-medium order on earth. That a "sci-fi" world is just around the corner. Our current society has indeed been based on constantly, even exponentially increasing technology. But there's no visible way to sustain that exponential growth to the scale of the stars. Indeed, our society's growth is increasingly, visibly unsustainable and our ability to counter our destructive tendencies isn't making progress. So maybe what has to replace our unsustainable trajectory is a society with no technological progress. You could this as "maybe the 'great filter' lies ahead of us" or maybe you could say the image of both the Fermi Paradox and science fiction is based on a belief that Earth's future has a strong potential, a strong tendency to look like the previous 300 years of the increasingly technological expansion of European capitalist society over the globe. And that belief, for good or ill, may be not at all justified. And the thing is that such "filtering" might imply that a given technological species fails, just that it reaches stability and isn't part of this a stellar colonization effort.

cgrealy 6y ago

If humanity turns out to be the most intelligent thing the galaxy has produced... then the galaxy really needs to do better.

at_a_remove 6y ago

A Great Filter? Just the one? Unaddressed is the scenario wherein multiple filters exist. One or more could be behind us; one or more ahead. And so, not finding life on Mars or Titan or anything nearby would be nothing to celebrate.

ByteJockey 6y ago
That's covered on page 6: > Nothing in the above reasoning precludes the Great Filter from being located both behind us and ahead of us. It might both be extremely improbable that intelligent life should arise on any given planet, andvery improbable that intelligent life, once evolved, should succeed in becoming advanced enough to colonize space.
- at_a_remove 6y ago
  Oh good, I was wondering if I had missed it. I tend to think of the Drake equation as a series of hurdles, myself. It's unpopular but each level of "advancement" doesn't seem to be a given to me.

joe_the_user 6y ago

Another thing to consider is the Fermi paradox arguments assume something like a steady state universe. However, another hypothetical would be this; suppose life appears many places once the universe gets cool enough and thus whatever life has appeared on earth has been developing at a similar speed to whatever life that exists elsewhere. So it's reasonable to think societies as advanced as us exist but it may not be reasonable to expect societies a whole lot more advanced than us exist. Again, how practical and how time-consuming the hypothetical "colonization of a galaxy" would be is relevant and very hard to answer question.

marcosdumay 6y ago
There aren't many reasonable reasons for life not to appear ~2 billion years earlier than we did in our own galaxy.
- joe_the_user 6y ago
  A) Some level of residual radiation or lack of complex chemicals might have delayed life ~2 billion years. B) Proto-life might indeed have evolved 2 billion earlier than earth and have been brought to earth by asteroids. Which is to say it took ~2 billion years for a primordial soup to become single-celled organisms (with viruses being an intermediate stage). C) If life evolves "everywhere", then the odds are we are "typical life" (axiom of mediocrity), so the odds are for whatever reason life was ~2 billion later than some estimates.
  - deleted 6y ago
    [deleted]
  - Reelin 6y ago
    Dinosaurs existed in the Triassic ~250 Mya. Following multiple extinction events primates showed up something like ~80 Mya. Australopithecus only dates to something like 3 Mya, Homo habilis to only ~2 Mya, and humans to a mere ~0.3 Mya. 250 vs 3 (or even 80) is a huge difference, and it's unreasonable to assume that all planets would experience extinction events at anywhere near the same rates. To put it in terms of your axiom of mediocrity, it looks like the "typical" timeline we followed has a lot of wiggle room so why don't we see anyone else?

ncmncm 6y ago

Any of the following suffices to account for silence. All three could be true. 1. Advanced societies develop controlled fusion energy, and lose interest in terrestrial planets. Future activity occurs in the resource-rich Kuiper belts of their and neighboring stars. (Perhaps the most valuable resource there is low temperature.) Extreme primitives stuck on rocky inner planets have nothing of interest to offer, or to say. Aliens who happen by get no closer than Neptune. 2. Expansionist civilizations soon encounter other expansionist civilizations, and annihilate one another. Remaining civilizations are not expansionist, and therefore do not arrive. Humanity will likely be expansionist unless long communication delays make participating in society too difficult. If not, we will eventually encounter another, and either join it, annihilate it, be annihilated, or both of the latter. Having joined, expansion continues until the next such encounter. 3. Life we would recognize develops only on an inner terrestrial planet with a large moon. A planet otherwise like ours with no large moon develops like Venus, as solar tides nearly halt its rotation, and thence its tectonic processes and magnetic field. Earth-like planets equipped with a large moon could be vanishingly rare.