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The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. e.g. Say chance o

The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. e.g. Say chance of a random planet ever being hit by a water-carrying comet is one in a billion, then with 100B - 1T planets in the milky way it'd happen here 100-1000 times. If chances are only one in a trillion, and we're the one in the milky way, then there are still another 100B - 1T galaxies out there and therefore a similar number of such events.

pavlov 1y ago
Do other galaxies matter here? A civilization would need to be incredibly powerful to be detectable from another galaxy.
- ben_w 1y ago
  At the moment, rapid and massive expansion seems likely with tech only just on the horizon. Enough AI and robotics for an autonomous factory may be a mirage (such mirages have (metaphorically) happened before), but it seems like it's on the horizon. Even with relatively mundane growth assumptions, that can go from "species inventing writing" to "Dyson sphere completed, is now sending out seeds to every accessible galaxy" on significantly less than the timescale of light crossing a spiral galaxy's disk.
  - kingkawn 1y ago
    Cmon the number of hypothetical extrapolations based on no data in these statements is beyond superstition to something like delusion
    - ben_w 1y ago
      If I put citations into everything I write, I'd be a Wikipedia article, and people would still criticise the conclusions without reading any of them. But contrawise, I do have data, they're broadly categorised as "history", "biology", and "all the stuff cited by Stuart Armstrong that time".
    - javier2 1y ago
      I think its the fact that if we really wanted to, we could probably make it happen already today. On a scale of a couple hundred million years, its possible we could reach most of our own galaxy, which is a small slice of time in the life span of the Milky Way. So the question remains, why hasn't this already happened, or has it?
- pfdietz 1y ago
  Galactic colonization, carried to saturation, would detectably modify the appearance of a galaxy. So called "type 3 civilizations" would convert a significant fraction of starlight to lower grade heat, which would be radiated. Searches have been conducted for this signature, with the result that no more than 1 in 100,000 galaxies has such a civilization, and with the result being consistent with none.
  - pavlov 1y ago
    This is interesting speculation, but it adds one more completely unknown variable to the Drake equation. What’s the probability that a radio-capable civilization becomes a galactic type 3 one? Looking at the only example we have, it appears very unlikely. It seems much more probable that we’ll destroy ourselves within the next centuries.
  - runarberg 1y ago
    I am not an astrophysicist but I have a hunch any speculations of galactic colonization fails to entertain just how big space actually is. I feel like there is ample reason to suspect the probability of galactic (or even interstellar) colonization is exactly 0, and no civilization in the history of the entire universe will ever colonize an entire galaxy (and probably not even more than a handful of solar systems outside their home world; if any).
    - pfdietz 1y ago
      Your argument shows a lack of understanding of exponential growth. Any given colony has to create only slightly more than 1 additional colony in order to drive exponential growth. There doesn't have to be any coordinated action by a central authority for it to happen. For it not to happen (if it is physically feasible), in contrast, every species has to refrain from doing it at all points in their history, almost without exception. And those that do the colonization will seed additional colonies with a mindset that led to colonization; such mindsets will be selected for for further expansion.
      - runarberg 1y ago
- HarHarVeryFunny 1y ago
  I guess it depends what question are we trying to ask. It may well be that there is no other intelligent life close enough to us, or coexisting with us in time, that we will ever be aware of it, but yet the universe may still be teeming with intelligent life. In either case it's a statistical question of how common is life, and intelligent life, but of course there's the human interest in potential contact with another intelligent life form.
tshaddox 1y ago
> The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. But numbers can go arbitrarily low.
- echelon 1y ago
  And you have to have multiple low probability events. These probabilities multiply. We had a good start. A Jupiter to clear the debris, a Theia impact to create tides and contribute to tectonics, a magnetic core, a shielded atmosphere. We had water delivered to us. Maybe even panspermia. Maybe cell walls and mitochondria are hard. Maybe multicellular is hard. Maybe life on land is hard. Building lungs, rebuilding eyes, having actual energetic gasses on land... Maybe life is easy, but intelligence is hard. Maybe civilization is hard. Maybe technology development can only happen on dry land, because aqueous chemistry is hard in water. Sorry mollusks and cetaceans: you'll probably never be able to do chemistry or materials science. Maybe you need water and carbon and other chemistries aren't robust enough. Maybe you need lots of fossil fuel deposits to develop industry. And that requires growth without bacteria and decomposers for millions of years, implying a certain order to evolution. Maybe you need a certain sized gravity well to escape. Maybe surviving the great filter is hard and still ahead of us. Maybe every species can build tech where a kid in their garage can extinct the entire species by 3d printing grey goo. There's just so much we don't know about how life could happen. Let alone intelligent life. We don't even know where we're headed.
  - leoedin 1y ago
    Even on Earth, the only reason humans exist is because the “local maximum” of the dinosaurs was wiped out by a meteor. Perhaps comparably intelligent dinosaurs would have eventually evolved - but it’s not a given!
    - TuringTest 1y ago
      It took several environment-changing events to get our unique kind of intelligence; mammals had to thrive in place of saurs; and then, Africa needed to be split by the Rift and to create the dry savannah. This forced some apes to climb down the trees and depend on a diet of scavenging for meat, which happened to both increase brain size AND require improved intellect to survive, forcing the evolution of our hypertrophied symbolic brain. Had this not happened however, other intelligent species could have filled the niche. There's no shortage of other intelligent species in our planet, not just other mammals but octopus and some birds. And then you get hive intelligence, which could equally be forced to evolve into a high problem-solving organism.
rdtsc 1y ago
Just as easily as we can multiply planets times systems times galaxies times cluster groups we can multiply multiple small probabilities of each chemical being present at the right time and right type, temperature ranges, gravity ranges, etc
mattmaroon 1y ago
If the numbers you propose turn out to be accurate then the odds of there being other life are near zero because even 1/1000 planets are not habitable likely.
- HarHarVeryFunny 1y ago
  Huh? Even in the 1-in-a-trillion case, there's still maybe 1 trillion galaxies each with one planet that was struck by a water bearing comet, so even if only 1/1000 of those are otherwise habitable, that still leaves a billion habitable planets in the universe with water. I doubt water (H2O) is actually that rare. The most common elements by far, both in our own galaxy and the universe as a whole, are Hydrogen and Helium, but the next two most common are Oxygen and Carbon.

pavlov 1y ago

Do other galaxies matter here? A civilization would need to be incredibly powerful to be detectable from another galaxy.

ben_w 1y ago
At the moment, rapid and massive expansion seems likely with tech only just on the horizon. Enough AI and robotics for an autonomous factory may be a mirage (such mirages have (metaphorically) happened before), but it seems like it's on the horizon. Even with relatively mundane growth assumptions, that can go from "species inventing writing" to "Dyson sphere completed, is now sending out seeds to every accessible galaxy" on significantly less than the timescale of light crossing a spiral galaxy's disk.
- kingkawn 1y ago
  Cmon the number of hypothetical extrapolations based on no data in these statements is beyond superstition to something like delusion
  - ben_w 1y ago
    If I put citations into everything I write, I'd be a Wikipedia article, and people would still criticise the conclusions without reading any of them. But contrawise, I do have data, they're broadly categorised as "history", "biology", and "all the stuff cited by Stuart Armstrong that time".
  - javier2 1y ago
    I think its the fact that if we really wanted to, we could probably make it happen already today. On a scale of a couple hundred million years, its possible we could reach most of our own galaxy, which is a small slice of time in the life span of the Milky Way. So the question remains, why hasn't this already happened, or has it?
pfdietz 1y ago
Galactic colonization, carried to saturation, would detectably modify the appearance of a galaxy. So called "type 3 civilizations" would convert a significant fraction of starlight to lower grade heat, which would be radiated. Searches have been conducted for this signature, with the result that no more than 1 in 100,000 galaxies has such a civilization, and with the result being consistent with none.
- pavlov 1y ago
  This is interesting speculation, but it adds one more completely unknown variable to the Drake equation. What’s the probability that a radio-capable civilization becomes a galactic type 3 one? Looking at the only example we have, it appears very unlikely. It seems much more probable that we’ll destroy ourselves within the next centuries.
- runarberg 1y ago
  I am not an astrophysicist but I have a hunch any speculations of galactic colonization fails to entertain just how big space actually is. I feel like there is ample reason to suspect the probability of galactic (or even interstellar) colonization is exactly 0, and no civilization in the history of the entire universe will ever colonize an entire galaxy (and probably not even more than a handful of solar systems outside their home world; if any).
  - pfdietz 1y ago
    Your argument shows a lack of understanding of exponential growth. Any given colony has to create only slightly more than 1 additional colony in order to drive exponential growth. There doesn't have to be any coordinated action by a central authority for it to happen. For it not to happen (if it is physically feasible), in contrast, every species has to refrain from doing it at all points in their history, almost without exception. And those that do the colonization will seed additional colonies with a mindset that led to colonization; such mindsets will be selected for for further expansion.
    - runarberg 1y ago
HarHarVeryFunny 1y ago
I guess it depends what question are we trying to ask. It may well be that there is no other intelligent life close enough to us, or coexisting with us in time, that we will ever be aware of it, but yet the universe may still be teeming with intelligent life. In either case it's a statistical question of how common is life, and intelligent life, but of course there's the human interest in potential contact with another intelligent life form.

tshaddox 1y ago

> The thing is that even for a super low probability event, the size of the universe is so huge and such events must be happening all the time. But numbers can go arbitrarily low.

echelon 1y ago
And you have to have multiple low probability events. These probabilities multiply. We had a good start. A Jupiter to clear the debris, a Theia impact to create tides and contribute to tectonics, a magnetic core, a shielded atmosphere. We had water delivered to us. Maybe even panspermia. Maybe cell walls and mitochondria are hard. Maybe multicellular is hard. Maybe life on land is hard. Building lungs, rebuilding eyes, having actual energetic gasses on land... Maybe life is easy, but intelligence is hard. Maybe civilization is hard. Maybe technology development can only happen on dry land, because aqueous chemistry is hard in water. Sorry mollusks and cetaceans: you'll probably never be able to do chemistry or materials science. Maybe you need water and carbon and other chemistries aren't robust enough. Maybe you need lots of fossil fuel deposits to develop industry. And that requires growth without bacteria and decomposers for millions of years, implying a certain order to evolution. Maybe you need a certain sized gravity well to escape. Maybe surviving the great filter is hard and still ahead of us. Maybe every species can build tech where a kid in their garage can extinct the entire species by 3d printing grey goo. There's just so much we don't know about how life could happen. Let alone intelligent life. We don't even know where we're headed.
- leoedin 1y ago
  Even on Earth, the only reason humans exist is because the “local maximum” of the dinosaurs was wiped out by a meteor. Perhaps comparably intelligent dinosaurs would have eventually evolved - but it’s not a given!
  - TuringTest 1y ago
    It took several environment-changing events to get our unique kind of intelligence; mammals had to thrive in place of saurs; and then, Africa needed to be split by the Rift and to create the dry savannah. This forced some apes to climb down the trees and depend on a diet of scavenging for meat, which happened to both increase brain size AND require improved intellect to survive, forcing the evolution of our hypertrophied symbolic brain. Had this not happened however, other intelligent species could have filled the niche. There's no shortage of other intelligent species in our planet, not just other mammals but octopus and some birds. And then you get hive intelligence, which could equally be forced to evolve into a high problem-solving organism.

rdtsc 1y ago

Just as easily as we can multiply planets times systems times galaxies times cluster groups we can multiply multiple small probabilities of each chemical being present at the right time and right type, temperature ranges, gravity ranges, etc

mattmaroon 1y ago

If the numbers you propose turn out to be accurate then the odds of there being other life are near zero because even 1/1000 planets are not habitable likely.

HarHarVeryFunny 1y ago
Huh? Even in the 1-in-a-trillion case, there's still maybe 1 trillion galaxies each with one planet that was struck by a water bearing comet, so even if only 1/1000 of those are otherwise habitable, that still leaves a billion habitable planets in the universe with water. I doubt water (H2O) is actually that rare. The most common elements by far, both in our own galaxy and the universe as a whole, are Hydrogen and Helium, but the next two most common are Oxygen and Carbon.