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>that they share this universe and communicate in it. Why shouldn't this also be possible on millions of other earth-like planets out there? one trivial but po

>that they share this universe and communicate in it. Why shouldn't this also be possible on millions of other earth-like planets out there? one trivial but powerful observation that von Neumann made was that our galaxy say, is actually pretty small. It's about 100k light years big, which means that any civilization spreading at only a tiny fraction of the speed of light could expand through the entire milky way in only a million years. We could very well spread through the entire galaxy in the near future if we manage to get to like, 1% of light speed in the next few hundred years. So our galaxy, which contains a few hundred billion stars almost certainly has no other intelligent life in it for the simple reason that it'd be everywhere. That doesn't mean there's no microbial life or maybe technological life billions of light years out there but the fact that we're so alone in our neighborhood is a pretty strong indicator in the direction that advanced life might be much more rare than some people assume.

lm28469 3y ago
> So our galaxy, which contains a few hundred billion stars almost certainly has no other intelligent life in it for the simple reason that it'd be everywhere. By that account another civilisation as advanced as us would say they're equally alone in the galaxy no ? yet here we are. And you forget time, they might have done that 2b years ago and there is nothing left for us to detect, or they might do it in 2b years and we might not be there to witness it. Also there might be barriers we're not aware of, for example advanced civilisations could go through things like extinction through pollution, over consumption of resources before reaching a tipping point to being multi planetary, &c. Plus we're far from the only galaxy, there might be galaxy wide civilisations out there, far far away. And more important, nothing guarantees the premise of multi-planetary civilisation has any validity outside of sci-fi It's like going in the woods twice a year, not seeing mushrooms and concluding mushrooms don't exist on earth because surely you'd have seen them by now! The bottom line is that we just have absolutely no clue
gitaarik 3y ago
Or we are as ignorant about the aliens as ants are about us.
the_af 3y ago
I don't think this is a good indication. Assuming that von Neumann was right, and assuming it's even technologically possible to achieve 1% of light speed, here's some alternative explanations of why we don't see aliens in the Milky Way: - Maybe we're ahead of the race here. It's unlikely, but it has to be the truth for some intelligent lifeform. Why not us? I admit this is unlikely. - Maybe galaxy exploration is technically feasible but economically unfeasible. Aliens would have to solve the same problems than us. - Maybe galaxy exploration is technically and economically feasible, but the overwhelming majority of lifeforms go extinct before reaching this point, an none have been able so far (additional assumption: life is relatively new in the universe, much like it's relatively new on Earth itself). - Maybe galaxy exploration is possible and evidence of life forms has reached us, but we didn't understand them because we weren't looking for the right things. - Maybe galaxy exploration is possible and aliens want us to remain untouched and unaware, much like some wish would happen with lost Amazonian tribes (only the aliens would be more successful).

lm28469 3y ago

> So our galaxy, which contains a few hundred billion stars almost certainly has no other intelligent life in it for the simple reason that it'd be everywhere. By that account another civilisation as advanced as us would say they're equally alone in the galaxy no ? yet here we are. And you forget time, they might have done that 2b years ago and there is nothing left for us to detect, or they might do it in 2b years and we might not be there to witness it. Also there might be barriers we're not aware of, for example advanced civilisations could go through things like extinction through pollution, over consumption of resources before reaching a tipping point to being multi planetary, &c. Plus we're far from the only galaxy, there might be galaxy wide civilisations out there, far far away. And more important, nothing guarantees the premise of multi-planetary civilisation has any validity outside of sci-fi It's like going in the woods twice a year, not seeing mushrooms and concluding mushrooms don't exist on earth because surely you'd have seen them by now! The bottom line is that we just have absolutely no clue

gitaarik 3y ago

Or we are as ignorant about the aliens as ants are about us.

the_af 3y ago

I don't think this is a good indication. Assuming that von Neumann was right, and assuming it's even technologically possible to achieve 1% of light speed, here's some alternative explanations of why we don't see aliens in the Milky Way: - Maybe we're ahead of the race here. It's unlikely, but it has to be the truth for some intelligent lifeform. Why not us? I admit this is unlikely. - Maybe galaxy exploration is technically feasible but economically unfeasible. Aliens would have to solve the same problems than us. - Maybe galaxy exploration is technically and economically feasible, but the overwhelming majority of lifeforms go extinct before reaching this point, an none have been able so far (additional assumption: life is relatively new in the universe, much like it's relatively new on Earth itself). - Maybe galaxy exploration is possible and evidence of life forms has reached us, but we didn't understand them because we weren't looking for the right things. - Maybe galaxy exploration is possible and aliens want us to remain untouched and unaware, much like some wish would happen with lost Amazonian tribes (only the aliens would be more successful).