8 ms·

The basic idea of rare Earth as an answer to Fermi is that if the frequency of advanced life is around 1 per galaxy per billion years or something like that the

by api 2y ago

The basic idea of rare Earth as an answer to Fermi is that if the frequency of advanced life is around 1 per galaxy per billion years or something like that then we'd likely never meet any aliens. Intergalactic travel is borderline impossible barring unknown physics or travel very close to the speed of light. Even at speeds like 0.5c (50% the speed of light) the trip would take so long you'd have problems like cosmic rays tearing you apart over such long spans of time, and in the vastness of intergalactic space there's no place to pitch a tent and chill and repair things. 0.5c would get you to the stars but not the galaxies. Intergalactic flight would require something more like 0.95c to 0.99c. The energy requirements for that are insane and possibly unachievable, and if you hit a dust particle at that speed the yield will be like a thermonuclear bomb. The cosmic microwave background also becomes a beam of hard gamma rays aimed at your head. All kinds of crazy extreme physics things happen. Lastly, why do it? Galaxies are huge and if you're alone then it's all yours. The only conceivable reason would be to flee some galactic-scale super-catastrophe like your galaxy's central black hole behaving badly and frying everything with gamma rays. Even for that it might be easier to burrow deeply into planetary bodies instead. Of course one can imagine ultra-far-future scenarios like: what if Andromeda hosts some galactic-scale super civilization by the time it hits the Milky Way which by then also hosts such a thing. That'd be a hoot.

pfdietz 2y ago
> Intergalactic flight would require something more like 0.95c to 0.99c Why would it require speeds that high? Sure, it's going to take a very long time, but why is that an insurmountable obstacle? There are enough isolated stars in intergalactic space that one can even imagining making the trip in smaller steps, with colonization in between. At a stellar density nine orders of magnitude lower than our galaxy stars are still within thousands of light years of each other.
- lazide 2y ago
  Because most people go nearly insane in solitary confinement? and that isn’t even really solitary. And gov’ts and social structures rarely last a few generations, let along 100 of them. Not to mention inbreeding. What makes you think any humans stuck in something the size of even the most generously sized starships won’t go full lord-of-the-flies and be unable to effectively maintain the ship long before it ever arrives?
  - pixl97 2y ago
    Of course I see this as a conflation of life versus intelligence. Do I suspect we'll see life commuting between galaxies, seems unlikely life as is fragile compared to how damned harsh space is. But intelligence is a completely different story. We send rudimentary intelligences to space and have racked up billions of miles on them. It seems far more likely that any space faring civilization would look like the following. 1. They would ship the instruction to build life when the reach the destination they are heading too. Machines with error correction seem much more resilient would be much more likely to reach a destination if they had enough energy for the trip so they could refurbish themselves over time. 2. Getting rid of the bodies/life part in the first place. Who cares if it's a million years if you can just pause yourself? Of course the fact the entire universe isn't filled with Von Neumann probes (at least that we see) points out that this hasn't happened yet.
    - lazide 2y ago
      1) that seems to be a lot harder than it seems. Entropy is a nightmare, and data corruption is a big problem. And having a general purpose system capable not only adapting to all the various situations and challenges likely to be faced, that also would have the reserves to deal with them usefully AND reproduce is something we can only hope for in our dreams right now. And until such a thing exists, it’s only speculation it wouldn’t have similar types of problems, eh? Humans are the most adaptable and intelligent anything we have yet run across, and we still regularly struggle to solve the problems we run across even in our comfy and well known existing biosphere which is right here, and that we’re quite well adapted to. And that is assuming a one way trip. Energetically, what could it hope to return to us that would be worth the cost we’d sink into it to try? Panspermia/species wide genetic reproductive drive, maybe - but then sending a robot doesn’t scratch that itch does it? 2) opportunity cost of time is a thing. Some would argue even that time itself is the most valuable thing we have. Pausing yourself for a million years while your competitors don’t, could be a real problem. Also, think of all the new TV shows you’d miss! Agree on the von neumann probe problem. The lack of them doesn’t lend credence to it actually being straightforward or even possible solution for sure. But hey, maybe all the UFO folks are onto something, warp drives/wormholes exist and are cheap, etc. In which case, disclose it already assholes so we can start doing cool stuff with it!
lazide 2y ago
Eh, the biggest blocker IMO is far more esoteric. Money. There is nothing we are aware of that is even close to expensive/worthwhile enough (except perhaps information) to justify the cost in energy to move it that distance. Even if the energy is essentially free. Do the math - rocket fuel isn’t very expensive in bulk, but even moving ‘free’ gold, platinum, iridium, etc. is not even close to worth it. And information can be gathered with telescopes or transmitted with lasers or radio at faster speeds, so why bother with the trek?
- JumpCrisscross 2y ago
  > Do the math - rocket fuel isn’t very expensive in bulk, but even moving ‘free’ gold, platinum, iridium, etc. is not even close to worth it What math are you on? The entire reason moving the "free" ore in the asteroid belt to Earth is expensive is propellant. If we had cheap interplanetary transport, it would absolutely make sense to mine and return matter.
  - lazide 2y ago
    ‘If we had cheap interplanetary transport’ Which we don’t. And how do you expect to get it? Especially when the ‘cheap’ part is already too expensive to make it cost effective even within our own neighborhood? That’s the point! You might as well complain there is no point in being poor when you could just be rich. Or that I could take all vacations I wanted if it was free to take vacations. Thanks?
- pixl97 2y ago
  I mean, that's not a great backup plan. If you're not running a Redundant Array of Independent Planets then you're just one crash away from total data loss. I mean just looking at the energy expenditure growth rate of Earth, you spend as much energy as kings used to in a day. And there is still an absolutely massive amount of solar energy left to harvest.
  - JumpCrisscross 2y ago
    > Redundant Array of Independent Planets Might want to keep workshopping that one.

by api 2y ago

pfdietz 2y ago

> Intergalactic flight would require something more like 0.95c to 0.99c Why would it require speeds that high? Sure, it's going to take a very long time, but why is that an insurmountable obstacle? There are enough isolated stars in intergalactic space that one can even imagining making the trip in smaller steps, with colonization in between. At a stellar density nine orders of magnitude lower than our galaxy stars are still within thousands of light years of each other.

lazide 2y ago
Because most people go nearly insane in solitary confinement? and that isn’t even really solitary. And gov’ts and social structures rarely last a few generations, let along 100 of them. Not to mention inbreeding. What makes you think any humans stuck in something the size of even the most generously sized starships won’t go full lord-of-the-flies and be unable to effectively maintain the ship long before it ever arrives?
- pixl97 2y ago
  Of course I see this as a conflation of life versus intelligence. Do I suspect we'll see life commuting between galaxies, seems unlikely life as is fragile compared to how damned harsh space is. But intelligence is a completely different story. We send rudimentary intelligences to space and have racked up billions of miles on them. It seems far more likely that any space faring civilization would look like the following. 1. They would ship the instruction to build life when the reach the destination they are heading too. Machines with error correction seem much more resilient would be much more likely to reach a destination if they had enough energy for the trip so they could refurbish themselves over time. 2. Getting rid of the bodies/life part in the first place. Who cares if it's a million years if you can just pause yourself? Of course the fact the entire universe isn't filled with Von Neumann probes (at least that we see) points out that this hasn't happened yet.
  - lazide 2y ago
    1) that seems to be a lot harder than it seems. Entropy is a nightmare, and data corruption is a big problem. And having a general purpose system capable not only adapting to all the various situations and challenges likely to be faced, that also would have the reserves to deal with them usefully AND reproduce is something we can only hope for in our dreams right now. And until such a thing exists, it’s only speculation it wouldn’t have similar types of problems, eh? Humans are the most adaptable and intelligent anything we have yet run across, and we still regularly struggle to solve the problems we run across even in our comfy and well known existing biosphere which is right here, and that we’re quite well adapted to. And that is assuming a one way trip. Energetically, what could it hope to return to us that would be worth the cost we’d sink into it to try? Panspermia/species wide genetic reproductive drive, maybe - but then sending a robot doesn’t scratch that itch does it? 2) opportunity cost of time is a thing. Some would argue even that time itself is the most valuable thing we have. Pausing yourself for a million years while your competitors don’t, could be a real problem. Also, think of all the new TV shows you’d miss! Agree on the von neumann probe problem. The lack of them doesn’t lend credence to it actually being straightforward or even possible solution for sure. But hey, maybe all the UFO folks are onto something, warp drives/wormholes exist and are cheap, etc. In which case, disclose it already assholes so we can start doing cool stuff with it!

lazide 2y ago

Eh, the biggest blocker IMO is far more esoteric. Money. There is nothing we are aware of that is even close to expensive/worthwhile enough (except perhaps information) to justify the cost in energy to move it that distance. Even if the energy is essentially free. Do the math - rocket fuel isn’t very expensive in bulk, but even moving ‘free’ gold, platinum, iridium, etc. is not even close to worth it. And information can be gathered with telescopes or transmitted with lasers or radio at faster speeds, so why bother with the trek?

JumpCrisscross 2y ago
> Do the math - rocket fuel isn’t very expensive in bulk, but even moving ‘free’ gold, platinum, iridium, etc. is not even close to worth it What math are you on? The entire reason moving the "free" ore in the asteroid belt to Earth is expensive is propellant. If we had cheap interplanetary transport, it would absolutely make sense to mine and return matter.
- lazide 2y ago
  ‘If we had cheap interplanetary transport’ Which we don’t. And how do you expect to get it? Especially when the ‘cheap’ part is already too expensive to make it cost effective even within our own neighborhood? That’s the point! You might as well complain there is no point in being poor when you could just be rich. Or that I could take all vacations I wanted if it was free to take vacations. Thanks?
pixl97 2y ago
I mean, that's not a great backup plan. If you're not running a Redundant Array of Independent Planets then you're just one crash away from total data loss. I mean just looking at the energy expenditure growth rate of Earth, you spend as much energy as kings used to in a day. And there is still an absolutely massive amount of solar energy left to harvest.
- JumpCrisscross 2y ago
  > Redundant Array of Independent Planets Might want to keep workshopping that one.