5 ms·

To me the Fermi paradox is easily explained by the speed of light being a hard limit on how fast something can go and the fact that space is absolutely enormous

To me the Fermi paradox is easily explained by the speed of light being a hard limit on how fast something can go and the fact that space is absolutely enormous. Every expectation of multi planet civilizations simply hand waves away physics. How would they move between stars? "You know, alien stuff. They'll figure it out." There are also unstated economic assumptions that don't make a lot of sense. Why would they leave their planet anyway? A civilization wealthy and advanced enough to consider traveling to other planets probably does not have a population big enough to support the kind of large scale emigration needed to set up big colonies. Wealthy societies have fewer children. Then of course there is the question of why would you ever leave a planet with such advanced technology and apparent wealth? I would much rather live in any city on earth than a colony on the moon or Mars. How long would it take for those colonies to be as attractive a living space as the place we have right now?

samanator 4y ago
You don't need to hand wave physics away. von Neumann probes + a lot of time would give space faring civilizations ways to arrive at the furthest reaches of the galaxy, even with our current understanding of physics.
techdragon 4y ago
To me there’s an obvious counter to “the speed of light is too slow” and that’s reframing it as “we don’t live long enough” and since we as a society are trying to extend the length of our lives on a multitude of fronts from egocentric rich people to public health institutions, at the end of the day, people who can live longer tend to be healthier and socially productive longer than those who won’t live as long. Effectively by working to conquer cancers and age related diseases/decline, and the general effort to “extend our lives”… we are making space slightly smaller for our future selves once our propulsion technology advances to the point we can achieve decent percentages of the speed of light… which there are no real technical barriers against. From solar sails to muon fusion to all sorts of other interesting technology we have yet to develop, we may not be able to break a warp barrier and go faster than light… but if we live longer, say 10 times longer, the. Suddenly 5 years shipboard time travelling to another star system doesn’t seem so bad. 5 years in a millennium of years is equivalent to a 6 month journey for someone who will live to 100.
pjdemers 4y ago
I agree with this. Given the vast time necessary to move (or even communicate) between stars, there is no social, political or economic reason to travel more than a few light years from your home planet. That's leaves science, religion and adventure as the only reasons to go really far out int space, and the cost of interstellar travel limits how many other planets can be visited for those reasons, even over tens of thousands of years.
rockfishroll 4y ago
I think your first point ignores one of the fundamental insights of the Fermi Paradox, which is that while space on an astronomical scale is massive, so is time. The milky way galaxy is ~100,000 light years across. So traveling at 1% of the speed of light, you could go end to end in 10,000,000 years. That sounds like a long time, but it's really not. The earth is ~4.5 billion years old. So we can say with certainty that it's possible (not guaranteed) to become a space faring race (although not a galaxy crossing one) in 4.54 billion years. If we tack the amount of time it takes to cross the whole galaxy end to end we get 4.55 billion years. The milky way galaxy is 13.61 billion years old. That means the galaxy had 9.06 billion years worth of chances to churn out a another planet that could have expanded across the galaxy from edge to edge and been here waiting when humans arrived on the scene. Planets with Earth like conditions are certainly rare but my, admittedly limited, understanding is that they're not "1 in 9.06 billion years" rare. There are obviously other constraints here. I think your second point about wealthy technological races potentially stabilizing at zero population growth is totally reasonable. But I think the fact that space's apparent scale doesn't actually matter is the whole reason the Fermi Paradox was such an "ah-ha!" moment for many people. The reason it's a paradox is that, given all of our assumptions for variable values in the Drake Equation at the time, it really seemed like we should have met some aliens. The point was that if distance wasn't the hurdle we thought it was in the equation as currently defined, then we were either missing some relevant variables, or we had made some bad assumptions for the ones we had.
- saiya-jin 4y ago
  > wealthy technological races potentially stabilizing at zero population growth It doesn't have to, in fact (relatively) endless population growth is the prime force to push even lazy non-curious fearful aliens out of their planet and sun. That and obvious unavoidable necessity of every sun eventually becoming killer of its own ecosystem, even if their planet would be super duper stable with all meteorites under total control. The rest I agree with, even civilization having mere 100 million years of advantage on us would be able to properly colonize non-trivial part of milky way by now, we just have to abandon star trek/wars expectations of instant communication and travel which is fine. We humans are generally pretty bad at grasping true meaning of numbers when it comes to ie astronomy.
zackees 4y ago
kanzenryu2 4y ago
THANK YOU! It mystifies me how people manage to ignore this. Interstellar travel is going to be enormously difficult. Maybe just too hard to overcome regardless of technology level.
- coldpie 4y ago
  I find the fact that FTL travel is almost certainly impossible to be so depressing that I choose to ignore it ;)
Zigurd 4y ago
The speed of light is a limiting factor, but most models I have seen of galactic civilizations take that into account, yet they project that interstellar expansion of a hypothetical civilization is possible. There are other factors that are more likely to explain why we are apparently alone: civilizations might not last long enough that they would encounter us before dying out, or that they have not yet emerged. IOW we might be alone in time more than we are alone in space.
shagymoe 4y ago
Doesn't wormholes make the speed of light argument moot?
- mr_mitm 4y ago
  Even if wormholes were real, and even if we could manipulate matter with negative energy density (which doesn't exist) on the order of many times the mass of the sun (which is needed for wormholes), constructing one that spans from A to B would take longer than light travels from A to B.
squatrackcurls 4y ago
The premised of "Wealthy societies have fewer children." is wrong; correlation != causation. You're posing these things as though they're axiomatic for all beings; as if these beings (which don't exist) would operate exactly as we do and not have their own cultures and ways of being distinct from our own here (of which are vastly different amongst people of other countries on Earth). It's a very narrow, human-centric view.

samanator 4y ago

You don't need to hand wave physics away. von Neumann probes + a lot of time would give space faring civilizations ways to arrive at the furthest reaches of the galaxy, even with our current understanding of physics.

techdragon 4y ago

To me there’s an obvious counter to “the speed of light is too slow” and that’s reframing it as “we don’t live long enough” and since we as a society are trying to extend the length of our lives on a multitude of fronts from egocentric rich people to public health institutions, at the end of the day, people who can live longer tend to be healthier and socially productive longer than those who won’t live as long. Effectively by working to conquer cancers and age related diseases/decline, and the general effort to “extend our lives”… we are making space slightly smaller for our future selves once our propulsion technology advances to the point we can achieve decent percentages of the speed of light… which there are no real technical barriers against. From solar sails to muon fusion to all sorts of other interesting technology we have yet to develop, we may not be able to break a warp barrier and go faster than light… but if we live longer, say 10 times longer, the. Suddenly 5 years shipboard time travelling to another star system doesn’t seem so bad. 5 years in a millennium of years is equivalent to a 6 month journey for someone who will live to 100.

pjdemers 4y ago

I agree with this. Given the vast time necessary to move (or even communicate) between stars, there is no social, political or economic reason to travel more than a few light years from your home planet. That's leaves science, religion and adventure as the only reasons to go really far out int space, and the cost of interstellar travel limits how many other planets can be visited for those reasons, even over tens of thousands of years.

rockfishroll 4y ago

I think your first point ignores one of the fundamental insights of the Fermi Paradox, which is that while space on an astronomical scale is massive, so is time. The milky way galaxy is ~100,000 light years across. So traveling at 1% of the speed of light, you could go end to end in 10,000,000 years. That sounds like a long time, but it's really not. The earth is ~4.5 billion years old. So we can say with certainty that it's possible (not guaranteed) to become a space faring race (although not a galaxy crossing one) in 4.54 billion years. If we tack the amount of time it takes to cross the whole galaxy end to end we get 4.55 billion years. The milky way galaxy is 13.61 billion years old. That means the galaxy had 9.06 billion years worth of chances to churn out a another planet that could have expanded across the galaxy from edge to edge and been here waiting when humans arrived on the scene. Planets with Earth like conditions are certainly rare but my, admittedly limited, understanding is that they're not "1 in 9.06 billion years" rare. There are obviously other constraints here. I think your second point about wealthy technological races potentially stabilizing at zero population growth is totally reasonable. But I think the fact that space's apparent scale doesn't actually matter is the whole reason the Fermi Paradox was such an "ah-ha!" moment for many people. The reason it's a paradox is that, given all of our assumptions for variable values in the Drake Equation at the time, it really seemed like we should have met some aliens. The point was that if distance wasn't the hurdle we thought it was in the equation as currently defined, then we were either missing some relevant variables, or we had made some bad assumptions for the ones we had.

saiya-jin 4y ago
> wealthy technological races potentially stabilizing at zero population growth It doesn't have to, in fact (relatively) endless population growth is the prime force to push even lazy non-curious fearful aliens out of their planet and sun. That and obvious unavoidable necessity of every sun eventually becoming killer of its own ecosystem, even if their planet would be super duper stable with all meteorites under total control. The rest I agree with, even civilization having mere 100 million years of advantage on us would be able to properly colonize non-trivial part of milky way by now, we just have to abandon star trek/wars expectations of instant communication and travel which is fine. We humans are generally pretty bad at grasping true meaning of numbers when it comes to ie astronomy.

zackees 4y ago

kanzenryu2 4y ago

THANK YOU! It mystifies me how people manage to ignore this. Interstellar travel is going to be enormously difficult. Maybe just too hard to overcome regardless of technology level.

coldpie 4y ago
I find the fact that FTL travel is almost certainly impossible to be so depressing that I choose to ignore it ;)

Zigurd 4y ago

The speed of light is a limiting factor, but most models I have seen of galactic civilizations take that into account, yet they project that interstellar expansion of a hypothetical civilization is possible. There are other factors that are more likely to explain why we are apparently alone: civilizations might not last long enough that they would encounter us before dying out, or that they have not yet emerged. IOW we might be alone in time more than we are alone in space.

shagymoe 4y ago

Doesn't wormholes make the speed of light argument moot?

mr_mitm 4y ago
Even if wormholes were real, and even if we could manipulate matter with negative energy density (which doesn't exist) on the order of many times the mass of the sun (which is needed for wormholes), constructing one that spans from A to B would take longer than light travels from A to B.

squatrackcurls 4y ago

The premised of "Wealthy societies have fewer children." is wrong; correlation != causation. You're posing these things as though they're axiomatic for all beings; as if these beings (which don't exist) would operate exactly as we do and not have their own cultures and ways of being distinct from our own here (of which are vastly different amongst people of other countries on Earth). It's a very narrow, human-centric view.