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Or that long-distance space travel or even communication is simply not feasible for any civilization at any level of technological advancement.

Houshalter 13y ago
It should be possible to transmit radio signals between planets. Although it's possible we just aren't listening or they aren't doing it frequently enough. Space travel is more speculative but it seems theoretically possible to reach a significant fraction of c even with 20th century technology. Even today's spacecraft could reach other solar systems in a few thousand years, which is reasonable on a geological timescale. If probes are self-replicating, or the mother civilization simply sends a lot of them, they could cover the entire galaxy in a few million years at most.
- jotm 13y ago
  There's really no point in either. A radio signal would need to be extremely powerful to travel 500 light years without degrading (not to mention that even the senders may not be able to decode it after 1000 years :-)), and sending spacecraft to navigate 500 light years hoping it will perform all maneuvers correctly and not get hit by something in order to reach a planet without being able to send any useful information back seems naive and pointless. If there's any space faring civilization out there, they're probably content with their own star system and maybe the ones closest to it - there are so many planets and asteroids to mine for resources (plus recycling would be a big thing) they could last for hundreds of millions of years...
  - Houshalter 13y ago
    Difficult yes, but neither of those things are inconceivable for even our civilization. Imagine one that's millions of years ahead of us. Interstellar distances do prevent a lot of practical expansion, but it'd be nice to say hello to your neighbors, and start making preparations for when your star dies, or the even longer term heat death of the universe.

Houshalter 13y ago

It should be possible to transmit radio signals between planets. Although it's possible we just aren't listening or they aren't doing it frequently enough. Space travel is more speculative but it seems theoretically possible to reach a significant fraction of c even with 20th century technology. Even today's spacecraft could reach other solar systems in a few thousand years, which is reasonable on a geological timescale. If probes are self-replicating, or the mother civilization simply sends a lot of them, they could cover the entire galaxy in a few million years at most.

jotm 13y ago
There's really no point in either. A radio signal would need to be extremely powerful to travel 500 light years without degrading (not to mention that even the senders may not be able to decode it after 1000 years :-)), and sending spacecraft to navigate 500 light years hoping it will perform all maneuvers correctly and not get hit by something in order to reach a planet without being able to send any useful information back seems naive and pointless. If there's any space faring civilization out there, they're probably content with their own star system and maybe the ones closest to it - there are so many planets and asteroids to mine for resources (plus recycling would be a big thing) they could last for hundreds of millions of years...
- Houshalter 13y ago
  Difficult yes, but neither of those things are inconceivable for even our civilization. Imagine one that's millions of years ahead of us. Interstellar distances do prevent a lot of practical expansion, but it'd be nice to say hello to your neighbors, and start making preparations for when your star dies, or the even longer term heat death of the universe.