Apart from possible scientific communities on the Moon or, perhaps, Mars; just for knowledge.
Although astronomers are detecting any number of planets around stars in our region of the galaxy (those close enough to detect), they can't yet establish those planets' conditions, hence establish if they might be humanly explorable. Anyway the distances to them are far too great for any form of spacecraft presently predictable.
The distances would also make communications extremely difficult if not impracticable. The nearest star outside of the Solar System is about 4 light-years away, so let's make a fair guess at the nearest planet of any use to us, being found 8 light-years away.
Let's do some simple sums......
May 15, 2117. The astronauts send, "Mission Icarus to Earth: We are now in orbit around Icarus." I imagined the name as being suitably romantic.
May 15, 2125: Mission control listens to that, and promptly replies, "Earth to Mission Icarus: Thank you. Safe landings."
May 15, 2133 "Mission to Earth, actually when ... "
May 15 2141, Mission Control hears, ".... you hear this message, we had landed 24 Earth-years ago, and sent this 8 years ago."
Always assuming of course, the spacecraft designers could build radio transmitters hence also their power supplies, powerful enough to transmit signals detectable over 1.4 X 10^14 miles away, of course.
All right, conversation would be rather stilted then. What about travel time? If we could crack the problem of accelerating the craft to the speed of light? Well, then the voyage would still have taken 8 years, as our story has put planet Icarus a mere 8 light-years away.
So no, we cannot seriously countenance travelling, or even sending autonomous probes, to even the nearest planets in the galaxy.
Thank you for a wonderfully thoughtful and informative reply. What about shortcuts through wormholes or bends/folds in time? The stuff on which much of science fiction is based but might it not be scientific fact and we just have not yet discovered it? Yes. I love quantum physics and science fiction. Yes I dream of time travel in any direction and black holes and wormholes and ripples in the timespace continuum. I think about the perplexing possibility of going back in time and meeting my younger self and trying to tell the me of then whom the me of today will be. Would that change anything/ruin everything? Inquiring minds want to know. The cover of Scientific American Magazine of May 2003 is " Infinite Earths in Parallel Universes Really Exist". Pages 41-51 discuss the multiverses that exist from 1-4. That was 14 years ago. What about multiple dimensions? Does our world consist of 26 dimensions and we can only access 3 of them? If it does how could we ever know that? Inquiring minds are curious about such things. If you have any answers or opinions on any of the above I'd sure like to hear them! Happy Wednesday! :)
Well, of course we can never predict what might happen, but one aspect to consider is whether anyone would want to risk entering in some form of wormholes or other quantum-physics mechanism. So far the limiting speed known in the Universe is that of light (also radio waves etc), and it was that which I used above.
I would not like to say whether these other dimension exist or not. I think so far at least they live in masses of mathematics, but I've no idea who they might be proven to exist in reality, if they do s.. As you say, it's a fascinating area.
Durdle 