The answer is actually yes if you're willing to wait.
Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical. We've barely even left our own planet, and we've managed to throw a few chunks of metal out of our solar system so far. We lack the industrial capacity to build an interstellar ship, we do not lack the physics.
>Interstellar travel is not impossible, no matter what anyone tells you. We know how, it's just wildly impractical.
This was provocative and intriguing so I looked into it and this is my understanding of some of the options (theoretically).
First, "interstellar" means between stars and the closes star is 4.2465 light years away (Proxima Centauri in Alpha Centauri star system) so I used that. c=speed of light
- Chemical (Voyager), ~0.006% c: ~75,000 years
- Nuclear pulse (Orion), ~3-10% c: ~40-130 years
- Fusion (Daedalus), ~12% c, flyby: ~35 years
- Laser sail (Starshot), ~20% c, flyby: ~21 years (gram-scale probes only)
- Antimatter, ~20-30% c stopping: ~14-21 years; ~50% c flyby: ~8-9 years
Nuclear pulse surprised me in particular. My understanding is you basically just detonate a bunch of nukes to propel yourself. There are legal hurdles not to mention fallout, but it sounds like the physics of simply getting there in 40+ years (not stopping, mind you) is possible with todays physics. That's pretty amazing and I had no idea.We also lack the biological knowledge to build stable closed ecosystems that last for years with minimal degradation of essential elements and processing systems, the engineering knowledge to build complex machines that last for years without any significant failures while being ablated by space dust and occasional rocks, and the political and psychological knowledge to keep a crew sane, focused, and functional.
Apart from that - solved problem.
We don't lack the industrial capacity either, we mostly lack a good reason to spend these resources in that direction.
And IMHO that's the main explanation for the Fermi paradox: we don't see aliens everywhere because they don't have a good reason to colonize other planets than their own either.
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There’s a huge asterisk here.
IIRC, it is possible to get anywhere in the observable universe in one human lifetime assuming 1g of constant acceleration.
This does not permit you to slow down and halt at your target, which greatly increases travel times.
It is also effectively a one-way ticket for anything other than objects in our immediate stellar neighborhood. If you turned around and returned to Earth after getting to an object 1,000ly away—still well within our own arm of the galaxy—at least 2,000 years will have passed on Earth. It’s probable that no civilization you know of would still exist, nor would anyone be able to understand your language.
This isn’t even beginning to address the problem of running into stray atoms at 99.99…% of the speed of light. Or god forbid a handful of stray molecules. We also haven’t discussed the real elephant in the room which is the sheer amount of energy required to accelerate a human and human life support systems at 1g for several decades.