It’s not theoretically impossible, it’s just really hard. If we go fast enough, we can even do it within the current lifespan of a human (from the perspective of that human).
Well, it starts with "assuming we had something we don't have (i.e. the capability to accelerate at 1G for 100 years)"...
I meant it's theoretically impossible with the theory that we have now. Of course if we make breakthroughs in the theory, then the theory will change and it may become possible.
But SpaceX going to Mars is not exactly revisiting this theory. They are just having fun with the current state of the theory, which says that they won't bring humans further, period.
I don't mean to be nitpicky, but you specified the difference between a theoretical impossibility and an engineering impossibility in your parent comment. I assume the reply is just referring to the fact that technically getting to a star system within the 10s of light-years away is an engineering feat, not a break-the-known-rules-of-the-universe feat. I don't take it that they're actually claiming it's a realistic feat that may be accomplished soon.
Sure, I guess I shouldn't have used the word "theoretically". My point was that with our current knowledge and capabilities, it is completely unrealistic to consider it remotely possible to achieve such a thing. We are orders of magnitudes more likely to disappear as a civilization in the short term than to achieve any kind of meaningful space travel.
Continuous acceleration to relativistic speeds is impossible without magic. Reasonable drives require impossibly enormous amounts of fuel. Antimatter drives require impractically enormous amounts of fuel.
Relativistic speeds require too much energy, too much reaction mass, and too much fuel. None of the reaction drives are good enough. It would only be possible with magic reactionless drive, and magic source of power.
I meant it's theoretically impossible with the theory that we have now. Of course if we make breakthroughs in the theory, then the theory will change and it may become possible.
But SpaceX going to Mars is not exactly revisiting this theory. They are just having fun with the current state of the theory, which says that they won't bring humans further, period.