>>13431569The faster you move the more energy it takes (and you need more fuel to keep accelerating). But assuming we figure out a way around that, you still have some leeway with how far you can go. According to pic related (found on wikipedia:
https://en.wikipedia.org/wiki/Space_travel_using_constant_acceleration) you can get to Andromeda and back home (although you will effectively be an alien to whoever's on Earth when you arrive) if you're young enough and you fly the whole way at 1g. You also get onboard gravity for free with that acceleration.
Haldeman had an idea in The Forever War where for short periods of time, up to a month or so, the crew would be strapped into special tanks that would allow them to withstand up to 25g. Taking 1/12.5 of a year just to make the numbers line up, and because iirc in-universe going for a month straight in high-g already had a sizable mortality rate, you'd end up traveling 0.04(cosh(2)-1) = about 0.11 lightyears, or 55 times as far as Voyager. You'd still need another session in the tank or a long break on the ship to actually exit the Solar system (1.6 ly)
If you somehow managed to spend a year in the tank (not sure how the math works if you assume short sessions in the tank and then longer sessions doing some sort of onboard recovery, like 1 week high-g and then 8 weeks rest or something), you'd get 0.04(cosh(25)-1) which is on the order of magnitude of a billion lightyears. So you could certainly get places. Assuming your ship doesn't break because it hit a microscopic piece of dust at a healthy fraction of lightspeed. But you'd be effectively dead to everyone you knew on Earth anyway, so maybe it'd be better if you just joined them in the afterlife.