This is using the fact that at 1g acceleration, one will quickly approach the speed of light relative to its starting rest frame and time dilation will give the astronaut a _very long_ life relative to that frame.

The closer to lightspeed you get the more shit you would collide with. I think you would reach an equilibrium speed where drag balances thrust?

Ahh fair enough. Guess I wasn’t measuring the length of the observable universe in the frame of the astronaut…