My point is that even if it is 10% efficient, which is only 5 times more than your estimate， you have 4 months. Even if it is 2% efficient, you get ALMOST a mon

My point is that even if it is 10% efficient, which is only 5 times more than your estimate， you have 4 months. Even if it is 2% efficient, you get ALMOST a month. Re: accelerating for many months at 1G is definitely bad physics, not only are you relativistic, you start getting into the kind of speeds where a minor meteorites will wipeout your ship. 1 gram meteorite with a relative velocity of 0.5c has 1.4e13 J of kinetic energy = 3.5 kton of TNT, so a small nuke.