Is possible, and easy if one accelerates at 1 G for half the trip, then decelerates at 1 G for half the trip. Conventional nuclear fission AND fusion rocket eng

Is possible, and easy if one accelerates at 1 G for half the trip, then decelerates at 1 G for half the trip. Conventional nuclear fission AND fusion rocket engines, like NERVA, already exist and are flight-certified. 1 light year could be traveled in 2 pilot years.