Maintaining a 1G acceleration for years is either impossible or so hard it may as well be impossible. Even if you had a magic drive that could do it you would

Maintaining a 1G acceleration for years is either impossible or so hard it may as well be impossible. Even if you had a magic drive that could do it you would soon reach velocities where colliding with the smallest spec of dust would be like a small nuclear bomb. 1G to Proxima Centauri would reach a peak velocity of .95 c and hitting a 1g particle would release 48451 tons of TNT of energy. So you would need BOTH a magic drive and a magic shield.