Immortality

There are so many things about quantum mechanics that makes it so fun to play around with it in my head when i'm bored. 

Schrodinger's cat is famous for being alive and dead at the same time, right? (Though he really proposed it as a way to point out the absurdity of the Copenhagen interpretation of the quantum mechanics) 

Well, following that same logic it is fully possible to turn someone near-immortal in the eyes of the humanity. Lock him or her in a box that allows for complete separation from the observable universe. It needn't even be a box of physical walls. It can be a box of, say, distances. So far that the man/woman is effectively outside the range of observable sphere around the known space. 

(using time and space as an effective 'wall' is a notion frequently used by military strategists of old and new alike, btw. It's a principle of maneuverability)

It sounds funny, but technically we won't be able to tell if the subject of such a process is alive or dead, so that's immortality in a sense.