Combinatorical problems tend to grow in the amount of effort to try out all possible elements quite quickly, and quickly growing things in turns often hit physi

Combinatorical problems tend to grow in the amount of effort to try out all possible elements quite quickly, and quickly growing things in turns often hit physical limits. The following post on Security.Stackexchange explains it quite nicely; excerpt: the sun doesn't emit enough energy over its lifetime to power an extremely efficient computer able to try all combinations. http://security.stackexchange.com/a/25878/25947 http://security.stackexchange.com/a/25878/25947 So basically we need some new form of computer (one that's not flipping individual physical bits), and not "just faster" ones, to crack certain encryptions by brute force.