Reversible computing techniques 'cheat' around the entropy limit. This means they can reach effective speeds far, far beyond what are possible with current computers, as they are effectively capable of performing nondeterministic operations.
Wait, what? I thought reversible computation just uses less energy. Where does the non-determinism come in?
Anyway, about the hashing being insecure: Wikipedia says that attacks on SHA-256 still take on the order of 2
250 operations. And unless I made a big thinko here, doesn't the hash target change every ~10 minutes? Wouldn't that throw of an attacker? And if it was possible to break SHA faster, wouldn't the system adjust by raising the difficulty level?