So two things that are not accounted for here:
- This covers only brute force attacks, meaning you try every different combination. Shor’s Algorithm exploits patterns in RSA keys and is much, much more efficient than brute force.
- There actually is an algorithm (Grover’s search algorithm) that can speed up brute force search. However, this speedup is only quadratic, so brute forcing something like a 256 bit key is still infeasible. The discrepancy is quantum information doesn’t flow the same way that classical information does. A related concept is the idea of reversible classical computing: this derivation relies on the assumption that you change set a bit, thereby erasing the information of what that bit was before. If your operation doesn’t erase that information (e.g. if it’s specifically a bit flip, you know what the original bit was, it’s the opposite), then this argument about the minimum required energy falls apart. Most operations in a quantum computer are inherently reversible.
No matter how bad it gets, the moon and mars will never be more inhabitable than earth