Exponential growth. 640k is obviously not enough. Nor is double that. Or double that. Or double that. But keep doubling long enough, and eventually the length o

Exponential growth. 640k is obviously not enough. Nor is double that. Or double that. Or double that. But keep doubling long enough, and eventually the length of time before you need to do it again will be considerable. We might be there. And 128 bits is a lot of bits. You know what bit width you need to represent twice as many states as a 64 bit value? That's right, a 65 bit value.