All the way back in 2006, I wrote about the problem of the
philosopher's axe: if you replace the shaft, and then later you replace the head, is it still the same axe? So as you can imagine, I was delighted to discover the existence of the
Helko modular axe system.
In contrast to my ice-climbing friend, I was interested to note, they think that having to replace the axe's handle is more likely.
But according to the always-interesting Eliezer Yudkowsky, the whole notion of particles having a continuing identity in time makes
no sense on a quantum-mechanical level, so the whole question is moot anyway.