It's true that it's unpredictable for a single atom, but when you're dealing with a macroscopic object (say, a metal part), it's quite predictable. The law of l

It's true that it's unpredictable for a single atom, but when you're dealing with a macroscopic object (say, a metal part), it's quite predictable. The law of large numbers helps out quite a bit here (and the number of atoms is very large).