In the case where the reader doesn't understand `.join()`, they should look up the following page and read its documentation (which is about as clear as it can possibly be): https://docs.python.org/2/library/multiprocessing.html#multi...

Also, I would suggest that the physicist in your example hire a software practitioner [who can be expected to know 'join'] to write his software correctly (rather than trying to half-ass it himself).