So, Bob asked me a doozy this evening in the office. “How, if you were an
evil overlord bent on using your time machine to destroy everyone else’s time
machines, would you go about it?”

If you start in the past, destroying all the time machines people have used
in the future to go -back- in time, you may be missing out on all the ones
invented in the past used by people who go forward in time to where you just
were. We have a theory about starting out on the future end of time and
working your way backwards. It’s harder than it sounds, though. Particularly
if someone’s out to foil you.

There’s a bunch of intricacies involved, too. You could say “Hey, why not
just kill off the time machine inventor?” but that’d wreck -your- time
machine. Furthermore, someone further on in the future is bound to invent one
sooner or later, so you’ll just screw yourself out of being able to wipe them
out when they figure it all out, unless they happen to stumble into your
time. They can go back in time and pollute the timeline with lots more new
time machines and undo all of your work.

If I sound like a complete nutjob, that’s because it’s a pretty bizarre thing
to try to figure out. It’s a problem I’d like to see some people try to apply
an algorithm to.