If you run through the functional specifications of your time machine, and it looks as if it’s going to print bullion, or proliferate doubles, it’s been badly assembled. Time-travel is the dramatization of something else, and you’re still trapped in the simulation.
Forbes on Seth Lloyd:
In Type 1 time travel — the type highlighted in the “Back to the Future” films — all possible pasts and futures in some sense exist simultaneously, says Lloyd. So, that when you go back and change the past in order to enter a different future, your “old” future is in some sense still “there.”
“From a theoretical physics standpoint,” said Lloyd, “Type 1 is certainly possible, but we still don’t have a very good theory of how it would work.”
He notes that current physical theory favors Type 2 time travel scenario in which the past can’t be changed no matter how hard one tries.
“Our theory of time travel is Type 2,” said Lloyd, “[which means] no matter how hard you try to mess with the past you can’t do it.”
HP Lovecraft fixed the principle.