re: #139 Kragar

If one had a time machine and went back in time to kill Hitler before he rose to power, what impetus would there be for the future you to travel back in time and kill Hitler? He would never have done anything in the new timeline.

Altering history to noticeable effect would be impossible.

Yes.

I would say altering history is impossible as such.

To alter it, you must travel to the past. To travel to the past, the past must exist in the first place, that is, the possibility of time travel refutes presentism and affirms the “4D”/block view of spacetime. But such a view is “static” - everything “‘has already happened”, including you traveling to the past.