re: #58 Nyet

But let’s say it were possible to change the past. By changing the past significantly at a spacetime point you make all persons causally connected to that point change, and, practically speaking, you make most of them disappear (because the set of those people includes all the children born in the old timeline that will either never have been born or will have had entirely different personalities in the changed timeline). IOW, in practical terms, depending on where you change the past, you’re making thousands, or millions, or billions of people disappear. How is that not murder?

As a specific example, suppose someone went back in time and somehow killed Hitler before he became Chancellor. Perhaps WWII would then not have happened, and millions of lives would have been spared. But there were WWII servicemen who met their future brides while serving abroad, got married and had kids. Without WWII, they would have never met and those kids would never have been born. The “Bye bye Marty McFly” dilemma. So you have saved the lives of people who would have died, while killing those who were already born in your timeline. I’m not sure that’s an acceptable trade-off.

A “surgical strike” in time travel could not possibly exist.