Hey Michael,

Thanks for your comment. As you point out, it’s a thought experiment and traveling to the past is a physical impossibility. So just because of that it’s already more than a technical challenge.

But even without that, as I understand it (and I’m not a physicist), the movement of objects in the solar system and galaxy is fundamentally unpredictable because it’s a chaotic system. Physicists refer to this as the n-body problem.

That doesn’t mean you can’t predict with sufficient accuracy where a planet will be within human timescales. But if you go far enough into the past, the accuracy becomes lower and lower and eventually it’s impossible to predict where something will be. So I think that fundamentally limits how far back into the past you can jump and still be sufficiently certain where everything will be in space.