As I mentioned a few times, HPMoR time turners violate general relativity, as they result in objects appearing and disappearing without any energy being extracted from or dissipated into the environment. E.g. before the loop: 1 Harry, during the loop: 2 Harries, after the loop: 1 Harry.
Yes, but you could very well think about something equivalent to the time-turner that exchange matter between the past and the present, instead of just sending matter to the past, in a way that keeps energy conservation. It would be harder to use practically,but wouldn’t change anything to “energy conservation” vs “determinism” issues.
Don’t forget that to fully conserve energy, you have to maintain not only the total mass, but also the internal chemical potentials of whatever thing you’re shifting into the past and its gravitational potential energy with respect to the rest of the universe. I think you’ll have a hard time doing this without just making an exact copy of the object. “Conservation of energy” is a much harder constraint than is obvious from the three words of the English phrase.
I don’t see that as a theoritecal problem against a plausible universe having such a mechanism. We could very well create a simulation in which when you timetravel, the total energy (internal from mass and chemical bounds, external from gravity and chemical interaction with the exterior) is measured, and exchanged for exactly that amount from the source universe. If we can implement it on a computer, it’s possible to imagine a universe that would have those laws.
The hard part in time-turner physics (because it’s not computable) is the “stable time loop”, not the “energy conservation” part (which is computable).
As I mentioned a few times, HPMoR time turners violate general relativity, as they result in objects appearing and disappearing without any energy being extracted from or dissipated into the environment. E.g. before the loop: 1 Harry, during the loop: 2 Harries, after the loop: 1 Harry.
Yes, but you could very well think about something equivalent to the time-turner that exchange matter between the past and the present, instead of just sending matter to the past, in a way that keeps energy conservation. It would be harder to use practically,but wouldn’t change anything to “energy conservation” vs “determinism” issues.
Don’t forget that to fully conserve energy, you have to maintain not only the total mass, but also the internal chemical potentials of whatever thing you’re shifting into the past and its gravitational potential energy with respect to the rest of the universe. I think you’ll have a hard time doing this without just making an exact copy of the object. “Conservation of energy” is a much harder constraint than is obvious from the three words of the English phrase.
I don’t see that as a theoritecal problem against a plausible universe having such a mechanism. We could very well create a simulation in which when you timetravel, the total energy (internal from mass and chemical bounds, external from gravity and chemical interaction with the exterior) is measured, and exchanged for exactly that amount from the source universe. If we can implement it on a computer, it’s possible to imagine a universe that would have those laws.
The hard part in time-turner physics (because it’s not computable) is the “stable time loop”, not the “energy conservation” part (which is computable).
Yep.