Teleportation can work. A targeted short-lived neutrino beam would do the trick, with a bit of work.
Once you have teleportation you also have (the appearance of) mass altering transmogrification by simple application of the former to mass unknown to the observers. One you have apparent transmogrification and advanced-prediction-in-advance you have Time Turning. Again, through applying teleportation to carefully synthesized and selected matter that the observers aren’t aware of. For example, to a fully synthesized extrapolation of “MoR!Harry!2.hours.from.now”. From first personal perspective of Harry this is equivalent to time travel.
This is childs play to Omega, it’s nearly exactly what he is contrived for in Newcomb’s Problem. It may be a tad more difficult for a mere superintelligence but it remains an engineering problem, not so much a physics one.
At least you don’t have to break conservation of energy or momentum.
The above possibile solution isn’t “true” time travel. But it is to time travel precisely what targeted short-lived neutrino beams are to perceived “apparition”. There is little qualitative difference in either relationship to described magical events or the phisical possibility.
It gets scarier if you realize that anything sufficiently advanced to model “MoR!Harry!2.hours.from.now” can probably model “MoR!Harry!2.hours.from.now+afraid.to.mess.with.time”.
Once you have teleportation you also have (the appearance of) mass altering transmogrification by simple application of the former to mass unknown to the observers. One you have apparent transmogrification and advanced-prediction-in-advance you have Time Turning. Again, through applying teleportation to carefully synthesized and selected matter that the observers aren’t aware of. For example, to a fully synthesized extrapolation of “MoR!Harry!2.hours.from.now”. From first personal perspective of Harry this is equivalent to time travel.
This is childs play to Omega, it’s nearly exactly what he is contrived for in Newcomb’s Problem. It may be a tad more difficult for a mere superintelligence but it remains an engineering problem, not so much a physics one.
The above possibile solution isn’t “true” time travel. But it is to time travel precisely what targeted short-lived neutrino beams are to perceived “apparition”. There is little qualitative difference in either relationship to described magical events or the phisical possibility.
It gets scarier if you realize that anything sufficiently advanced to model “MoR!Harry!2.hours.from.now” can probably model “MoR!Harry!2.hours.from.now+afraid.to.mess.with.time”.