> then paradoxical situations could be constructed--e.g. going back in time and killing yourself (the earlier you) before you entered the machine, or killing your grandfather before your father was born
Can't the paradox be resolved by considering it as a fork/branching of a new reality/timeline where the grandfather is killed, kind of similar to many world interpretation in QM. I'd speculate that using model of lazy fork it may be possible to get some ballpark estimates on energy requirements/etc. below the typical "all the energy in the Universe". Such forks/perturbations possibly also dissipate, like a small wave in the pond, and the forked reality gets naturally merged into the mainline ( i think this is how QM's many world while possibly true is still compatible with "realistic" situation of limited number, may be even just 1, Universe mainlines)
Can't the paradox be resolved by considering it as a fork/branching of a new reality/timeline where the grandfather is killed, kind of similar to many world interpretation in QM. I'd speculate that using model of lazy fork it may be possible to get some ballpark estimates on energy requirements/etc. below the typical "all the energy in the Universe". Such forks/perturbations possibly also dissipate, like a small wave in the pond, and the forked reality gets naturally merged into the mainline ( i think this is how QM's many world while possibly true is still compatible with "realistic" situation of limited number, may be even just 1, Universe mainlines)