People regularly say this, and I've yet to find a convincing argument for it.
The "backwards time travel" argument presupposes that an object is actually moving through space at a speed faster than light - i.e. with an imaginary Lorentz factor (1/sqrt(1-(v^2/c^2))) and all the shenanigans that entails. That presupposition ignores hypothetical approaches like wormholes and Alcubierre drives that outright shorten the distance to be traversed and thus don't entail actually moving at such speeds (and therefore keeping the Lorentz factor right around its normal happy 1).
Put differently: such an argument presupposes that a light cone is actually cone-shaped, whereas wormholes and Alcubierre drives throw a wrench in that, producing all sorts of lumpiness that keeps events within the same (really weird looking) light cone despite taking place at long distances.
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People regularly say this, and I've yet to find a convincing argument for it.
The "backwards time travel" argument presupposes that an object is actually moving through space at a speed faster than light - i.e. with an imaginary Lorentz factor (1/sqrt(1-(v^2/c^2))) and all the shenanigans that entails. That presupposition ignores hypothetical approaches like wormholes and Alcubierre drives that outright shorten the distance to be traversed and thus don't entail actually moving at such speeds (and therefore keeping the Lorentz factor right around its normal happy 1).
Put differently: such an argument presupposes that a light cone is actually cone-shaped, whereas wormholes and Alcubierre drives throw a wrench in that, producing all sorts of lumpiness that keeps events within the same (really weird looking) light cone despite taking place at long distances.