OK. I'll try again. My, or rather the Cheshire Cat's notion of time travel can constitute genuine time travel only if for a universe to be in at a given instant all that is required is for the matter and energy in that universe to be arranged in a certain way. (See fig 1-3.) Let us the universe contains only three particles. At time t1 they are arranged in absolute space as shown in fig.1. At time t2, a little later, they are arranged as shown in fig. 2. At time t3 they are arranged as shown in fig. 3. This is the same arrangement as at t1. This means that t1 and t3 are the same instant. How this works in a universe involving beings with memory is not so straightforward. Let us take a new universe. On the 15th December Alice(b) was talking to the Cheshire Cat. She had brown hair. While she was doing so another Alice, very similar but with red hair, appeared next to her out of thin air. Let us call that Alice Alice(r). Alice(b) and Alice(r) have a chat. It turns out that Alice(r) has come from the future. She has memories of being Alice(b), including having their conversation. They wander off in separate directions. Alice(b) lives her life in an unremarkable fashion until the 25th December. This year Santa has brought her a time machine and a tube of red hair dye. Alice dyes her hair and decides to try out the time machine. The time machine works in this way: When you get in an identical copy is made of you. Then the whole universe outside the time machine, including the copy of you, is rewound. All the changes that happened in the universe between the time you get in and the time you go back to are reversed. Alice(b) goes back to the 15th of December. She is now identical to Alice(r). The girl she meets is identical to Alice(b) when we first meet her in this story (she is the Alice(b) left outside the time machine and rewound). The situation is now identical to the situation on the 15th December. If one accepts the account above of what defines the universe as being at a specific instant then one is compelled to admit that Alice has time travelled. This account is also compatible with presentism. I think. Hugs and Kisses James
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