The assumption that time always works the same way doesn’t apply to anti-matter (Ambjorn, Jurkiewicz, & Loll, 2008). For example, in the Feynman diagram of an electron hitting an anti-electron, the latter enters the collision going backwards in time (Figure 4.8). The logic is symmetric, so to the anti-electron the electron is going back in time. Yet both the electron and anti-electron are entering the interaction not leaving it.
Minkowski interpreted Einstein’s theory to mean that objects can move faster or slower along the time dimension in a block theory of time, where every event that ever was or will be can be paged like a book (Barbour, 1999). Minkowski’s model has one time dimension so a particle going “backwards in time” is reversing causality but the anti-matter particle in Figure 4.8 isn’t doing that. The anti-electron is entering the collision just as the electron does with no causal reversal, so Minkowski’s interpretation struggles to explain how time runs backwards for anti-matter. If time is an independent dimension, to reverse time is to travel back in time and deny the causality behind all physics.
In quantum realism, time is a construct that passes as processing cycles complete not part of space-time “canvas” upon which matter exists. This fits Einstein’s conclusion that every particle in the universe in effect has its own “clock” because in a distributed quantum network, every node runs at a rate that varies with the local load.
If time passes as processing cycles finish, matter has a tick of time for every forward processing cycle and anti-matter has a tick of time for every backward cycle. Anti-matter exists in anti-time as matter exists in time because for matter a forward cycle is a tick of time and for anti-matter a reverse cycle is a tick of time. To a matter being, anti-matter runs time in reverse but to an anti-matter being, we are the ones running time in reverse. Matter exists by processing while anti-matter exists by anti-processing, but in both cases there is “forward” processing that defines their time.
That anti-matter runs time in reverse is possible because our time is virtual. This doesn’t mean that anti-matter time can reverse causality but that Feynman diagrams need dual time axes, one for matter time and one for anti-matter anti-time. Anti-time is an alternate virtual time that exists because anti-matter processing is the reverse of matter processing. That processing creates time means that not only does every particle in the universe have its own clock, it also decides its own clock direction.
One might suppose that if reality is virtual, then time can rewind just as an Internet browser has a “Back” button. But a browser back button only undoes your last act, it doesn’t undo interactions like online registrations as this must reverse both parties. With six degrees of separation, rolling back just six events for one person could affect the entire web! To undo interactions one must roll-back the entire network and this is also true for the quantum network.
In quantum realism, anti-time doesn’t imply time reversal because a physical event is a processing reboot that can’t be undone. Anti-matter exists in anti-time between physical events but it can no more undo its physical interactions than matter can. In our universe, physical events cannot be reversed, rewound or fast-forwarded, whether by matter or anti-matter, so there is no time travel. If the past is gone and the future is not yet defined, there is only an eternal now.