_ _ _ __ | |__ | | ___ __ _ | '_ \| '_ \| |/ _ \ / _` | | |_) | | | | | (_) | (_| | | .__/|_| |_|_|\___/ \__, | |_| ...2020-12-20 |___/## What if time had another dimension ?

Physics sometimes describe three spatial dimensions and a fourth temporal. That's probably why it's commonly said that "time is the fourth dimension". For time travel, one-dimensionality poses some issues, like the predestination paradox. I'm not going to go into these issues as they are well discussed elsewhere. Seemingly unrelated to time-travel, we have the many-worlds interpretation (MWI) of quantum mechanics. The concept is somewhat convenient for "forking" the time-line in time-travel. This is probably also old-hat, what I want to bring to the discussion, is an idea that may be novel. I don't know how to search for it, so if it's already been suggested, please let me know!## I want to define time as the progression of discrete states of the universe.

Now, usually, we then picture time as a one-dimensional line: +--------------------------+ x = time, _ = "path through time" |...b_____________e........| . = discrete state +--------------------------+ b,e = begin, end of a time-line.## What if, instead, we stole from the MWI, and assumed that all states

of the universe exist along another axis ? +--------------------------+ |..........................| x = time (progression axis, Tx) |......b_____________e.....| y = time (state axis, Ty) |..........................| . = discrete state |..........................| |..........................| +--------------------------+ This allows for multiple time-lines to unfold in parallel, which is as far as I understand compatible with the MWI. Well, that's the gist of it. One way of looking at this, dimension-wise, is to see each dot as a set of the three spatial coordinates, and everything else in the universe, and then the Tx and Ty coordinates as the two higher time coordinates. I originally wanted to describe them: time and state.## We can have fun time-travel stuff with this model, we need to

add one thing to time travel, which is very logical anyway. In 1d time, we have to move along the X axis only and that gives us a problem if all states exist only along that axis, in short: "You cannot travel back in time, since the you that travelled back in time don't exist in that time". +--------------------------+ |...b_____________e........| +---^----------------------+ | + The you that DIDN'T travel back in time is the only inhabitant In this state, because if you did travel back to that state, you'd destroy it, replacing it with a new state. This does not mean time-travel can't be done, we just need to travel back to a time that we do exist in! So, we simply have to also move along the Y axis to a time where the you that travelled back in time exist. +--------------------------+ |..........................| |......b_____________TE....| |.........B______?.........| |..........................| |..........................| +--------------------------+ b = beginning of time-line (the specific time-line where you travel back). B = beginning of time-line where you travelled back in time, where both the you who've not yet travelled back in time (but is about to), and the you who travelled back in time exist at the same time. _ = progression of discrete states ? = End of the time-line, you might decide to stay there, getting to know yourself better, or forward to E which is the discrete moment after you went back in time. The time-state dimension may have the annoying property of not being linear as the four others, the position along the state axis, containing you + the you that travelled back in time may not lie right next to the original. I don't know if this disqualifies it as a dimension, if it can be one, it's definitely non-Euclidean, it may be that finding the right state-dimension to travel to is way harder than anything else about this form of time-travel, on the other hand, knowing it exists, maybe there's enough comfort in knowing that you already did it, even if it was not from this time-line ?## What was this?

No idea.