_ _
_ __  __   ___ __ _
 '_ \ '_ \ / _ \ / _` 
 _)      (_)  (_ 
 .__/_ __\___/ \__, 
_ ...20201220 ___/
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, onedimensionality 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 timetravel, we have the manyworlds
interpretation (MWI) of quantum mechanics. The concept is somewhat convenient
for "forking" the timeline in timetravel. This is probably also oldhat,
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 onedimensional line:
++ x = time, _ = "path through time"
...b_____________e........ . = discrete state
++ b,e = begin, end of a timeline.
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 timelines 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, dimensionwise,
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 timetravel 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 timetravel 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 timeline (the specific timeline where you travel back).
B = beginning of timeline 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 timeline, 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 timestate 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 nonEuclidean, it may be that finding the right statedimension
to travel to is way harder than anything else about this form of timetravel,
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 timeline ?
What was this?
No idea.