@Theory 4: But at what speed do the time waves travel? And, is there a way to even measure their "speed"? (as in, is there a "time" layer over time so that after some time has passed on the layer one can expect the effect of time waves to have been affected later? Like, for every 5 minutes of change the time waves would have moved 10 minutes or something?)
Anyway, theory 5:
Let's start with a normal time line, this is the one we perceive every day and things are simple, past is on the left, present some time in the middle (or, at the right in the middle, since our brain takes some time to process them, and sometimes processes them before they happen, etc.) Future is on the right.
Here's just a guy counting up. For the purposes of this example, the guy is counting veeery slowly, so the time between pictures isn't just one second.
Okay, so this simplified version doesn't allow time travel at all, because, after this guy counts to 5, he HAS counted to 5. It's on the past, no matter what you do, you can't change that (well, you'd need to invent time travel in reality and use some other theory from stopping me from drawing the guy counting to 5, but alas, I don't think this has happened yet.)
In this theory, time travel is impossible, however, one can perceive things the same way as if one traveled through time, by accessing further dimensions:
They run parallel to each other, and there seems to be an infinite number of them up and down. This has some problems, and it's that, people already have problems thinking about all the things that may be on the Multiverse, and it also includes an infinite number of such timeline copies of the whole Multiverse? Isn't that inelegant and unnecessary?
It also poses the following problem: free will. If all the things we're going to do are in a copy of the future in some other dimension, then we never decide what to do at any point, we just copy the moves of the guy in the next time line. This also leads to a deterministic universe, and fatalism (what is going to happen already happened so you may as well get under your bed and rot, because, if you do that, THAT was going to happen anyway). People can't also be made responsible from their actions, they're just following the steps set up by fate, like marionettes.
Theory 5 deals with these problems.
At first, this last image I posted looks like a box that contains all events that happened since the beginning of time up until the end of time, and the present time is just us traveling through the box like zombies. This is not the case.
Just like in reality, there is a NOW, a present time, in the box, it looks like this:
Okay, I lied. The guy hasn't counted to five yet. The diagonal line represents the true present, and anything at the right of the line represents the future. What is in blue, is just one possible future, and we know that, in one of them, the guy decides to count to five. That's the one we'll be looking at, but that doesn't mean it was pre-scripted that he was going to, or that he didn't have another option. He used his free will to do it and the other mainlines did it simultaneously.
What this means is that, for all practical purposes, there's only one time line, because, there's no time line ahead of the other, all of them resolve events at the true present.
The difference appears when, the guy is bored from counting, so, instead of counting to eight, he pulls up his time machine:
Let's focus on the guy in red, this is the guy in the true present on the time machine. What the time machine does is bending the true present line, so that events that were previously black below him, become blue, possible events. they become changeable.
He can now travel vertically, though, he can't ever travel to the left of the red line, because these events are already in the true past and unchangeable. But, who cares about that? For the purposes of time travel, traveling down the red line gives him access to his past. Traveling upwards is indistinguishable from traveling to the right, but he'd be basically freezing up until the true present (the blue line) catches him up.
Anyway, so he wants to experiment with time travel, the very first thing he does is traveling to the possible past and killing his own self before he pulls up the time machine. he's going to go at the point he counted to seven, and kill himself (erm, his past self, not commit suicide).
Here, the question: "if he killed himself when he counted seven, how come he was able to travel to kill himself?" answers itself: the guy that he killed was the one that was going to come back to kill him.
Also, in the time it took him to kill himself, time has moved on, so, his red line, has moved too, and now, he doesn't have access to times at which his past self counted to six (they're all in black) but he has access to timelines in where he's right now still counting to six (on blue below the frame), or yet to count to six.
Due to the way the true present works, for all practical purposes, there's only two mainlines, one where he disappears into nothingness, and another where he comes out of nowhere and kills himself. But "for all practical purposes" is reality, since all the timelines have the same distance from the true present, they are one and the same.
At this point, it seems as if he could travel down and stop himself from going back in time to kill himself. However, this would just create a third timeline:
Here, the guy kicks himself in the face, and the other guy will not be able to stop the kick on his face because it has already happened.
It's called time travel because, if instead of putting the time lines in the previous way, one does it in this one, it looks as if the red guy managed to travel to the left.
And that's it, thanks to the concept of the true present, one doesn't need to keep a copy of all the dimensions, only as many time lines as have been changed, since the other ones will be "in sync", and events beyond the true present are yet to happen, they're in blue, allowing us to change them by just traveling to the future one second per second.