I love the Flash show, but can someone explain Time Travel because it doesn't make any sense.

ARROW WIKI has an article on ARROWVERSE Time Travel. Hope this helps.

Time travel.

 

I don't think there's any true explanation for CW time travel. Rules change and fit when and where they suit the storyline.

 

You can look up the different forms (rules) of fictional time travel. There are quite a few; but they can be boiled down to three main types:

1. “Can’t change the past.” E.g., time traveller goes back in time to kill Hitler. But at the crucial moment, his gun jams. Hitler lives and history unfolds as we know it. (This is hardly ever used because it rarely makes for interesting drama. )

2. The so-called “closed causal loop” or “predestination paradox.” Like #1, this results in history remaining unchanged. But the added, mind-bending wrinkle is that that very act of time travelling into the past creates the history we know or come to know in more detail. A good example of this is the Heinlein short story All You Zombies (made into the recent movie Predestination). The archetypal predestination tale goes all the way back to Oedipus Rex. By trying to avoid his prophesized destiny, Oedipus actually causes it.

3. With “multiple timelines” or “alternative realities,” the time traveller can make all sorts of changes. Classic example is Bradbury’s A Sound of Thunder. (During a trip back in time to do some dinosaur hunting, the hero accidently steps on a butterfly — which causes dramatic changes to his present-day reality.) Implicitly or explicitly, the original timeline/reality remains unchanged. However, the act of time travel has caused a splitting or branching of reality and history. Whether the time traveller is stuck on this new branch or can (somehow) transport back to the original branch is at the discretion of the author. S/he makes the rules.


In the Arrowverse, it seems most of the time travel shenanigans use #3.

 

Well technically speaking, time travelling requires a lot of energy in the sense that you need energy to travel back in time plus energy to transport every bit of your body (organs, skin, flesh, etc.) to that time in 'healthy' pieces otherwise you would have bits and pieces of yourself put back together in that time destination with bits of you decaying and if you're really unfortunate enough, the decay is on vital organs that you need to live on (i.e. Heart, brains, lungs, etc.). Therefore, in truth, for you to actually survive travelling back into time your whole body should be comprised of cells that are capable of surviving throughout the journey back into time (or into the future) and act just like your normal cells now except you would be more like Electro, Dr Manhatten or Flash and not a human being named Mr or Mrs so and so who only verbally talks about their status and money as power compared to the genes of the aforementioned mutants that could ultimately destroy any human as they wish. That said, travelling back into time is really a difficult thing to do and so humans would literally die or materials that they wear throughout the journey would decay if it is not durable enough to sustain the heat and speed of travelling extremely fast. A good example of this would be astronauts travelling back to earth in a space shuttle capsule. When it travels back down to earth it is travelling with such force and speed due to gravity that heat is acquired and causes the black soot on the metal upon landing in the water (or ground). Now that is at the normal speed of objects entering into earth with the current force of gravity and speed that space capsule is travelling at. Turn up the speed and force of the capsule entering into earth and watch as everything inside the capsule heats up and burns. Enough said by me.

 

I don't this is the way the shows operate. At least I haven't really gotten that impression. And I think makes time traveling less entertaining. I think the show uses altering of reality, but without the branch aspect, in that the timeline changes alter the current timeline.