There is no such thing as time travel.
And the reason for this is because time is not a dimension.
"WHAT?!"
Yes, that's true. Time is not a dimension.
"But they said spacetime and..."
No, they're wrong. There is only space.
Time is ONLY a Measurement.
A measurement of what? A measurement of change.
That's all.
Time is a measurement of change. This is why two 40 year old women could appear as mother and daughter though they have the same earthly calendar age measured by revolutions of the earth around the sun. 40 sun revolutions but these two women look like mother and daughter and why?
Because their biological patterns of change are different.
One looks closer to 55 and the other looks closer to 30. Habits you have and things you undertake make you "age" differently too.
I know someone about to be 50 but could pass for her 30's or early 40's at most. I knew another one around 50 who looked like closer to 60 to me.
You wanna go back in time? Simple. Take a clock and set it at an earlier hour. Take a wind-up clock and just wind the opposite way. Congratulations you've gone back in time.
Time does not exist as a dimension as in like we see VCR tapes & DVD's which can be rewound and reviewed. It is simply a measurement of change that without constant patterns of objects in the universe could never exist.
We have a constant or constant enough as far as we can see Sun and Moon pattern. This is the only reason we were able to create a measurement of time in the first place. Sundial? Moon phases to mark the months? Lunar calendars? The slow evolution of weather seasons when days and night periods change? But only in certain parts of the world that don't include the poles where a day can last a calendar 6 months and a night another 6?
All other clocks and time measurement devices built upon these early measurements of time by mankind. We refined them and elaborated on them but it's still based off the same thing.
It is mankind's way of documenting change which can be random and unpredictable at "times".
You can undo change if you know how but that doesn't mean you can undo things done at a certain time. When it's done it's done. You can medically fix a scar gained in your past, the measurements of time before your current standing. But you cannot go back from your current measurement in time to prevent that scar from occuring in the first place. That is impossible. Time only means it has been, say, 8 months since you gained that scar and nothing more. It measures the amount of change that biologically and socially happened since obtaining that scar. Your body heals and the scar's look changes. Your job may have changed since getting that scar and your life may be different since getting scarred. But it's just change of circumstances. You can't reverse or prevent what was already done. All you can do is fix it in the now if possible.
Time travel doesn't exist because the premise is faulty to begin with. It assumes time is a dimension like point, line, and shape which makes space when it is only a mere measurement of change from one aspect to another.
If I want to "go back in time" to June all I have to do is flip the calendar back one page from its current July setting. Voilá! I've gone back in time.
John Lucas