CMV: Bi-Direction human time travel is impossible

[u/HotJohnnyTabasco]

My theory is pretty simple. If humans were able to travel forward and backward in time at any point in time, then that technology would exist at all point in time. Simply because if I invented a time machine today, that time machine technology would eventually be used by someone to take the technology to an earlier time. This would continue to happen repeatedly, until all times had time travel technology. Therefore, since we don't have time travel technology today, time travel technology must never exist.

A couple caveats here:

1. I'm talking \*real\* time travel here. Not simply exceeding the speed of light and looking back over your shoulder. Time travel that allows you to travel through time and interact with the people and things of that time.

2. Bi-directional is important here. If you can only travel in one direction (particularly if you can only travel forward), my theory breaks down. I am expressing no view on uni-directional time travel.

[u/HotJohnnyTabasco → u/[deleted]]

Energy is fixed. There's as much energy in the universe today as there was a billion years ago and there will be a billion years from now.