I Is Time Travel Really Possible: Can We Move Backward in Time?

LYCON
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How can we travel back and forth in time?

And is it really possible?
 
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Forward in time is easy. I go forward a day every day.

Backward in time is probably impossible. There are solutions to the equations of general relativity that permit it, but they are generally believed to be unphysical. That is, we can describe a universe with "loops" in it that allow you to cross your own history, but the distribution of mass and energy needed to create it is impossible (negative energies or other stuff that doesn't exist).
 
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