Why does time only go forward?

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Why does time only go forward?

In: Physics

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Time is the word humans use to describe entropy, or change and decay in the universe. It is not a medium but a process, unable to be undone

We don’t know. Its an unsolved problem in physics. It seems to simply be a fundamental property of it, and currently all evidence suggests that it does only go forward.

Though its also clear that it doesn’t necessarily need to. It could go backwards and things would work just fine. It just doesn’t.

While it is not LI5, there is a good story about it at the BBC website with historical context of who came up with it and how it all was figured out:

http://www.bbc.com/earth/story/20150309-why-does-time-only-run-forwards

Time doesn’t exist in the universe. Time is a human convention we use to measure our experiences. Thus, time does not go forward at all, because outside of humanity, the universe is timeless.