My last post about free will has caused me to think of this.
Do you believe time travel is possible?
My answer is both yes and no. It is not possible to literally "travel" from one place in time to another, while they both exist at once, but it is physically possible to (somehow) turn time back/forward by changing the state of the universe. That is, that if time travel existed, it would likely be by physically changing everything in the universe to a way it was/will be. I stated in my free will post, that the universe follows an inevitable cause and effect. We could hypothetically just turn this cause and effect backwards or forwards.
...Hypothetically. As far as actually being able to build the technology to do so: Absolutely not.