There will never be time travel. Time isn't a dimension of its own that can be crossed. Space and Time are one. To go back in time, all objects in space must move backwards too, including yourself. This would mean producing a massive machine to make all atoms and theyre subcomponents of the universe reverse direction and speed. And even then, you wouldnt be able to turn it on. OOooOo, maybe you could bring time to a standstill with it, you press the button, then unpress it, then press it again. crazy. Theres no magic field you can surround yourself with that would make it powerless against you. since your actions are tied to everyone elses, your "not showing up for the great time reversal" would cause quite a ripple, if it could even happen. hmmmm.