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The bottom line is that time travel is allowed by the laws of physics.

The question of causality is complex. For some philosophers and physicists, time might not exist. And since cause-and-effect reasoning needs the concept of time - of one thing preceding another - the effort to establish causality is a mug's game, an infinite regression of increasingly unanswerable questions.

Time is nature's way of keeping everything from happening at once.

The only reason for time is so that everything doesn't happen at once.

Even if it turns out that time travel is impossible, it is important that we understand why it is impossible.

Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.

Time is an illusion. Time only exists when we think about the past and the future. Time doesn't exist in the present here and now.

Before 1915, space and time were thought of as a fixed arena in which events took place, but which was not affected by what happened in it. Space and time are now dynamic quantities... space and time not only affect but are also affected by everything that happens in the universe.

Time changes everything except something within us which is always surprised by change.

Time can behave like another direction in space under extreme conditions.