If time travel is possible, where are the tourists from the future?

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.

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

Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a 'crank.'

There is a fundamental difference between religion, which is based on authority, and science, which is based on observation and reason. Science will win because it works.

A zero-gravity flight is a first step toward space travel.