Is time travel possible? What would happen if you did it? How would you do it? The answers to these questions are surprisingly complicated and weird.

A new experiment shows that the quantum world obeys causality only begrudgingly, and sometimes, not at all...

Quantum time travel experiments hint that physics creates closed time loops, meaning you can't change history.

Laplace was worried this sort of thing might happen and drive mere mortals insane...

If time travel is possible, what direction would be the easiest to visit and have the fewest limitations?

Time machines may be possible, but the laws of physics will impose limits on what they'll be able to do.