speed of light

Physics students often ask how it is that a massless photon can have momentum. In this video, Don Lincoln shows that the question arises from a misuse of equations and also shows that, when you think about it, it’s not surprising at all.

Traveling faster than light is one of humanity’s dreams. Sadly, modern physics doesn’t cooperate, but there are examples where it really is possible to travel faster than light. Don Lincoln discusses ways in which the universe breaks the ultimate speed limit.