The speed of light is a fundamental constant, approximately 299,792,458 meters per second. It's the same for all observers and hasn't changed measurably over billions of years. Nothing can travel ...

From early experiments with lanterns to Einstein’s revelations about space and time, the speed of light has proven to be far more than a number: it’s the cosmic constant that defines reality.

Imagine you’re in a car driving across the country watching the landscape. A tree in the distance gets closer to your car, passes right by you, then moves off again in the distance behind you. Of ...

James is a published author with multiple pop-history and science books to his name. He specializes in history, space, strange science, and anything out of the ordinary.View full profile James is a ...

Note: Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. (THE CONVERSATION) – Why does time change ...

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com. Why does time change when traveling close to the ...