So, you’re driving a car at half the speed of light. (Both hands on the wheel, please.) You turn on the headlights. How fast would you see this light traveling? What about a person standing by the ...

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 ...

Science fiction authors and readers dream of travelling at the speed of light, but Einstein tells us we can’t. You might think that’s an arbitrary rule, but [FloatHeadPhysics] shows a different way to ...

Einstein’s claim that the speed of light is constant has survived more than a century of scrutiny—but scientists are still daring to test it. Some theories of quantum gravity suggest light might ...

If there is an absolute law in the universe, it’s that nothing can travel faster than the speed of light. For science-fiction enthusiasts, that’s a bit depressing. Space is big, and while the speed of ...

When I was a teenager, I was—shockingly, I know—deeply nerdy. At a science-fiction convention, I bought a button that read, “186,282 miles/second: Not just a good idea, it’s the law.” It was poking ...