Scientists pushed photons across the universe to test the speed of light—and found Einstein’s cosmic speed limit still holds ...

For the first time in history, scientists have succeeded in visually capturing the speed of light. Through an innovative use of high-speed photography and lasers, researchers have managed to ...

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 ...

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 ...