This puzzle is known as the problem of time, and it remains one of the most persistent obstacles to a unified theory of ...

Time feels like the most basic feature of reality. Seconds tick, days pass and everything from planetary motion to human memory seems to unfold along a single, irreversible direction. We are born and ...

In the strange corner of modern physics where spacetime itself becomes the engine, the old rule that nothing can outrun light ...

Here’s what you’ll learn in this story: Time might actually have 3 dimensions. But it also means that the space would actually be one-dimensional, instead of the three dimensions we’re familiar with.

Chinese researchers say they have created a new "lunar time ephemeris" that can calculate the time on the Moon and sync it with time on Earth. Currently, there is no agreed-upon time zone on the Moon.

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

There’s an adage coined by [Ian Betteridge] that any headline ending in a question mark can be answered by the word “No”. However, Lorentz invariance – the theory that the same rules of physics apply ...

A newly detected gravitational wave, GW250114, is giving scientists their clearest look yet at a black hole collision—and a powerful way to test Einstein’s theory of gravity. Its clarity allowed ...

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 ...

General relativity describes gravitation in a geometrical framework generalizing special relativity and classical mechanics. This term includes theoretical studies of gravity, experimental studies of ...