On September 14th, 2015, a ripple in the fabric of space, created by the violent collision of two distant black holes over a billion years ago, washed across the Earth. As it did, two laser-based detectors momentarily twitched, confirming a century-old prediction by Albert Einstein and marking the opening of a new era in astronomy.

We spend a third of our lives asleep. Every organism on Earth—from rats to dolphins to fruit flies to microorganisms—relies on sleep for its survival, yet science is still wrestling with a fundamental question: Why does sleep exist?

In his research, U.K. Astronomer Royal Martin Rees has tackled topics as varied as the Big Bang, quasars, and more far-out ideas like the search for dark matter and the …

A few decades ago, we knew of no other planets beyond those in our solar system. Today, astronomers have confirmed over 700 planets circling other suns and believe billions more lay undiscovered.

In 1935, Albert Einstein and two colleagues published a landmark paper revealing that quantum mechanics allows widely separated objects to influence one another, even though nothing travels between them. Einstein called it spooky and rejected the idea, arguing instead that it exposed a major deficiency in the quantum theory.

The nature of time is an age-old conundrum for physicists, philosophers, biologists and theologians. The Newtonian picture of time—a kind of cosmic clock that ticks off time in a manner that applies identically to everyone and everything—tightly aligns with our experience. But with special and general relativity, Einstein showed the fallacy inherent in experience.