How fast is the universe expanding? Two prominent approaches are finding different answers, propelling cosmology toward a crisis. Wendy Freedman, a renowned astronomer who has spent decades seeking the expansion …

Have you ever spent hours looking for something you just know is there, only to be doubted? In 1987, most astronomers thought there was nothing in the outer solar system, …

Extra dimensions of space — the idea that we are immersed in hyperspace — may be key to explaining the fundamental nature of the universe. Relativity introduced time as the fourth dimension, and Einstein’s subsequent work envisioned more dimensions still — but ultimately hit a dead end.

As physicists attempt to answer some of science’s biggest questions about the universe, they are testing the limits of experimental and observational science itself. In this program leading physicists, astronomers, …

Stephen Wolfram joins Brian Greene to explore whether the ultimate theory of the universe might emerge from a computationally simple framework. This program is part of the Big Ideas series, …

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.