What’s it like to face a faceless world? Acclaimed neurologist Oliver Sacks once apologized for almost bumping into a large bearded man, only to realize he was speaking to a mirror.

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.

Nobel laureate Kip Thorne joins Brian Greene to trace a story that runs from the trenches of World War I to the rise of gravitational-wave astronomy—a journey that eventually carried …

What we touch. What we smell. What we feel. They’re all part of our reality. But what if life as we know it reflects only one side of the full story? Some of the world’s leading physicists think that this may be the case.

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?

Known for his work in television, theater, and film, Alan Alda is also a passionate advocate of science. Through his years as host of Scientific American Frontiers, his founding of …