Famed neurologist Oliver Sacks joined award-winning journalist John Hockenberry to discuss Sacks’ latest book, which explores the bewitching and surreal world of hallucinations.

Today, cryptography has moved beyond the realm of dilettantes and soldiers to become a sophisticated scientific art—combining mathematics, physics, computer science, and electrical engineering. It not only protects messages, but it also safeguards our privacy. From email to banking transactions, modern cryptography is used everywhere.

Albert Einstein spent his last thirty years unsuccessfully searching for a ‘unified theory’ — a single master principle to describe everything in the universe, from tiny subatomic particles to immense clusters of galaxies. In the decades since, generations of researchers have continued working toward Einstein’s dream.

Today’s equation shows that simultaneity is in the eye of the beholder. Two people who are moving relative to one another will not agree on what happens at the same …

Live Q&A with Brian Greene – #YourDailyEquation: Join a live session with Brian Greene, 3 PM EDT. Relativity, quantum, the universe — ask him anything that’s on your mind.

For the last half century we have slipped the surly bonds of earth with landers, rovers and spacecraft that have allowed us to touch the very edge of the Solar …