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?

Cosmology is the one field in which researchers can—literally—witness the past. The cosmic background radiation, ancient light streaming toward us since the Big Bang, provides a pristine window onto the birth and evolution of the universe.

Einstein dreamed of a unified theory of nature’s laws. String theory has long promised to deliver it: a mathematically elegant description that some have called a “theory of everything.” Join …

What is time? Isaac Newton described it as absolute, but Einstein proved that time is relative, and, shockingly, that time and space are intricately interwoven. Now recent work in string theory and quantum gravity suggests that space and time may not be fundamental. If this is true, what new picture of reality will emerge?

#YourDailyEquation with Brian Greene offers brief and breezy discussions of the most pivotal equations of the ages. Even if your math is a bit rusty, these accessible and exciting stories …

Today, there are robots that make art, move like dancers, tell stories, and even help human chefs devise unique recipes. But is there ingenuity in silico? Can computers be creative? …