Gravity

Several areas of physics suggest reasons to think that unobservable universes with different natural laws could lie beyond ours. The theoretical physicist David Kaplan talks with Steven Strogatz about the mysteries that a multiverse would solve.

For the first time, mathematicians have proved that planetary orbits in a solar system will always be unstable.

Big Freeze, Big Rip, Big Crunch, Bounce or vacuum decay? Steven Strogatz speaks with theoretical cosmologist Katie Mack about the five ways that scientists think the universe could come to an end.

Richard Feynman’s path integral is both a powerful prediction machine and a philosophy about how the world is. But physicists are still struggling to figure out how to use it, and what it means.

By using fluids to model inaccessible realms of the cosmos, Silke Weinfurtner is “looking for a deeper truth beyond one system.” But what can such experiments teach us?

Physicists have discovered that the ring of photons orbiting a black hole exhibits a special kind of symmetry, hinting at a deeper meaning.

Surprising as it may sound, 107 years after the introduction of general relativity, the meanings of basic concepts are still being worked out.

Einstein’s description of curved space-time doesn’t easily mesh with a universe made up of quantum wavefunctions. Theoretical physicist Sean Carroll discusses the quest for quantum gravity with host Steven Strogatz.

Physicists are using quantum math to understand what happens when black holes collide. In a surprise, they’ve shown that a single particle can describe a collision’s entire gravitational wave.