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general relativity

Craig Callender holding a paddleboard at the beach.
Q&A

Are We All Wrong About Black Holes?

September 5, 2019

Since the 1970s, physicists have described black holes using borrowed versions of the laws of thermodynamics. But are black holes really thermodynamic systems? Craig Callender worries that the analogy has been stretched too far.

symmetry

The Simple Idea Behind Einstein’s Greatest Discoveries

June 26, 2019

Lurking behind Einstein’s theory of gravity and our modern understanding of particle physics is the deceptively simple idea of symmetry. But physicists are beginning to question whether focusing on symmetry is still as productive as it once was.

Illustration of a black hole with a Cauchy horizon
general relativity

Mathematicians Disprove Conjecture Made to Save Black Holes

May 17, 2018

Mathematicians have disproved the strong cosmic censorship conjecture. Their work answers one of the most important questions in the study of general relativity and changes the way we think about space-time.

520px illustration for black hole echoes
Quantized Columns

Black Hole Echoes Would Reveal Break With Einstein’s Theory

March 22, 2018

Gravitational waves have opened up new ways to test the properties of black holes — and Einstein’s theory of gravity along with them.

Photograph of Albert Einstein in his office at the University of Berlin, published in the USA in 1920.
Abstractions blog

How Einstein Lost His Bearings, and With Them, General Relativity

March 14, 2018

By 1913, Albert Einstein had nearly completed general relativity. But a simple mistake set him on a tortured, two-year reconsideration of his theory. Today, mathematicians still grapple with the issues he confronted.

Animated illustration of a black hole in a cube of jelly
mathematical physics

To Test Einstein’s Equations, Poke a Black Hole

March 8, 2018

Two teams of researchers have made significant progress toward proving the black hole stability conjecture, a critical mathematical test of Einstein’s theory of general relativity.

An illustration of gravity as particles
quantum gravity

Physicists Find a Way to See the ‘Grin’ of Quantum Gravity

March 6, 2018

A recently proposed experiment would confirm that gravity is a quantum force.

A wormhole split in two with swirls of blue on one side and swirls of pink on the other with a ringed planet in the background.
theoretical physics

Newfound Wormhole Allows Information to Escape Black Holes

October 23, 2017

Physicists theorize that a new “traversable” kind of wormhole could resolve a baffling paradox and rescue information that falls into black holes.

quantum gravity

What Sonic Black Holes Say About Real Ones

November 8, 2016

Can a fluid analogue of a black hole point physicists toward the theory of quantum gravity, or is it a red herring?