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

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.

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.

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

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

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

According to our best theories of physics, the universe is a fixed block where time only appears to pass.

The path from a revolutionary set of equations to the detection of gravitational waves was strewn with obstacles and controversy, explains the physicist Daniel Kennefick — and the struggle continues.

Ripples in space-time have been detected a century after Einstein predicted them, launching a new era in astronomy.

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