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General relativity
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A Defense of the Reality of Time
Time isn’t just another dimension, argues Tim Maudlin. To make his case, he’s had to reinvent geometry.
What Sonic Black Holes Say About Real Ones
Can a fluid analogue of a black hole point physicists toward the theory of quantum gravity, or is it a red herring?
A Debate Over the Physics of Time
According to our best theories of physics, the universe is a fixed block where time only appears to pass.
From Einstein’s Theory to Gravity’s Chirp
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.
Gravitational Waves Discovered at Long Last
Ripples in space-time have been detected a century after Einstein predicted them, launching a new era in astronomy.
The Physical Origin of Universal Computing
The physical nature of computers might reveal deep truths about their uniquely powerful abstract abilities.
Theories of Everything, Mapped
Explore the deepest mysteries at the frontier of fundamental physics, and the most promising ideas put forth to solve them.
The Fuzzball Fix for a Black Hole Paradox
By replacing black holes with fuzzballs — dense, star-like objects from string theory — researchers think they can avoid some knotty paradoxes at the edge of physics.
Interactive: What Is Space?
Imagine the fabric of space-time peeled back layer by layer.