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general relativity
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How to Think About Relativity
Albert Einstein’s ideas about space-time aren’t exactly intuitive, and they aren’t exactly Einstein’s, either.
At Long Last, Mathematical Proof That Black Holes Are Stable
The solutions to Einstein’s equations that describe a spinning black hole won’t blow up, even when poked or prodded.
Mass and Angular Momentum, Left Ambiguous by Einstein, Get Defined
Surprising as it may sound, 107 years after the introduction of general relativity, the meanings of basic concepts are still being worked out.
Gravitational Waves Should Permanently Distort Space-Time
The “gravitational memory effect” predicts that a passing gravitational wave should forever alter the structure of space-time. Physicists have linked the phenomenon to fundamental cosmic symmetries and a potential solution to the black hole information paradox.
An Ultra-Precise Clock Links the Quantum World With Gravity
Time was found to flow differently between the top and bottom of a single cloud of atoms. Physicists hope that such a system will one day help them combine quantum mechanics and Einstein’s theory of gravity.
The Uselessness of Useful Knowledge
Today’s powerful but little-understood artificial intelligence breakthroughs echo past examples of unexpected scientific progress.
New Black Hole Math Closes Cosmic Blind Spot
A mathematical shortcut for analyzing black hole collisions works even in cases where it shouldn’t. As astronomers use it to search for new classes of hidden black holes, others wonder: Why?
Quantum Mischief Rewrites the Laws of Cause and Effect
Spurred on by quantum experiments that scramble the ordering of causes and their effects, some physicists are figuring out how to abandon causality altogether.
In Violation of Einstein, Black Holes Might Have ‘Hair’
A new study shows that extreme black holes could break the famous “no-hair” theorem, and in a way that we could detect.