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Trouble Detected in Infamous Dark Matter Signal
Independent scientists have cast serious doubt on a claimed detection of dark matter.
Quantum Correlations Reverse Thermodynamic Arrow of Time
A recent experiment shows how quantum mechanics can make heat flow from a cold body to a hot one, an apparent (though not real) violation of the second law of thermodynamics.
Whisper From the First Stars Sets Off Loud Dark Matter Debate
A surprise discovery announced a month ago suggested that the early universe looked very different than previously believed. Initial theories that the discrepancy was due to dark matter have come under fire.
A Victory for Dark Matter in a Galaxy Without Any
Paradoxically, a small galaxy that seems to contain none of the invisible stuff known as “dark matter” may help prove that it exists.
Black Hole Echoes Would Reveal Break With Einstein’s Theory
Gravitational waves have opened up new ways to test the properties of black holes — and Einstein’s theory of gravity along with them.
Why Stephen Hawking’s Black Hole Puzzle Keeps Puzzling
The renowned British physicist, who died at 76, left behind a riddle that could eventually lead his successors to the theory of quantum gravity.
How Einstein Lost His Bearings, and With Them, General Relativity
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.
Why the Tiny Weight of Empty Space Is Such a Huge Mystery
The amount of energy infusing empty space seems too small to explain without a multiverse. But physicists have at least one alternative left to explore.
To Test Einstein’s Equations, Poke a Black Hole
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.