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The core of a neutron star is such an extreme environment that physicists can’t agree on what happens inside. But a new space-based experiment — and a few more colliding neutron stars — should reveal whether neutrons themselves break down.
Newly discovered “standard sirens” provide an independent, clean way to measure how fast the universe is expanding.
Astronomers have for the first time matched a gravitational-wave signal to a kilonova’s burst of light, observations that will “go down in the history of astronomy.”
Repeating radio bursts are among the most mysterious phenomena in the universe. A new theory explores how some of their puzzling properties can be explained by galactic lenses made of plasma.