Simple

How to Reconcile Two Neutron Stars ⚡ экспресс

Original: "Reconciling GW170817 and GW190814 with a Nonmonotonic Sound-Speed Equation of State"
arXiv:2605.30369 · 2026-05-18 · CC BY · ⏱ 1 min · High Energy Instrumentation General Relativity
A contradiction between two merger observations was resolved by discovering a family of possible 'recipes' for neutron star interiors.
Abstract

Scientists resolved the dispute of two neutron stars whose characteristics didn't match. It turned out that the matter inside them can be simultaneously dense and elastic, like a universal dough for bread and cookies. This 'recipe' allows both light and record-heavy neutron stars to exist without contradictions. What other secrets does this state of matter hold?

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A neutron star is a superdense pie, and its equation of state is the dough recipe. The stiffer the dough, the less the star deforms when squeezed. Observations of two gravitational-wave bursts—GW170817 (merger of two neutron stars) and GW190814 (a neutron star swallowed by a black hole)—gave conflicting hints: one required a soft recipe, the other a stiff one. Like obsessed bakers, scientists sifted through thousands of compositions and found a family of recipes where the filling becomes two-layered, and sound inside races at nearly the speed of light. Only a few dozen out of thousands passed the strict test of observations.

The fastest sound wave in the universe: up to 99% of the speed of light.

Thus they managed to reconcile the data on the merger of two neutron stars and the absorption of one by a black hole, without going beyond Einstein's theory.

🎯 If someone shouted inside a [tag:neutron_star]neutron star[/tag], the sound would circle Earth 7 times per second—its speed is comparable to the [tag:speed_of_light]speed of light[/tag].

🎬 In Larry Niven's story 'Neutron Star,' the hero survives near such an object. Reality turns out to be no less exciting.

Scientists
Christian DopplerD. B. McLaughlinDidier QuelozMichel MayorR. A. RossiterStephen Hawking
Tags
neutron star gravitational waves speed of light black hole
Laws
Doppler effectHawking radiationgravitational lensingprinciple of constancy of the speed of lightBekenstein-Hawking entropymass–energy equivalence
Original: arXiv:2605.30369 · CC BY · bridge42worlds