event horizon

American  

noun

Astronomy.

1. the boundary around a black hole on and within which no matter or radiation can escape.

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event horizon British  

noun

1. astronomy the surface around a black hole enclosing the space from which electromagnetic radiation cannot escape due to gravitational attraction. For a non-rotating black hole, the radius is proportional to the mass of the black hole

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event horizon Scientific  

/ ĭ-vĕnt′ /

1. A spatial boundary around a black hole inside which gravity is strong enough to prevent all matter and radiation from escaping. The inability of even light to escape this region is what gives black holes their name.

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Etymology

Origin of event horizon

First recorded in 1970–75

Example Sentences

At the microscopic level, the bridge allows information to pass across what appears to us as an event horizon – a point of no return.

From Science Daily • May 22, 2026

They imagine a spherical shell of dust of a given radius and mass lurking behind the event horizon and distorting spacetime there.

From Science Magazine • Mar. 28, 2024

“We’re seeing for the first time the invisible structure that shepherds the material within the black hole’s disk," said Broderick, and which "drives plasma to the event horizon, helping it to grow.”

From Salon • Mar. 28, 2024

This constitutes a great nuisance for science: after all, it means that no information can escape from a black hole beyond the so-called event horizon.

From Science Daily • Feb. 15, 2024

In theory, a naked singularity with no event horizon might allow you to travel faster than light or backward in time.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife