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

See Examples For:

event horizon

Unlike an event horizon, a dynamical horizon is defined by the black hole's properties at a specific moment in time, avoiding the complications created by relying on future events.

From Science Daily ● Jul. 13, 2026

The team's solution replaces the traditional event horizon with what physicists call a "dynamical horizon," a concept that is already widely used in computer simulations of black holes.

From Science Daily ● Jul. 13, 2026

That distance defines the black hole’s spherical event horizon.

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

One could well say of the event horizon what the poet Dante said of the entrance to Hell: “All hope abandon, ye who enter here.”

From "A Brief History of Time: And Other Essays" by Stephen Hawking