Schwarzschild radius

The Schwarzschild radius or gravitational radius is a characteristic radius associated with every mass. The term is used in physics and astronomy, especially in the theory of gravitation, general relativity. It was found in 1916 by Karl Schwarzschild and results from his discovery of an exact solution for the gravitational field outside a static, spherically symmetric star (see Schwarzschild metric, which is a solution of the Einstein field equations).

Related Topics:
Radius - Mass - Physics - Astronomy - Gravitation - General relativity - 1916 - Karl Schwarzschild - Star - Schwarzschild metric - Einstein field equations

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The Schwarzschild radius is proportional to the mass.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The Sun has a Schwarzschild radius of approximately 3 km, the Earth's being approximately 9 mm.

Related Topics:
Sun - Earth

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

An object smaller than its Schwarzschild radius is called a

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

black hole. The surface at the Schwarzschild radius acts as an

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

event horizon in a static body. (A rotating black hole operates slightly differently.) Neither light nor particles can escape through this surface from the region inside, hence the name "black hole". The Schwarzschild radius of the Supermassive black hole at our Galactic Center is approximately 7.8 million km.

Related Topics:
Event horizon - Rotating black hole - Supermassive black hole - Galactic Center

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Connie Willis's hard science fiction short story "The Schwarzschild Radius" offers both an accessible and accurate explanation of the phenomenon which makes it surprisingly applicable to not-so-scientific pursuits.

Related Topics:
Connie Willis's - Hard science fiction

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

It is coincidental that Schwarzschild also means "black shield", which is befitting for the idea of a black hole.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~