Dictionary

Kerr-Newman black hole

The simplest kind of a rotating, electrically charged black hole: a model universe containing a single rotating, charged black hole and nothing else. This solution to Einstein’s equations was found independently by Roy Kerr and Ted Newman in 1963.

The Kerr-Newman solution is more general and includes the Kerr solution if the charge of the black hole is zero.

Definitioner

solution

In the context of general relativity: a solution or, more precisely, a solution of the Einstein equations is a model universe that follows the law of gravity as prescribed by general relativity. See also exact solution.

Kerr-Newman solution (Kerr-Newman black hole)

The simplest kind of a rotating, electrically charged black hole: a model universe containing a single rotating, charged black hole and nothing else. This solution to Einstein's equations was found independently by Roy Kerr and Ted Newman in 1963. The Kerr-Newman solution is more general and includes the Kerr solution if the charge of the black hole is zero.

charge

A measure of the strength of a force (action-at-a-distance) originating from a body, and of how susceptible it is to being influenced by other bodies via the same force. The most famous example is electric charge: Electrically charged bodies act on other electrically charged bodies via an electric force whose strength is proportional to the electric charges of the bodies involved. It is a characteristic property of charges that they are conserved; they can neither be created from nothing nor simply disappear. For instance, when a positron with electric charge +1 (in suitable units) and an electron with electric charge -1 annihilate to give electromagnetic radiation, overall charge conservation is satisfied: Before the annihilation, the sum of the electric charges was 1+(-1)=0, and afterwards, when there is only uncharged electromagnetic radiation left, it is also zero. In the context of particle physics, there are more abstract charges not directly connected with forces and interaction, but subject to similar conservation laws.

black hole

Region in space where a sufficient amount of mass is concentrated so that it forms a gravitational prison - a region into which matter or light can enter from the outside, but from which nothing that has once entered can ever leave. Basic information on this key phenomenon of Einstein's general theory of relativity can be found in the chapter Black holes & Co. of Elementary Einstein. Selected aspects of the physics of black holes and neutron stars are described in the category Black holes & Co. of our Spotlights on relativity. In Einstein's theory, black holes are truly black, due to the fact that no radiation or light can ever escape them. Once quantum theory is taken into account, this assumption no longer holds - on the contrary, it seems as if black holes should emit so-called Hawking radiation. However, for astrophysical black holes (that typically have more or even much more than one solar mass), that radiation would be undetectable, even if we could transport today's most sensitive sensors into the immediate vicinity of the black hole.

Dictionary

Kerr-Newman black hole

Further Articles

Tag Cloud