In theoretical physics, a near-extremal black hole is a black hole which is not far from the minimal possible mass that can be compatible with the given charges and angular momentum. The calculations of the properties of near-extremal black holes are usually performed using perturbation theory around the extremal black hole; the expansion parameter is called non-extremality.
In supersymmetric theories, near-extremal black holes are often small perturbations of supersymmetric black holes. Such black holes have a very small Hawking temperature and consequently emit a small amount of Hawking radiation. Their black hole entropy can often be calculated in string theory, much like in the case of extremal black holes, at least to the first order in non-extremality.
Famous quotes containing the words black and/or hole:
“I asked her if she wanted to go to the movies that night. She laughed again and told me that she felt like seeing a Fernandel movie. When we got dressed, she seemed very surprised to see me wearing a black tie and asked me if I was in mourning. I told her that my mother was dead. Since she asked me since when, I answered, “Since yesterday”.”
—Albert Camus (1913–1960)
“The anger
that my friends
planted in my heart
when they somehow found
a hole in it
ran off
like an illicit lover
as soon as I saw my man.”
—Hla Stavhana (c. 50 A.D.)