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This paper predicted the existence of what are today known as black holes. [1] [7] The term "black hole" was coined decades later, in the fall of 1967, by John Archibald Wheeler at a conference held by the Goddard Institute for Space Studies in New York City; [7] it appeared for the first time in print the following year. [8]
The soft-hair resolution posits that information about the initial state is stored in such soft particles. The existence of such soft hair is a peculiarity of four-dimensional asymptotically flat space and therefore this resolution to the paradox does not carry over to black holes in Anti-de Sitter space or black holes in other dimensions.
While in a non-rotating black hole the singularity occurs at a single point in the model coordinates, called a "point singularity", in a rotating black hole, also known as a Kerr black hole, the singularity occurs on a ring (a circular line), known as a "ring singularity". Such a singularity may also theoretically become a wormhole. [18]
The process not only provides a neverending fuel source for black holes, the researchers said, but also plays another important cosmic role: allowing for new stars to form. Eric Lagatta covers ...
The concept of a vacuum is not invariant under diffeomorphisms. This is because a mode decomposition of a field into positive and negative frequency modes is not invariant under diffeomorphisms. If t ′ (t) is a diffeomorphism, in general, the Fourier transform of exp[ikt ′ (t)] will contain negative frequencies even if k > 0.
Cosmic censorship is not merely a problem of formal interest; some form of it is assumed whenever black hole event horizons are mentioned. [citation needed] Roger Penrose first formulated the cosmic censorship hypothesis in 1969. The hypothesis was first formulated by Roger Penrose in 1969, [2] and it is not
In astrophysics, the gravastar (a portmanteau of "gravitational vacuum star") is an object hypothesized in a 2006 paper by Pawel O. Mazur and Emil Mottola as an alternative to the black hole theory. It has the usual black hole metric outside of the horizon, but de Sitter metric inside. On the horizon there is a thin shell of matter.
This book is a collection of essays and lectures written by Hawking, mainly about the makeup of black holes, and why they might be nodes from which other universes grow. Hawking discusses black hole thermodynamics, special relativity, general relativity, and quantum mechanics.