Black holes | Wikipedia audio article
Channel: wikipedia tts
Date: 2019-10-04

This is an audio version of the Wikipedia Article:
https://en.wikipedia.org/wiki/Black_hole


00:03:19 1 History
00:04:33 1.1 General relativity
00:08:03 1.1.1 Golden age
00:10:41 1.2 Etymology
00:11:47 2 Properties and structure
00:13:49 2.1 Physical properties
00:18:13 2.2 Event horizon
00:20:15 2.3 Singularity
00:22:35 2.4 Photon sphere
00:23:32 2.5 Ergosphere
00:24:55 2.6 Innermost stable circular orbit (ISCO)
00:26:07 3 Formation and evolution
00:27:34 3.1 Gravitational collapse
00:30:17 3.1.1 Primordial black holes and the Big Bang
00:31:31 3.2 High-energy collisions
00:33:05 3.3 Growth
00:33:53 3.4 Evaporation
00:37:04 4 Observational evidence
00:40:07 4.1 Detection of gravitational waves from merging black holes
00:42:09 4.2 Proper motions of stars orbiting Sagittarius A*
00:43:34 4.3 Accretion of matter
00:45:43 4.3.1 X-ray binaries
00:47:35 4.3.1.1 Quiescence and advection-dominated accretion flow
00:48:19 4.3.1.2 Quasi-periodic oscillations
00:48:52 4.3.2 Galactic nuclei
00:50:31 4.4 Microlensing (proposed)
00:51:23 4.5 Alternatives
00:53:43 5 Open questions
00:53:53 5.1 Entropy and thermodynamics
00:56:39 5.2 Information loss paradox
00:58:03 5.3 Firewall paradox
01:00:04 6 See also



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SUMMARY
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A black hole is a region of spacetime exhibiting gravitational acceleration so strong that nothing—no particles or even electromagnetic radiation such as light—can escape from it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of the region from which no escape is possible is called the event horizon. Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, no locally detectable features appear to be observed. In many ways, a black hole acts like an ideal black body, as it reflects no light. Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation, with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe.
Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace. The first modern solution of general relativity that would characterize a black hole was found by Karl Schwarzschild in 1916, although its interpretation as a region of space from which nothing can escape was first published by David Finkelstein in 1958. Black holes were long considered a mathematical curiosity; it was during the 1960s that theoretical work showed they were a generic prediction of general relativity. The discovery of neutron stars by Jocelyn Bell Burnell in 1967 sparked interest in gravitationally collapsed compact objects as a possible astrophysical reality.
Black holes of stellar mass are expected to form when very massive stars collapse at the end of their life cycle. After a black hole has formed, it can continue to grow by absorbing mass from its surroundings. By absorbing other stars and merging with other black holes, supermassive black holes of millions of solar masses (M☉) may form. There is general consensus that supermassive black holes exist in the centers of most galaxies.
The presence of a black hole can be inferred through its interaction with other matter and with electromagnetic radiation such as visible light. Matter that falls onto a black hole can form an external accretion disk heated by friction, forming some of the brightest objects in the universe. If there are other stars orbiting a black hole, their orbits can be used to determine the black hole's mass and location. Such observations can be used to exclude possible alternatives such as ...