41. [astro-ph/0202032] Quantum Aspects Of Black Holes A brief (graduate level) introduction to the quantum aspects of black holes, from the laws of black hole mechanics and Hawking radiation to more advanced aspects such as the interpretation of the entropy and the possible existence of primordial black holes. Written by Claus Kiefer (University of Cologne). http://arxiv.org/abs/astro-ph/0202032

arXiv.org astro-ph Search or Article-id Help Advanced search All papers Titles Authors Abstracts Full text Help pages Full-text links: Download: PDF PostScript Other formats Current browse context: astro-ph new recent SLAC-SPIRES HEP refers to ... what is this? Bookmark what is this? Astrophysics Title: Quantum aspects of black holes Authors: Claus Kiefer (Submitted on 1 Feb 2002) Abstract: This is a brief introduction to quantum aspects of black holes, addressed at an astrophysics-oriented audience. The topics are: The laws of black-hole mechanics, Hawking radiation, interpretation of entropy, and primordial black holes. Comments: 20 pages, 4 figures, contribution to the conference "The galactic black hole", Bad Honnef, Germany, August 2001 Subjects: Astrophysics (astro-ph) Cite as: arXiv:astro-ph/0202032v1 Submission history From: Claus Kiefer [ view email Fri, 1 Feb 2002 15:09:46 GMT (42kb) Which authors of this paper are endorsers? Link back to: arXiv form interface contact

42. Black Holes, Black Holes Information, Facts, News, Photos Get information, facts, photos, news, videos, and more about black holes from National Geographic. http://science.nationalgeographic.com/science/space/universe/black-holes-article

43. Black Holes (Section Not Complete) Photons always travel at the speed of light, but they lose energy when travelling out of a gravitational field and appear to be redder to an external http://csep10.phys.utk.edu/astr162/lect/blackhole/blackhole.html

Black Holes (Section Not Complete) Photons always travel at the speed of light, but they lose energy when travelling out of a gravitational field and appear to be redder to an external observer. The stronger the gravitational field, the more energy the photons lose because of this gravitational redshift . The extreme case is a black hole where photons from within a certain radius lose all their energy and become invisible. Indeed, light in the vicinity of such strong gravitational fields exhibits quite bizarre behavior . Here are links to some movies illustrating virtual trips to black holes and neutron stars. Event Horizons The event horizon is the point outside the black hole where the gravitational attraction becomes so strong that the escape velocity (the velocity at which an object would have to go to escape the gravitational field) equals the speed of light. Since according to the relativity theory no object can exceed the speed of light, that means that nothing, not even light, could escape the black hole once it is inside this distance from the center of the black hole. A more fundamental way of viewing this is that in a black hole the gravitational field is so intense that it bends space and time around itself so that inside the event horizon there are literally no paths in space and time that lead to the outside of the black hole: No matter what direction you went, you would find that your path led back to the center of the black hole, where the singularity is found.

44. FAQ To SCI.PHYSICS On Black Holes By Matt McIrvin Frequently Asked Questions (FAQs) on Black Holes to Internet newsgroup sci.physics Answers posted by Matt McIrvin of Harvard University, last updated 02FEB-1995. http://antwrp.gsfc.nasa.gov/htmltest/gifcity/bh_pub_faq.html

Frequently Asked Questions (FAQs) on Black Holes to Internet newsgroup: sci.physics Contents: What is a black hole, really? What happens to you if you fall in? Won't it take forever for you to fall in? Won't it take forever for the black hole to even form? Will you see the universe end? ... Where did you get that information? 1. What is a black hole, really? In 1916, when general relativity was new, Karl Schwarzschild worked out a useful solution to the Einstein equation describing the evolution of spacetime geometry. This solution, a possible shape of spacetime, would describe the effects of gravity *outside* a spherically symmetric, uncharged, nonrotating object (and would serve approximately to describe even slowly rotating objects like the Earth or Sun). It worked in much the same way that you can treat the Earth as a point mass for purposes of Newtonian gravity if all you want to do is describe gravity *outside* the Earth's surface. Nobody really worried about this at the time, because there was no known object that was dense enough for that inner region to actually be outside it, so for all known cases, this odd part of the solution would not apply. Arthur Stanley Eddington considered the possibility of a dying star collapsing to such a density, but rejected it as aesthetically unpleasant and proposed that some new physics must intervene. In 1939, Oppenheimer and Snyder finally took seriously the possibility that stars a few times more massive than the sun might be doomed to collapse to such a state at the end of their lives.

45. Science NetLinks: Water 1: Water And Ice 4A The Universe 2 On the basis of scientific evidence, the universe is estimated to be over ten billion years old . 4A The Universe 3 Increasingly sophisticated technology http://www.sciencenetlinks.com/lessons.php?BenchmarkID=4&DocID=272

46. Black Holes | Define Black Holes At Dictionary.com –noun Astronomy . a theoretical massive object, formed at the beginning of the universe or by the gravitational collapse of a star exploding as a supernova, whose http://dictionary.reference.com/browse/black holes

47. Black Holes And Beyond Part of the Spacetime Wrinkles exhibit published by the National Center for Supercomputing Applications descriptions of what black holes are, how they might be detected, and what kinds of gravitational waves they should produce. Aimed at a general audience. http://archive.ncsa.illinois.edu/Cyberia/NumRel/BlackHoles.html

Forward Back Up Map ... Information Black Holes and Beyond Einstein's general theory of relativity describes gravity as a curvature of spacetime caused by the presence of matter. If the curvature is fairly weak, Newton's laws of gravity can explain most of what is observed. For example, the regular motions of the planets. Very massive or dense objects generate much stronger gravity. The most compact objects imaginable are predicted by General Relativity to have such strong gravity that nothing, not even light, can escape their grip. Scientists today call such an object a black hole . Why black? Though the history of the term is interesting, the main reason is that no light can escape from inside a black hole: it has, in effect, disappeared from the visible universe. Do black holes actually exist? Most physicists believe they do, basing their views on a growing body of observations. In fact, present theories of how the cosmos began rest in part on Einstein's work and predict the existence of both singularities and the black holes that contain them. Yet Einstein himself vigorously denied their reality, believing, as did most of his contemporaries, that black holes were a mere mathematical curiosity. He died in 1955, before the term "black hole" was coined or understood and observational evidence for black holes began to mount.

48. Black Holes Pages by the relativity group at Cambridge University, aimed at a general audience. They include a brief introduction to black holes, information about observational evidence, and a section on black holes and critical phenomena. http://www.damtp.cam.ac.uk/user/gr/public/bh_home.html

BLACK HOLES Introduction to black holes Observational evidence for black holes Black holes and critical phenomena [Back] ... [Next]

49. Science NetLinks: Black Holes 4A The Universe 2 On the basis of scientific evidence, the universe is estimated to be over ten billion years old . 4A The Universe 3 Increasingly sophisticated technology http://www.sciencenetlinks.com/lessons.php?DocID=272

50. [gr-qc/9808035] Black Holes Review article by Gary T. Horowitz (UCSB) and Saul A. Teukolsky (Cornell); includes information on the observational evidence for black holes, some developments involving cosmic censorship, and the statistical origin of black hole entropy. http://arxiv.org/abs/gr-qc/9808035

arXiv.org gr-qc Search or Article-id Help Advanced search All papers Titles Authors Abstracts Full text Help pages Full-text links: Download: PDF PostScript Other formats Current browse context: gr-qc new recent SLAC-SPIRES HEP refers to ... what is this? Bookmark what is this? General Relativity and Quantum Cosmology Title: Black Holes Authors: Gary T. Horowitz Saul A. Teukolsky (Submitted on 12 Aug 1998) Abstract: Black holes are among the most intriguing objects in modern physics. Their influence ranges from powering quasars and other active galactic nuclei, to providing key insights into quantum gravity. We review the observational evidence for black holes, and briefly discuss some of their properties. We also describe some recent developments involving cosmic censorship and the statistical origin of black hole entropy. Comments: 13 pages, To appear in the American Physical Society Centenary issue of Reviews of Modern Physics, March 1999 Subjects: General Relativity and Quantum Cosmology (gr-qc) Journal reference: Rev.Mod.Phys.71:S180-S186,1999 DOI 10.1103/RevModPhys.71.S180

51. ASP: Black Holes The Astronomical Society of the Pacific is an international nonprofit scientific and educational organization founded in 1889 that works to increase understanding and http://www.astrosociety.org/education/publications/tnl/24/24.html

www.astrosociety.org/uitc No. 24 - Summer 1993 Black Holes by John Percy, University of Toronto What is a black hole? Mini black holes How can you "see'' a Black Hole? Supermassive black holes ... For Further Reading About Black Holes What is a black hole? A black hole is a region of space in which the pull of gravity is so strong that nothing can escape. It is a "hole'' in the sense that things can fall into it, but not get out. It is "black'' in the sense that not even light can escape. Another way to say it, is that a black hole is an object for which the escape velocity (the velocity required to break free from an object) is greater than the speed of light the ultimate "speed limit'' in the universe. In 1783, British amateur astronomer, Rev. John Mitchell, realized that Newton's laws of gravity and motion implied that the more massive an object, the greater the escape velocity. If you could somehow make something 500 times bigger than the Sun, but with the same density, he reasoned, even light couldn't move fast enough to escape from it and it would never be seen. But it took Einstein's general theory of relativity, the modern theory of gravity, for astronomers and physicists to understand the true nature and characteristics of black holes. The boundary of a black hole is called the event horizon , because any event which takes place within is forever hidden to anyone watching from outside. Astronomer Karl Schwarzschild showed that the radius of the event horizon in kilometers is 3 times its mass expressed in units of solar masses; this radius is called the Schwarzschild radius. The event horizon is the one-way filter in the black hole: anything can enter, but nothing can leave.

52. [astro-ph/9801252] Black Holes : A General Introduction Review article by Jean-Pierre Luminet (Observatoire Paris-Meudon), which presents in a pictorial way the basic concepts of black hole physics; includes information about astronomical objects that are black hole candidates. http://arxiv.org/abs/astro-ph/9801252

arXiv.org astro-ph Search or Article-id Help Advanced search All papers Titles Authors Abstracts Full text Help pages Full-text links: Download: PDF PostScript Other formats Current browse context: astro-ph new recent SLAC-SPIRES HEP refers to ... what is this? Bookmark what is this? Astrophysics Title: Black Holes : A General Introduction Authors: Jean-Pierre Luminet (Submitted on 26 Jan 1998) Abstract: Our understanding of space and time is probed to its depths by black holes. These objects, which appear as a natural consequence of general relativity, provide a powerful analytical tool able to examine macroscopic and microscopic properties of the universe. This introductory article presents in a pictorial way the basic concepts of black hole's theory, as well as a description of the astronomical sites where black holes are suspected to lie, namely binary X-ray sources and galactic nuclei. Comments: LateX 32 pages, 23 Postscript figures, uses lamuphys.sty. To appear in BLACK HOLES : THEORY AND OBSERVATION, Springer, 1998 Subjects: Astrophysics (astro-ph) ; General Relativity and Quantum Cosmology (gr-qc) Journal reference: in Black Holes : Theory and Observation, Eds. F. Hehl, C. Kiefer, R. Metzler, Springer Verlag, 1998, Lecture Notes in Physics, pp. 3-36.

53. Black Holes And Neutron Stars Black Holes and Neutron Stars offers a nontechnical discussion about black holes and neutron stars. Topics include what they are, how they form, and how we detect them. There http://www.eclipse.net/~cmmiller/BH/blkmain.html

Black Holes and Neutron Stars INTRODUCTION BLACK HOLES NEUTRON STARS AND PULSARS HOW THEY FORM HOW WE DETECT THEM ... BOOKS Many people think black holes continually suck in everything like great big cosmic bathtub drains. And what the heck are neutron stars? Understanding the nature of black holes and neutron starshow they form, what they're like, and how we know they are therecan lead to a better understanding of how our Universe works. The information in this web site is intended for a non-technical audience. If you are interested in more scientifically complex discussions of black holes and neutron stars (you know, where they use all those great big words Make sure you check out the Online Books section, where you can order books about black holes and neutron stars from amazon.com! Please check out the Black Holes and Neutron Stars Awards and Banners page. Use the menu to the left to learn about black holes and neutron stars. Choose the PRINTOUT option if you want to print out the entire text. Hits since 27 April 1996: This Web page was written and is maintained by Chris Miller . Last updated 17 September 2003. cmmiller@eclipse.net

54. Spacetime Geometry Inside A Black Hole Text by Jim Haldenwang describing the foundations of general relativity and some basic properties of black holes. Presupposes knowledge of calculus and basic concepts of special relativity. http://members.cox.net/jhaldenwang/black_hole.htm

Spacetime Geometry Inside a Black Hole by Jim Haldenwang written Nov. 12, 2004 revised May 28, 2008 In this paper, general relativity theory (GRT) is used to describe the geometry of spacetime inside a black hole. The reader is assumed to be familiar with calculus and special relativity (SRT). We start with a review of the parts of SRT needed to understand GRT. Special Relativity Theory Special relativity concerns itself with inertial frames of reference. Two observers who are in uniform, straight-line motion relative to one another are said to be in inertial frames of reference. Such observers are called inertial observers. If two observers are accelerating relative to one another, they are not inertial observers. Einstein developed SRT first, by ignoring acceleration. Later on, he was able to generalize his theory to include acceleration and develop GRT. SRT is based on two principles. First, the principle of relativity: the laws of physics are the same in all inertial frames of reference. This means that there is no absolute rest frame. Second, Einstein's light postulate: the speed of light in vacuum is constant, and has the same value in all inertial frames of reference. All experimental measurements to date have in fact found the speed of light in empty space to be constant, regardless of the (uniform) motions of the measuring devices. The speed of light, about 300,000 km/sec, is represented by the letter c, which stands for celeritas (latin for "swift"). In order for the speed of light to be constant in different inertial frames which are in motion relative to one another, Einstein realized that space and time cannot be absolute. For example, if observer A is in motion relative to observer B, then, from B's point of view, A’s units of measuring space must be shorter than B’s (in A's direction of motion). Also, according to B, A’s units of measuring time must be longer (slower) than B’s. Relative to B, space for A is contracted in his direction of motion and time is lengthened or slowed down (dilated). (Two handy mnemonics are: "moving sticks are shortened" and "moving clocks run slow.") The sizes of these relative distortions of space and time are precisely what is needed so that when A measures the speed of a passing light ray, he will always obtain the same value that B does.

55. Lives And Deaths Of Stars Black Holes Chapter index in this window — — Chapter index in separate window This material (including images) is copyrighted!. See my copyright notice for fair use practices. http://www.astronomynotes.com/evolutn/s13.htm

Black Holes Chapter index in this window Chapter index in separate window This material (including images) is . See my for fair use practices. If the core remnant has a mass greater than 3 solar masses, then not even the super-compressed degenerate neutrons can hold the core up against its own gravity. Gravity finally wins and compresses everything to a mathematical point at the center. The point mass is a black hole . Only the most massive, very rare stars (greater than 10 solar masses) will form a black hole when they die. As the core implodes it briefly makes a neutron star for just long enough to produce the supernova explosion. Ultra-strong gravity The gravity of the point mass is strong enough close to the center that nothing can escape, not even light! Within a certain distance of the point mass, the escape velocity is greater than the speed of light. Remember from the gravity chapter that the escape velocity is the speed an object needs to avoid being pulled back by the gravity of a massive body. The escape velocity v escape Sqrt G where G is the gravitational constant.

56. Black Holes - Astronomy For Kids - KidsAstronomy.com Learn How Big Space Is With KidsAstronomy.com Click on the item you would like to explore, or select from this list http://www.kidsastronomy.com/black_hole.htm

57. Black Holes What would happen if gravity were so strong that even light could not escape its pull? The answer to this question is the shocking and amazing http://www.superstringtheory.com/blackh/index.html

The Official String Theory Web Site Black Holes Quiz yourself on the content of this section Some basic books for further reading Some advanced books for further reading What would happen if gravity were so strong that even light could not escape its pull? The answer to this question is the shocking and amazing object known as the black hole basic advanced What is a black hole like? How were they first discovered? How do astronomers know if they're seeing one? basic advanced Quantum mechanics turns black holes from cold, eternal objects into hot shrinking thermodynamics. Physicists wondered: Is there a microscopic origin for black hole entropy? basic advanced Find out how and why string theory modifies the spacetime equations of Einstein. basic advanced Thanks to the string duality revolution of the early nineties, a microscopic derivation for black hole entropy has been discovered, at least in theory. basic advanced Previous Next ... Gravitational collapse!

58. Frequently Asked Questions About Black Holes Why do some stars end up as black holes? Or, What does the exclusion principle have to do with whether or not a star becomes a black hole? How is time changed in a black hole? http://www.phys.vt.edu/~jhs/faq/blackholes.html

Frequently Asked Questions About Black Holes Compiled by Dr. John Simonetti of the Department of Physics at Virginia Tech Back to Frequently Asked Astronomy and Physics Questions Why do some stars end up as black holes? [Or,] What does the exclusion principle have to do with whether or not a star becomes a black hole? How is time changed in a black hole? Does the E=mc^2 equation apply to a black hole? If nothing travels at the speed of light, except light, how can a black hole also pull light into itself? What is the best evidence for the existence of black holes? Is it all really just a theory? I've heard that a black hole 'belches' light and radiation whenever something falls into its event horizon. What does that mean and why does that happen? Can you see a black hole? What does a black hole look like? How big can a black hole get? How small can a black hole be? ... I read somewhere that in the VERY distant future black holes could leak and disperse. Can that happen? If it can, how? Why do some stars end up as black holes? The answer involves the gravity and the internal pressure within the star. These two things oppose each other the gravitational force of the star acting on a chunk of matter at the star's surface will want to cause that matter to fall inward, but the internal pressure of the star, acting outward at the surface, will want to cause the matter to fly outward. When these two are balanced (i.e., equal in strength) the star will maintain its size: neither collapse not expand. Such is the case for the Sun at the moment, and even, for that matter, for the Earth.

59. Contents Web exhibition with visualizations of various properties of both Schwarzschild black holes and rotating (Kerr) black holes, such as curvature, light cones, and the gravitational frequency shift, produced by the Danish physics student Michael Cramer Andersen. http://www.astro.ku.dk/RelViz/cramer/text/geom_web/node1.html

Contents General Relativity and Spacetime Spacetime and World Lines Arc length separation in 3D-Space Surfaces and Curvature ... About this document ... Geometry Around Black Holes Michael Cramer Andersen June 1996 In this paper I will investigate the geometry around Black Holes, and how this affects freely falling relativistic particles along geodesics which is certainly not straight lines as in normal flat spacetime. Stellar Black Holes are the relicts of collapsed massive stars which provides extreme mass-/energydensities. Nothing can escape from the Black Hole, not even light. This is because of the extreme curvature of space. The detailed description of Black Holes is included in The Einstein Field Equations. Historically one of the first exact solutions to these equations was that of Schwarzschild 1916 describing a spherical symmetric point mass, later identified as a Black Hole. I will concentrate on the Schwarzschild-solution, describing a non-rotating Black Hole and the Kerr solution, describing Black Holes with angular momentum. There exists of course more general - and complicated - solutions including charge, and electromagnetic fields around the Black Holes. But I will not go into this exciting area. The aim of this work is to use some of the fundamental results to get a view of the geometry around a Black Hole. Curvature is one of the most remarkable geometrical properties, but some other basic concepts has to be introduced, these are: world lines, geodesics and metric tensors. Through out this text, I will use the space-like sign convention: (-,+,+,+) for the metrics considered; indices going from 1 to 3 are written in

60. Black Holes BLACK HOLES Introduction to black holes Observational evidence for black holes Black holes and critical phenomena Cosmic strings Quantum gravity http://www.damtp.cam.ac.uk/research/gr/public/bh_home.html

BLACK HOLES Introduction to black holes Observational evidence for black holes Black holes and critical phenomena [Back] ... [Next]

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