21. Black Holes - What Is A Black Hole? A black hole is a curvature of spacetime geometry due to an intense gravitational field. The effects of a black hole are so extreme that even light cannot escape it, thus the name http://physics.about.com/od/astronomy/f/BlackHole.htm

zWASL=1;zGRH=1 zJs=10 zJs=11 zJs=12 zJs=13 zc(5,'jsc',zJs,9999999,'') zDO=0 Home Education Physics Physics Search Physics Basic Concepts Theories Experiments ... Share w(x2+zWl+'?p=1" zT="18/1[N" rel="nofollow">Print') Free Physics Newsletter! Sign Up Discuss in my Forum By Andrew Zimmerman Jones , About.com Guide See More About: black holes astrophysics stephen hawking general relativity ... cosmology Artistic rendering of a Black Hole NASA zSB(3,3) Question: What is a Black Hole? What is a black hole? When do black holes form? Can scientists see a black hole? What is the "event horizon" of a black hole? Answer: A black hole is a theoretical entity predicted by the equations of general relativity . A black hole is formed when a star of sufficient mass undergoes gravitational collapse, with most or all of its mass compressed into a sufficiently small area of space, causing infinite spacetime curvature at that point (a "singularity"). Such a massive spacetime curvature allows nothing, not even light, to escape from the "event horizon," or border. Black holes have never been directly observed, though predictions of their effects have matched observations. There exist a handful of alternate theories, such as

22. Do Black Holes Exist? Brief text by Pablo G. Ostrov about the evidence for the existence of black holes, aimed at a general audience. http://pgostrov.googlepages.com/e3.html

23. [astro-ph/0310692] Evidence For The Black Hole Event Horizon Review article by Ramesh Narayan about possible observational evidence for the defining feature of black holes. http://arxiv.org/abs/astro-ph/0310692

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 ... NASA ADS Bookmark what is this? Astrophysics Title: Evidence for the Black Hole Event Horizon Authors: Ramesh Narayan (Submitted on 23 Oct 2003) Abstract: Astronomers have discovered many candidate black holes in X-ray binaries and in the nuclei of galaxies. The candidate objects are too massive to be neutron stars, and for this reason they are considered to be black holes. While the evidence based on mass is certainly strong, there is no proof yet that any of the objects possesses the defining characteristic of a black hole, namely an event horizon. Type I X-ray bursts, which are the result of thermonuclear explosions when gas accretes onto the surface of a compact star, may provide important evidence in this regard. Type I bursts are commonly observed in accreting neutron stars, which have surfaces, but have never been seen in accreting black hole candidates. It is argued that the lack of bursts in black hole candidates is compelling evidence that these objects do not have surfaces. The objects must therefore possess event horizons. Comments: Subjects: Astrophysics (astro-ph) ; General Relativity and Quantum Cosmology (gr-qc) Report number: Oct. 23, 2003

24. No Escape: The Truth About Black Holes The Truth about Black Holes An Amazing Space activity designed to teach students about black holes. http://amazing-space.stsci.edu/resources/explorations/blackholes/lesson/index.ht

25. Black Holes, Black Holes Information, Information On Black Holes At SPACE.com Space.com explains black holes, black holes information, information on black holes, black holes in space, theories on black holes http://www.space.com/blackholes/

dartTag = 'homepage/home'; All About Black Holes The anomalous black holes are concentrated areas of mass so immense, that the mammoth force of gravity denies anything within a certain area around it from passing. This area is called the event horizon of a black hole. We have given black holes their name because light inside the event horizon can never be seen by mankind, or any outside observer. We believe that black holes in space are created by the collapse of a red super giant star. As these stars reach the end of their lives, an imbalance of inward and outward pressure forces the star to collapse. Information on black holes is limited, though numerous schools of theory exist. We know black holes exist not because we can see them, but because of the impact they have on the space around them. Scientists like Karl Schwarzschild, Jayant Narlikar and Stephen Hawking have built upon ideas from Einstein and others to offer theories on black holes. And yet, they remain an enigma. Because extensive, proven black holes information is scarce, they remain a constant area of intrigue and curiosity. For additional information on black holes, refer to our articles, pictures and other interactive resources below.

26. Black Holes & Co. — Einstein Online Collection of articles about various aspects of black hole physics, from astronomical observations to the question of why black holes have no hair. Part of the Spotlights on Relativity series on Einstein Online; written for a general audience. http://www.einstein-online.info/en/spotlights/blackHoles/

Skip to content. Skip to navigation Contact Site Map Search Site only in current section You are here: Home Spotlights on relativity Personal tools Main Navigation Home Elementary Einstein Spotlights on relativity ... About Einstein Online Einstein Online is provided by the Info g-spotlight-c2 Black holes, neutron stars and supernovae: Flight into a black hole, the black hole in the center of the Milky Way, how many different kinds of black hole are there, how black holes light up their neighbourhood This page features an overview of all our Spotlights dealing with black holes and other compact objects, notably neutron stars. Under the heading Close encounters with black holes , a Spotlight explores what an observer on a space-ship would see as, step by step, the ship approaches a black hole. The texts in the category How to track compact objects explores the phenomena that can be used by astronomers to track black holes and other compact objects in their telescopes, from their gravitational influence on neighbouring stars to the different ways that compact objects have of lighting up their immediate cosmic neighbourhood. The category The physics of black holes is dedicated to general theorems that have been proved about these objects. The category

27. Science News For Kids: Feature: Black Hole Journey Research on weird, invisible objects called black holes might help explain how the universe began. http://www.sciencenewsforkids.org/articles/20050202/Feature1.asp

Home About Us Sponsors Article Archive ... Weather SNK RSS Feed MatheMUSEments En Espańol: Arte Digital For Teachers and Parents Search Black Hole Journey Emily Sohn E-mail this article Print this article Feb. 2, 2005 There are all sorts of holes: big ones and little ones, deep ones and shallow ones. There are swimming holes and buttonholes, cheese holes and bullet holes. Then, there are black holes. These mysterious, bizarre objects pack a huge mass into a tiny volume. Their gravity is so strong that they gobble up anything that comes near them, even stars, gas, and light. They're invisible. They're like cracks in space, and they lurk all over the universe. An invisible, massive, spinning black hole may lie at the center of this galaxy, as shown in an artist's illustration. The black hole would pull in material from a swirling disk of nearby gas and stars. The extremely high temperatures and pressures produced near the black hole would also cause some of the gas to be ejected, creating a huge galactic jet (from center to top right). Dana Berry, Space Telescope Science Institute

28. Black Holes A one-hour lecture given by David M. Harrison (University of Toronto) to senior liberal arts students on the basic properties of black holes. http://www.upscale.utoronto.ca/GeneralInterest/Harrison/BlackHoles/BlackHoles.ht

Black Holes Click here to go to the JPU200Y home page. Click here to go to the Physics Virtual Bookshelf Click here to go to the UPSCALE home page. Introduction: "A luminous star, of the same density as the Earth, and whose diameter should be two hundred and fifty times larger than that of the Sun, would not, in consequence of its attraction, allow any of its rays to arrive at us; it is therefore possible that the largest luminous bodies in the universe may, through this cause, be invisible." Pierre Laplace, The System of the World , Book 5, Chapter VI (1798). Evolution of Stars Clouds of Hydrogen begin condensing into more dense clusters due to gravitation. Eventually the density gets high enough that the Hydrogen begins fusing into Helium. This fusion releases energy, mostly in the form of electromagnetic radiation. Our sun is currently in this phase. Note that the gravitational attraction of the matter of the star is trying to make it smaller; this is balanced by the radiation pressure that is trying to push the matter outward making the star bigger. In class we showed a photograph of a birthplace of stars; the URL is http://www.seds.org/hst/M16WF2.html

29. Simulating EXtreme Spacetimes—A Caltech–Cornell Project A beginner's guide to black holes, warped spacetime, gravitational waves, and other bizarre ideas from astrophysics. http://www.black-holes.org/

The SXS project is a collaborative research effort involving groups at the California Institute of Technology and Cornell University. Our goal is the simulation of black holes and other extreme spacetimes to gain a better understanding of Relativity, and the physics of exotic objects in the distant cosmos. Explore Sounds Movies Videos ... Log In The SXS project is supported by the Sherman Fairchild Foundation, the NSF, and NASA. We also thank Michael Scott for generously providing support for this website.

30. Light In Nature: Black Holes Black Holes. Black holes are the most fascinating and mysterious objects in the heavens. In the 1960's, the most important discoveries in astronomy were pulsars and quasars. http://library.thinkquest.org/27356/n_blackholes.htm

31. [gr-qc/9707012] Black Holes Lecture notes for Paul K. Townsend s course on Black holes at Cambridge University. Covers the basics of black hole physics, the mechanics of black holes, and related geometrical concepts at a level suitable for advanced physics students. http://arxiv.org/abs/gr-qc/9707012

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: P.K. Townsend (Submitted on 4 Jul 1997) Abstract: Lecture notes for a 'Part III' course 'Black Holes' given in DAMTP, Cambridge. The course covers some of the developments in Black Hole physics of the 1960s and 1970s. Comments: 145 pp. Many diagrams Subjects: General Relativity and Quantum Cosmology (gr-qc) Cite as: arXiv:gr-qc/9707012v1 Submission history From: Paul Townsend [ view email Fri, 4 Jul 1997 15:13:06 GMT (140kb) Which authors of this paper are endorsers? Link back to: arXiv form interface contact

32. StarDate's Black Hole Encyclopedia - The Latest Black Hole News And Details On T A solid overview of black holes and details on the bestknown individual black holes for the general public. StarDate's Black Holes Encyclopedia is an extension of the research http://blackholes.stardate.org/

Contact StarDate About StarDate Friends of McDonald Sign up for SkyTips ... Take our survey! Content on this page requires a newer version of Adobe Flash Player. Bad Neighbors Hubble News Center - October 7, 2010 M31 Black Hole Gets Frisky StarDate - May 25, 2010 Black Hole Runs Away Netherlands Institute for Space Research - May 10, 2010 More A supermassive black hole in the constellation Centaurus. The center of the giant elliptical galaxy Messier 60 is relatively quiet and peaceful. In this calm environment, gas is falling inward from all directions at a steady pace. Astronomers have used this infalling gas to estimate the mass of the black hole in the galaxy's core. In 2003, Texas astronomer Karl Gebhardt estimated the mass at about 2 billion times by the mass of the Sun by measuring the motions of stars near the center of the galaxy. The stars are accelerated by the black hole's powe... More Can anything ever escape from a black hole? Nothing that falls into a black hole can come back out again at least not in its original form. More Fact vs. Fiction

33. Black Holes - College Essays - Kpa0412A Read this college essay and over 200,000 others like it now. Don't miss your chance to earn better grades and be a better writer! http://www.oppapers.com/essays/Black-Holes/187915

Skip to Navigation Skip to Content OPPapers.com Research Papers and Essays for All Join Login Writing Service Help ... Contact Us Question? Email Us Join Search words.comment_error_title="A comment heading is required."; words.comment_error_text="A comment is required."; words.enter_query="No query entered!"; Black Holes Home Page Science Astronomy We have many premium term papers and essays on Black Holes. We also have a wide variety of research papers and book reports available to you for free. You can browse our collection of term papers or use our search engine Black Holes Black Holes. Black holes are one of the many universes many wonders. Something with so much pull and so much gravitational force that nothing can escape it, not even light. With light not being to escape there is no feasible way to see the interior. General Relativity describes blackholes as nothing more than empty space, for that whatever goes into it, can’t come back out and will just put a void in the universe. The concept of black holes have been discussed by many great thinkers such as the likes of Karl Schwarzschild, Stephen Hawking and Pierre-Simon Laplace. These thinkers have came to the conclusion that there are at least four different types of black holes; Supermassive Blackholes, Intermediate-mass blackholes, Stellar-mass black holes, and Primordial Black holes. All these separate types have a distinction between size and mass. Black holes have three properties. Mass, charge and angular momentum. If there are two black holes that share these properties than they are considered indistinguishable. This counteracts the fact that stars have many parameters. But when a star collapses it loses unfortunately a great deal of information and leaving only mass, charge, and the angular momentum. The black hole information paradox is a question astronomers have because usually in almost all cases information is preserved, so losing information about the star and transforming into in some sense a gravitational junk yard is puzzling.

34. [gr-qc/0201053] Black Holes Review article by Piotr Chrusciel (Universit de Tours), covering the evidence for the existence of black holes, their mathematical definition, global aspects, and the most important black hole theorems. Special care is taken in exploring aspects relating to numerical simulations of black hole systems. http://arxiv.org/abs/gr-qc/0201053

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 ... NASA ADS Bookmark what is this? General Relativity and Quantum Cosmology Title: Black holes Authors: Piotr T. Chrusciel (Submitted on 16 Jan 2002) Abstract: Comments: 43 pages, springer style, several ps files. to appear in the proceedings of the Tuebingen conference on conformal structure of space-time, J. Frauendiener, H. Friedrich, eds, Springer Lecture Notes in Physics Subjects: General Relativity and Quantum Cosmology (gr-qc) Journal reference: Lect.Notes Phys. 604 (2002) 61-102 Report number: Tours preprint, 2002 Cite as: arXiv:gr-qc/0201053v1 Submission history From: Piotr Chrusciel [ view email Wed, 16 Jan 2002 09:26:22 GMT (306kb) Which authors of this paper are endorsers? Link back to: arXiv form interface contact

35. NASA - Black Hole World Book Article on Black Holes A black hole is a region of space whose gravitational force is so strong that nothing can escape from it. http://www.nasa.gov/worldbook/blackhole_worldbook.html

36. Black Holes: Fact And Fiction Selected talks (slides and audio) from a 1999 Teachers Educational Forum on black holes at the Kavli Institute for Theoretical Physics (UCSB); topics black hole basics, astrophysical aspects, how to build a black hole in your classroom, and the relation with string theory. http://online.kitp.ucsb.edu/online/bh_teach/

HOME DIRECTORY FOR SCIENTISTS TALKS ... HELP Nov 14, 2010 INSTITUTE FOR THEORETICAL PHYSICS ITP Teachers Educational Forum on Black Holes: Fact and Fiction Saturday, February 6, 1999 Coordinators: O. Blaes. R. Blandford, D. Eardley and J.P. Lasota Schedule Time: Speaker: Title: 8:00 am Registration ITP Lobby 9:00 am David Gross Omer Blaes Welcome to ITP Welcome to Conference 9:30 am Kip Thorne (Caltech) Black Holes: Predicted Properties and Behaviors Refreshment Break ITP Courtyard Roger Blandford (Caltech) New horizons in black hole astrophysics 12 Noon Jim Lochner (NASA/GSFC) Building a Black Hole in Your Classroom Lunch Break ITP Courtyard 1:45 pm Joe Polchinski (ITP) What is String Theory and What Does It Have to Do With Black Holes? 2:45 pm Town Hall Meeting O. Blaes, R. Blandford, D. Eardley, D. Gross, J. Lochner, J. Polchinski,K. Thorne 3:30 pm Refreshment Break ITP Courtyard Stephen Hawking (Cambridge) **TBA** 5:00 pm Conference Ends last updated 2/11/99 dme

37. Black Holes The Truth about Black Holes An Amazing Space activity designed to teach students about black holes. http://amazing-space.stsci.edu/resources/explorations/blackholes/

38. General Relativity & Black Holes Gene Smith's Astronomy Tutorial General Relativity Black Holes http://casswww.ucsd.edu/public/tutorial/GR.html

University of California, San Diego Gene Smith's Astronomy Tutorial Einstein's General Theory of Relativity The General Theory of Relativity is an expansion of the Special Theory to include gravity as a property of space. Start with this Gravity Tutorial The Equivalence Principle The Theory of Special Relativity has as its basic premise that light moves at a uniform speed, c = 300,000 km/s , in all frames of reference. This results in setting the speed of light as the absolute speed limit in the Universe and also produced the famous relationship between mass and energy, E = mc . The foundation of Einstein's General Theory is the Equivalence Principle which states the equivalence between inertial mass and gravitational mass Inertial Mass is the quantity that determines how difficult it is to alter the motion of an object. It is the mass in Newton's Second Law: F = ma Gravitational mass is the mass which determines how strongly two objects attract each other by gravity, e.g. the attraction of the earth: It is the apparent equivalence of these two types of mass which results in the uniformity of gravitational acceleration Galileo's result that all objects fall at the same rate independent of mass: Galileo and Newton accepted this as a happy coincidence, but Einstein turned it into a fundamental principle. Another way of stating the equivalence principle is that gravitational acceleration is indistinguishable from other forms of acceleration. According to this view a student in a closed room could not tell the difference between experiencing the gravitational pull of the earth at the earth's surface and being in a rocketship in space accelerating with a = 9.8 m/s

39. Black Hole Thermodynamics Brief introduction to the basic ideas of black hole thermodynamics; written by David M. Harrison (University of Toronto); uses no mathematical formulas; suitable for a general audience. http://www.upscale.utoronto.ca/GeneralInterest/Harrison/BlackHoleThermo/BlackHol

Black Hole Thermodynamics Click here to go to the JPU200Y home page. Click here to go to the Physics Virtual Bookshelf Click here to go to the UPSCALE home page. Author This document was written by David M. Harrison, Department of Physics, University of Toronto, mailto:harrison@physics.utoronto.ca. in November, 1999. This is version 1.9, date (m/d/y) 04/10/02. This material may be distributed only subject to the terms and conditions set forth in the Open Content License, v1.0 or later (the latest version is presently available at http://opencontent.org/opl.shtml Introduction: "Time and space are modes in which we think and not conditions in which we live." Einstein "Space is the order of coexistence, and time is the order of succession of phenomena." Leibniz "For the sage, time is only of significance in that within it the steps of becoming can unfold in clearest sequence." I Ching Background Information One of the features of Hawking and Bekenstein's development of black hole thermodynamics is that it ties many many pieces of physics together. Among those pieces are: The realisation from Quantum Mechanics that we can think of all matter-energy as waves. A document on this appears

40. Introductory Lectures On Black Hole Thermodynamics A (graduate level) review of black hole thermodynamics by Ted Jacobson (University of Utrecht). Includes information on black hole basics, classical black hole thermodynamics, and quantum aspects. http://www.fys.ruu.nl/~wwwthe/lectures/itfuu-0196.ps

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