[gr-qc/9803002] Higher Dimensional Chern-Simons Theories And Topological Black H It has been recently pointed out that black holes of constant curvature with a chronological singularity can be constructed in any spacetime dimension. In this paper, a brief summary of these new black holes is given. http://arxiv.org/abs/gr-qc/9803002
Extractions: It has been recently pointed out that black holes of constant curvature with a "chronological singularity" can be constructed in any spacetime dimension. These black holes share many common properties with the 2+1 black hole. In this contribution we give a brief summary of these new black holes and consider them as solutions of a Chern-Simons gravity theory. We also provide a brief introduction to some aspects of higher dimensional Chern-Simons theories. References and citations for this submission:
PhysicsWeb - A New Spin On Black Holes A new spin on black holes 29 October 2003. Astronomers believe that a supermassive black hole exists at the centre of every galaxy in the universe. http://physicsweb.org/article/news/7/10/15
Extractions: 29 October 2003 An international team of astrophysicists has discovered that the supermassive black hole at the centre of our galaxy is spinning. Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Germany and colleagues in the US, Israel and France have observed periodic bursts of infrared radiation coming from the black hole which, they say, is evidence for its rotation (R Genzel et al. Nature 934). The results will usher in a new era of observational black hole physics and tests of general relativity according to the team. Astronomers believe that a supermassive black hole exists at the centre of every galaxy in the universe. Recent X-ray observations and measurements of the orbits of stars around Sagittarius A* - a powerful radio source at the centre of our galaxy - confirm that it is a black hole that is 3.6 million times more massive than the Sun. Accretion disk Now, for the first time, Genzel and colleagues have detected periodic bursts of infrared radiation from Sagittarius A* with the Very Large Telescope (VLT) in Chile. Moreover, they found that these bright flares arrived periodically - roughly every 17 minutes. This can only happen if the accretion disk of hot gas around the black hole is rotating, which means that the black hole itself must be rotating.
2001: A Spacetime Odyssey Two theories revolutionized the 20th century view of space and time Einstein's General Theory of Relativity and Quantum Mechanics. Their union has spawned elementary particle theories with extra spacetime dimensions, the inflationary model of bigbang cosmology, dark matter in the universe, radiation from quantum black holes and the fuzzy spacetime geometry of superstrings and M-theory. http://www.umich.edu/~mctp/sto2001/
Extractions: University of Michigan, Ann Arbor Two theories revolutionized the 20th century view of space and time: Einstein's General Theory of Relativity and Quantum Mechanics. Their union has spawned elementary particle theories with extra spacetime dimensions, the inflationary model of big-bang cosmology, dark matter in the universe, radiation from quantum black holes and the fuzzy spacetime geometry of superstrings and M-theory. These developments, derived from the 19th century mathematics of Riemannian geometry and Lie groups, have in their turn inspired new directions in the pure mathematics of topology and knot theory. In view of the mission of the Michigan Center for Theoretical Physics to provide a venue for interdisciplinary studies in the mathematical sciences, this Inaugural Conference will bring together Astronomers, Cosmologists, Particle Physicists and Mathematicians to share their different perspectives on the 21st century view of spacetime. John Bahcall (IAS)
An Introduction To Black Holes What are black holes? A black hole is a super dense object that has an intense gravitational pull. Cool things about black holes http://design.lbl.gov/education/blackholes/
Extractions: What are Black Holes? A black hole is a super dense object that has an intense gravitational pull. There are two parts to a black hole, a singularity and a event horizon. If you were to take a slice of a black hole right through its center it would look like this: The event horizon is where the force of gravity becomes so strong that even light is pulled into the black hole. Although the event horizon is part of a black hole, it is not a tangible object. If you were to fall into a black hole, it would be impossible for you to know when you hit the event horizon. For a mathematical derivation of the radius of a event horizon see below. The singularity is not really a tangible object either. According to the General Theory of Relativity the Singularity is a point of infinite space time curvature. This means that the force of gravity has become infinitely strong at the center of a black hole. Everything that falls into a black hole by passing the event horizon, including light, will eventually reach the singularity of a black hole. Before something reaches the singularity it is torn apart by intense gravitational forces. Even the atoms themselves are torn apart by the gravitational forces. Imagine a star which is much more massive than our sun, and which has a mass, called the critical mass, which is large enough to cause a black hole to form. What keeps this star from collapsing onto itself and becoming a black hole? The answer is that there is an intense pressure caused by nuclear reactions within the sun. When the fuel that feeds the nuclear reactions gets used up the massive star cannot support itself anymore. It then collapses to form a black hole.
Black Holes To Blackboards Laying your hands on a black hole is hard (and dangerous) to do, but there are ways to understand these objects and avoid the pain of dimensionbending. http://www.aspsky.org/mercury/mercury/9802/lockwood.html
Extractions: Sahuaro High School Laying your hands on a black hole is hard (and dangerous) to do, but there are ways to understand these objects and avoid the pain of dimension-bending. A couple of weeks ago, I was sitting in the second-floor bathroom at Steward Observatory, not thinking at all about astronomy or writing columns. On the stall door in front of me, written perhaps by a clever astronomy student, was an equation in bold black ink: BLACK HOLES = GOD/0. As I pondered the philosophical significance of the equation, I realized that I have never tried to bring black holes to blackboards as my column title states. One of the most esoteric and fascinating objects for students to ponder, a black hole comes with virtually no lab activities. How do you lay your hands on a black hole and survive? There are, in fact, a few demonstrations that can bring about some understanding of black holes. It's pretty easy to describe a non-rotating black hole: a single point of infinite density surrounded by a protective sheath called the event horizon. Throw in rotation, though, and things get more complicated. I have never liked the funnel-like diagrams in most textbooks that try to show a black hole's distortion of space-time. A sharp student will always question this representation, which shows a 3-dimensional warpage, and ask what happens when you approach from a different direction, like from "underneath."
FreeWebs - Page Not Found Contains members area, newsletter, planets, black holes, and charts. http://www.freewebs.com/aharlac/
Extractions: 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 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.
Black Holes Portal linking to sites about very high density objects black holes, neutron stars. http://www.galacticsurf.com/trounoirGB.htm
Extractions: http://pages.infinit.net/mycroft/suppleme... 9 photos of black holes with associated explanations. http://pages.infinit.net/gafen/ Introduction to the black hole physics: the best way to be in ! http://tpe.trousnoirs.free.fr/ A web site dedicated to black holes: their birth, relativity, index etc... A web site easy to understand for all. http://www.trous-noirs.fr.st/ From the end of the life of a star to the formation of a black hole. very nice site. http://www.iquebec.com/trounoir/ Black hole formation (a web site entirely dedicated to this subject). http://www.cybersciences.com/Cyber/3.0... An article of cyber science: How to make a black hole without danger ! http://www.geocities.com/CapeCanavera... Black hole and singularity: very fine web page.
Astronomy Today - Space Science - Black Holes Contributor Marc Delehanty. Space Science Section black holes. black holes can t be seen, as they do not emit any electromagnetic radiation * . http://www.astronomytoday.com/cosmology/blackholes.html
Extractions: Marc Delehanty A black hole is an (almost invisble) body in space, created most likely from a collapsed red super giant star, that is so dense that neither light nor matter can escape its gravitational pull. Inside a star there is a constant battle between inward pressure from gravity, and outward pressure from heat. If you were to throw an unopened can of soda into a fire, the beverage would expand from the heat and explode. This is the same principle at work when a star is burning, it's heat is generating great outward pressure but this constant explosion is matched by gravity that is equally strong, thus a star maintains its shape and size. When a star nears the end of its life it cools off slowly and the outwards pressure grows weaker and weaker as the temperature of the star drops. When the outward pressure from the heat is nearly gone, the inward pressure of gravity still remains and is determined by the size of the star. It is theorized that when a star roughly ten times the size of our own nears the end of its life, it shrinks as its own gravity slowly pulls it in, but as it becomes more and more dense the gravity becomes stronger. The gravity becomes so intense that not even light can escape it. If you have ever watched water swirling down a drain, then you have a pretty good idea what happens as a black hole pulls things in. As matter and light approach the vicinity of a black hole they are slowly drawn in. If they are not headed straight for the spacial anomaly then they are taken into a violent and unstable orbit around the black hole until finally the orbit falls apart and it is sucked down by the immense gravity.
Cosmology - Black Holes Quantum Gravity An overview of Quantum Cosmology and topological structure of the early universe. Information from the University of Cambridge. http://www.amtp.cam.ac.uk/user/gr/Report96-html/Report96-html.html
Black Holes The fiveminute guide to black holes black holes are points in space that are extraordinarily dense. They apparently arise when http://whyfiles.org/052einstein/frame_drag3.html
Extractions: The black hole located at the bottom of the "funnel" warps the fabric of space and time, shown by the lines. If you shine a laser toward the hole, its light would curve along these lines. A jet of particles leaves the region near the black hole at almost the speed of light. The glowing stuff is matter being sucked into the hole. Courtesy Sky and Telescope magazine, Joe Bergeron, artist. Ironically enough, although the prediction for black holes was based on Einstein's theories, he himself argued against their existence in a rare instance of public blundering (see "The Reluctant Father of Black Holes" in the bibliography At any rate, scientists now think black holes form after an old star explodes as a supernova. The remaining junk can no longer withstand its own gravity, so it collapses in on itself and forms a strange celestial item. Small stars proceed to become neutron stars, extremely dense items about the size of a Manhattan that retain most of the mass of the original star. Unlike black holes, neutron stars are not dense enough to restrain light.
Howstuffworks "How Black Holes Work" black holes are some of the most amazing objects in the universe they may even hold many galaxies together! Learn all about them! http://www.howstuffworks.com/black-hole.htm
Extractions: Table of Contents Introduction to How Black Holes Work What is a Black Hole? Types of Black Holes How We Detect Black Holes Lots More Information Shop or Compare Prices You may have heard someone say, "My desk has become a black hole!" You may have seen an astronomy program on television or read a magazine article on black holes. These exotic objects have captured our imagination ever since they were predicted by Einstein's Theory of General Relativity in 1915.
CERN To Spew Black Holes CERN to spew black holes. Mini black holes could reveal hidden dimensions of space. Physicists at may soon be manufacturing copious quantities of black holes. http://www.nature.com/nsu/011004/011004-8.html
Gamma Ray Astrophysics At The NSSTC Research into gammaray phenomena, such as pulsars, black holes, other galaxies, gamma-ray bursts and exotic astrophysical objects. http://gammaray.msfc.nasa.gov
Extractions: The Compton Gamma Ray Observatory, about to be released from Space Shuttle Atlantis in 1991 April. The eight BATSE detector modules are mounted on the corners of the satellite. Four are visible in the image. T he Burst and Transient Source Experiment. During 9 years of successful operation, the BATSE detectors on the Compton Gamma-Ray Observatory (CGRO) continually recorded observations of gamma-ray bursts, pulsars, and other transient gamma-ray phenomena. Although the CGRO mission was terminated by NASA in June 2000, new science from BATSE and complete data archiving projects continue to occupy members of the GRA team and provide services to the high-energy astrophysics community. The Principal Investigator of this project is
Jean-Luc Movies: Virtual reality and informational movies on black holes. This site is associated with the National Center for Supercomputing Applications(NCSA), and is for students in middle school and above. http://jean-luc.ncsa.uiuc.edu/Movies/
ESA - Science - LISA Overview An ESA space mission to detect and observe gravitational waves from massive black holes and galactic binary stars in the frequency range 104 to 10-1 hz. Useful measurements in this frequency range cannot be made on the ground because of the unshieldable background of local gravitational noise. http://www.esa.int/science/lisa
Extractions: The Laser Interferometer Space Antenna (LISA) is a joint mission with NASA. It is a three-spacecraft mission, designed to detect the 'ripples' in space given out when very massive objects undergo strong acceleration. For example, they are produced when a black hole swallows a massive neutron star. Such ripples are called 'gravitational waves' and LISA will be the first mission to try and detect them from space. To achieve that goal, the relative position of several solid blocks placed in different spacecraft, 5 million kilometres apart, will have to be constantly monitored with high accuracy using laser-based techniques. A gravitational wave passing through the spacecraft will change the separations between them, thereby revealing itself.
Welcome To PhyCon Explains astrophysical concepts such as relativity, quantum mechanics, gravity, black holes, dark matter, quasars, macrocosmos and microcosmos. http://www.solnabrass.com/phycon/
Extractions: by Amir Alexander November 5, 2001: The SETI@home receiver at Arecibo scans the skies, searching for a signal from an alien civilization. So far no signal has been found, but SETI@home scientists are not losing hope. Searching for a signal is bound to be a long-term process, says chief scientist Dan Werthimer, and its success can only be evaluated on the time scale of generations. In the meantime, Werthimer and his colleagues are making sure that the mountains of data gathered in the search do not go to waste, and are used in shorter-term scientific projects. Most recently, astronomers have begun sifting through SETI@home's data looking for signs of "evaporating black holes." "Black holes" are those astronomical objects, predicted by Einstein's theory of relativity, whose mass and density are so great that their gravity allows nothing to escape their surface - not even light itself. As a result they are like black bottomless pits, which swallow anything in their vicinity. Stephen Hawking Until quite recently it was believed that black holes had an unlimited lifespan. "Once a black hole, always a black hole" summed up the understanding of these objects' longevity. This view changed when Stephen Hawking, the famed quadriplegic astro-physicist from Cambridge, showed that black holes do indeed expire. According to Hawking, at some point in their lifetime black holes begin to shrink, until in the end they practically evaporate in a great burst of energy.
[hep-th/9801025] Quantum Fields Near Black Holes This review gives an introduction into problems, concepts and techniques when quantizing matter fields near black holes. The first part focusses on quantum fields in general curved spacetimes. The second part is devoted to a detailed treatment of the Unruh effect in uniformly accelerated frames and the Hawking radiation of black holes http://arxiv.org/abs/hep-th/9801025
Extractions: This review gives an introduction into problems, concepts and techniques when quantizing matter fields near black holes. The first part focusses on quantum fields in general curved space-times. The second part is devoted to a detailed treatment of the Unruh effect in uniformly accelerated frames and the Hawking radiation of black holes. Paricular emphasis is put on the induced energy momentum tensor near black holes References and citations for this submission:
Black Creek Golf Club With 18 holes, each 9 offering a different golfing look, located in Ellaville, Georgia. http://www.blackcreek.com/
