1. Virtual Trips To Black Holes And Neutron Stars Page Ever wonder what it would look like to travel to a black hole or neutron star? http://antwrp.gsfc.nasa.gov/htmltest/rjn_bht.html

Virtual Trips to Black Holes and Neutron Stars by Robert Nemiroff ( Michigan Technological University Ever wonder what it would look like to travel to a black hole? A neutron star? If so, you might find this page interesting. Here you will find descriptions and MPEG movies that take you on such exciting trips. These movies are scientifically accurate computer animations made with strict adherence to Einstein's General Theory of Relativity. The descriptions are written to be understandable on a variety of levels - from the casually curious to the professionally inquisitive. It is hoped that students from grade school to graduate school will find these virtual trips educational. "A stimulating, relativistically accurate trip!" - Kip Thorne The Feynman Professor of Theoretical Physics, California Institute of Technology, Author of "Black Holes and Time Warps - Einstein's Outrageous Legacy" Earth if compressed to ultracompact density and viewed from the photon sphere. Written Description of Visible Distortion Effects Below is a published paper understandable to undergraduates: "Visual Distortions Near a Black Hole and Neutron Star," Nemiroff, R. J. 1993, American Journal of Physics, 61, 619

2. Black Holes And Neutron Stars This site offers a nontechnical discussion about black holes and neutron stars. Topics include what they are, how they form, how we detect them, 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

3. Geometry Around Black Holes A WWW Exhibition in Relativistic Computer Dynamics and Visualization http://www.astro.ku.dk/~cramer/RelViz/

Award June 10th 1997 Award July 7th 2000 'Highly Rated by Schoolzone' Cramer's Homepage Geometry Around Black Holes A WWW Exhibition in Relativistic Computer Dynamics and Visualization By Michael Cramer Andersen, June 1996. Contents of this WWW Visualization Exhibition: General Relativity and Black Holes. Curvature and lightcones. Kerr's rotating Black Holes. Gravitational redshift. ... Other sites with black holes... You are guest no. Updated June 18th 1997 by cramer@astro.ku.dk . Links to this site: http://www.astro.ku.dk/~cramer/RelViz/

4. Black Holes An overview of black holes and information on current research from Cambridge. 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]

5. BLACK HOLES By Ted Bunn Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its http://cosmology.berkeley.edu/Education/BHfaq.html

B lack H oles FAQ (F requently A sked Q uestions L ist by Ted Bunn What is a black hole? How big is a black hole? What would happen to me if I fell into a black hole? My friend Penelope is sitting still at a safe distance, watching me fall into the black hole. What does she see? ... Where can I go to learn more about black holes? What is a black hole? Loosely speaking, a black hole is a region of space that has so much mass concentrated in it that there is no way for a nearby object to escape its gravitational pull. Since our best theory of gravity at the moment is Einstein's general theory of relativity, we have to delve into some results of this theory to understand black holes in detail, but let's start of slow, by thinking about gravity under fairly simple circumstances. Now imagine an object with such an enormous concentration of mass in such a small radius that its escape velocity was greater than the velocity of light. Then, since nothing can go faster than light, nothing can escape the object's gravitational field. Even a beam of light would be pulled back by gravity and would be unable to escape. The idea of a mass concentration so dense that even light would be trapped goes all the way back to Laplace in the 18th century. Almost immediately after Einstein developed general relativity, Karl Schwarzschild discovered a mathematical solution to the equations of the theory that described such an object. It was only much later, with the work of such people as Oppenheimer, Volkoff, and Snyder in the 1930's, that people thought seriously about the possibility that such objects might actually exist in the Universe. (Yes, this is the same Oppenheimer who ran the Manhattan Project.) These researchers showed that when a sufficiently massive star runs out of fuel, it is unable to support itself against its own gravitational pull, and it should collapse into a black hole.

6. Index Of /~cramer/RelViz/text/exhib1 An exhibition on relativistic computer dynamics used to present the theory of black holes. http://www.astro.ku.dk/~cramer/RelViz/text/exhib1

Index of /~cramer/RelViz/text/exhib1 Name Last modified Size Description ... Parent Directory 22-Sep-1999 08:23 - contents.pl 14-Jun-1996 23:34 1k exhib1.css 14-Jun-1996 23:34 1k exhib1.html 15-Jun-1996 01:41 4k images.aux 14-Jun-1996 23:34 1k images.log 14-Jun-1996 23:34 3k images.pl 14-Jun-1996 23:34 1k images.tex 14-Jun-1996 23:34 1k img1.gif 14-Jun-1996 23:34 1k img2.gif 14-Jun-1996 22:15 1k img3.gif 14-Jun-1996 22:15 1k img4.gif 14-Jun-1996 22:15 1k img5.gif 14-Jun-1996 23:07 1k img6.gif 14-Jun-1996 23:07 1k img7.gif 14-Jun-1996 23:07 1k img8.gif 14-Jun-1996 22:16 1k img9.old 14-Jun-1996 22:15 1k node1.html 14-Jun-1996 23:34 2k sections.pl 14-Jun-1996 23:34 1k test.gif 14-Jun-1996 23:23 1k Apache/1.3.26 Server at www.astro.ku.dk Port 80

7. Black Holes black holes What Are They? http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

8. Introduction To Black Holes A black hole is a region of spacetime from which nothing can escape, even light. It is impossible to see a black hole directly because no light can http://www.damtp.cam.ac.uk/user/gr/public/bh_intro.html

Introduction to Black Holes What is a black hole? A black hole is a region of spacetime from which nothing can escape, even light. To see why this happens, imagine throwing a tennis ball into the air. The harder you throw the tennis ball, the faster it is travelling when it leaves your hand and the higher the ball will go before turning back. If you throw it hard enough it will never return, the gravitational attraction will not be able to pull it back down. The velocity the ball must have to escape is known as the escape velocity and for the earth is about 7 miles a second. As a body is crushed into a smaller and smaller volume, the gravitational attraction increases, and hence the escape velocity gets bigger. Things have to be thrown harder and harder to escape. Eventually a point is reached when even light, which travels at 186 thousand miles a second, is not travelling fast enough to escape. At this point, nothing can get out as nothing can travel faster than light. This is a black hole. Do they really exist?

9. StarChild: Black Holes Information about black holes and how we know they exist, links to glossary terms and a movie about a Journey into a Blackhole. http://starchild.gsfc.nasa.gov/docs/StarChild/universe_level2/black_holes.html

Black Holes Guess what? Some scientists believe that there is a black hole here in our very own Milky Way. Black holes are extremely compact space objects that were once massive stars which collapsed inward due to the force of their own gravity . Consequently, black holes are very dense. If it were not for the effect that black holes have on the objects around them, we would be unable to detect them. A black hole has a powerful gravitational field which traps everything that goes near it. Scientists now theorize that some galaxies have huge black holes in their centers which release tremendous amounts of energy that powers the spectacular energetic events that go on within the galaxy. The fuel for the black hole, scientists believe, may be the trapped gas, stars, and dust that are pulled into the hole. Gas that is pulled into a black hole swirls down into the hole much like a whirlpool. By using a spectroscope , the Hubble Space Telescope has the ability to clock the speed of this gas as it swirls around the entrance to the hole. The speed with which the gas swirls is considered the black hole's signature. By knowing the speed of the gas, the mass of the black hole can be calculated.

10. BLACK HOLES By Ted Bunn Answers to black hole questions like _QUOTATION_How big is a black hole?_QUOTATION_ _QUOTATION_How do black holes evaporate?_QUOTATION_, and http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

11. Physics Central A page on modern physics, such as quantum mechanics and black holes, and some mathematics. http://www.physlib.com/

The NOFRAMES element is to be used to give useful content to people with browsers that cannot display frames. One example is Lynx, a text-based browser. Website map Hosting provided by: optics Astronomy optics Electronics ... Dedicated servers All material is available under the terms of the GNU Free Documentation License

12. Black Holes - Science Background No Escape The Truth About black holes http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

13. Black Holes And Beyond From the University of Illinois. Educational sequence suitable for high school students. http://archive.ncsa.uiuc.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.

14. Your Gateway To Entire Knowledge About The Universe Provides information about the beginning of universe and solar system. About the planets, quasars, the Milky Way, black holes. Life of a star. Travel in space and extra terrestrial beings. http://www.geocities.com/beyondearth2001/

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15. Black Holes And Beyond black holes and Beyond. Einstein's general theory of relativity describes gravity as a curvature of spacetime caused by the presence of matter. http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

16. Geometry Around Black Holes. Kerr's Rotating Black Holes. A brief mathematical description of this phenomenon and diagrams of the mathematical results. http://www.astro.ku.dk/~cramer/RelViz/text/exhib4/exhib4.html

Kerr's rotating Black Holes. Let's generalise some of the formulas used in the static Schwarzschild case, to the case of rotating Black Holes. The Kerr metric is written in Boyer-Lindquist coordinates: where the coordinate functions are given (with G=c=1): the specific angular momentum is: The physical value of J is for a star like the sun: corresponding to a M . If a =0 we have the Schwarzschild case for a nonrotating Black Hole (or star). We define FIDucial Observers (FIDOs) as little (experimental) physicists locatedat each point in spacetime measuring all possible physical quantities in their local proper units. They'll get a hard job in the Kerr geometry. To keep their job, they have to follow the geometry which actually rotates with increasing speed towards the center. How can this be? All physical objects are dragged into circular motion by the Black Hole's rotation. Our FIDOs (which are supposed to be at rest) will follow the (absolute) space around the rotating hole. The Boyer-Lindquist coordinates naturally includes this rotating coordinate system, so in the Kerr reference frame, the geometry actually swirls like the air in a tornado. The angular velocity of a FIDO as viewed from infinity is: This angular velocity depends on a and r. The larger a, the larger

17. Virtual Trips To Black Holes And Neutron Stars Page Here you will find descriptions and MPEG movies that take you on trips to black holes and neutron stars. These movies are scientifically accurate http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

18. General Relativity And Black Holes A set of notes on aspects of black holes. http://www.astro.ku.dk/~cramer/RelViz/text/exhib1/exhib1.html

General relativity and Black Holes. How is the geometry around a Black Hole? A Black Hole is one of the most fascinating objects in the universe, and it can be understood on basis of Einstein's general theory of relativity. In the following pages, you will get an impression of how the curvature changes near a Black Hole, what happens when the hole rotates, and what special effects the Black Hole has on particles and light moving close to the Black Hole. I will not go in much detail with the formulas, because the aim of this World Wide Web Exhibition is presentation and graphics. You can, if you want, read all the relevant details about metric tensors of Black Holes in this hypertext about "Geometry Around Black Holes". Instead, I will use some of the fundamental results to get a view of the geometry around a Black Hole. I will concentrate on curvature and the trajectories of relativistic particles. In flat (euclidian) space, bodies move in a background of space and time. Newton called it absolute space and absolute time. Einstein changed this view radically in 1915 when he completed his general theory of relativity which resulted in a unified 4-dimensional space-time . All distances along a world line are called separations , and they are measured by the metric: This metric defines flat Minkowski space-time , and is much like Newtons absolute space plus a time dimension (note the sign of the time is negative).

19. Black Holes black holes black holes are peculiar objects with many strange properties, but most books and articles have emphasised their exotic aspects, and http://tmsyn.wc.ask.com/r?t=an&s=hb&uid=24312681243126812&sid=343126

20. APOD Index - Stars: Black Holes APOD 1999 October 17 black holes in Galactic Centers Explanation Do all galaxies have black holes at their centers? Although not even a single galaxy http://antwrp.gsfc.nasa.gov/apod/black_holes.html

Astronomy Picture of the Day Index - Stars: Black Holes Today's APOD Title Search Text Search Editor's choices for the most educational Astronomy Pictures of the Day about black holes: APOD: 1999 October 17 - Black Holes in Galactic Centers Explanation: Do all galaxies have black holes at their centers? Although not even a single galaxy has yet been proven to have a central black hole , the list of candidates continues to increase. Results by astronomers using instruments like the Hubble Space Telescope now indicate that most - and possibly even all - large galaxies may harbor one of these dense beasts . In all the galaxies studied, star speeds continue to increase closer the very center . This in itself indicates a center millions of times more massive than our Sun is needed to contain the stars. This mass when combined with the limiting size make the case for the central black holes Will we ever know for sure? APOD: 1997 January 15 - Black Hole Signature from Advective Disks Explanation: What does a black hole look like? If alone, a black hole would indeed appear quite black, but many black hole candidates are part of

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