101. Untitled black holes, wormholes, time dilation factor, gravity, graphs and equations. http://themaclellans.com/timetravel.html

Space-Time Physics and the Future of Time Travel By Alex MacLellan Human beings have always tried to explain the world around them. They have worked to organize it, to measure it, and to understand it. These efforts at understanding such basic concepts as space and time and light have led to many discoveries. In the last one hundred years many changes have been made to how we understand these concepts. You may not be able to move as quickly and easily through time as the hero of H.G. Well's Time Machine, but scientists have been able to understand how certain variables can affect time - to slow it down and speed it up - leading them to believe that it is possible that time travel may become possible. Before looking at time travel, an understanding of the terms and history are required. Space, time, and light have been studied and the definitions have evolved as research has advanced. Looking at these concepts as they have been explained through history will help us understand what may be possible in the future. Portrait of Euclid Over history many people have come up with many different views about what time is and what space is, and how to understand them. Space was defined be Euclid, a Greek mathematician. He was the creator of geometry in 295 B.C.

102. Imagine The Universe Science The science section of Imagine the Universe! from NASA. Explore a universe of black holes, dark matter, and quasars http://imagine.gsfc.nasa.gov/docs/science/science.html

What's New Site Map NASA Homepage Search: ... Imagine Home Explore a universe of black holes, dark matter, and quasars... A universe full of extremely high energies, high densities, high pressures, and extremely intense magnetic fields which allow us to test our understanding of the laws of physics. For more advanced articles, try the Advanced Science page The Basics Start your exploration of the high energy universe here. This section includes explanations of the concepts used to study the universe. The Electromagnetic Spectrum Multiwavelength Astronomy X-ray Astronomy Lightcurves, Spectra, and Images ... Gamma-Ray Astronomy Cosmic Objects The universe is more than just stars, dust, and empty space. Explore some of the objects that make up our universe, from our own sun to distant pulsars and black holes. Stars Black Holes The Sun White Dwarfs ... Cosmic Rays Cosmic Questions Scientific discoveries often reveal new mysteries. Take a look at a few of the mysteries that astronomers and astrophysicists are working on right now. Origin and Destiny of the Universe Growth of Massive Black Holes Nature of Dark Matter Dark Energy ... The Solar Corona The Search for Answers A look at the tools and methods scientists use to study the high energy universe.

103. An Introduction To Black Holes There are actually many methods used to see if black holes really exist Another method of finding black holes is to look for an acceleration of matter. http://design.lbl.gov/education/blackholes/

by David Ando Purpose: The purpose of this page is to give an easy to understand explanation of what black holes are. 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. Formation of a Black Hole: 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.

104. CNN.com - Sci-Tech - Space - X-ray Map Finds Universe Teeming With Black Holes - CNN http://cnn.com/2001/TECH/space/03/13/chandra.deepfields/index.html

MAIN PAGE WORLD U.S. WEATHER ... ABOUT US CNN TV what's on show transcripts CNN Headline News CNN International ... askCNN EDITIONS CNN.com Asia CNN.com Europe set your edition Languages Spanish Portuguese German Italian Danish Japanese Korean Arabic Time, Inc. Time.com People Fortune EW X-ray map finds universe teeming with black holes larger Chandra snaps the deepest X-ray exposure ever, located in the Southern Hemisphere skies. The blues, yellows and reds depict X-ray intensities from highest to lowest energy March 13, 2001 Web posted at: 3:29 p.m. EST (2029 GMT) WASHINGTON (CNN) The most thorough X-ray survey ever taken of the universe shows an abundance of active super-massive black holes, two independent teams of astronomers said Tuesday. NASA's Chandra X-ray Observatory provided pictures that contain the faintest X-ray sources ever detected, leading some astronomers to believe that black holes of all sizes once ruled the universe. "The Chandra data show us that giant black holes were much more active in the past than at present," said Riccardo Giacconi of Johns Hopkins University. The images, known as the Chandra Deep Fields, were obtained during many long exposures over the course of more than a year.

105. FAQ To SCI.PHYSICS On Black Holes By Matt McIrvin An FAQ list by Matt McIrvin containing basic questions and answers related to black holes. 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.

106. Black Holes black holes are theoretical objects. A black hole is an object which has such black holes may form as the result of the collapse of a very massive star http://www.windows.ucar.edu/tour/link=/the_universe/BH.html

Black Holes A spiral-shaped disk of dust fueling a massive black hole in the center of the galaxy NGC 4261. L. Ferrarese (Johns Hopkins University) and NASA. Black Holes are theoretical objects. A black hole is an object which has such high gravitational pull that not even light can escape. Hence it is black. Which makes it pretty hard to observe directly. Black Holes may form as the result of the collapse of a very massive star at its death. Just as neutron stars form during a supernova explosion of a very massive star so do black holes. But in the black hole case the initial star was so massive that nothing could stop its gravitational collapse. All the matter of the star's core is crushed to an infinitely small point, a singularity. A black hole is sheilded from the outside world by what is called an event horizon . This is a sphere around the black hole where light can no longer escape. Everything that crosses the event horizon is gone forever. Despite the blackness of black holes there is evidence of their existence. If a black hole forms near a star it may get gobbled up by the black hole. And this can be seen by Astronomers. Some believe that many if not most galaxies harbor suppermassive black holes in their cores. These black holes have gobbled so much matter that they have the mass of billions of suns. What would it be like to enter a black hole? Not pleasant. First, as you approach the black hole the difference in the gravitaional pull on your head compared to your feet (known as tidal forces) would rip you apart. But suppose you survived that. Once you cross the event horizon there is no turning back. Then the only thing to do is avoid the black hole itself at all costs. If you run into that singularity it will crush your body right out of existence.

107. Ask An Astrophysicist: Black Holes Commonlyasked questions, and a way to ask an astronomer a question about black holes. http://imagine.gsfc.nasa.gov/docs/ask_astro/black_holes.html

What's New Site Map NASA Homepage Search: ... Ask an Astrophysicist Current page Relativity Binary Star Systems Resources for this Topic How Do We See Black Holes? Virtual Trip to a Black Hole Black Hole Frequently Asked Questions Usenet Physics Frequently Asked Questions List ... Imagine the Universe! Black Holes Library of Past Questions Black Holes First time visitors: Please be sure to read our main page Check out the resource links. These are the sites we often point to in answering your questions. Browse through the library of questions below. Also try our Ask an Astrophysicist Search Engine! If your question is still not answered, follow the link at the bottom of this page Library of Past Questions and Answers Common Questions about Black Holes How many black holes are currently known? Where is, and how far is the nearest known Black Hole? Is it true that time stops at the Event Horizon? If light has no mass, how can it get trapped in a Black Hole? ... Can black holes/worm holes transport you to other worlds? Evidence for Black Holes Who was the first person to discover a black hole and what was the date?

108. Black Holes: General Information s of the workings of these stellar phenomenons known as black holes.......black holes To learn the general ideas about black holes. http://www.geocities.com/blackholeinfo/

109. Science And Mathematics Education Learn about Einstein's Theory of Relativity online. The class covers cosmology, the Twin Paradox, space travel, and black holes. http://www.drphysics.com/

Classes Einstein's Theory of Relativity Calculus I Calculus II Instructor About the instructor Student reviews Contact us Physics resources Books Physics links around the web Acoustics of drink containers Other links DrPhysics store Education policy The engineer's prayer Site map Natural Philosophy The workings of nature have intrigued man since the dawn of civilization. At the heart of the understanding of nature is physics, or natural philosophy as it was known in Newton's time. As the Nineteenth Century drew to a close, it became clear that the world-view we inherited from Newton was not complete. Two great changes were on the horizon, in the form of relativity and quantum mechanics. Einstein had a hand in both, though his principal contribution was creation of the theory of relativity. On the other hand, calculus has withstood the test of time since Isaac Newton invented it to understand gravitation and the clockwork of our Universe. The mathematical tools Newton invented have served us for nearly 350 years. Learn about the ideas that have shaped our understanding of the Universe. Without them, we would know little of our origins or of our destiny.

110. Black Hole -- From Eric Weisstein's World Of Physics Nonspinning charged black holes are called ReissnerNordström black holes. Charged, spinning black holes are called Kerr-Newman black holes. http://scienceworld.wolfram.com/physics/BlackHole.html

Astrophysics Black Holes Black Hole A massive astrophysical object that is theorized to be created from the collapse of a neutron star . The gravitational forces are so strong in a black hole that they overcome neutron degeneracy pressure and, roughly speaking, collapse to a point (known as a singularity). Even light cannot escape the gravitational pull of a black hole within the black hole's so-called Schwarzschild radius Uncharged, zero angular momentum black holes are called Schwarzschild black holes . Uncharged nonzero angular momentum black holes are called Kerr black holes . Nonspinning charged black holes are called . Charged, spinning black holes are called Kerr-Newman black holes . The black hole no hair theorem shows that mass charge , and angular momentum are the only properties which a black hole can possess. type of black hole mass angular momentum charge Kerr black hole M J Q Kerr-Newman black hole M J M J Schwarzschild black hole M J Q In 1965, R. Penrose proved the singularity theorem , which says that a singularity must reside inside every imploding star, and therefore every black hole. In 1969, Lifschitz, Khalatnikov, and Belinsky showed that tidal gravity oscillates chaotically near the singularity. They also found the particular type of singularity, now known as a BKL singularity . Black holes can pulsate, as was recognized by Press (1971). Over the next decade or so, the pulsations were shown to always be stable using perturbation methods. In 1973, S. Hawking showed that black holes radiate as if they have a

111. AEI-LSU Numerical Relativity Groups Home Page Uses supercomputers to study black holes, gravitational waves, and other phenomena predicted by Einstein's Theory of General Relativity. http://jean-luc.aei.mpg.de/

AEI LSU Numerical Relativity Group Cooperation Computing Resources for the AEI Numerical Relativity Group Welcome People Papers Projects Movies In The Press Exhibits Codes Look for changes to these pages soon to reflect the new cooperation between the AEI and LSU numerical relativity groups. We use supercomputers to study black holes, gravitational waves, and other phenomena predicted by Einstein's Theory of General Relativity. Our WWW servers are an integral part of our research efforts. Here you will again be able to find information on group projects, members, publications, collaborations, and much, much more. Enjoy our Server! Keywords for this server : Numerical Relativity, General Relativity, Einstein, Astrophysics, Black Holes, Gravitational Waves, Relativistic Hydrodynamics, Neutron Stars, Hyperbolic and Elliptic PDEs, Parallel Computing, Scientific Visualization. Search Astronomylinks for links: provided by astronomylinks.com more search options... Impressum Please contact Webmaster with your comments. Last Updated: June 21st

112. Black Hole Recipe: Slow Light, Swirl Atoms: Science News Online, Feb. 5, 2000 Physicists may soon create artificial analogs of black holes in the laboratory. http://www.sciencenews.org/articles/20000205/fob4.asp

Science News Books. Subscribe to Science News ... Science News for Kids Math Trek A Minimal Winter's Tale Food for Thought Sickening Food Science Safari Beams of Our Lives TimeLine 70 Years Ago in Science News Science News e-LETTER. ... Week of Feb. 5, 2000; Vol. 157, No. 6 , p. 86 Black hole recipe: Slow light, swirl atoms Peter Weiss Physicists may soon create artificial black holes in the laboratory, analogous to the ones expected to lurk in distant space. A new study by a pair of theorists in Sweden describes how swirling clouds of atoms could slug down all nearby light, making them as black as their astronomical cousins. Computer-generated plot shows paths of light rays sucked into an optical black hole. Leonhardt and Piwnicki/ Physical Review A Called optical black holes, these eddies could provide an extraordinary test-bench for the theory of general relativity, which gave rise to the concept of gravitational black holes, the researchers say. Ulf Leonhardt and Paul Piwnicki of the Royal Institute of Technology in Stockholm find that the same mathematics describes both the terrible tug of an astronomical black hole on light and the gentle corralling of rays by an atom vortex. "We were quite surprised that it worked that well," Piwnicki says. "We're still working on it to understand it more deeply," he adds. The researchers report their findings in the Jan. 31

113. Chandra :: Field Guide To X-ray Astronomy :: X-Ray Sources Stars, supernovae, black holes, white dwarfs, galaxies. http://chandra.harvard.edu/xray_sources/

Solar System - The Sun's hot outer atmosphere produces X-rays, but because it is so close (a mere 93 million miles!), it is too bright for Chandra's sensitive eyes. Chandra can observe other objects in our solar system such as comets and Jupiter. Stars - The hot outer atmospheres, or coronas, of normal stars such as our sun produce X-rays. X-ray observations are useful for understanding how the flaring activity of stars can change as stars evolve, and how the evolution of stars is changed if they are in a close binary system. White Dwarf Stars - White dwarf stars are dense, burnt-out remnants of stars like the sun. They are formed when the star contracts after using up its nuclear fuel. When matter from a nearby star falls onto a white dwarf star, X-rays are produced. - When a star blows apart in a supernova, the explosion creates a remnant of multi-million degree gas that shines brightly in X-rays for thousands of years. X-ray observations can reveal the dynamics of the explosion and heavy elements present in the remnant.

114. Time Travel - A Discussion Hyperspace, spacetime continuum, black holes, wormholes, parallel universes, quarks, tachyons, quantum and super string theories. http://www.cix.co.uk/~antcom/

"Time is nature's way to keep everything from happening all at once" Prof. John Wheeler - Princeton University This site last updated 7th December 2002 The Links and Replies pages updated * * GUEST BOOK ADDED * * To this site there have been accesses since January 1997 Accesses from unique IP addresses are now 1000-1200 per month One of man's fantasies is to be able to travel through time. Maybe to visit a famous event such as a battle. Imagine gazing down over the fields of England and seeing the arrow that struck King Harold in 1066. Or to see the Great Exhibition of 1851. Imagine walking down the central aisle of this amazing glasshouse and seeing firsthand the latest works of art and science from around the world. Or to solve a mystery. Imagine watching the visit of President Kennedy to Dallas in November 1963 to see if anybody was on the grassy knoll. Or to travel back to a time where the countryside is unspoilt by the hand of man. Imagine walking on a sunny summers day through a meadow full of wild flowers down to a bubbling clear water stream. Or to travel to the future.

115. Frequently Asked Questions About Black Holes Or, why do some stars end up as black holes but others don t? I read somewhere that in the VERY distant future black holes could leak and disperse. 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 What does the exclusion principle have to do with whether or not a star becomes a black hole? [Or,] why do some stars end up as black holes but others don't? PLM, 8th grade, Blacksburg Middle School, Blacksburg, Virginia, USA. 1995 How is time changed in a black hole? PLM, 8th grade, Blacksburg Middle School, Blacksburg, Virginia, USA. 1995 Does the E=mc^2 equation apply to a black hole? PLM, 8th grade, Blacksburg Middle School, Blacksburg, Virginia, USA. 1995 If nothing goes [at] the speed of light except light how can a black hole also pull light into itself? PLM, 8th grade, Blacksburg Middle School, Blacksburg, Virginia, USA. 1995 What is the best evidence for the existence of a black hole? Is it all really just a theory or is there real information that can't be explained any other way? PLM, 8th grade, Blacksburg Middle School, Blacksburg, Virginia, USA. 1995 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?

116. Laser Interferometer Space Antenna The NASA mission studies the mergers of supermassive black holes, tests Einstein's Theory of General Relativity, probes the early Universe, and searches for gravitational waves——the primary objective. http://lisa.jpl.nasa.gov/

+ View the NASA Portal Search JPL Download new LISA science brochure (1.6-Mb PDF file) Updated: Glossary Site Map Contacts LISA is a joint mission between the European Space Agency and NASA's Office of Space Science (Structure and Evolution of the Universe Beyond Einstein Program NASA Science Team Site Webmaster: Diane K. Fisher

117. CNN.com - Space - Australian Telescope Searching Southern Skies For Black Holes CNN http://www.cnn.com/2000/TECH/space/05/09/australia.telescope/index.html

space Editions myCNN Video ... Feedback CNN Sites CNN CNN Europe CNNfn CNNSI myCNN CNNfyi AllPolitics Languages Search CNN.com CNNSI.com CNNfn.com The Web SPACE TOP STORIES Mir cargo vessel abandoned John Zarrella: Lessons learned from Challenger Last rendezvous for Mir Beginning of the end for Mir ... MORE TOP STORIES Bush signs order opening 'faith-based' charity office for business Rescues continue 4 days after devastating India earthquake DaimlerChrysler employees join rapidly swelling ranks of laid-off U.S. workers Disney's GO.com is a goner ... MORE MARKETS 4:30pm ET, 4/16 DJIA NAS SPORTS Jordan says farewell for the third time ... LOCAL EDITIONS: CNN.com Europe change default edition MULTIMEDIA: video video archive audio multimedia showcase ... more services E-MAIL: Subscribe to one of our news e-mail lists Enter your address: DISCUSSION: chat feedback CNN WEB SITES: CNNfyi.com CNN.com Europe AsiaNow Spanish ... Korean Headlines TIME INC. SITES: Go To ... Time.com People Money Fortune EW CNN NETWORKS: CNN anchors transcripts Turner distribution SITE INFO: help contents search ad info ... jobs WEB SERVICES: Australian telescope searching southern skies for black holes Cangaroo II telescope against backdrop of star-trails and the Large Magellanic Cloud.

118. HubbleSite - Massive Black Holes Dwell In Most Galaxies, According To Hubble Cen Massive black holes in Galaxies NGC 3377, NGC 3379 and NGC 4486b View all images. Announcing the discovery of three black holes in three normal galaxies, http://hubblesite.org/newscenter/newsdesk/archive/releases/1997/01/

news GALLERY DISCOVERIES FUN ... releases Massive Black Holes Dwell in Most Galaxies, According to Hubble Census View all images Announcing the discovery of three black holes in three normal galaxies, astronomers suggest that nearly all galaxies may harbor super-massive black holes that once powered quasars (extremely luminous objects in the centers of galaxies), but are now quiescent. This conclusion is based on a census of 27 nearby galaxies carried out by the Hubble telescope and ground-based observatories in Hawaii. The three galaxies in these images are believed to contain central, super-massive black holes. The galaxy NGC 4486B [lower left] shows a double nucleus [lower right]. The picture at lower right is a close-up of the central region of NGC 4486B. Read the full press release text Credit: Karl Gebhardt ( University of Michigan ), Tod Lauer ( NOAO ), and NASA Find more news releases: About Exotic Black Hole From about us contact us Cosmology Exotic Galaxy Miscellaneous Nebula Solar System Star Star Cluster Survey more options Search all of HubbleSite: Have you seen this?

119. Black Holes: Portals Into The Unknown An interactive journey into a black hole. Artist s conception of a black hole. Go to the main menu Click here to begin http://library.thinkquest.org/10148/

Portals into the Unknown Click here to begin by Benjamin, Steven, and Lee

120. Freeservers.com -- File Not Found References to cosmological sites featuring indepth coverage of issues like dark matter, black holes and symmetric theory. http://1st-spot.freeservers.com/topic_cosmology.html

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