BLACK HOLES http://www.cfa.harvard.edu/seuforum/darkenergylanding.htm

Facts about Black Holes A Black Hole is, by definition, a region of space-time where escape to the outside universe is impossible, an object so massive that nothing could escape the grasp of its gravity.

Black holes are created when a star goes supernova. Facts about Black Holes The idea of a black hole dates back to the 1700s. But the modern story of black holes really starts with Einstein's revolutionary theory of gravity, completed in 1917. Over the past century, scientists have used Einstein's theory of gravity to develop a picture of what black holes must be like. Here are some of the amazing properties of black holes that they have predicted. Black holes are created when a star goes supernova.

Facts about Black Holes The gravity of a Black Hole is so strong that nothing, not even light, traveling at 186,000 miles (300,000 km) per second can escape it. Near a black hole, the slowing of time is extreme . Times stops. And at the center of the black hole, Einstein’s theory predicts that time is destroyed.

The outer edge of a Black Hole is surrounded by the Event Horizon. Facts about Black Holes The outer edge of a Black Hole is surrounded by the Event Horizon.

The Photon Sphere A photon sphere is the radius around a Black Hole at which light paths are gravitationally bent into a circle, thus causing the photons to orbit the hole.

The Event Horizon The Event Horizon is the gravity field of a Black Hole, this means that, upon entering, nothing can return, vanishing without a trace. The Event Horizon

The “Singularity” is the center of a black hole.

The Singularity It has been theorized that the size of the Singularity is smaller than an atom.

The Singularity Just imagine! Our school, our country, the Earth, our Sun and millions of other Stars, all being crushed by gravity into a size that too small to be seen by any microscope.

Distance The nearest known Black Hole is thought to be about 1600 light years away from Earth.

New Discoveries In recent studies of Black Holes, scientists have discovered a Black Hole in the Milky Way. It is unique because it involves a stellar black hole, one that resulted from the collapse of a dead star here in our Galaxy.

New Discoveries This picture of what is thought to be a Black Hole came back when the Hubble telescope was pointed toward galaxy NGC 4438.

Conclusion Not much is known about Black Holes, but science is making new discoveries every day. This is what they are looking at: What happens to space and time near a black hole? What role do black holes play in the unfolding universe? Can we see a black hole being formed? What happens inside a black hole?     What happens to space and time near a black hole?   At the edge of a black hole time should appear to slow to a halt, and if the black hole is spinning, the very fabric of space should be twisted, carrying any nearby objects around with it. Scientists can probe this hostile environment by observing nearby matter that spirals in towards the hole. The atoms in the matter emit X-ray light, whose vibrations serve as clocks that can help us precisely measure the flow of time and the distortion of space. This light will be collected by NASA's Constellation-X mission, revealing for the first time what conditions are like at the very edge of a black hole. What role do black holes play in the unfolding universe? It is now thought that almost every galaxy has a giant black hole at its center. These black holes were probably present when the galaxy itself was formed and may have aided in the galaxy's formation. If this is true, then black holes may play a pivotal role in the formation of conditions in the universe that are necessary for life. The very earliest galaxies in the universe cannot be observed with existing telescopes, but that is about to change: NASA's James Webb Space Telescope will be able to glimpse the earliest galaxies in the process of formation – galaxies whose light will have taken 13 billion years to reach Earth – and the Constellation-X mission will observe the giant black holes that live within them. Can we see a black hole being formed? About once a day, there is a dazzling flash in the sky. It is not a flash of visible light, but a flash of gamma rays, a high-energy form of light even more powerful than X-rays. These flashes, called gamma-ray bursts, come from the tremendous explosion of a star going "supernova." The event is the last gasp of a star's core before it collapses into a black hole. The bursts are being detected by NASA's HETE space telescope, which beams the location of the flash to other telescopes on the ground and in space. From these telescopes we see the fading glow of the dying star, and witness the birth of a black hole. NASA's new Swift mission will spot gamma-ray bursts more quickly, allowing the first few seconds of a black hole's life to be observed in detail. What happens inside a black hole? The only way to answer this question is by developing a better, more fundamental theory of space, time, and matter. Unfortunately, Einstein's theory of gravity – which gave us the idea of black holes in the first place – does not accurately predict what happens at the very smallest scales of distance. For example, the atoms in our body all contain electrons, yet electrons are so small and so dense that they ought to form black holes. Obviously, they don't. Why not? If new theories of physics, such as "string theory," are correct, then there may be additional dimensions of space beyond the three dimensions we see; these extra dimensions may be important in explaining the behavior of matter at very small scales of distance, including what happens at the center of a black hole. This may be the ultimate value of black holes: helping us to understand how the universe works at the most basic level. In the meantime, physicists will probe the behavior of the smallest particles in giant accelerators, and astronomers will hone in on the behavior of black holes in the great reaches of space. And just as everything in nature is in some way connected, so too are the various fields of science connected.

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Assignment How can we see and study black holes? Read and summarize the information that comes here: http://www.cfa.harvard.edu/seuforum/bh_reallyex ist.htm http://scienceinsociety.wikispaces.com/5.+UNIVER SE