Black holes may seem like nothing but empty space, but that could not be further from the truth. A black hole is actually a region of space in which such an enormous amount of matter is packed, that the pull of gravity becomes so strong that nothing can escape. It is "black" in the sense that not even light can escape, and a "hole" in the sense that things may fall into it, but are unable to get out. Black holes "rip and twist" space and time, and are the "ultimate endpoints" of matter.
The idea of an object that was so massive and dense that not even light could escape was formed centuries ago, in 1783, by scientist John Mitchell, using Newton's laws of gravity, although the name 'black hole' wasn't used until 1967. Black holes were predicted by Albert Einstein's theory of general relativity, which showed that when a massive star collapsed, the force of gravity would overwhelm all else, creating a black hole. Black holes cannot be directly seen with telescopes that detect light, x-rays or other electromagnetic radiation, but they can observed in other ways. The presence of a black hole can be inferred and studied by their effect on the surrounding environment. The strong gravitational force exerted draws matter inward, crushing and heating it as it gets squeezed in. Black holes also seem to exist in radically different sizes. "Stellar mass" black holes, are about 10-24 times as massive of the sun, and many are impossible to detect, although scientists believe there are more than 10 million in the Milky Way galaxy alone. However, "supermassive" black holes are millions to billions of times as massive of the sun, and are believed to lie in the center of all large galaxies. Although much is known about black holes, there is still so much more to discover. |
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