IN 1783 John Michell reasoned they must be out there. In 1916 Karl Schwarzschild calculated how big they would be. In 1930 Subrahmanyan Chandrasekhar showed that big enough stars were doomed to become them. Yet it took until the 1970s to convince holdouts among astronomers that black holes actually exist. That was when studies of a celestial X-ray source called Cygnus X-1 revealed an object so massive that it could be nothing else.
Even before that, though, black holes had caught the imagination of astronomers and public alike. The idea of something so dense that its gravitational attraction can stop light (or anything else) escaping from its surface is mind-boggling. Yet such holes are crucial building blocks of the universe. Most, if not all galaxies have one at their centre. Meanwhile, on Earth, the idea that something or someone has “fallen into a black hole” and thereby, from the speaker’s point of view, vanished, has become proverbial.
In fact, black holes—or, rather, their surroundings—are often not black. The process of attracting and swallowing matter acts like a giant particle accelerator as the matter spins around the...Continue reading
Source: Science and technology http://ift.tt/1RvmrZ2
EmoticonEmoticon