"It is now widely accepted that the Universe we inhabit emerged from a hot, dense fireball called the Big Bang. In the 1920s and 1930s, astronomers first discovered that our Galaxy was simply one island of stars scattered among many similar galaxies and then that groups of these galaxies were moving apart from one another as the space between them stretched. This idea of an expanding universe had actually been predicted by Einstein's general theory of relativity, completed in 1916, but it had not been taken seriously until the observers made their discoveries. When it was taken seriously, mathematicians discovered that the equations exactly describe the kind of expansion we observe, with the implication that if galaxies are getting farther apart as time passes then they must have been closer together in the past; and long ago all the matter in the Universe must have been piled up in a dense fireball.
It is the combination of theory and observation that makes the idea of the Big Bang so compelling; clinching evidence in support of the idea came in the 1960s with the discovery of a weak hiss of radio noise, the cosmic background radiation, that comes from all direction in space and is interpreted as the leftover radiation from the Big Bang itself. Like the expansion of the Universe, the existence of this background radiation was predicted by theory before it was observed experimentally. By the end of the twentieth century, the combination of theory and observations had established that the time that has elapsed since the Big Bang is about 14 billion years, and that there are hundreds of millions of galaxies like our own scattered across the expanding Universe. The question cosmologists are now confronting is how the Big Bang itself occurred -- or, if you like, how did the Universe begin?"
-- The Origins of the future: ten questions for the next 10 years P. 51-52
1 comment:
You funny.
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