misconceptionsBigBang

misconceptionsBigBang - MISCONCEPTIONS BIG BANG Baffled by...

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CREDIT BafF ed by the expansion of the universe? You’re not alone. Even astronomers frequently get it wrong By Charles H. Lineweaver and Tamara M. Davis MISCONCEPTIONS BIG BANG 36 SCIENTI±IC AMERICAN MARCH 2005 ABOUT THE COPYRIGHT 2005 SCIENTI±IC AMERICAN, INC.
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www.sciam.com SCIENTIFIC AMERICAN 37 CREDIT INFLATING BALLOON is a good analogy for understanding the expansion of the universe. The galaxies on the surface of the balloon are effectively at rest, and yet as the universe expands, the distance between any two galaxies increases. The galaxies themselves do not increase in size. COPYRIGHT 2005 SCIENTIFIC AMERICAN, INC.
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38 SCIENTIFIC AMERICAN MARCH 2005 we have ever discovered about our origins. You would not be reading this article if the universe had not expanded. Human beings would not exist. Cold molecular things such as life- forms and terrestrial planets could not have come into exis- tence unless the universe, starting from a hot big bang, had expanded and cooled. The formation of all the structures in the universe, from galaxies and stars to planets and Scientif c American articles, has depended on the expansion. Forty years ago this July, scientists announced the discov- ery of de± nitive evidence for the expansion of the universe from a hotter, denser, primordial state. They had found the cool afterglow of the big bang: the cosmic microwave back- ground radiation. Since this discovery, the expansion and cooling of the universe has been the unifying theme of cos- mology, much as Darwinian evolution is the unifying theme of biology. Like Darwinian evolution, cosmic expansion pro- vides the context within which simple structures form and develop over time into complex structures. Without evolution and expansion, modern biology and cosmology make little sense. The expansion of the universe is like Darwinian evolution in another curious way: most scientists think they understand it, but few agree on what it really means. A century and a half after On the Origin oF Species, biologists still debate the mechanisms and implications (though not the reality) of Dar- winism, while much of the public still ² ounders in pre-Dar- winian cluelessness. Similarly, 75 years after its initial discov- ery, the expansion of the universe is still widely misunder- stood. A prominent cosmologist involved in the interpretation of the cosmic microwave background, James Peebles of Prince- ton University, wrote in 1993: “The full extent and richness of this picture [the hot big bang model] is not as well understood as I think it ought to be . .. even among those making some of the most stimulating contributions to the ² ow of ideas.” Renowned physicists, authors of astronomy textbooks and prominent popularizers of science have made incorrect, misleading or easily misinterpreted statements about the ex- pansion of the universe. Because expansion is the basis of the big bang model, these misunderstandings are fundamental.
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misconceptionsBigBang - MISCONCEPTIONS BIG BANG Baffled by...

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