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Big Bang Links:
This is Big History. Big
history requires students to examine big questions:
No, not the television show!
The term Big Bang has become part of the standard scientific vocabulary, but it was first coined in the 1940s as a putdown. The idea that the universe actually had a beginning seemed just plain wacky -- especially since there was almost no evidence at the time to support it. Yet by the end of the 1960s, virtually all astrophysicists were convinced that the cosmos was born in a single massive explosion, and doubters were left out on the fringe.
According to the conventional explanation, the cosmos began to expand and cool immediately after the moment of the Big Bang. For 300,000 years or so, the expansion continued, but enormous numbers of tightly packed, free-ranging electrons created a dense fog that kept light from shining: the universe was hellishly hot, but utterly dark. Finally, the electrons were incorporated into atoms, and the light broke free in a gigantic flash. Astronomers can still see that ancient light, known as the cosmic background radiation, although it has cooled to about -270 degrees C (-454 degrees F) and is visible only to sensitive radio telescopes.
Yet the Big Bang theory remains essentially intact because it is based on three fundamental pieces of evidence, none of which can be accounted for by any competing model. The first is the cosmic background radiation: its evenness and the mix of electromagnetic wavelengths it contains can only have come about, as far as anybody knows, if the universe was once dense, hot and small. The second is the fact that the universe is expanding. Calculating backward, one easily concludes that all the galaxies must have come from a single point. Finally there is the fact that hydrogen makes up 75% of the matter in the universe and helium nearly 25%. These elements can only be forged in a furnace as hot as the Big Bang, and the proportions correspond exactly to what the Big Bang model posits.
There's something to keep in mind: Theories are sometimes wrong. There ARE credible scientists that think the Big Bang Theory gets the creation of the Cosmos wrong. So the question is left begging. Is the Big Bang a modern form of mythology?