"The overall "Big Bang model" is healthier than it's ever been. That's just the basic idea that the universe is uniform on large scales and expanding from a hot, dense state. We don't know much about the Bang itself, but we still know an awful lot about early times, all the way back to a few seconds after the Bang. At that point the universe was a nuclear reactor, and we can look at the leftover elements to check whether their abundances match what we predict -- and they do! The fact that we can extrapolate our theories fourteen billion years into the past to a time just a few seconds after the Big Bang, and check that they give the right answers, is one of the most impressive feats in all of modern science.Go look at the diary. It is fascinating, with pictures and everything.
Even though the Big Bang model works really well, it raises questions. Why is the universe so smooth, and what made it "Bang" in the first place? The best current answer is inflation, proposed by Alan Guth in 1981. Inflation imagines that a tiny region of space can be dominated by "false vacuum energy" for a brief time, stretching out space and making it smoother as it expands. This model both explains why the universe is smooth on large scales but not perfectly so, since tiny quantum jiggles lead to fluctuations in the density of matter. These fluctuations show up in the Cosmic Microwave Background, leftover radiation from the Big Bang itself, and recent observations from NASA's WMAP satellite confirm that they look exactly like inflation predicts. A few billion years later, gravity has magnified these small perturbations into the galaxies that we observe today."
Friday, June 23, 2006
Darksyde over at dKos has a fascinating diary on the universe, Dark Matter, and Dark Energy. Here is just one paragraph from his Cosmologist:
Posted by Richard at 4:42 PM