On the heels of the Nobel Prize committee announcing that John Mather and George Smoot had been awarded the 2006 Physics Prize “for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation,” I thought it might be nice to flash back briefly.
I was in grad school when the Cosmic Background Explorer (COBE) results were first analyzed and announced, and the graph above was the first result I saw. For astrophysicists and cosmologists, the result confirmed expectations stunningly well. The solid, curved line in the graph depicts the blackbody spectrum predicted by theory; the dots and squares lying along the curve indicate actual data collected by the satellite (some of which have lines attached to them indicating uncertainty in the measurements). The match between data and theory rarely matches so precisely, and (as I remember) the astronomical community was quite impressed with itself.
However, cosmologists expected some variation around this simple curved line—little squiggles, if you will, that would tell us about the structure of the early Universe. But as the COBE scientists dug deeper and deeper into their data, they didn’t find anything. Hubris turned to worry until fluctuations were discovered at the level of one part in 100,000! Tiny variations in this otherwise smooth curve. Depicting these variations as color differences in pink and purple led to the classic, garish COBE image depicting the entire sky as an oval.
In the past few years, the Wilkinson Microwave Anisotropy Probe (WMAP) has refined these measurements and told us even more about the structure and origins of the Universe, bt as I recall, it all started with the graph you see above…