The Nobel Prizes announced the week of October 2nd (Medicine or Physiology, Chemistry, and Physics) certainly covered 3 very wide (literally) areas of study. While the prizes in Medicine and Chemistry are much more likely to produce some benefit to humanity in the immediate or near future, the work that led to the Physics prize is another step toward an explanation of why I can be sitting at my computer writing this article and you are sitting at your computer reading it.
The Physics prize was awarded jointly on Tuesday to John Mather (NASA Goddard Space flight Center) and George Smoot (University of California) for their studies regarding what is known as Cosmic Microwave Radiation (CMR). The CMR represents the remnants of the energy released during the “Big Bang,” the explosive event that gave birth to our Universe. The Big Bang Theory is the mathematical model that predicts what may have happened in the very early Universe to cause it to appear as it does today.
Using data obtained with NASA’s COBE (COsmic Background Explorer) satellite the two scientists were able to study the precise current temperature of the CMR across the entire visible Universe. Their studies produced several findings that led to Mather and Smoot’s Nobel Prize:
1. As the early Universe expanded its temperature fell at a definite rate. The mathematical model of the Big Bang predicted that this temperature would now be ~ 3o Kelvin. The results obtained by NASA satellites indicated a temperature of ~ 2.73o Kelvin, which confirmed the predicted age of the universe (~ 13.7 billion years) was correct.
2. Data obtained using the COBE satellite and the subsequently-launched WMAP (Wilkinson Microwave Anisotropy Probe) confirmed that, although the background radiation was detected in every direction, there were “spots” detected that were a few millionths of a degree Kelvin cooler than their surroundings. These indicate that the early Universe was not completely homogenous and that the first stars and galaxies began to form at around 350,000 years after the Big Bang.
3. The Big Bang Theory is dependent on the Theory of General Relativity (which explains gravity’s effects on the very large scale in the same way that Newton’s Laws explain gravity on a smaller scale). According to General Relativity, the Universe may exist in only 1 of 3 possible states which are in turn dependent on the amount of matter present (and hence, gravity) in the Universe. If the amount of matter is less than a certain average (called the Cosmological Constant) the Universe is shaped like a saddle. If the average density of matter exceeds the Constant then the Universe is spherically shaped. If the average amount of matter is equal to the Cosmological Constant then the Universe is flat.
The COBE and WAMP missions were used to measure the size of the previously seen “cool spots” in the Cosmic Background Radiation and, based on those measurements (as well as some very intimidating mathematics) the Universe is now felt to be flat.
The above explanations are generalizations only and are in no way intended to be definitive. For further information on the Big Bang and the Cosmic Background Radiation, log into any of the following links.
The Swedish Academy of Sciences (the group that actually “recommends” the Nobel Prize winners) has released summaries of Mather and Smoot’s research. The summary for those with limited knowledge of the Big Bang Theory can be found at this URL. A more advanced summary (for those with a university-level introduction to astronomy or better) is located here.
The National Aeronautics and Space Administration (NASA) maintains several web pages devoted to the Big Bang Theory and Cosmic Background Radiation.