Two US scientists today received the 2006 Nobel Prize in Physics for their work, which analyzed background radiation left from the beginnings of the universe and provided researchers with a better understanding of the origin of galaxies and stars. The Royal Swedish Academy of Sciences in Stockholm awarded the SEK 10 million ($1.4 million) prize jointly to John C. Mather of the NASA Goddard Space Flight Center in Greenbelt, Md., and George F. Smoot of the University of California, Berkeley, for their discovery of the "blackbody" form of cosmic microwave background radiation, a relic of the earliest phase of the universe after it was formed by what scientists call the "Big Bang". The academy said that the very detailed observations the laureates carried out from NASA's COBE (Cosmic Background Explorer) satellite, launched in 1989, "played a major role in the development of modern cosmology into a precise science." Smoot and Mather together led the building and launch of COBE to look for telltale signs of the primordial explosion. They announced in 1992 the discovery of residual heat from the explosion, in addition to variations in temperature across the sky that indicated the beginnings of structure in the early universe. "Those measurements really confirmed our picture of the Big Bang," Smoot said. "By studying the fluctuations in the microwave background, we found a tool that allowed us to explore the early universe, to see how it evolved and what it's made of." The COBE measurements also marked the inception of cosmology as a precise science, the academy said. Launched after COBE, the WMAP satellite yielded even clearer images of the background radiation, and soon the European Planck satellite will be launched in order to study the radiation in even greater detail. An artist's rendering of the COBE satellite. (Image: NASA) According to the Big Bang scenario, the cosmic microwave background radiation is a relic of the birth of the universe. Immediately after the big bang itself, the universe can be compared to a glowing "body emitting radiation in which the distribution across different wavelengths depends solely on its temperature. The shape of the spectrum of this kind of radiation has a special form known as blackbody radiation. When it was emitted the temperature of the universe was almost 3000 °C. Since then, according to the Big Bang, the radiation has gradually cooled as the universe has expanded. The background radiation measured today corresponds to a temperature that is barely 2.7 degrees above absolute zero. The laureates were able to calculate this temperature thanks to the blackbody spectrum revealed by the COBE measurements. The success of COBE was the outcome of teamwork involving more than 1000 researchers, engineers and other participants. Mather coordinated the entire process and also had primary responsibility for the experiment that revealed the blackbody form of the microwave background radiation measured by COBE. Smoot had main responsibility for measuring the small variations in the temperature of the radiation, the academy said. Mather and Smoot will receive the prize from the king of Sweden in Stockholm on Dec. 10. For more information, visit: http://nobelprize.org