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2 US scientists get 2006 Physics Nobel Prize

Last updated on: October 03, 2006 17:29 IST

American scientists John C Mather and George F Smoot have been jointly awarded the 2006 Nobel Prize in physics for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.

According to the official nobelprize.org website, the scientists' work looks back into the infancy of the Universe and attempts to gain some understanding of the origin of galaxies and stars. Their work is based on measurements made with the help of the COBE satellite launched by the National Aeronautics and Space Agency on November 18, 1989.

The COBE results provided increased support for the Big Bang scenario for the origin of the Universe. The measurements also marked the inception of cosmology as a precise science. It was not long before it was followed up, for instance by the WMAP satellite, which yielded even clearer images of the background radiation. Soon, the European Planck satellite will be launched in order to study the radiation in even greater detail.

John Mather, senior astrophysicist with NASA, 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 while George Smoot, a Physics professor at California University, had main responsibility for measuring the small variations in the temperature of the radiation, the portal said.

According to the Big Bang scenario, the cosmic microwave background radiation is a relic of the earliest phase 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 3,000 degrees Centigrade. Since then, according to the Big Bang scenario, radiation has gradually cooled as the Universe has expanded.

The background radiation we can measure 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 website revealed.

COBE also had the task of seeking small variations of temperature in different directions (anisotropy). Extremely small differences of this kind in the temperature of the cosmic background radiation -- in the range of a hundred-thousandth of a degree -- offer an important clue to how the galaxies came into being.

The variations in temperature show us how the matter in the Universe began to 'aggregate.' This was necessary if the galaxies, stars and ultimately life like us were to be able to develop. Without this mechanism, matter would have taken a completely different form, spread evenly throughout the Universe.