The 2006 Nobel Prize in Physics was awarded to John Mather of NASA's Goddard Space Flight Center and George Smoot of the University of Berkeley. The prize was awarded for the "discovery of the blackbody radiation profile."
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The 2006 Nobel Prize in Physics was awarded to John Mather of NASA's Goddard Space Flight Center and George Smoot of the University of Berkeley. The prize was awarded for the "discovery of the black body radiation profile, together with the angular non-uniformity of the cosmic background radiation". "This year's award is given to work that looks back, to the infancy of the universe, and tries to gain some understanding as to the origins of galaxies and stars.
The work is based on measurements made with the help of the COBE satellite which was launched by NASA in 1989. COBE's measurements provided additional support for the Big Bang scenario as to the origin of the universe, since this is the only scenario that yields (theoretically) the background microwave radiation measured by COBE. To that extent, these measurements marked the birth of cosmology as an exact science."
(Quotations from the award committee's press release - see links below).
Background radiation measurements - milestones:
* 1963 - Penzias/Wilson - first discovery
* 1989 - COBE - in the picture above
* 2003 – WMAP first results
* 2007 - Planck satellite of the European Space Agency - launch
Black body radiation
According to the Big Bang scenario, the cosmic background radiation is the result of an early stage in the life of the universe. At this initial stage, the universe can be compared to a hot body emitting radiation whose intensity depends exclusively on its temperature at each of its wavelengths. Such a radiation spectrum has a unique form called "black body radiation".
When radiation was originally emitted, the temperature of the universe was about 3000 degrees Celsius. Since then, according to the Big Bang scenario, the radiation cooled as the universe expanded. Today it is expected that the background radiation will reflect a temperature of 2.7 degrees above absolute zero. The laureates measured a black body radiation profile at this value, to such a precise degree, that the drawing of the measured results on the theoretical graph on the left does not make it possible to distinguish measurement errors, since their size is narrower than the thickness of the line used to draw the graph.
Angular intensity changes
Completely uniform background radiation, in every direction in the universe, reflects full uniformity in the density of the primordial matter. The universe that is expected to develop in such a case will be completely different from the one we know today - since it will contain matter scattered throughout the universe at a uniform density - without the concentrations of density known to us as stars and galaxies. The theoretical calculations showed that in order to create the universe we know today, density changes on the order of 1 to 100,000 are needed. COBE detected density changes in the theoretical range of values.
The temperature map of the primordial universe. Top image - COBE, bottom image - the improved resolution of WMAP
COBE was launched on November 18, 1989. The first results were obtained after 9 minutes of observation. When the measurement graph was subsequently presented at an astronomy conference - all those present stood up and applauded. The success of COBE is the result of the work of a team that numbered more than 1000 scientists, engineers and other participants.
John Mather led the entire process and was also primarily responsible for the experiment that discovered blackbody radiation. George Smoot was primarily responsible for measuring angular intensity changes.
