2006 Nobel Prize - 地球科學討論

John C. Mather
NASA Goddard Space Flight Center, Greenbelt, MD, USA,

and

George F. Smoot
University of California, Berkeley, CA, USA

"for their discovery of the blackbody form and anisotropy of the
cosmic microwave background radiation".





Pictures of a newborn Universe
This year the Physics Prize is awarded for work that looks back into
the infancy of the Universe and attempts to gain some understanding
of the origin of galaxies and stars. It is based on measurements made
with the help of the COBE satellite launched by NASA in 1989.

The COBE results provided increased support for the Big Bang scenario
for the origin of the Universe, as this is the only scenario that
predicts the kind of cosmic microwave background radiation measured
by COBE. These 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. Very soon the European Planck satellite
will be launched in order to study the radiation in even greater detail.

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, the 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.

COBE also had the task of seeking small variations of temperature in
different directions (which is what the term 'anisotropy' refers to).
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.

COBE was launched using its own rocket on 18 November 1989. The
first results were received after nine minutes of observations: COBE
had registered a perfect blackbody spectrum. When the curve was later
shown at an astronomy conference the results received a standing ovation.

The success of COBE was the outcome of prodigious team work involving
more than 1,000 researchers, engineers and other participants. John
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. George Smoot had main responsibility
for measuring the small variations in the temperature of the radiation.


Public information,
http://nobelprize.org/nobel_prizes/physics/laureates/2006/info.pdf

Advanced information,
http://nobelprize.org/nobel_prizes/physics/laureates/2006/phyadv06.pdf

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