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Friday, 20 September, 2002, 14:52 GMT 15:52 UK
Telescope finds Big Bang evidence
Degree Angular Scale Interferometer
Dasi makes observations of the sky in microwaves

Scientists have made a discovery that represents an important confirmation of the Big Bang theory of the origin of the Universe.

Almost 5,500 hours of observations by a radio telescope at the South Pole have shown the Cosmic Microwave Background (CMB) to be polarised.

The CMB has been called the afterglow of the Big Bang. It is radiation that comes from all directions in space and has its origin when the cosmos was just 400,000 years old.

The polarisation can be used to probe conditions in the early Universe. Cosmologists say although such an effect was expected they are relieved to find it.

The discovery should open a new era of cosmic measurements and understanding.

Prediction 'bang on'

The discovery was made by the Degree Angular Scale Interferometer (Dasi) at the Amundsen-Scott base at the South Pole. It makes observations of the sky in microwaves.

The CMB has transfixed astronomers since it was discovered in 1965 by radio astronomers Arno Penzias and Robert Wilson.

Detailed observations of it can reveal clues about the structure and evolution of the cosmos.

The CMB is difficult to study from the ground: many of the better observations of it have been made from satellites.

On Earth, the South Pole is a good place to look at it as the local atmosphere lacks the water vapour that obscures the CMB at other places on the Earth's surface.

Faint detail in the CMB has been seen before but Dr Carlstrom of Chicago University, US, says mapping its polarisation has the potential of obtaining much more information, "like going from a black-and-white to colour".

'Preposterous Universe'

"It's going to triple the amount of information that we get from the CMB," says researcher John Kovac.

"The prediction is bang on," says Dr Carlstrom. "We think we know the Universe, but if the polarisation was not there at the predicted level we were back to the drawing board."

However, the new observations are pointing to an ever-more puzzling Universe: a Universe whose birth was dominated by mysterious dark matter and dark energy.

"We're stuck with a preposterous Universe," he says.

The observations confirm the inflation theory of the early evolution of the Universe, which describes an explosive spurt of expansion when the Universe was young.

"We can go from checking inflation to actually testing it," Dr Carlstrom adds.

The next step astronomers say is to achieve a tenfold increase in instrumental sensitivity that is required to detect the signature of inflation in the CMB. Only then will they have detected definite proof of cosmic inflation.

See also:

30 Jun 01 | Science/Nature
12 May 00 | Science/Nature
28 Apr 00 | Science/Nature
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