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Last Updated: Wednesday, 23 June, 2004, 13:46 GMT 14:46 UK
'Birth cry' of the cosmos heard
By Dr David Whitehouse
BBC News Online science editor

Mark Whittle, Virginia
Mark Whittle, cosmic conductor
Astronomers have recaptured the sounds of the early Universe showing it was born not with a bang but a quiet whisper that became a dull roar.

Mark Whittle of the University of Virginia has analysed the so-called background radiation that was born 400,000 years after the Big Bang.

Ripples in the radiation are like sound waves bouncing through the cosmos.

Over the first million years the music of the cosmos changed from a bright major chord to a sombre minor one.

Below human hearing

"It really is a very obvious thing to do," Professor Whittle told BBC News Online. "I was a little surprised that someone had not done it before."

He took the latest data about the Cosmic Microwave Background radiation (CMB) which comes from an era just after the Big Bang.

Listening to it I have to say that the Universe is a lousy musical instrument
Professor Mark Whittle
They show ripples in the CMB which are subtle variations in the density of matter which can, in one sense, be thought of as sound waves.

These cosmic sound waves are 30,000 light-years wide and are 55 octaves below what humans can hear.

But when they are shifted to regions of the audible spectrum, the cry from the birth of the cosmos can be heard.

Unique perspective

One sound compresses the first million years of the Universe into just five seconds.

The Big Bang would have taken place in complete silence but as the Universe expanded sound waves would have been able to grow.

Cosmic Microwave Background   WMap
Sounds of the cosmos: The microwave background
"For the first 400,000 years it sounds like a scream declining to a dull roar," says Professor Whittle.

He believes that hearing the sounds of the cosmos provides a unique perspective on the evolution of the Universe.

"It draws the listener closer to the subject in a different way from what images do," he told BBC News Online.

During the expansion there is a change in the frequencies of the sound waves that results in the characteristic sound of the Universe changing from a major third chord to a minor third.

"Listening to it I have to say that the Universe is a lousy musical instrument," says Professor Whittle.

The first million years
compressed to five seconds

The sound of the universe
when 400,000 years old

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