Click on the picture to hear the sound of the Big Bang! The image shows the time development of different sound waves traversing the Universe when it was very young --- from the Big Bang itself until 400,000 years later. Time runs down from top to bottom, and is shown by the decending horizontal line when the movie plays. Notice how the pitch descends as the wavelengths get longer and the frequencies get smaller. The sound volume also grows with time, although that aspect has been suppressed in this version.

The sound waves are driven by gravity, which pulls gas into denser regions and away from less dense regions. Like a spring, once forced the gas then oscillates in an out of the dense patches, making the sound. The true sound pitches are 50 octaves below the human hearing range (and so have been transposed upwards), while the volume is about that of a rock concert.

The sounds and image have been made by and were inspired by the extraordinary results emerging from the various studies of the Microwave Background. In particular, the basic observed acoustic signal comes from the WMAP, COBE, BOOMERANG, DAISI, CBI and other teams, while the more detailed modelling comes from public domain computer programs, such as CMBFAST and DASh.

Much more on these cosmic sounds can be found on Mark's homepage.