Dark Sounds

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[SFX: Guitar note, slowly fading]

Like a guitar string that continues to vibrate long after it was strummed, the sound of the Big Bang reverberates across the universe. Astronomers are hoping that the sound will tell them the secrets of dark energy.

Dark energy appears to be causing the universe to expand at a faster rate as it ages. It may come from the vacuum of space itself, or from some unknown particle or field. Or it might just be a flaw in our understanding of gravity.

Astronomers plan to use several techniques to decide which answer is right. One technique will rely on sound waves created in the Big Bang, which rippled across the early universe. These ripples helped matter clump together, forming the first structure in the universe.

The ripples grow along with the universe. They should show up in the way galaxies are spread through the universe -- there should be a standard "yardstick" for measuring the distances between them. The yardstick grows as the universe expands. The way it grows will reveal the influence of dark energy at different times.

A new project at McDonald Observatory will look for this yardstick. The project is HETDEX -- the Hobby-Eberly Telescope Dark Energy Experiment. It'll produce a 3D map of more than a million galaxies, and reveal how the cosmic yardstick has changed through the ages. That yardstick -- the imprint of ancient sound waves -- may reveal the nature of dark energy.

Script by Damond Benningfield, Copyright 2008

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