Hunting for dark energy with the WiggleZ
Box 2 | Where next?
The WiggleZ program is not the only current effort to measure dark energy. Nor is dark energy the only way to explain an accelerating universe. This is frontier science, which is one of the reasons it is so exciting. There are a number of other possibilities that are being explored.
It may be that the space around us is relatively empty of matter compared to the average across the universe. With less matter there would be less gravity to slow the flight of galaxies. So the expansion we observe would be faster, with no need for dark energy.
Fainter than expected supernovae could appear dim for reasons that have nothing to do with dark energy. For example, our measurements of supernovae may be affected by the patchy distribution of matter between us and them.
But evidence for the existence of dark energy seems to be growing. There are other research teams hunting for dark energy in much the same way as the WiggleZ group. But the case to support its existence will be stronger if evidence comes from other techniques. And it does.
The cosmic microwave background images on their own, give some clues that dark energy exists and how much there is. In addition, some studies have shown that galaxies are clumping together under gravity more slowly that expected, suggesting dark energy is acting against gravity. Perhaps in the future, physicists will come up with further evidence for dark energy through experiments with particle accelerators.
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Posted June 2009.