Dark-matter basketballs could explain a lot
20 September 2005
From New Scientist Print Edition
Marcus Chown
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THE universe's invisible matter may not be made of exotic unknown particles after all. Instead, "dark" matter could be clumps of the ordinary stuff trapped in a previously unsuspected state of the vacuum of space.
The dark-matter balls envisaged by Colin Froggatt of the University of Glasgow, UK, and Holger Nielsen of the Niels Bohr Institute in Copenhagen, Denmark, are relics of a vacuum state which theory suggests could have been widespread in the first second after the big bang (
www.arxiv.org/abs/astro-ph/0508513). Each ball would not be much bigger than a basketball and atomic nuclei would have formed inside them just as they do everywhere else in the universe, only bound by a stronger nuclear force. The balls would be much denser than ordinary matter, with each one weighing 100 million tonnes.
To account for the known density of dark matter in the cosmos, there would have to be just one such ball drifting through every volume of space about the size of our solar system.
The new theory makes one important prediction - that there should be five times as much dark matter as ordinary matter. "That's exactly what is observed," says Froggatt.
Ben Allanach of CERN, the European centre for particle physics near Geneva, Switzerland, admits the idea is wildly speculative. "But I can't think of anything specifically to rule it out," he says.
From issue 2517 of New Scientist magazine, 20 September 2005, page 10
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