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…
