Spare a thought for the dark-matter hunters. Every time they're on the verge of trapping the elusive stuff thought to make up the bulk of the universe's matter, it slips away. They don't see the expected signals, or they spot something exciting only to watch it fade into background noise. Each time it's the same: put on a brave face, go back to the drawing board and begin the hunt again. Perhaps it's time for a change of tack. Instead of going after a single species of dark matter particle, maybe we should be looking for a menagerie of dark particles and forces -a whole new "dark sector". After all, there is no reason to think dark matter will be any less intricate than the visible stuff we consider ordinary, with its panoply of particles from electrons to quarks.
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