We've identified particles that could secretly cross from the regular world to the shadowy realm of dark matter. Now we just need to catch them in the act

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WE KNOW it is out there. It makes up the bulk of matter in the universe and sculpts its grandest features with a hidden gravitational hand. And yet, despite a long campaign to expose it, the mysterious cosmic architect known as dark matter continues to evade detection.

Myriad dark-matter hunters have spent decades trying to trap their prime suspect. They may yet prevail. But their struggle has led a new wave of hunters to try a different approach. Rather than tailoring their search for a single candidate, they are embracing the possibility that dark matter consists of a panoply of particles and forces – an entire dark sector operating in parallel to our own.

This hidden realm would be accessible by only the faintest lines of communication: particles capable of carrying messages from the dark side to the world of familiar matter. Now the plan is to track those go-betweens as they pass messages through these dark portals, wiretapping them to learn about the universe on the other side. “This is a shift in the way we think about the problem,” says Jonathan Feng, a theorist at the University of California, Irvine. “It has reinvigorated the search.”

All we know about dark matter comes from the way stars in the outer reaches of galaxies move faster than expected, given the amount of visible mass present. So fast, in fact, that the galaxies we see should have long since been torn apart. For some physicists, this is reason enough to believe that Einstein’s laws of gravity are wrong. Others insist that some invisible form …