We still can't see dark matter. But what if we can hear it?

The most mysterious and yet ubiquitous stuff in the cosmos, dark matter is effectively invisible. This is simply because it doesn't interact with light. But what if instead of trying to see dark matter, scientists attempted to hear it instead? New research suggests dark matter could leave a tiny but discernible imprint in the cacophony of ripples in spacetime called " gravitational waves " that ring through the cosmos when two black holes slam together and merge. However, this is only if spinning black holes can "churn" dark matter like cosmic butter. (We'll get to that shortly.) The team behind this new research suggests that if two black holes merge in a region of space populated by dense dark matter clouds, then the gravitational waves emerging from the event could carry the imprint of dark matter across the universe. And it's possible, they say, that our detectors could find that imprint. This would be akin to someone coughing at a Metallica concert, and that cough being only discernible over the fury of "Seek and Destroy" or "Master of Puppets" with the most sensitive instruments. Fortunately, when it comes to detecting gravitational waves from colliding black holes, humanity's instruments, such as LIGO (Laser Interferometer Gravitational-Wave Observatory), are getting more and more sensitive all the time. …