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Physicists detect waves from a black hole collision for the fourth time
Illustration: Rebecca Zisser / Axios

Physicists today reported observing waves in space and time from the collision of two black holes 1.8 billion light years away. It's the fourth time in two years these ripples formed from black hole mergers have been spotted, but this time they were able to more precisely locate where the collision took place in our universe.

Why it matters: It demonstrates that three detectors — two are nearly aligned and one is not — can be used to track these events in three dimensions. Ultimately, physicists want to combine observations from these detectors with those from optical telescopes to both "see" and "hear" events like neutron stars colliding, which could explain the origins of heavy elements, and test Einstein's general theory of relativity.