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Locations of detected gamma-ray bursts mapped as dots on an image of the entire sky. — Green dots show the locations of 186 gamma-ray bursts detected by the Large Area Telescope (LAT) over its first 10 years. New evidence suggests the odd signal showing up in these gamma ray bursts may be a sign that speeding jets of plasma are traveling faster than light in a medium.(Image: © NASA/DOE/Fermi LAT Collaboration)

October 2019

In a distant corner of the universe, something is traveling faster than light.

No, the laws of physics aren’t being violated: It’s still true that nothing can travel faster than light in the vacuum of empty space. But when light travels through matter, like interstellar gas or a soup of charged particles, it slow downs, meaning other matter might overtake it. And that may explain the weird symmetry in pulses of some of the most energetic light in the universe, called gamma-ray bursts.