
How a 3.7-PeV Photon Put Space-Time’s Rules to the Test
A gamma-ray flare from Cygnus X-3 sent PeV photons across the Galaxy, turning their survival into a test of relativity’s hidden limits.

A gamma-ray flare from Cygnus X-3 sent PeV photons across the Galaxy, turning their survival into a test of relativity’s hidden limits.