The universe isn't as bright as we thought, which means we’ve been totally miscounting the light from about a trillion different stars.
April 13, 2026
Original Paper
A TeV-based Determination of the Local Extragalactic Background Light and its Consistency with Galaxy Counts and Direct Measurements
arXiv · 2604.09397
The Takeaway
For years, telescopes reported an extra "glow" in space that shouldn't be there. New high-energy gamma-ray data suggests this extra light was an error, cleaning up a major mystery about the total light in the cosmos.
From the abstract
The extragalactic background light (EBL), the cumulative radiation from all extragalactic sources, traces galaxy formation and cosmic evolution. High-energy $\gamma$ rays attenuated via pair production with EBL photons are a powerful probe of the EBL. In this work, we use very-high-energy (VHE; $E_\gamma > 100\,\mathrm{GeV}$) $\gamma$ rays to measure the local EBL intensity and test its consistency with galaxy counts and direct measurements. Our analysis employs a sample of 268 spectra from 45 s