Caught: The Light That Lit Up the Young Universe express

Original: "The Great Escape of ionizing photons during Cosmic Morning"
arXiv:2604.13267 · 2026-04-14 · CC BY 4.0 · 1 min
For the first time, astronomers have directly observed the radiation that cleared the cosmic fog after the Big Bang.

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After the Big Bang, the Universe was filled with cold gas — mostly neutral hydrogen and helium. It enveloped the cosmos like a morning fog, impenetrable to light. The Dark Ages began.

When the first galaxies ignited, their radiation, like a searchlight beam, started knocking electrons out of atoms. This process, reionization, gradually dispersed the fog, making space transparent.

For the first time, astronomers have directly detected that very cleansing light. The James Webb Space Telescope and other instruments studied galaxies seen a billion years after the Big Bang. Spectrum analysis revealed: nearly 80% of ultraviolet light burst out — far more than models predicted. But the main surprise — some photons carried energy above 24.6 electron volts, enough to strip electrons even from helium. Previously, this was thought possible only at later stages. So the first stars were true titans, and their light was sufficient to clear the fog even from the most stubborn atoms.

The most energetic photons had energies above 24.6 electron volts — enough to strip electrons even from helium. Previously, this was thought to have happened much later.

In the series "Firefly," the ship "Serenity" flies through worlds aglow with the light of many suns. Astronomers, however, have captured that ancient light that ignited those suns.

Scientists
Fritz ZwickyEdwin HubbleSubrahmanyan ChandrasekharAdam RiessJohn Archibald WheelerNancy Grace Roman
Concepts
cosmic dawn Reionization cosmic dawn magnetic signatures photosphere high redshift galaxies jwst red sources early universe star formation starlight dark ages radiation dominated era red giant james webb space telescope ionization helium flash observable universe light travel time neutron star light emission interstellar object ejection photoelectron big bang