Story perspectives

New Data Challenges Cold-Start Model of Cosmic Reionization

12/2/2025

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Summary

Story summary

The Big Bang produced a hot, dense universe that cooled after about 380,000 years, forming the cosmic microwave background.
In the cosmic dark ages, neutral hydrogen and helium cooled and emitted no light.
Hydrogen emits a faint 21 cm signal via proton–electron spin interactions.
Recent data from the Murchison Widefield Array show hydrogen warming about 800 million years after the Big Bang.
The warming challenges the cold-start model of reionization.

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Story summary

The Big Bang produced a hot, dense universe that cooled after about 380,000 years, forming the cosmic microwave background.
In the cosmic dark ages, neutral hydrogen and helium cooled and emitted no light.
Hydrogen emits a faint 21 cm signal via proton–electron spin interactions.
Recent data from the Murchison Widefield Array show hydrogen warming about 800 million years after the Big Bang.
The warming challenges the cold-start model of reionization.