Star formation across the cosmos has fallen by roughly 59 per cent in 4.5 billion years, yet its reservoir of neutral atomic hydrogen declined by only about 11 to 26 per cent—a mismatch that rules out
New research using FAST and DESI data reveals that the universe's star-formation rate has dropped by 59% over 4.5 billion years, while neutral atomic hydrogen levels declined by only 11-26%. This mismatch suggests that the decline in star formation is not simply due to a lack of fuel, but rather a failure in the conversion of gas into molecular structures.
Why it matters
This finding challenges existing models of galactic evolution and forces astronomers to rethink the mechanisms that regulate star formation across the cosmos.
FAST and DESI data show that the universe retained most of its neutral atomic hydrogen while its star-formation rate fell by more than half, shifting attention to gas phase conversion and regulation.
Published September 5, 2026 · How we edit
The universe did not simply run out of raw gas as its rate of star formation declined. That is the clearest implication of a new measurement spanning almost 2.5 million galaxies and the past 4.5 billion years.
Over that interval, the cosmic star-formation rate density fell by a factor of 2.46. Put another way, the present universe forms stars at about 41 per cent of the rate it did at the beginning of the period, a decline of roughly 59 per cent.
Get smarter about the news
Sign up free for a feed built around what you actually care about, Dive Deeper research on any story, and the full text of every article.
Create free accountAlready have an account? Sign in