NEW YORK, June 19, 2025
Astronomers have confirmed that a significant portion of the universe’s ordinary matter resides in the space between galaxies, solving a decades-long mystery.
Scientists have been searching for “missing” baryonic matter. Recent studies reveal that 76% of visible matter exists between galaxies.
- Most of the universe’s ordinary matter, like protons and neutrons, is located between galaxies.
- Scientists used fast radio bursts to measure this matter.
- A massive filament, 230 million light-years long, of hot gas was identified.
Where is the missing matter? It turns out that 76% of the visible material is located between galaxies, according to recent findings by astronomers from the California Institute of Technology and the Harvard astrophysics center.
The Cosmic Hide-and-Seek
For years, astrophysicists have grappled with a perplexing puzzle: the location of baryonic matter. This ordinary matter, composed of protons, neutrons, and electrons, forms stars and planets. However, when astronomers looked through their telescopes, only half of this baryonic material was visible.
Theoretical models predicted the amount of baryonic matter emitted during the Big Bang, but much of it was seemingly lost. The remaining matter was theorized to be in the form of hot gas filaments between galaxies.
Unveiling the Intergalactic Web
Astronomers have long suspected the missing matter resided in the filaments of hot, yet sparse, gas connecting galaxies. This cosmic web, a vast structure resembling a spiderweb, has now been measured by both American and European teams.
One of the methods scientists used to measure this “fog” was analyzing 69 fast radio bursts (FRBs). These bursts of energy, whose origin remains mysterious, pass through the intergalactic environment, and by measuring the way in which their light slows down, astronomers can measure this fog, even when it is too weak to be observed.
The American scientists utilized the DSA-110, a network of radio stations in California, and detected the most distant FRB ever observed, located a staggering nine billion light-years away.
A Giant Cosmic Filament
An independent study, published the same week, focused on measuring this hidden material. Using the European Space Agency’s XMM-Newton Spatial Observatory and its Japanese counterpart, European astronomers identified and measured one of these filaments.
This cosmic structure, though low in density, is a colossal entity. It is 10 times more massive than the Milky Way, stretching an astonishing 230 million light-years and connecting a group of four galaxies.
The temperature within this filament reaches approximately 10 million degrees Celsius, far surpassing the surface temperature of our sun. The exploration of these filaments, which astronomers believe form the universe’s hidden scaffolding, is only just beginning.
The European space telescope Euclid, launched last year, aims to further investigate these structures to unravel the mysteries of dark matter and energy.
