building up over billions of yearsReputable source · 2 sourcesWell documented
Dark Matter: The Invisible Scaffolding
On the timeline · around building up over billions of years · The Age of Galaxies
What happened
Most of the universe's matter is invisible 'dark matter' — roughly five times more abundant than ordinary matter and detectable only by its gravity. It forms a vast cosmic web of filaments along which galaxies gather.
Why it matters
Without dark matter's gravity, galaxies would never have come together. It is the hidden scaffolding on which the entire visible universe is built.
How we know
Astronomers have mapped dark matter in 3D using the way its gravity bends the light of distant galaxies.
Sources
- European Space Agency. First 3D map of the Universe's dark matter scaffolding · Reputable source
- NASA. Hubble Maps the Cosmic Web of 'Clumpy' Dark Matter in 3D · Reputable source