Ingredients of the universe vs voids

The universe Voids

Dark matter

Sites of invisible dark matter were the gravitational ‘seeds’ that attracted the universe’s primordial hydrogen and helium gas. This dark matter formed shortly after the Big Bang.

Gas

Largely made of primordial hydrogen (75 per cent) and helium (24 per cent), gas concentrates in cosmic filaments, where large concentrations of dark matter are already present. This then collapses to form galaxies full of stars.

Dust

When the largest stars explode as supernovae, they spread heavy elements into intergalactic space. Some of this forms into molecules, including organic compounds. Some then forms into dust grains.

Stars

Residing in the stellar metropolises of galaxies, stars illuminate a web-like structure on the largest cosmic scales, consisting of clusters, filaments, arcs, sheets and walls.

Dark energy

Dark energy, comprising 68 per cent of the universe’s energy density, is responsible for the accelerated expansion of space. Changes in a void’s shape will partly be down to dark energy.

Neutrinos

Because they hardly interact with normal matter, neutrinos travel the entire universe almost unhindered. But their masses can affect the number of small and large voids, something that is being explored further.

Dwarf galaxies

Of the few galaxies that do reside in voids, many – if not all – are dwarf galaxies with slow evolutions.