Presumably, most of an FRB's dispersion comes from interactions with the tenuous plasma of the intergalactic medium, a vast cosmic web that stretches through the mostly
empty space between galaxies.
According to theory, the bulk of the matter in the universe consists of large, dark filaments of gas in the vast
empty space between galaxy clusters.
Not exact matches
In about 100 billion years, as future humans are enjoying an extended stay near Proxima Centauri, some physicists like Starkman believe that dark energy will drastically stretch out the vast amounts of
empty space between the Milky Way and other
galaxies, creating an impassable gulf
between them.
The intergalactic medium — the
space between galaxies and clusters of
galaxies — is not entirely
empty.