Astronomers say all of the galaxies in the universe are connected by a vast cosmic web of filaments, but we've never actually seen this supposed network. That's changed, however, thanks to the tumultuous activity of a distant quasar that's illuminating the celestial backdrop.
We already know about these filaments, at least conceptually, because computer simulations tell us they're there. As the universe cooled after the Big Bang, most of its matter (including and especially dark matter) congealed into a network of filaments that spanned the cosmos. Certain points of this web contained more mass than others, eventually resulting in the formation of stars, galaxies, and galactic clusters. So even though the Big Bang happened long ago and its galaxies are now far apart, virtually everything's still connected within this web of vestigial matter.