Kurzgesagt - In a Nutshell (2013) : 14x3

Most of the universe is not made of stars, galaxies, or beautiful glowing nebulae. Instead, the majority of it is what seems to be vast, silent emptiness. Huge cosmic voids stretching hundreds of millions of light years across, containing almost nothing at all. But these dark regions are not just empty space. They are dynamic structures that grow, merge, and shape the entire architecture of the universe. What exactly are cosmic voids and how did they form? What makes them so strange, and what role might they play in the future of the universe?