What is the universe made of? If you answered stars, planets, gas and dust, you'd be dead wrong. Thirty years ago, scientists first realized that some unknown dark substance was affecting the way galaxies moved.
Today, they think there must be five times as much dark matter as regular matter out there. But they have no idea what it is - only that it's not made of atoms, or any other matter we are familiar with. And Dark Matter is not the only strange substance in the Universe - a newly discovered force, called Dark Energy, seems to be pushing the very fabric of the cosmos apart.
The composition of the universe may seem straightforward, something you mastered back in your junior high science class - galaxies made up of planets and stars, stars made up of burning gases and dust. But this idea of the universe only includes the parts that we can see, either with the naked eye or even with powerful telescopes.
According to scientists, the visible portions of the universe account for less than 95 percent of what is actually out there in the great expanse of space. Much of the universe is made up of something we can't see. We call this something "dark matter," and we only discovered its existence because something else was missing.
This is the eight episode. See the list of all episodes here: Through The Wormhole.
Watch the full documentary now. Available only in United States.