Weird Matter, Part 1: Dark Matter and Dark Energy
Dark Matter and Dark Energy
Dark matter and dark energy. These are things you might have heard about and maybe wondering what on Earth they are. While they sound like magical forces from Harry Potter, they are most likely real things that exist in our universe. Today we will be going over what these awesome and mysterious things are. However, keep in mind that our understanding of dark matter and dark energy is not very strong, and there is still so much we have to learn about. Take a look at your hands, computer or phone, and house. Maybe touch the wall or stomp on the floor. All of the stuff around you that you can see is made of normal matter. As you might know, normal matter is made up of atoms and reflects light, making it visible to you. Here’s the crazy thing, though –normal matter, which makes up oceans, mountains, planets, and galaxies, only makes up 5% of the universe! In fact, the other 95% is made up of dark matter and dark energy. Dark matter makes up 26% and dark energy makes up the remaining 69%.
Dark Matter
So, what exactly is dark matter, and how can there be so much of it? Well, first of all, you can think of dark matter as a sort of glue that surrounds galaxies and solar systems, helping them to stay together. However, unlike normal matter, it is invisible – impossible to detect directly with current technology. Then how do we know it exists? Well, if there was only normal matter in the universe, there wouldn’t be enough gravity to hold galaxies and solar systems together. Suns and planets would drift apart from each other. So there has to be some other hidden matter that uses its gravity to help keep everything together. This is what dark matter is thought to be.
Dark Energy
Dark energy, on the other hand, is a force that threatens to rip the universe apart – all of its solar systems and galaxies! Back in 1925, astronomer Edwin Hubble proved that the universe is actually expanding. This was a huge discovery because, for most of history, people had thought that the universe didn’t move at all. Hubble showed that, since the Big Bang, the Universe has never stopped expanding. In fact, his observations showed that this expansion is actually speeding up –getting faster and faster. You can think of it like this: imagine a deflated rubber balloon. Nothing inside of it. But suddenly, you blow a burst of air in, and the balloon starts to expand, bigger and bigger. And every second, you blow harder, so that the balloon expands at a faster and faster rate. This is kind of how the universe works. 14 billion years ago, the Big Bang occurred, which was an explosion of energy, like the burst of air you initially blew. Over billions of years, this energy continued to expand, creating suns, planets, galaxies – everything in the universe. And it’s still expanding, and this expansion keeps getting faster and faster. Like if you keep blowing air into a balloon harder and harder. This is where dark energy comes in. It is thought that dark energy causes this expansion to speed up. What’s scary is that if the universe keeps expanding at a faster rate, then one day in the future, billions and billions of years in the future, it might cause everything to rip apart! All the suns and planets from galaxies and solar systems would be so far apart that traveling to other places in the universe would probably be impossible. But don’t worry – this is something that might never even happen, and even if it did, you wouldn’t be alive to experience it.
