Dark Energy: The Void Filler

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In 1999, Saul Perlmutter was asking himself a question that many of us may have thought of before: will the universe exist forever, or will it have an end?

Will the universe slowly expand for the rest of eternity, or will gravity control the ultimate fate of the universe, slowly pulling galaxies together until everything is condensed into one spot—a Big Crunch?

At this time, the way scientists observed the universe's expansion was through the study of exploding stars, which we call supernovae. When these stars died, they exploded—one of the brightest events in the known universe. The stars expand as they lived their last days, and once a certain critical mass has been reached, these stars eject almost all of their mass resulting in some of the brightest light you'll ever observe.

There are many different types of supernovae, but one particular type always explodes the same way: type 1a supernovae. They all live the same life, explode at relatively the same size (when the mass is about 1.4 times the mass of our Sun), and they emit the same amount of light. This is perfect for observing the far reaches of the universe; it's like you can explode the same star but just put them at different distances. With this knowledge, you can determine how far away any particular supernova occurs, as well as how long ago it occurred.

Saul Perlmutter and his team observed multiple of these explosions; they watched these specific stars explode. They observed their most important features down to the smallest detail. They eventually had enough data to try and explain the universe's expansion, as well as the apparent end of the universe—the Big Crunch.

However, the data didn't exactly show what they were expecting. The supernovae they observed were much fainter than they were expecting. The further away the explosion, the less bright it appeared in the sky. Time and time again, they recalculated their results. They triple-checked all the numbers, but every time they got the same results. This isn't a fluke.

What's the big deal? Well, the data showed that the universe was, in fact, not looking like it was slowing down but rather speeding up. The universe is accelerating. Saul Perlmutter had discovered something amazing; he was even awarded a Nobel Prize for his work.

But this changed the entire view of not only physics and mathematics but the view of the entire universe. We now had literal proof that the universe's expansion is speeding up. The problem is we don't know why. There's nothing we can see; we can't perform experiments because we don't know what to experiment on. We don't know what it is made from. We know it's there; we observe its results, but we don't know what it is or what it's going to do. I'm, of course, talking about dark energy.

Since this discovery about 20 years ago, we've done at least one good thing, and that's to give this catalyst a name: dark energy. To be honest, it's a pretty bad name. For some reason, in science, whenever we find the existence of something that we don't know how to handle or have no idea how to explain, we just say it's dark. It isn't dark; it's unknown.

When scientists and physicists alike mention dark energy, they mean the unknown form of energy that permeates throughout the entire universe, which also sequentially causes the universe to expand at an accelerated rate. Dark energy is literally everywhere.

To explain, imagine a fish tank. Inside, you have fish, maybe some plants, some logs, a couple of rocks—you get the idea. Imagine that this fish tank is the universe. All of the fish and other things inside the tank are ordinary matter, which are things like you and I, and everything else you see in life. This includes buildings, galaxies, stars, plants, dogs, planets, and so on; it's all considered ordinary matter.

However, the fish tank isn't only filled with just ordinary matter; it's completely engulfed in water. The water fills every nook and cranny inside the fish tank, and yet all the ordinary matter inside still remains. There's much more water than anything else in our fish tank universe. The amount of water is similar to th...