We all know about atoms, stars, galaxies, planets, trees, rocks, and ourselves. But guess what? These things make up less than 5% of the entire universe.

Around 25% of the universe is dark matter, and a whopping 70% is dark energy. Sounds strange, right?

Both dark matter and dark energy can't be observed, which means the world we're familiar with is just a tiny fraction of what's actually out there.

The worst part? We have no idea what dark matter and dark energy are, or how they work.

Why We're Sure They Exist

So, why are we so sure dark matter and dark energy exist if we can't even see them? It's because we've found solid evidence that shows they're real. Let's start with dark matter. When we study the structure of the universe, we've discovered that the gravity from "ordinary matter" isn't enough to hold galaxies together. Without something more powerful, stars would be scattered and galaxies wouldn't exist as we know them.

That's why we're certain something invisible is holding galaxies in place. Something that doesn't emit or reflect light—that's why we call it "dark". But even though we can't see it directly, we can detect its presence. For example, places with high concentrations of dark matter bend light that passes through them, which is a sign that something is there, interacting with gravity.

What is Dark Matter?

So, what exactly is dark matter? It's not just a bunch of ordinary matter that doesn't emit light. Ordinary matter emits particles that we can observe, but dark matter doesn't.

It also isn't antimatter, which would react with regular matter and release specific gamma rays. And no, it's not made of black holes either. Black holes are extremely dense objects that have a strong gravitational pull, but dark matter seems to be spread out throughout the universe.

At this point, all we know about dark matter is three things: 1) It's definitely there. 2) It interacts with gravity. 3) There's a lot of it. It could be made of some strange, complex particles that don't interact with light or regular matter. But right now, we just don't know exactly what it is.

Dark Energy: The Ultimate Mystery

Now, let's talk about dark energy. If dark matter is weird, dark energy is even stranger. We can't detect it, measure it, or touch it, but we can see the impact it has.

Back in 1929, astronomer Edwin Hubble noticed something unusual while studying the light from distant galaxies. The light from farther galaxies had a "redshift", meaning it was stretched out as it traveled through the universe.

Hubble concluded that the universe was expanding, and this redshift happened because light waves were stretched as space itself expanded. In recent years, studies have shown that the expansion of the universe is actually speeding up.

Before this discovery, scientists believed gravity would slow down the expansion of the universe, and maybe even cause it to collapse. But now, we know that space is just growing—new space is being created everywhere. Galaxies are bound by gravity, so we don't feel the expansion directly, but we can observe its effects all around us. It seems that dark energy is some sort of energy that exists in the empty space of the universe.

The Power of Dark Energy

Dark energy is incredibly powerful, and it's growing stronger. In fact, the energy in empty space is greater than all the matter and energy in the entire universe combined. That's pretty mind-blowing when you think about it!

There are several theories about what dark energy might be. One possibility is that dark energy is not a thing at all. Instead, it could just be a property of space itself. Empty space isn't really "empty" at all—it has its own energy. This energy could create more space as the universe expands, filling in the gaps and causing the universe to accelerate in its expansion. This idea is similar to what Albert Einstein proposed in 1917 with his concept of the cosmological constant.

Another theory is that empty space is full of temporary, intangible particles that pop into existence and then disappear. The energy from these particles might be what we call dark energy.

Or perhaps dark energy is some kind of unknown dynamic energy fluid or force field that permeates the entire universe. But for some reason, it has the opposite effect of regular matter and energy. If this is true, we have no idea how or where to detect it. So, many questions remain unsolved.

The Ongoing Mystery

Our understanding of dark matter and dark energy is still very much in the theoretical stage. On one hand, this can be a bit frustrating. On the other hand, it's thrilling because this is cutting-edge science. The fact that we still have so much to discover means there's so much more to explore about the universe and how it works.

Ultimately, this reminds us that, despite all our technological advancements and the fact that we think of ourselves as the dominant species on Earth, we're really just a tiny island of life in the vast universe. We're still learning, still discovering, and still trying to understand the mysteries that lie beyond us.

So, Lykkers, let's keep looking up at the stars and chasing the truth behind how our universe works!