The Secret Influence of Dark Matter on Our Universe

Across the universe an endless war rages, a bitter struggle between invisible forces, dark matter and dark energy, battling for control of the universe. We've seen this cosmic battle go on for the past 14 billion years. Like two navies fighting it out in the ocean of space time. Shadowy forces dictating our past, our present, and our future. The dark universe is kind of a puppet master behind the scenes, guiding the universe that we can see. It's taken over the universe and eventually it may well destroy the universe. As we look out across the universe, we see nebulas, stars, and planets, all constructed from visible matter. But what we see is just a small part of the cosmos. The rest is invisible, unknown. The dark universe. Dark universe is a very common phrase to describe our universe because it turns out most of our cosmos is dark. Dark not as in night, dark as in doesn't interact with light, and dark as in we don't really understand it. The dark universe is made of two forces, dark matter and dark energy. In a way, the dark matter and dark energy sort of oppose each other. Dark matter has positive gravity that pulls things together, and dark energy has repulsive gravity that pushes things apart. Dark matter and dark energy are locked in this epic struggle. The dark matter is trying to bring things together, the dark energy is trying to drive everything apart. All the objects in our daily experience, our bodies, the air, the chair that you're sitting in, the planets and stars, all of that only adds up to 5% of the universe. It's the other 95% that is the dark stuff, the dark universe. To encapsulate that in one sentence, dark matter is attractive, dark energy is repulsive. Since the dawn of time, two forces are slugging it out for control of the universe. It's a struggle that started 13.8 billion years ago in the cosmic furnace of the Big Bang. The infant universe was a super hot ball of intense radiation, but suddenly it started to transform. It cooled and expanded, triggering the birth of the regular universe and the dark universe. Scientists believe that both dark matter and dark energy formed in the first moments of the Big Bang. It would have formed probably just fractions of a second after the Big Bang, around the time that normal matter formed. And the processes that created the normal matter we know all about, similar processes probably created the dark matter. During these first microseconds, the universe was a hot, dense ball of matter and energy. They're two sides of the same coin. Matter can convert into energy, and energy can convert directly into matter. Invisible particles of regular matter, forming atoms, planets, stars, and us, and other particles, they are invisible. They are dark matter. One of the big mysteries that we as astronomers have to solve is what this dark matter is. We just don't know. The idea of a type of matter that you can't see and that acts differently than normal matter is sort of out there. It's sort of weird. It's like a crime scene. You know that a crime has been committed, even though you don't know the perpetrator yet. We see the hints, we see the signs, we see the signals that something funny is happening in our universe, even though we don't know exactly what's causing it. There are several contenders for what dark matter could be. It could be normal matter that we just don't see, or it could be some sort of exotic matter a particle of some sort that we haven't detected yet. It could be a species of particle, like an electron, like a proton, like a quark, but a special kind that doesn't interact with light. Dark energy has existed since the time of the Big Bang. Dark energy was always there. We don't know how much of it there was, but it's possible that the same amount of dark energy was always there. Dark energy is nothing more than a placeholder name for this enormous gap in our understanding of how the cosmos works. But we don't understand it at all. That's true. One potential answer to what dark energy actually is may be found in so-called empty space. Could this be the source of dark energy? We used to think of space as just boring emptiness. But now I think it's healthier to think of space as a kind of substance. A substance that carries a strange type of energy. Every small region of space has a little bit of energy in it, just associated with the vacuum itself. Vacuum energy is the idea that vacuum isn't empty, that there's something there, there's an energy in it with a kind of anti-gravity. Perhaps this vacuum energy that pushes against gravity is the mysterious dark energy. We simply don't know. We're not sure that the dark energy is the vacuum energy. It could be a new type of energy that permeates all of space. This is what we're trying to measure now. Dark energy and dark matter, forged in the intense heat of the Big Bang. Two opposing forces, one attractive, one repulsive. But together, over 13.8 billion years, they will shape the history of the universe. As the cosmic web evolves into a more complex structure, gaps form between the filaments, the cosmic voids. The cosmic voids formed because other, more dense regions of the universe gravitationally stole material away from them. So the dense parts of the universe accumulated more matter at the expense of the less dense parts, which then became voids. Dark energy played no role. It was insignificant. But at some stage in the 14 billion years since the Big Bang, these roles became reversed. Dark energy came to be the more powerful force. The question was, when? The answer came at the end of the 20th century. The beginning of the universe, shaping it, and actually creating the conditions for us to be here. And it's taken over the universe. And eventually, it may well destroy the universe. Our universe may be dominated by the long struggle between dark matter and dark energy. But all of this conflict has led to a creative outcome, an outcome for which we should all be grateful.