We’ve been asking questions about the universe we live in since the dawn of time. These days, given the sudden boost in expansion, the biggest mystery is about what lies beyond the universe. Does it have an edge? Is it infinite? We’re still struggling to figure these things out, so let’s struggle together.
Through extensive research, scientists concluded that the universe must have come into existence approximately 13.8 billion years ago. At this point, everyone’s heard about the famous Big Bang, the huge blast that led to the creation of the universe. After the initial explosion, it continued to grow and to expand for a while. Eventually, the growth rate started to diminish and the universe entered a certain status of inertia.
That is, until recently.
Scientists have observed that the universe is doing the exact opposite of slowing its growth rate down – it’s actually accelerating! And although most of them are scratching their heads trying to figure out a reason, most of them find dark energy as the “culprit.” What are we talking ahead? Read ahead.
A Historical Development
Humanity has a long histoire of trying to figure out the great mysteries of the universe. Ancient Greeks were the first to start asking questions as they observed the night sky. They were also the first to bring up one of the greatest debates (and disputes) regarding the nature of the universe. Is it finite or is it infinite? If there really is an edge to the universe and we’d manage to send a ship beyond the universe at that point, what would we find on the other side? In many ways, the possibility of it being infinite or finite posed some great problems alike.
In the 1800s, astronomer Heinrich Olbers claimed that the universe couldn’t be anything but finite. He argued that an infinite universe would mean that everywhere we’d look, the sky would be filled with stars. This theory was famously debunked by Isaac Newton, who made a monumental discovery: gravity. Since every object, regardless of mass, is surrounded by gravitational energy, a supposed closure to the universe would be pretty disastrous. Because of gravity, it would essentially collapse into itself.
Later, Einstein developed the renowned theory of gravity which placed him right in the middle of the typical two perspectives. According to him, the universe is neither expanding nor collapsing, but it’s static, managing to cancel the gravitational effects that Newton had brought up. The final line in this thread of discoveries came through Edwin Hubble.
Hubble discovered that galaxies were pulling away from each other, a crucial proof that the universe wasn’t static, but actually constantly expanding. Upon the release of this theory, Einstein responded by calling his own thesis “his greatest blunder.”
An Infinite Or A Finite Universe?
Let’s face it: we’ve all wondered this at some point. And we weren’t the first. As depicted earlier, even people of Antiquity had trouble trying to figure out this daunting mystery. It becomes even more confusing when you think about the universe while also knowing that it keeps expanding. This only brings about another troublesome question: since it’s expanding, what is it exactly expanding into?
Possibility A: Finite Universe
Even if the universe truly were finite, that still wouldn’t mean it has any real boundaries. When trying to think of the edge of the universe, we likely imagine ourselves gazing beyond the universe at what stretches before us. This is the same as walking to the edge of a cliff and observing the landscape in front of you. Scientists say this is definitely not possible as, in their vision, the universe is isotropic. In simple terms, this means that all matter looks the same no matter where you look.
There’s also a very likely possibility that the universe does have a finite mass, but it folds over itself in a way that makes it with no boundaries. To try and help people envision this image, people launched the ant and balloon comparison, which is very popular and appropriately explicative.
Try to picture yourself as a small ant, wandering on the surface of a balloon. Because of your limited ant perspective, the otherwise sphere-shaped balloon suddenly feels like a flat surface. If you decide to go on a journey, no matter the direction you decide to pursue, you will end up at some point in the same place you’ve started.
But that still leaves that one annoying question: what is the universe expanding into? According to Stephen Hawking, it’s completely ridiculous to even ask this. By default, the term “universe” defines everything. There’s just no other better way to put it. Even if there would be a supposed edge, whatever lies beyond it is still considered the universe. Is all of this giving you any headaches? Good, it’s supposed to.
Possibility B: Infinite Universe
But wait, if it turns out that the universe IS infinite after all, doesn’t that make this whole expansion thing even more confusing? What is it even expanding into? Stephen Hawking says that this is yet another completely senseless thing to think about. The universe is simply expanding. There’s no such thing as “expanding into something.”
The concept of infinity is certainly difficult to grasp for the normal human brain, though one may say that, even with an edge (as blurry as it is), the universe is practically infinite. There is a space known as the “observable universe” which is everything that we’ve managed to explore and observe so far. Even though the universe came into existence 13.8 billion years ago, we’ve managed to observe up to 46 billion light years. This is just another reason to believe that the universe has expanded, even beyond our exploration capabilities. It’s basically similar to the feeling of walking up to a door and having it distance itself constantly.
That being said, it’s pretty much impossible for us to ever reach the end of the universe if it does exist. The accelerated expansion rate of the universe is so fast that the universe grows even bigger before light beams travel back to earth. Cue the door analogy, which we’ll be chasing forever.
There is nothing beyond the universe because the universe represents everything, including things “outside” of it. Alternatively, there’s nothing beyond the universe because it’s simply infinite and it molds into itself in a four-dimensional space. It’s headache-inducing, yes, but it wouldn’t be one of the greatest themes of humanity if it weren’t.