A few years back, I got curious about exactly what the universe is like.
My curiosity wasn’t necessarily focused on whether God, or karma, or luck exist (though certainly those ideas do seem to affect human actions quite a bit, despite no real physical evidence of them), but more about the what of what the universe is.
Like, what is it all made up of? What does it actually look like? If you looked at a map or a model of the universe (however it could impossibly be constructed), what would you see?
This interest quickly led me to cosmology, which is the study of the nature of the universe (from the Greeks’ – the origins of so much of our science – kosmos, meaning the order or the world). I will preface here by pointing out that even though I am hoping to spread expertise and insight here, I am certainly no expert. I am an interested tourist of this study still, just taking pictures as I safari across the broad shoulders of various giants.
But I have developed a picture, a mental model, of what I understand the universe is like. I am sure that true scientists could poke holes in it all day long, and I am also sure I have embellished certain parts into inaccuracy just to keep them clear in my own memory. But in sharing it, I hope to both solidify my own understanding of it, and perhaps update the understanding of the universe in your own mind, reader, whoever you are.
So: We are made of atoms, the building blocks of the universe (or at least as good a place to start as any). Atoms are often mentally pictured, thanks to most elementary educations, as very tiny balls, and most people either imagine them as balls, or remember that there is a nucleus in the center of the atom (which itself is made up of little balls including protons), with electrons hovering around it (meaning the atom is often imagined as a ball with other balls circling it – which leads to associations with a radiation warning sign, given that atomic power often comes with unseen danger. See how your culture protects you in this strange, hopefully effective way).
Of course, like most simplifications of scientific matter and processes (like this one I’m writing now), this model is wrong in its lack of specificity. Atoms aren’t balls – they’re more like locations of energy. The particles that make up atoms are perhaps better pictured as vibrations in the air, in that they are so small and so energetic that when we look as closely as possible at them, all we can often see are their effects. We can’t see them directly – we can only understand them by looking at what they do.
Which leads us to the universe, and specifically how the universe started. Because when you study the effects of all of these atoms around us, and how they interact and how we age, and how volcanoes erupt and water flows and how minerals form and continents shift and planets spin over time, you start to see an arrow, a pattern. And that arrow generally shifts in one direction: From beginning to end, from uniformity to entropy. “Time’s arrow,” it is often called. Things generally go from more uniform and more ordered to less, and while exceptions can be the case in specific areas, if you zoom out to an even larger picture, what you find is that even though some parts of whatever you’re studying seem way more uniform than they used to be, the entire picture itself is more chaotic, less ordered, than before. Things more easily shift forwards than backwards, and forward is often more shattered, detailed, and chaotic than what came previous.
Case in point: The entire universe, every atom that makes up us and all of the birds and bees and gold and carbon and suns and meteorites and galaxies, used to be hydrogen. Hydrogen is an atom that contains a proton (which remember, is just a vibration) and one electron (a smaller more transitive kind of vibration), and in mere seconds after “The Big Bang” – which, if you ask me, was more of a crack than a bang, which I’ll explain in longer time than it took to happen – most of everything that we know has ever existed had gone from whatever it was before into a bunch of small wild particles, which then formed into mostly hydrogen atoms. Which are still here – 74% of the universe is still hydrogen.
Helium (which is a proton with two electrons, also relatively simple to form) came soon after, all within about 20 minutes after the crack (and 24% of the universe is still helium). And then the other atoms came around eventually – it only took about a billion years or so for it to kind of resemble something we’d recognize, and this all happened about 13.8 billion years or so, according to what we can currently verify with the technology we have.
What was the crack? In the beginning, there are four forces. There are only four actual forces that can move or change any of the atoms in our universe, and they are: Gravity, electromagnetism, the strong force, and the weak force. Gravity and electromagnetism you may be familiar with – one is very clear whenever you drop something on your foot, and the other is behind the movements that you see in electricity and magnetism, where atoms and electrons are attracted to or repelled from each other. The strong force and the weak force are not as apparently familiar, but you already know them. Something has to keep the tightly knit center of the atom, the nucleus, together, and scientists call that force the strong force. And something has to keep that electron rotating around that nucleus, and that force is called the weak force. Scientists are still learning about both of those forces, and the more we understand of them, the more we can better understand the atom and how it connects, both to itself and to the many things (everything) that atoms make up.
(A short aside here: “Which force moves my arm up?” you may ask. And I regret to say I don’t know enough to have the answer, except to say that your movement is governed by these forces – gravity keeps you from being flung away from the planet, and the strong and weak forces keep your atoms from spinning apart. Presumably, the atoms in the cells in your body interact to send electrical signals from your brain to your arm telling your muscles to contract and pull on each other, but how that happens, we’d have to speak to a real scientist to explain clearly.)
But in the before the beginning, there was only one force. Gravity, electromagnetism, the strong force, and the weak force all have “shapes” of a sort – they all seem to fit together somehow, or have fit together in the past, like a dropped plate that broke into four pieces (with perhaps a few extra shards – we aren’t sure). As scientists figure out how the four forces connect, we’ve seen huge leaps in technology – Einstein needed Newton to understand gravity in order to understand the strong and weak forces better, and dropping and moving magnets to create machines allowed for advances in electromagnetism, all the way up to the intricate circuitry built with a deep understanding of nanophysics today. The forces are all interrelated though different, which suggests that they have a common root, a common source.
And as I understand it (again, from my layman’s perspective, so please forgive me if I’m wrong), that’s the “why” of our existence. Something that existed before the universe, some ancestral force, cracked. Something broke. Something that was quiet and whole and stable became not so, for some reason outside of our perception. Perhaps the thing that was our universe collided with something else, or perhaps conditions changed and something finally shattered, or perhaps what really exists is a series of universes – cracks in some larger structure that are all broken in different ways, with completely different types of forces emerging. For all we know, things are still breaking, and we’re just a single splinter of many cracks and bangs out there, with these four forces only specifically working the way they do in our universe because they happened to crack the way they did.
But we’ve gotten off track: Whatever the universe was cracked itself apart, and that caused the forces to start differentiating, and as those forces worked on developing atoms in their own ways, that eventually created hydrogen, then helium, and then (as time passed and things cooled and expanded and crashed together and exploded and re-condensed and exploded again over billions and billions of years) we eventually got all of the atoms and everything that exists today.
What does it all look like now?
Well, if you’re a human who’s not an astronaut or Katy Perry, then you’re standing on Earth, which is what we call an oblong rotating chunk of magma with a crust of minerals and organic material and a thin layering of oxygenated atmosphere currently flying through space at around 67,000 miles an hour, both spinning on its axis and rotating around a much larger superheated orb of plasma known as the Sun. The sun is not a deity as far as we know (which is news to most of humanity that’s existed previously, I think), and in fact isn’t even our first sun. The Earth (and in fact, your body) happens to contain minerals like calcium that could only have been created in the shrapnel of a supernova, and our sun hasn’t yet supernova’d, meaning that this rock has been blasted with some other sun’s remains, probably before our sun even existed yet.
The Earth is not the only thing rotating around the sun, and here we arrive at the solar system, which you have likely heard about. There’s a lot of stuff in our solar system – most people know the planets, but there’s also plenty of asteroids, comets, and as you get farther away from the sun, things get quieter, colder, and the atoms seem to be older and less active. There may be a lot of things floating out there past what we know of our solar system – if they’re not reflecting light it might be hard to see them, and without seeing light from them, we have a hard time telling what they are.
Light is worth a short explanation at this point, as we will need it to see beyond the solar system (to see anything, actually, but that gets us back into biology, which is, again, beyond the scope of this description). Light is made up of photons. Photons were first formed back when the universe cracked, and in fact they’re still around – scientists have identified the Cosmic Microwave Background, which is the very oldest remnants of the very first vibrations of the universe, basically. If the Big Bang left blast marks, the CMB is the blast marks, and it is made up of various photon waves, which themselves are (like everything, really) vibrations in space. Light is a particle, in that it exists at a specific point, and travels (very quickly) through time and space. But it’s also a wave, in that it’s being created all the time from collisions and vibrations and bounces, and flashes and pops. Atoms are tightly compacted vibrations, but light is much flimsier, like ripples on water.
When we look up at all of the stars above us, we’re seeing blips of light from all of the other stars in the universe. This light has traveled to us very quickly, but often from extremely far. In fact, and this is where we start to get into how mind bogglingly big our existence is, even though the universe started out from a very localized point, where everything that has ever existed was within literally a meter or so, when the forces cracked, the space that made up the universe expanded so fast that within a single second, it was about 10 light years across (a light year being the time a light photon will travel in an Earth year – a very long distance). Why isn’t the entire sky full of light? Because the universe expanded faster than light, and the light from distant stars is still too far away to reach us. Enjoy that perspective for a bit, if you like.
Currently, according to calculations done on the light and processes we can see, the universe is about 13.8 billion years old. It has gone from about the size of a meter to 10 light years across in the first second of existence, to 92 billion light years across in the ensuing time. And here is perhaps the most incredible thing about our universe: Not only has it expanded to a great distance extremely fast, but our most knowledgeable scientists currently believe that it is continuing to expand. And while in the past, we believed it might be slowing down and might even return to that meter-sized space it came from, it currently appears that it’s expanding even faster by the second.
If you want to get off the ride at this point, that’s understandable. 92 billion light years is an unimaginable distance for any human – with the universe “only” 13.8 billion years old, no physical object could ever have made a journey all the way across it. But that’s because the universe has expanded across that space – the universe is the space that exists. It’s the space that has developed within the crack of these forces. That makes it very hard to determine what it “looks like” from the outside – presumably, on the outside, since the forces aren’t broken out there, time itself might not really exist (since time is determined by things changing, and if gravity and electromagnetism can’t interact, because they’re the same thing, then there’s no real “time” to mark or speak of). And of course, outside the universe, there isn’t “space” either – space and time are related, and as the universe continues to expand, space must be growing “thinner” somehow, but even what that means, we aren’t sure. Beyond the limits of space and time, we don’t have the ideas needed to even perceive what’s there.
What does it look like “inside” the universe? Galaxies are the main building block we’ve identified, I think, though at places in the universe, there are sometimes just vast tracts of emptiness, or giant clouds of particles, suns supernovaing around each other and crashing and forming and reforming. There are also black holes, which are relatively new to our understanding, because they (they might be “holes” in space time? or “rips” where matter can’t exist or the forces reform in some way?) play with and interact with light in ways that aren’t easily noticeable or understandable
All of that stuff is just out there, bubbling away, and for all we know, it’ll just keep doing it. Maybe the universe will eventually just expand and expand until it’s all cold and desolate. Maybe the conditions are right for the forces to crack again at some point, or maybe whatever caused them to shatter will happen again? Or will happen right next to us and demolish all known existence in a matter of moments? Who knows. For a while, before we discovered the CMB, many people thought the universe was just an ever-refreshing soup of galaxies, forming and unforming for eternity. But now that we can see and perceive the CMB, we know that the universe has a history and a beginning (and now that the four forces have “broken,” it seems unlikely they will ever re-fit back together).
I’ll leave you with the one thing we do know, and it’s what’s driving the biggest questions cosmology is currently trying to answer. Even though the universe is mostly a bunch of big, noisy happenings inside a bunch of bigger empty quiet nothing that’s expanding more and more quickly over time, it’s surprisingly uniform. That is, on a large enough scale, it’s basically the same throughout.
This needs some explanation. Locally, where we are, the universe is not uniform at all – you’re sitting here, your cat is over there, and from what you can see, the two of you are very, very different. And on a stellar scale, it’s also not uniform – our solar system is hanging out here in the middle of a vast stretch of space, so much so that it’s light years to the next star, and once you go beyond that (which you never will, given that physics says the distance is farther than you can ever physically travel in your lifetime), you can see our system is part of a giant cluster of stars called the Milky Way, which is the galaxy that we’re in. “Giant” is perhaps underplaying it a bit. There are hundreds of billions of stars in the Milky Way, of which ours is one, sat about ⅔ of the way out on one of the spiral arms (at the center of which, scientists guess, probably lies a huge black hole that holds the whole thing together with gravity, though we can’t really see it yet because of all of the stars in between us and it).
Outside of the Milky Way, things get dark and quiet again for a while – there is another galaxy that’s about 2.5 million light years from us, which, if you were looking at our galaxy and this other galaxy (called Andromeda) on a 2D plane from a great distance out, would kind of look like another spiral slightly down and to the left of us. Andromeda is currently moving towards us, and in about 4.5 billion years, it will probably collide with the Milky Way Galaxy. That’ll be quite a light show, and could result in the complete destruction of our solar system and either have Andromeda bounce off of the Milky Way or combine with it, but of course none of us alive now will be here to see it.
After that, we arrive at where things are, surprisingly, uniform. There are some other smaller galaxies rotating around both ours and Andromeda, just floating out there in the ether but still affected by our gravity. Then as we zoom out, we start to see clouds of galaxies, and from there (zooming out on an incredible scale), it’s just galaxies as far as the eye can see – there are large ones and small ones, newer ones and older ones as stars form and blow up and fade away, and galaxies that are more stable and others that rotate around each other or are in the middle of crashing or spinning out of control.
Across the entire universe, there are likely trillions of galaxies, and they contain from millions of stars to trillions of stars themselves. They’re all, every one of them, formed from the initial atoms that appeared as the forces cracked. They’re all moving around and affecting each other, and all of our knowledge about how the universe works today comes from watching them – we watch them spin around each other and calculate how much they must weigh, how much matter they must contain (some of them move weirdly, which suggests there may be “dark matter” that we can’t see affecting their movements). We see them flashing or even blinking at different rates, and determine that they must be emitting light at various periods (exploding, condensing, and re-exploding again) or that they must be orbiting something that doesn’t emit as much light, like a black hole or something we haven’t even discovered yet.
And that’s where the uniformity comes in – if we look in one direction the galaxies look one way, and if we look in another direction, the galaxies are obviously different, but they’re generally spaced out and expand in about the same types of ways. In fact, if we look in both directions, we can’t quite tell where we are in the universe, because it seems to kind of expand in all directions. Uniformity from entropy, you might suggest, though it’s hard to argue that the uniformity we can see is somehow an improved, progressed state. The uniformity around us is more like a dust cloud hanging in the air after an explosion – would anyone suggest this preferable to whatever was there before the explosion?
We are still watching the skies to try to see how things work out there. We can see light from objects, or light bending around objects, or being spun or shifted as it moves towards us. We can see galaxies moving towards or away from us, and we can tell this by the wavelengths of light they emit – light with an increased frequency (called redshifted) usually indicates an object is incoming to us (though usually from many light years away, meaning that the light itself we’re seeing could already be millions of years old). Scientists can’t look at all parts of the sky at the same time, so sometimes it’s a miracle when we get to see a supernova happen, or we only get to see the effects of an event, and we have to predict how it worked. As technology and telescopes improve, we can investigate specific events more closely, or see things more clearly or evaluate different frequencies of light to determine what a celestial body might be made of, or what types of radiations it might emit and on what schedules (and we can make guesses as to why).
We’re still figuring this stuff out – sometimes an observation will suggest something that seems incredible and could never actually be true, but the next will remind us that there are always exceptions, or that the exceptions sometimes prove the rule. Science is like that – it’s only when you do it long enough that things eventually start to make some kind of sense, at least until the next discovery that changes your perspective, and then you get to start over knowing more than you did before.
In the end, the universe looks like us: spinning out of control in an elegant way, as ordered and majestic as it is messy and unfortunate sometimes. As far as science tells us, there’s no big bearded elephant man in the sky punishing or rewarding our behaviors, but there are atoms and chemicals interacting in often predictable but surprisingly complex ways, as they have since the very beginning of time itself, and as they probably will until the last chorus ends.
I presume in the next few years we’ll learn more about the ideas called dark matter or dark energy (so called because they generally don’t emit light, which makes them hard to detect – again, we’re studying effects of effects of effects and trying to draw lines back to how they began), and we will continue to learn more about how to perceive and eventually manipulate light and atoms. Undoubtedly, AI will look at these models we’ve created and help us improve them, and we’ll probably learn how to build things smaller and how to transfer matter and energy more effectively. We may even unify the four forces into a single model – already scientists have assembled three “pieces of the plate” into one big picture, and they’re working on breaking down atoms into smaller and smaller pieces to try and better understand how these pieces “broke” by understanding how they relate to each other, and maybe someday we can even understand what happened to create that break.
Then again, whenever scientists think they have something almost fully explained, someone like Kurt Gödel usually shows up to remind everybody that we don’t (or even can’t) know quite as much as we think we can. But we can always increase and improve our understanding, and the more we do, the more we can marvel at both how incredibly elegant and vast the universe can be and at the ingenuity and dedication of those scientists who help us understand it.
Reading:
- Galaxies: Inside the Universe’s Star Cities by David J. Eicher
- The Feynman Lectures on Physics (https://www.feynmanlectures.caltech.edu/)
- On the Origin of Time by Thomas Hertog
- Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos by Michio Kaku
- The Poincaré Conjecture by Donal O’Shea
- Elements of Mathematics: From Euclid to Gödel by John Stillwell