I’ve been a bit scared about doing this post, but thought I should, as I’ve done posts already on what a solar system is, and what galaxies are, and the Universe is next up in the cosmic scale, so it was only a matter of time until the nagging-voice from somewhere in my brain advocating ascetic completeness won the day and I sat down to do this.
I’ve been a bit scared because it’s a pretty big question, what is the Universe? And I’m primarily a student of geology and biology, so who am I to answer such a question? I’ll give it a stab though…
There’s the monumentally simple answer of course, the Universe is everything, all of the galaxies and stars, and all of their attendant planets, moons and asteroids, in fact, every particle of matter in existence, and all of time and space too. There, post done.
It’s not a very satisfactory answer though is it? Because if I tell you that the Universe is everything, it begs the question of what exists outside of the Universe? Well, not time and space. Time and space are both features of our Universe, if you were to somehow step outside of the Universe then you wouldn’t find any space or any time, which is absolutely 100% impossible to imagine, unless you’re William Blake, or Alan Moore.
This then prompts us to question what are time and space? Now this is where Einstein demonstrated the kind of Earth-shattering genius that would bring Ozymandias to his knees in a flood of tears and humility, probably. Einstein revealed to the rest of humanity that time and space are pretty much the same. He discovered that time is not the same everywhere, that it flows at different speeds depending on local conditions, basically, the faster you move, the slower time moves. Brilliantly odd isn’t it?
This occurs because time and space are the same thing, and due to an interesting quirk of physics, the faster you move, the heavier (more massive) you become, and the more you stretch and distort space around you, like a heavy object (you) stretching a rubber sheet (space). And if you’re stretching space, you’re also stretching time, making it pass more slowly. As each of us moves about our daily lives we are all moving at different speeds and distorting space-time by varying degrees, and thus all experience time slightly differently, but the affect is so tiny that no one notices.
So where are we so far? The Universe is all of the matter in existence, and is made out of space-time. Still with me?
Evidence from astronomy suggests that the Universe is 13.7 billion years old and started out as an infinitely dense point in space and time, and that it accelerated and rapidly expanded outwards in an event called the Big Bang.
Edwin Hubble, a scientist I’ve mentioned in an earlier post, found proof of this when he realized that the Universe is expanding. He discovered that everything in the Universe is moving away from everything else, and that the objects furthest away from each other are moving the fastest, a finding consistent with the fabric of the Universe itself expanding. Imagine marking a flaccid balloon with two dots and then blowing the balloon up, the dots (think of them as galaxy clusters) would move apart as the balloon inflated, and the further the dots where from each other the faster they would appear to move apart.
Further evidence was found in something called the cosmic microwave background radiation. When the Big Bang occurred, the Universe was initially extremely compact and hot, and this heat created a specific kind of microwave radiation (basically a kind of high-energy light) that still exists in the Universe today. When you tune an analogue radio and you pick up the crackly radiation between stations, around 1% of this is the cosmic background radiation from the birth of the Universe, which I think you’ll agree, is pretty damn cool.
Scientists don’t really agree on what happened before the Big Bang, and its particularly hard to imagine how the entire Universe could burst into existence from a microscopic singularity, if it can even be said that a specific point can exist without space and time. Still it appears to have happened though, and Terry Pratchett has offered the best description I’ve ever read of this in his Discworld book Lords and Ladies when he wrote “in the beginning there was nothing, which exploded.” Perfect.
So, the Universe is everything, and it probably had a definite beginning and may have an end too. And if you thought the whole space-time thing was weird, it’s about to get weirder, but good weird, like Boosh weird. It’s been hypothesised that the Universe may have up to 11 dimensions, may be made of string, and there may be an almost infinite number of parallel Universes existing at the same time.
You’re probably familiar with 4 dimensions; the three spatial dimensions are up and down, backwards and forwards, and diagonal, whilst the fourth is time. If you want to find an object in space-time, like a star or a satellite for instance, you need to know the 3 spatial coordinates, and give a time, as objects tend to move.
So what’s all this about other dimensions? Well, the other 7 dimensions are thought to be very small, and may be wrapped up tightly, so we can’t see them or experience them directly. Sounds a bit obscure and theoretical? Well these dimensions may have an affect on us.
It’s been hypothesised that gravity may exist mostly in these other dimensions, and may only leak into the 4 dimensions we inhabit. Gravity is everywhere, it’s one of the few forces that can operate over long distances, right now our planet’s oceans are being gravitationally attracted to the Moon, and you’re being held to the surface of the Earth as it hurtles free-fall through the void of space. Gravity is everywhere, but it’s actually very weak too. Lift your hand, there; you’ve just defeated gravity. To you and me this may be a commonplace achievement, but for physicists it’s a bit of a puzzle, how can gravity be so pervasive, but as the same time be so weak? One suggestion is that gravity exists primarily in one, or a few, of these other dimensions in its full might, and only leaks slowly into our Universe, as my neighbour’s loud music leaks into my house.
But these dimensions are more important than just potentially being the source of gravity, as all mater in the Universe may be made of string.
We know that matter is made up of electrons and quarks; these are called fundamental particles, as you can’t split them into smaller bits. Quarks and elections have different properties, such as mass, electric charge and spin. But physicists don’t yet understand where these properties actually come from; no one knows why an electron has a negative charge and almost no mass for example. One possibility is that these fundamental particles are actually made from extremely small vibrating strings, and the way these strings vibrate, in our 4 dimensions and in other dimensions too, defines the property of a given particle.
5 different versions of string theory exist, but they’ve been united in one theory called M-theory. The M stands for membrane, as M-theory hypothesises that the strings, when described in 11 dimensions, are actually membranes. One possible implication of this idea is that our Universe itself is one vast fluctuating membrane, but that we can’t experience the Universe as a membrane, as we only experience it in 4 dimensions.
It gets weirder though.
You’ve probably heard the term “parallel universe” from various Sci-Fi shows or books, and you may have a vague idea of what the concept entails. It’s normally something like – a vast number of alternative universes exist, and that every time a choice is made, a universe splits so that each possible choice happens somewhere. It’s a brilliant idea, and it implies that there are countless billions of different versions of you out there, living in alternative parallel universes, each slightly different, representing every possible version of your life that could have occurred. In fact, a much larger proportion of the parallel universes wouldn’t have a you in them, as every possible eventuality would be played out, so most of the universes likely won’t contain humans.
All this has been done to death in science fiction, but some theories, and even some evidence is arising that parallel universes may actually be a reality. A hard interpretation of quantum theory suggests that all possible outcomes of an interaction must occur somewhere, and actually provides a mechanism by which “choices” can cause universes to split into parallel, but slightly different versions.
In the version of M-theory in which entire universes are membranes, multiple universes could exist alongside each other as packed membranes. Its even been suggested that interaction between such membranes is the mechanism by which new universes are created; a collision between two membranes may have initiated the Big Bang that created our Universe. In this view each universe isn’t created through the different possibilities of a choice being manifested, but if an infinite number of universes exist, then every possible version of reality will exist somewhere, so there could still be a vast number of universes with different versions of you in them.
Evidence of parallel Universes may have been discovered in an analysis of the cosmic background radiation led by University College London (UCL). One parallel universe theory hypothesises that our Universe exists within a bubble inside a much larger multiverse, which is filled with a vast number of universe bubbles. You could think of the multiverse as a foam of universes, with new bubbles constantly being born though Big Bangs. Each big bang event would release a burst of microwave background radiation, and if big bangs occur in bubbles near each other then this radiation may spill into an affect the other universes. And this is what the team may have found, distinct patterns in our cosmic background radiation that have been affected by big bangs in nearby bubble universes.
There’s so much more I could write about the Universe, I’ve not even touched on different theories on what could have happened before the Big Bang, alternatives to the Big Bang and how astronomers are currently exploring the depths of our Universe, but this post is too big already, so I’ll stop here.
So there you have it, the Universe is everything, including space and time. Our Universe began 13.7 billion years ago, but there may be an unimaginable number of parallel Universes in existence, each with 11 dimensions and made out of string and membranes.
All this is pretty complex, I’m way out of my depth, and I’ve simplified quite a lot. If you’re more knowledgeable than me about this sort of thing and you want to chip in with your own thoughts and opinions then please do. I’d love to hear from any experts out there. No internet-style genuine-craziness though please.