The universe is pretty big, like really really BIG! Funnily enough, it is also growing in size and the rate at which it is growing is accelerating; so fast that it might out travel the speed of light which is a mind-numbing idea to try and comprehend… funny right? There are some cool things about the universe that we currently reside in; it might be the only one or one of many but we don’t know…currently. Let’s have a quick look at the universe; where it has come from, what it is doing and where it might end up.
The universe was ‘created’ approximately 14 billion years ago in an instance often called the Big Bang but was not an explosion but more of an expansion of space. The young universe then entered a period known as the Inflationary Universe. This model suggests that space was filled with an unstable form of energy and at some instance, this energy transformed into the fundamental particles that make up all matter. In this time of expansion, antimatter and matter is said to have combined in uneven amounts resulting in things still existing; you can read more here. As the expansion of the universe continued to grow, a drop in temperature occurred allowing for the creation of protons from the decay of neutrons and the first element was created; hydrogen. This matter was then scatter throughout the universe unevenly, resulting in it collecting due to gravity forming other elements and eventually the stars, planets and us. This is an incredibly basic breakdown of the beginning so if you have more questions, leave them in the comments below.
Here we are now. So as previously mentioned, the universe is expanding. This rate for some unusual reason isn’t a constant and it is accelerating. The source of this acceleration is unknown but it has been termed dark energy. Dark energy is currently very theoretical and there is no way of knowing its properties but we think it makes up a lot of the universe. All matter within the universe is approximately 5% of everything that there actually is. Approximately 25% of it is dark matter and the remaining 70% is dark energy. These 2 things of space have been given the term dark because we haven’t been able to accurately and directly observe what they are; they’re invisible in the most extreme sense. Scientists are pretty sure that it exists though because of how things work in the universe. Breaking down this complex topic, galaxies wouldn’t exist with current amounts of matter because there isn’t enough gravity to maintain their structure. Therefore, there must be some invisible matter that is keeping them together. We can detect the presence of dark matter because light is disordered around areas where it can be found. Dark energy is similar in that we can’t detect it but it is concluded that it is there because of the universe’s expansion. I might write up on what these things are in more detail if people want it. What about the end? Lets look at some likely scenarios for the end of everything.
One theory, a good one to start us off with, is The Big Rip. There is currently a balance between the constant expansion of space and the gravity that holds galaxies together. This scenario however talks of a moment with the accelerated expansion of the universe is too great for the force of gravity to hold everything together. Over time, galaxies, stars and even black holes die as the gravity needed to maintain them is not strong enough. Eventually, the expansion of space would be faster than light (300,000km/s), all subatomic particles would be pulled apart from within their structures resulting in a space in which no particle interacts with any other particle; there is just too much…space.
The second one has been given two lovely names; Heat Death or The Big Freeze. Similar to The Big Rip but in this theory, matter is eventually converted into energy thanks to the Second Law of Thermodynamics, also known as entropy. Essentially, everything likes to be uniform, like how the temperature of something will change depending on it’s surroundings until it is the same. The same idea works with the universe but on a much larger scale. High energy bodies, like suns, lose energy to its surroundings and will eventually have shared that energy evenly. Eventually everything will dissipate, until there is nothing and the universe will be still. This is a maximum state of entropy.
The final and preferred one, in my perspective because stuff will still exist is the combination of The Big Crunch and The Big Bounce. If in actual fact there is more gravity than what there is dark energy in the universe, the universe’s expansion will eventually start to slow down and gravity will take over. Once the expansion has stopped, due to gravity, the expansion will reverse resulting in all of the matter in the universe starting to move back towards each other. As the universe starts to contract and become smaller, it also starts to become hotter. As this happens, all matter is forced together in a supermassive black hole that contains all matter and energy of the entire universe. The black hole will eventually consume itself and from this singularity, the universe will be born again. This theory suggests that our universe is but part of the lifecycle; a continuation of the destruction and creation of universes before it.
These are some pretty daunting ideas for what is potentially going to happen to…everything. But whether it be The Big Crunch and Bounce, The Big Freeze or The Big Rip, there is still billions and billions of years between now and then so you shouldn’t worry too much.