In the previous post I have talked about the most probable cause for the creation of all reality, the Big Bang. As we know, all things that exist will (probably) die, and the same goes for the universe. In this post I will talk you through some of the most prominent theories and also make a case for optimistic nihilism, so you don’t kill yourself immediately after reading this.
I will provide a brief description of the few leading theories, but keep in mind these are likely to change as research into dark energy progresses. I will be leaving out the simulation theory or an infinite universe, as they deserve a separate article and are not seriously considered by many physicists. Also, don’t dismiss this subject because of its depressing nature, it is a really important field, which helps us learn more about the box, in which we are all stuck. Memento mori!
Let’s begin with the mostly agreed with theory, the heat death. Frankly, it is quite boring and uneventful when compared to others, but it’s the best one that scientists have come up with. We assume that we know two things, the universe is expanding at an accelerating rate and the universe is flat (you can read more about these in the sources below). We also know that there is a finite amount of matter in existence. Stars can only burn for a set amount of time, at some point they will all run out of fuel and either become black holes, or get consumed by black holes. This is predicted to happen in around 100 trillion years, a massive amount of time. Black holes are also mortal, due to Hawking radiation they decay as virtual particles form on the event horizon. In this process the universe will cool and approach absolute zero, or else maximum entropy, which would mean that no particles would be moving and the universe would stop existing. How chilling. I am really not going into much detail here, so check out the sources below if you want to know more.
Next up is the Big Rip, something I was really interested in when I was younger. Imagine you are holding a big, flat piece of pizza dough, and you stretch it out as much as you can. At first it holds up pretty well, but as it gets longer and longer, at some point it breaks. Now imagine everything in the universe is a piece of pizza dough. At first it expands and it seems fine, but remember that the expansion rate of the universe is increasing. Therefore, at a certain point in the future, all of matter would be ripped apart and disintegrate into unbound elementary particles and radiation. And as the expansion rate approaches infinity, the universe would go back into being a singularity. Much cooler than the heat death, don’t you think?
Now here are two more hopeful theories, although not as likely, the Big Crunch and the Big Bounce (cool names btw). Some physicists argue that the expansion of the universe cannot go on forever, and at some point everything will contract back into a singularity. I would compare this to a rubber band, which is not a very precise analogy, yet works in this context. You stretch out the rubber band, and at some point you let go, which makes it revert back into its original shape. Now this is optimistic, because as with a rubber band, the Big Bounce argues that this could happen indefinitely. What I mean is that the universe could begin again from the aforementioned singularity, experience another Big Crunch, and constantly oscillate between the two states like a pendulum. Sounds amazing, but we will be dead way before any of this happens, and even if we lived long enough, the gravitational forces needed to pull the universe back together would instantly obliterate us.
Why am I even talking about this? The sun will kill us long before the universe will even be able to conceptualize its own death. I probably exaggerated with the “killing yourself” in the introduction, but think about it. Everything you create, even if you get it far away from global warming, wars, the sun etc. ; everything will be gone at some point. Even reality, even the whole freaking universe, so your death will not be so special at all. The fear and nihilism are all logically correct, yet why not make the best out of what you have? You are not special, nothing is, and the only thing that we can do better than a dog, a tree or a cloud is to learn about things. Even if the pursuit of knowledge is pointless, it is the only reasonable thing to do, so it’s better to take the red pill and see the tragedy of the universe, than to die as a blind man in Plato’s cave.
Sources for further reading:
Wikipedia: https://en.wikipedia.org/wiki/Ultimate_fate_of_the_universe
Timeline of the heat death: http://www.ilovephilosophy.com/viewtopic.php?f=4&t=191649
For pessimistic nihilists: https://www2.hawaii.edu/~freeman/courses/phil360/16.%20Myth%20of%20Sisyphus.pdf
Good article summarizing my main points: http://theconversation.com/the-fate-of-the-universe-heat-death-big-rip-or-cosmic-consciousness-46157
Mathematical explanation of entropy and the heat death (video): https://www.youtube.com/watch?v=UXRFQBad1Hs