Ignoring the stupid ideas of creationism and doomsday (and the origin of these narcissistic ideas), the scientific community is on a well established consensus that our universe is about 13.7 billion years old. In fact, the discovery of Cosmic Microwave Background Radiation was a milestone in modern science as it cemented the Big Bang Theory.
Please notice how a scientific theory is different from the word ‘Theory’ as used in an unscientific and cruel way.
But this article is not about the beginning. It is about the end, to awaken our deeply rooted existential crisis and induce some nihilism.
All good things must come to an end.
Besides the philosophical aspect of the previous sentence, it has a scientific side too. Cells are born and die pretty soon. Human beings are born and we exist for quite a while, but not really on a cosmic scale. Planets and stars are formed and they die eventually (although white dwarfs tend to stick around much longer than any other star). Just like that, the universe, as we know it, will eventually cease to exist, or in simpler words, die.
Let’s get to know a few ways in which this might happen.
The Big Rip
Our universe came into existence with the Big Bang, and, as many physicists believe, will end with an equally dramatic cosmic finale, the Big Rip. We know that the universe has been expanding ever since the Big Bang happened. Physicists used to believe that the expansion will slow down and the universe will eventually come to a “steady state”. But recent advancements and discoveries suggest otherwise.
The expansion of space-time has been accelerating because of Dark Energy, the galaxies are moving away from each other faster than ever as the “fabric” of space-time keeps expanding. The galaxies are kept together because of its gravity. But once the expansion is fast enough, gravity won’t be able to keep up. First, the galaxies will be ripped apart. Large celestial bodies like stars, planets and black holes would be next followed by the particles at the atomic level.
Once the expansion is faster than the speed of light, no matter will ever interact with any other matter in the universe. The universe will dissolve into particles that won’t know the existence of other particles in a bizarre, timeless universe.
And you thought you felt lonely.
Heat Death or Big Freeze
All systems in and including the universe aim for higher entropy. So, if the universe does not meet any of the other possible endings, the entropy will continue to increase. This will continue to happen till there can be no further reactions, the stars will die, leaving the entire universe dark. The black holes will slowly degenerate and evaporate over trillions of years due to a phenomenon called Hawking Radiation.
All the matter will eventually decay into energy, till a time comes when only a dilute soup of photons remain, until even this decays. All the activity in the universe will cease, entropy will be at its maximum and the universe will be dead forever.
Well, that’s not the end of the story though. Theoretically, it is possible that there might be a spontaneous decrease in entropy by a process called Quantum Tunneling (quantum physics can get really weird), leading to a new Big Bang.
Big Crunch and Big Bounce
Feeling insignificant yet? Well, this theory is a bit uplifting.
If the Dark Energy in our universe is lesser than we think, or it decreases over time, gravity will eventually become dominant. The rate of expansion of space-time will slow down, and eventually stop.
Here’s where it starts getting weirder. Because of the dominant gravity, the expansion will eventually be negative (basically contraction). The universe will start shrinking and the temperature will increase. Just before the Big Crunch, the atom cores will be ripped apart and will be devoured by black holes. Eventually, the black holes will merge to form a super-massive mega black hole containing the entire mass of the universe. And at the end, it would devour the entire universe, including itself.
The Big Bounce theory suggests that this has happened before and that our universe is just one in the endless cycle of expansion and contraction. This means that there would be another Big Bang and the universe will start another journey lasting billions or even trillions of years.
Feel any better? Well, that’s how science works. It doesn’t care what one feels. It is what it is.
So, the point is… well, there’s no point. We’re here for a very insignificant amount of time and will be long gone before any of this happens. But scientific curiosity is what makes life beautiful. We are, in a way, the universe’s sensory organs, a way to experience itself. Let’s make the most of it by continuing the scientific quest for knowledge and truth that our ancestors started thousands of years ago.
Finally, I would like to mention a very special YouTube channel: Kurzgesagt – In a Nutshell. It is, in my opinion, the most beautiful science channel out there, explaining complex stuff in short animated videos, while not oversimplifying things. Do check it out.
The sources and references for this article are mentioned below. Do check them out if you are still curious.
Inspiration for this article: https://youtu.be/4_aOIA-vyB
Big Bang Theory: https://www.space.com/25126-big-bang-theory.html
Cosmic Microwave Background Radiation:
White Dwarfs: https://www.space.com/23756-white-dwarf-stars.html
The Big Rip: https://www.theguardian.com/science/2015/jul/02/not-with-a-bang-but-with-a-big-rip-how-the-world-will-end
Dark Energy: https://www.space.com/20929-dark-energy.html
Heat Death/Big Freeze: https://www.universetoday.com/36917/big-freeze/
Hawking Radiation: https://www.thoughtco.com/what-is-hawking-radiation-2698856
Quantum Tunneling: https://www.scienceabc.com/pure-sciences/what-is-quantum-tunneling.html
Big Crunch and Big Bounce: