The Universe. The word brings about a plethora of speculations and theories proposed about it over the course of many millennia. The very being of existence is encapsulated within the infinite fabric of the universe. A definite truth beyond the confines of the universe is not something that has been explored yet. It is an unknown realm and the thought of it, while intriguing, is rather formidable.
As we observe the age old saying “Nothing lasts forever”, it ticks into one’s inquisitive side and makes them question the perpetuity of the universe. It must apply for everything right? Most probably. There are definitive instances over the course of time to theorize the potential collapse of the universe in the distant (hopefully) future.
We can say with a convincing level of certainty that the universe will not last forever. The change in the proceedings and orientations of the cosmos has been exponential in the years since the time of its unknown inception.
It takes light immense amounts of time to travel from distant galaxies and cosmic bodies into our telescopes. The number can be as scary as billions of years old! This implies that if those telescopes could reach out into the depths of the universe, we can observe how the universe used to be a billion years ago. What we witness right now are cosmic occurrences and bodies that used to be closer and have since drifted away in a continuous expansion.
The mysterious force causing the expansion is rather enigmatic in its working and has been termed as “dark energy” by scientists. This energy is believed to be some sort of substance or field that exerts a sort of reverse gravity. It pushes while gravity pulls. But the universe can’t go on expanding forever. Something’s has got to give, and when it does, it’ll likely happen in one of these ways.
An expanding cloud of smoke eventually dissipates into nothingness, and that’s exactly what will happen to our universe if it succumbs to heat death. If there is enough dark energy in the universe, it’ll cause the eternal drift of galaxies and cosmic bodies away from each other.
Galaxies will have moved to distances beyond a point where they are not visible to each other and new stars will stop forming. Eventually, the atomic particles that make up everything will decay into subatomic particles, and those subatomic particles will move so far away from each other that they can no longer interact.
This will leave the universe dark, cold and motionless. Essentially dead. This scenario is also called “The Big Freeze.” In fact, the “heat” part is solely in reference to the fact that it’s the result of entropy, not the temperature that would result. This is the most likely fate of our universe.
THE BIG CRUNCH
We assume that dark energy is a constant force causing the eternal and persistent drift. However, we could consider an alternative theory of dark energy potentially weakening over time to a point where it couldn’t counteract the force of gravity. In this proposed scenario, the expansion of the universe eventually reverses.
Galaxies would get closer and closer together, eventually colliding with each other and collapsing under the force of their own gravity. All of the matter in the universe would fall in on itself until everything went back to the way it began: as a singularity, an infinitely dense speck. Given what we know about dark energy, the chances of a Big Crunch are fortunately (it doesn’t matter if there is an alternative ending does it?) slim.
THE BIG RIP
Heat death assumes dark energy to be a constant force while the big crunch assumes it be a force that eventually weakens. Now paddling the other way, this theory proposes the possibility of dark energy strengthening over time leading to not only the expansion of the universe, but expansion within the galaxies themselves. This would mean that galaxies, stars, and planets would be ripped apart, and eventually, dark energy would become so powerful that it would tear apart molecules and atoms.
“If the Big Rip is coming, it’s not coming for a very long time,” said theoretical astrophysicist Katie Mack in a talk at the NECSS conference in July. “We have at least 120 billion years before we have to worry about this. So you can rest easy — it’ll be a while.”
The last three scenarios gave the comfort (not really) of not occurring any time soon. However, vacuum decay could happen at any moment. It’s based on the nature of something called the Higgs field, which permeates our universe and varies in strength based on its potential. You can think of its potential like water in a waterslide. The higher up the waterslide you go, the more energy the water has. Essentially, you’re at a higher state of energy which decreases as you traverse down the slide. When the water splashes back into the pool, it is assumed to be in vacuum state or in its lowest possible state of energy.
Here’s the problem: There are two possibilities for the vacuum state of the universe. It might be a true vacuum, in which case the energy of the Higgs field really is the lowest it can go. However, it also might be a false vacuum, in which case there’s another lower-energy state we don’t know about — the pool happens to have a giant bathtub plug, and pulling it can make all of the water rush into an even lower state. The analogy in itself is quite terrifying.
An event possessing overwhelming amounts of energy taking place at any time in the universe could literally pull the plug on existence itself. Quantum particles have the ability to “tunnel” through a barrier, whether from one side of a wall to another or from one vacuum state to another, so random quantum fluctuations could do this too.
“That would be bad,” Mack said, “because the true vacuum has different constants of nature than the false vacuum. Constants of nature are things like the charge of the electron or the mass of the particles or even the strength of gravity sometimes. So if you take the molecules that you’re made of and put them into a true vacuum state, those molecules don’t hold together anymore. Total destruction.” All it takes is a lone particle drifting into a place it shouldn’t and boom. We are sorry for ruining your sleep tonight.