If there’s one thing scientists love discussing more than the beginning of the universe, it’s the end. Here are some of the most popular scientific theories on how the universe might meet its demise.
1. The Big Crunch
This is the opposite of the Big Bang, which started the expansion of the cosmos. It assumed that the average density of the universe will halt its expansion and begin contracting. The contraction will bring all matter in the universe back together, wiping out everything. In the end, the universe once again become an infinitely dense singularity. Of course, nothing will survive.
2. The Big Bounce
As in The Big Crunch, gravity slows the expansion of the universe and starts drawing everything back into a single point.
However, it posits that singularities violate the second law of thermodynamics, which stops the universe from being bounded by singularities.
In short, a Big Crunch is prevented and instead, we get a new Big Bang. In this way, the universe gets “recycled” over and over ad infinitum.
3. The Big Rip
In this theory, the unseen force known as “dark energy” causes the accelerating expansion of the universe.
Expansion speeds up, and it continues indefinitely. Eventually, matter can no longer hold itself together, and atoms themselves are ripped apart.
According to some estimates, if the Big Rip happens, it will occur in about 16 to 22 billion years.
4. The Big Freeze
This event is also referred to as “Heat Death” or “The Big Chill.”
It posits that, as the universe continues to expand and objects are the pulled farther and farther apart heat is dispersed throughout space.
It will become colder and colder. Eventually, all the stars will dissipate and there won’t be enough energy left to ignite new ones.
The entire universe will essentially go out. Matter will still be there, but in particle form, barely moving in an eternally dark void.
5. The big slurp
Based on the discovery of the Higgs, this event posits that the universe exists in a fundamentally unstable state, which could make way for a vacuum metastability event.
When this catastrophic event happens a bubble or alternate universe will appear.
This bubble will expand in all directions at the speed of light, and it will any annihilate everything it comes in contact with.
However the universe will still be there, though it wouldn’t be anything that we comprehend via our current understanding of Physics.
6. Multi Universe, Not Complete End
In a multiverse scenario, our cosmos is just one of many.
These individual universes may spring in and out of existence. Some may die through a big Crunch or a Big Rip while others are born through a Big Bang.
But it doesn’t matter. The larger “universe” will still be there.
Even though time itself could run out in some universes, in a multiverse, new universes are being born all the time. And the total will go on.