How will the universe end?
Thousands of stellar events (such as a gamma ray burst) occur everyday and most of these could quickly wipe out life on earth and plunge the Solar System into a state of chaos. However, the odds of this are quite slim, and although earth will perish one day (in about 4 billion years as its orbit decays due to energy lost in the form of gravitational waves) it isn't happening anytime soon.
As the earth and our sun will meet their inevitable end, the universe will too. In about 10^10^120 to 10^10^10^56 years, astronomers and scientists have predicted the formation of new universes. The main question is, how exactly will it happen? There are several theories that help explain the ways in which our universe might fall.
The Big Freeze
In this situation, the universe continues to grow and expand as it does today, but at an exponential rate. The gravitational waves and other forms of energy from various cosmological bodies are circulated and galaxies, along with their respective star systems begin to pull away from each other as their attractive force weakens. The universe eventually begins losing this heat and gets colder and colder until the temperature is at -273°C/absolute zero, where atoms stop moving and no energy is present. All stars, planets, etc. would die off completely, leaving the universe in a state of maximum entropy (total chaos/disorder).
The Big Crunch
The Big Crunch is the opposite of how the universe started - the Big Bang. Just as the universe expanded from a singularity, this theory states that the universe will end by everything contracting. If the average density of the universe (0.2-0.25 atoms/m^3) stops the expansion, all stellar objects would collapse on themselves into an extremely dense state, similar to how the universe is thought to have formed.
This theory also means that it is possible for the Big Crunch to happen immediately after the Big Bang, creating a never ending cycle referred to as an oscillatory universe.
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| Artist's illustration of a GRB (gamma ray burst) |
The Big Freeze
In this situation, the universe continues to grow and expand as it does today, but at an exponential rate. The gravitational waves and other forms of energy from various cosmological bodies are circulated and galaxies, along with their respective star systems begin to pull away from each other as their attractive force weakens. The universe eventually begins losing this heat and gets colder and colder until the temperature is at -273°C/absolute zero, where atoms stop moving and no energy is present. All stars, planets, etc. would die off completely, leaving the universe in a state of maximum entropy (total chaos/disorder).
The Big Crunch
The Big Crunch is the opposite of how the universe started - the Big Bang. Just as the universe expanded from a singularity, this theory states that the universe will end by everything contracting. If the average density of the universe (0.2-0.25 atoms/m^3) stops the expansion, all stellar objects would collapse on themselves into an extremely dense state, similar to how the universe is thought to have formed.
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| A model showing the contraction of the universe from top to down |
False vacuum
This theory is slightly more complex than the others. To understand it, it is essential to grasp the concept behind the Higgs field which is present throughout the universe. Similar to an electromagnetic field, it is based upon it's potential/strength. A real vacuum exists if the universe is in it's lowest energy state, as it is thought to be currently. However, if it isn't in the lowest energy state, then it is a false vacuum, i.e space isn't 'real', which is referred to as the vacuum metastability event. In layman terms, this essentially means that everything in space could instantly vanish, crumble and disappear without any warning.
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