From alien invasions to robot uprisings, there is no shortage of terrifying ways that the world might end.
But scientists have now worked out exactly when one terrifying scenario could bring the universe to a close.
According to the ‘Big Crunch’ theory, the universe will eventually collapse in on itself in a final climactic implosion.
As space itself contracts, the temperatures will soar until everything is destroyed in the ‘furnace of this cosmic hell’.
Finally, the entire cosmos will find itself packed back into an infinitely dense singularity just like it was before the Big Bang.
While this was once just a terrifying possibility, new measurements of ‘Dark Energy’ suggest the Big Crunch is the most likely outcome for the Universe.
In a recent study, scientists from Cornell University calculated exactly when the ‘Big Crunch’ could begin.
Thankfully, their calculations suggest we can relax for the time being… that is if something else doesn’t cause our demise.
Scientists have revealed the grisly details of what will happen to the universe during the Big Crunch, a time when all matter collapses into a black hole–like singularity
What is the Big Crunch?
The Big Crunch is essentially the opposite of the Big Bang which started the universe 13.8 billion years ago.
After the Big Bang, the universe rapidly expanded as a sea of superheated matter cooled into the familiar particles which make up the cosmos today.
During the Big Crunch, this process will run in reverse – compacting space back into a hot, dense state.
Scientists believe the current outward expansion of the universe is due to a mysterious force called Dark Energy.
If the pushing force of Dark Energy was constant, the universe would keep on expanding and cooling for ever.
But now, astronomers are beginning to question whether this really is the case.
Based on the latest data, some scientists believe that Dark Energy is weakening, leaving an inward force called the cosmological constant to pull the universe back together.
On the standard model of cosmology, the universe is being pushed apart by a constant force called dark energy. However, researchers now believe that this force could be weakening over time
The latest map of the known universe suggests that dark energy is getting weaker, which means the universe will one day fall back in on itself like a ball falling back to Earth under the influence of gravity
Dr Ethan Yu–Cheng, of Shanghai Jiao Tong University, told MailOnline: ‘It is just like throwing a basketball vertically upwards in daily life.
‘The negative cosmological constant acts like the Earth’s gravity, which pulls the basketball downward. The basketball will de–accelerate until reaching the maximum height and start to fall.’
Would we notice the Big Crunch starting?
If it’s difficult to imagine what life during the Big Crunch would be like, think about the universe as a balloon with lots of little dots drawn on its surface.
As you blow air in, the balloon expands, the surface stretches, and the distance between all the dots grows larger.
The Big Crunch is like letting all the air out of the balloon at once, bringing those distant points back together in a rush.
However, the process would start very slowly.
Dr Hoang Nhan Luu, a researcher at the Donostia International Physics Center, told MailOnline: ‘Intelligent civilisations at the scales of solar systems or even galactic scales would not notice any obvious phenomenon because these changes happen at much larger cosmological scales.
Just as the Hubble Space Telescope’s observations (pictured) showed that the universe is now expanding by measuring the light from faraway galaxies, astronomers in the far future would see galaxies suddenly come back towards them
‘Civilisations like us typically exist on time scales of hundreds to thousands of years while the changes happen on billion–year time scales, so we wouldn’t notice any obvious day–to–day phenomenon until the very last moment.’
But Dr Luu says that any observant humans still alive in the universe would be able to spot the warning signs.
Just as we can look at distant galaxies to see that the universe is expanding, astronomers of the future would be able to see that the galaxies are now rushing towards them.
What would the first signs of the Big Crunch be?
The first obvious sign that the universe was changing would be that the cosmic temperature would start to increase.
Professor Avi Loeb, a theoretical physicist from Cornell University, told MailOnline: ‘It is the reverse history of our expanding universe.’
The universe has been getting colder as it expands, like gas escaping from a pressurised container.
During the Big Crunch, this process will play out in reverse and raise the temperature of space.
As the universe collapses inwards, the temperature of the cosmic background radiation (pictured) would increase exponentially. Eventually, the cosmos would hit the ‘Planck temperature’, the hottest temperature possible according to physics
About 13 billion years from now, Professor Loeb predicts the density of energy in the universe will be about 1,000 times higher than it is now.
Just half a billion years after that, it would be another 1,000 times higher, making the universe room temperature.
Professor Loeb says: ‘At this point it wouldn’t be the sun warming that is warming us, but the equivalent of the Cosmic Microwave Background.’
Within a few million years, the entire universe would be as hot as the surface of the sun.
Eventually, the universe would reach the ‘Planck temperature’, the highest possible temperature according to our models of physics.
Professor Loeb says: ‘Needless to say, all humans will burn up in the furnace of this cosmic hell.
What will happen to the solar system during the Big Crunch?
During the Big Crunch, the universe will eventually become so dense that the planets and stars will be pushed together by the collapse.
Despite Dark Energy’s push, the solar system isn’t expanding because it is denser than the background universe. During the Big Crunch, the cosmos will become so dense that planets will be pulled into each other by the collapse of spacetime. Pictured: NASA’s map of dark matter in the universe
The only thing that will survive the collapse at first will be black holes. Black holes will actually thrive during the Big Crunch as they feed on a soup of ultra–dense matter
That means the planets of the solar system will come closer and closer together until they are crushed together.
As space approaches the final moments of the crunch, Professor Loeb says that the universe will be even denser than space inside an atom.
As the universe becomes even denser than an atomic nucleus, all matter in the cosmos will once again be squeezed back into this primordial state.
The only things in the universe to survive this transition would be black holes, which would thrive as they feed on the dense matter all around them.
Finally, this boiling mess of black holes and elementary particles would be crushed into a single infinitely dense point known as the singularity, bringing the universe to an end.
When will the Big Crunch happen?
Thankfully, scientists believe that the Big Crunch is still far off in the impossibly distant future.
Professor Henry Tye, a leading cosmologist from Cornell University, ‘We calculate that this will lead to a big crunch about 19.5 billion years from now.
By the time the Big Crunch even begins, the sun will have expanded into a red giant and swallowed up the inner planets, including Earth
‘Knowing that the age of the universe is 13.8 billion years, one obtains that the lifespan is 33.3 billion years.
In their pre–print paper, Professor Tye and his co–authors, Dr Luu and Dr Yu–Cheng, say that the Big Crunch will begin about 11 billion years from now.
The crunching phase would then last around 8.5 billion years before the universe completely collapses into a singularity.
Given that Homo sapiens have only been around for at most 300,000 years, that gives us plenty of time to relax.
Likewise, while it might not necessarily be a comforting thought, it is almost certain that humanity will have been wiped out long before then in any case.
Professor Tye says: ‘Before the big crunch, at about 5 billion years from now, the sun will use up its fuel and start growing dramatically.
‘Its outer layers will expand until they engulf much of the solar system, as it becomes what astronomers call a red giant. Eventually, it fades to a tiny white dwarf.
‘To survive, human beings have to move to the edge of our solar system or beyond. We have a few billion years’ time to prepare for that trip.’
THE BIG BANG THEORY DESCRIBES THE BEGINNING AND EVOLUTION OF THE UNIVERSE
The Big Bang Theory is a cosmological model, a theory used to describe the beginning and the evolution of our universe.
It says that the universe was in a very hot and dense state before it started to expand 13,7 billion years ago.
This theory is based on fundamental observations.
In 1920, Hubble observed that the distance between galaxies was increasing everywhere in the universe.
The Big Bang Theory is a cosmological model, a theory used to describe the beginning and the evolution of our universe, based on observations – including the cosmic background radiation (pictured), which is a like a fossil of radiation emitted during the beginning of the universe, when it was hot and dense
This means that galaxies had to be closer to each other in the past.
In 1964, Wilson and Penzias discovered the cosmic background radiation, which is a like a fossil of radiation emitted during the beginning of the universe, when it was hot and dense.
The cosmic background radiation is observable everywhere in the universe.
The composition of the universe – that is, the the number of atoms of different elements – is consistent with the Big Bang Theory.
So far, this theory is the only one that can explain why we observe an abundance of primordial elements in the universe.