Scientists are speculating whether the universe could ultimately collapse in a ‘Big Crunch’ as the mysterious force binding it is fading.

It’s well known that the universe began in an explosion known as the Big Bang, but scientists now say that it might end with a ‘Big Crunch’. 

One scary idea suggests that eventually, the universe will shrink inward until all matter is squeezed into a very hot and dense inferno.

And scientists now believe they have discovered a critical piece of evidence that shows this process could begin at any time.

A groundbreaking new study suggests the mysterious force which prevents the universe from shrinking could be weakening.

Scientists previously thought that this force, known as ‘dark energy’, was a constant which always pushed the cosmos apart at the same rate.

However, recent research, which incorporates the most extensive map of the universe ever created along with other essential observations, challenges this concept.

Dr. Willem Elbers, a scientist at Durham University’s Institute for Computational Cosmology involved in the study, points out that for many years, scientists have based their understanding of the universe on a standard model. Yet, the latest findings propose that dark energy could be changing as time progresses.

‘If this is true, it will change everything we thought we knew about the cosmos.’

Ever since the Big Bang, estimated to have occurred approximately 13.8billion years ago, the universe has been expanding like a balloon being blown up.

To explain why the universe is expanding, Albert Einstein proposed that there must be a constant force called ‘dark energy’ pushing things apart.

According to what scientists call the ‘standard model’, this force should mean that the universe keeps on expanding forever.

However, some scientists have proposed that gravity will eventually overwhelm dark energy and pull the universe back together in the reversal of the Big Bang.

If this were to happen, stars and galaxies would collide and merge into a burning core where the surface of stars would ignite other celestial bodies.

The energy of the universe would become hotter until it reached thousands of degrees Celsius, tearing hydrogen atoms into free protons and electrons.

Eventually, the universe itself would become a single, vast fireball in which all matter, life, and even time and space itself would ultimately be destroyed under the immense force of gravity.

Until now, this has been nothing more than a speculative theory about what might happen rather than a realistic scenario.

However, this new research suggests that dark matter is not a constant as Einstein proposed but, rather changes over time – meaning that the universe could start to collapse.

And this could all happen ‘remarkably’ quickly, according to study co-author Paul Steinhardt, Director of the Princeton Center for Theoretical Science at Princeton University in New Jersey. 

These new results emerge from the latest survey by the Dark Energy Spectroscopic Instrument (DESI) in Kitt Peak National Observatory, Arizona.

This is an exceptionally advanced telescope which uses robotically-controlled fibre-optic ‘eyes’ to capture the light from 5,000 different galaxies at once.

Through the efforts of 9,000 researchers around the globe, scientists have used this data to create the biggest and most detailed map of the known universe ever produced. 

Scientists then compared this map to other measurements, such as heat left over from the Big Bang called the Cosmic Microwave Background (CMB) and the light from exploding stars.

The standard model can explain almost all of these measurements individually but struggles to explain all the observations taken together.

Professor Will Percival, co-spokesperson for DESI and an astronomer from the University of Waterloo, says: ‘We’re guided by Occam’s razor, and the simplest explanation for what we see is shifting.

‘It’s looking more and more like we may need to modify our standard model of cosmology to make these different datasets make sense together – and evolving dark energy seems promising.’

In particular, the researchers looked at subtle patterns in how matter was distributed after the Big Bang called ‘baryon acoustic oscillations’ – essentially soundwaves spreading through the universe like ripples on a pond.

These ripples act like a standardised ruler, so, by looking at how big this ruler seems at different times in the universe’s evolution, researchers can work out how fast the universe is expanding.

That, in turn, lets researchers work out how hard dark energy has been pushing the universe outwards.

With new, extremely precise measurements, the researchers are now very confident – although not completely certain – that this force has been changing over time.

If so, that means a scenario in which weakening dark energy is overwhelmed by gravity and the universe collapses in a Big Crunch could be much more likely.

Not only that, but it may mean scientists need to chuck out everything they have assumed about the universe so far and come up with a new standard model.

Dr Andrei Cuceu, a researcher at Berkely Lab who worked on the study, says: ‘We’re in the business of letting the universe tell us how it works, and maybe the universe is telling us it’s more complicated than we thought it was.’

WHAT IS DARK ENERGY?

Dark energy is a phrase used by physicists to describe a mysterious ‘something’ that is causing unusual things to happen in the universe. 

The universe is full of matter and the attractive force of gravity pulls all matter together. 

Then came 1998 and the Hubble Space Telescope observations of very distant supernovae that showed that, a long time ago, the universe was actually expanding more slowly than it is today.

The universe is not only expanding, but it is expanding faster and faster as time goes by,’ Dr Kathy Romer, scientist at the Dark Energy Survey told MailOnline, as illustrated in this Nasa graphic

So the expansion of the universe has not been slowing due to gravity, as everyone thought, it has been accelerating. 

No one expected this, no one knew how to explain it. But something was causing it.

‘The universe is not only expanding, but it is expanding faster and faster as time goes by,’ Dr Kathy Romer, scientist at the Dark Energy Survey told MailOnline.

‘What we’d expect is that the expansion would get slower and slower as time goes by, because it has been nearly 14 billion years since the Big Bang.’

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.