Was the Big Bang actually a 'Big Bounce'? New theory claims universe sprang into life

Study says universe may have ‘sprung’ from a previous contracting state

This would mean a less violent birth than Big Bang or Big Crunch scenario

They say it may alternate from expansion to contraction without collapsing

The birth of the universe might not have been as violent as previously thought.

According to a new study, the universe may experience alternating periods of expansion and contraction, moving from one state to another without collapsing upon itself.

This theory – known as the ‘Big Bounce’ – has long been debated, but now, researchers have developed a model to show how such a scenario could be possible, allowing a new universe to ‘spring’ from a previous contracting state.


THE 'BIG BOUNCE'

Researchers say the start of the universe may have sprung as it transitioned from a previously contracting state.

They suggest that all particles in the early universe would have been governed by the laws of quantum mechanics.

So rather than collapsing and destroying itself at the end of a period of contraction, the universe was likely saved by quantum mechanics.

This would mean the universe did not experience a violent beginning or ending, as in the Big Bang and Big Crunch scenarios.

It’s commonly thought that the current expansion of the universe is a result of the Big Bang, bursting into existence from a point of dense, hot material.

While physicists have discussed the idea of a Big Bounce since 1922, this theory has been inhibited by the inability to explain how the universe could transition without collapsing completely.

In the new study, published in Physical Review Letters, researchers explain that all particles in the early universe would have been governed by the laws of quantum mechanics.


This, for example, enables atoms to exist, preventing electrons from losing energy and collapsing as they travel around the nucleus.

While quantum mechanics governs the behaviour of subatomic particles, larger matter behaves differently, breaking the conformal symmetry.

In the early universe, the researchers say the same physical laws would have worked for the entire structure, along with interactions on a scale smaller even than individual atoms.

So rather than collapsing and destroying itself at the end of a period of contraction, the universe was likely saved by quantum mechanics, the researchers say.


‘Quantum mechanics saves us when things break down,’ said Dr Steffen Gielen from Imperial College London, an author on the study.

‘It saves electrons from falling in and destroying atoms, so maybe it could also save the early universe from such violent beginnings and endings as the Big Bang and Big Crunch.’

The researchers built their model on the idea that the early universe had conformal symmetry, governed by the rules of quantum mechanics.

They also included a few ‘simple ingredients’ that would likely have been present, like radiation and almost no normal matter.

Though the model, the researchers predict that the universe could have sprung from a previous universe, which was contracting.


This would mean it was not born from a point of broken physics, in the case of a full collapse.

‘The big surprise in our work is that we could describe the earliest moments of the hot Big Bang quantum mechanically, under very reasonable and minimal assumptions about the matter present in the universe,’ said Dr Neil Turok, Director of the Perimeter Institute for Theoretical Physics in Canada, who was also involved in the study.

‘Under these assumptions, the Big Bang was a ‘bounce,’ in which contraction reversed to expansion.’

As the work continues, the researchers are looking to apply this model to explain how other elements arose from the simple universe, like galaxies.

According to Dr Gielen, ‘Our model’s ability to give a possible solution to the problem of the Big Bang opens the way to new explanations for the formation of the universe.’