'Gravity saved the universe after the Big Bang'

Shedding light on why the universe did not collapse immediately after the Big Bang, European researchers have found that gravity provided the stability needed for the universe to survive expansion during that period.

Physicists from the Imperial College London and the universities of Copenhagen and Helsinki investigated the interaction between the Higgs particle - discovered in 2012 and responsible for giving mass to all particles - and gravity, taking into account how it would vary with energy.

They found that even a small interaction would have been enough to stabilise the universe against decay.

The Standard Model of Particle Physics, which scientists use to explain elementary particles and their interactions, has so far not provided an answer to why the universe did not collapse following the Big Bang.

"Our research investigates the last unknown parameter in the Standard Model - the interaction between the Higgs particle and gravity. This parameter cannot be measured in particle accelerator experiments, but it has a big effect on the Higgs instability during inflation," said professor Arttu Rajantie from the department of physics at the Imperial College London.

"Even a relatively small value is enough to explain the survival of the universe without any new physics!" he added.

Studies of the Higgs particle suggested that the production of Higgs particles during the accelerating expansion of the very early universe should have led to instability and collapse.

Scientists have been trying to find out why this did not happen, leading to theories that there must be some new physics that will help explain the origins of the universe that has not yet been discovered.

"Our aim is to measure the interaction between gravity and the Higgs field using cosmological data," Rajantie said.

"If we are able to do that, we will have supplied the last unknown number in the Standard Model of particle physics and be closer to answering fundamental questions about how we are all here," Rajantie added.

The new study was detailed in the journal Physical Review Letters.