Since the Higgs boson was discovered at the Large Hadron Collider in Switzerland in 2012, researchers have studied this mysterious particle – which is responsible for giving mass to all particles – to learn its contributions to our universe’s inner workings. One startling announcement earlier this year was that the Higgs boson should have made our universe collapse less than one second after it began expanding outward from the Big Bang. The universe did not collapse – it has been known for decades to be expanding – and now European physicists say they can explain why without the need for “new physics.”
Publishing in Physical Review Letters on November 17, 2014, the researcher describe how the spacetime curvature – in effect, gravity – provided the stability needed for the universe to survive expansion in that early period.
The team investigated the interaction between the Higgs particles and gravity, taking into account how it would vary with energy. They show that even a small interaction would have been enough to stabilize the universe from collapsing back to nothing, within a second after the Big Bang. Arttu Rajantie of the Department of Physics at Imperial College London said in a press release:
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 [a faster-than-light expansion just after the Big Bang]. Even a relatively small value is enough to explain the survival of the universe without any new physics!
The team says it will now use observations of the universe on the largest scales to look at this interaction in more detail. In particular, they say, they will use data from current and future European Space Agency missions measuring cosmic microwave background radiation and gravitational waves. Rajantie explained:
Our aim is to measure the interaction between gravity and the Higgs field using cosmological data. 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.
Bottom line: A second after the Big Bang, the Higgs boson should have caused a Big Crunch, collapsing the universe to nothing. But gravity stepped in to save the day.