Gravitational Waves Could Solve a Crucial Mystery About the Big Bang
We're on the cusp of a revolution in physics.
Much about the early universe remains a mystery to us, but a team of researchers discovered that gravitational waves might hold the key to understanding why the Big Bang, the unthinkably colossal event that seeded the universe, created more matter than antimatter, according to a study recently published in the journal Physical Review Letters.
And this means the coming decade could reveal some of the most fundamental questions about the universe.
Filling the antimatter gap in physics with gravitational waves
The only reason we're here is because at one undefined moment in the first second of the history of the universe, more matter than anti-matter was generated. The former is literally everything you've ever seen, touched, and known — even in the most distant reaches of space. This asymmetry is so vast that only one extra particle of antimatter was generated per ten billion particles of matter. The issue is that, despite this imbalance, current theories of physicists have no explanation. The theories we have actually suggest that matter and anti-matter should have been created in equal numbers, but the persistence of humans, our planet, and everything else in the universe stress the need for a more comprehensive, unknown physics.
One promising idea hypothesized by many researchers is that this asymmetry is a result of the post-inflation conditions of the young universe, when everything was undergoing a mind-meltingly rapid expansion. If this is the case, a "field blob" might have stretched beyond observable horizons to evolve and fragment in a way suitable for the creation of an asymmetric distribution of matter vs. antimatter. But there's a catch to this theory. It's hard to verify, even with the world's largest particle accelerators, since the necessary energy is billions to trillions of times higher than what we simple humans can generate so far. But the team of researchers from the study might have found a way around it.
Q-ball decay creates violent vibrations in the early universe
Using blobs of field called "Q-balls," the researchers plan to analyze this popular hypothesis of a rapidly-expanding early universe causing an asymmetry. Q-balls aren't simple, but they're much like bosons or the Higgs boson. "A Higgs particle exists when the Higgs field is excited. But the Higgs field can do other things, like form a lump," said Graham White, a project researcher at Kavli IPMU, who is also the lead author of the study. "If you have a field that is very like the Higgs field but it has some sort of charge — not an electric charge, but some sort of charge — then one lump has the charge as one particle. Since charge can't just disappear, the field has to decide whether to be in particles or lumps."
"If it is lower energy to be in lumps than particles, then the field will do that," added White. "A bunch of lumps coagulating together will make a Q-ball." White and his colleagues argued that these blobs of fields (or Q-balls) remain for a while, and then dilute slower than "the background soup of radiation as the universe expands until, eventually, most of the energy in the universe is in these blobs. In the meantime, slight fluctuations in the density of the soup of radiation start to grow when these blobs dominate," and when the Q-balls undergo decay, it happens so fast that the resulting vibrations in the background plasma transform into violent soundwaves that create "spectacular ripples in space and time, known as gravitational waves, that could be detected over the next few decades." This means that our advancing study of gravitational waves is bringing us closer to the conditions of the very early universe. And it could provide an answer to the standing asymmetry between matter and antimatter.