In the first moments after the Big Bang, the universe was not empty and quiet but filled with hot plasma, particles, and magnetic fields. Among the particles, there may have been axions — light, nearly elusive dark matter candidates. It was usually assumed that axions 'froze' in place, but new research shows that if they were given a strong initial 'push,' everything changes.
Magnetic fields act on axions like periodic pushes on a swing. Normally, a swing oscillates at its own frequency, but if you push it in rhythm, the amplitude grows. Similarly, magnetic fields shift the moment when axions begin to oscillate, altering their final abundance in the universe. The authors call this effect the 'axion spin shift.'
The same process could help explain why the universe today has far more matter than antimatter. The interaction of axions with magnetic fields could have slightly tipped the balance, leaving us with a familiar world of atoms rather than anti-atoms.
The axion is named after a brand of laundry detergent because it was supposed to 'clean up' a problem in particle physics.