What’s going on here? It seems that protons are defying the law of physics. But that can’t be, can it?
Physicists studying atomic spin surprised themselves by discovering that spinning protons bizarrely change direction when they crash into larger particles, like the nuclei of gold atoms.
On a pool table, you’d expect a left-spinning cue ball to deflect off to the right after it hits another ball. What the physicists observed would be the equivalent of a left-spinning cue ball acting normally when striking another billiard ball, but deflecting to the left—and way more forcefully—after striking a bowling ball, according to a press release from the Brookhaven National Laboratory.
Brookhaven National Laboratory is one of 10 labs across the United States funded by the Office of Science of the U.S. Department of Energy. It contains the Relativistic Heavy Ion Collider (RHIC), the only collider for spin-polarized protons in the world, which was previously responsible for the discovery that antiprotons (antimatter protons) are capable of behaving like regular protons, according to Scientific American. The RHIC became the first instrument to cause a high-energy collision between polarized protons and gold nuclei in 2015.
A research team used the RHIC to study what happens when polarized protons collided with particles representing a range of different sizes—protons the same size as each other as well as larger aluminum nuclei and still larger gold nuclei. A paper describing the research was published in the scientific journal Physical Review Letters.
“What we observed was totally amazing,” said Brookhaven physicist Alexander Bazilevsky in the press release. “Our findings may mean that the mechanisms producing particles along the direction in which the spinning proton is traveling may be very different in proton-proton collisions compared with proton-nucleus collisions.”