Picturing the tiny world of fundamental particles it is very difficult. The traditional view of atoms as mini-solar-systems, seen so often, is wrong. Electrons, quark, and neutrinos behave both as particles and as waves, which is not an easy thing to imagine. Luckily, some features are much easier. For example, the charge of the electron has just been confirmed to be perfectly spherical.
In a new study published in Nature, researchers from Northwestern University, Harvard, and Yale showed the electron charge really is spherically symmetric, their work reaching a precision much, much higher than previous studies. The electron being a round boi has one important consequence: It strengthens the case for the Standard Model of particle physics, our current theory of the quantum world.
The Standard Model is a curious beast. On one hand, it is one of the best scientific ideas developed by humans. It has had incredible successes and it has a phenomenal power of prediction. On the other hand, it is limited. It doesn’t include gravity, or hypothetical substances like dark matter and dark energy. Researchers are always looking for small mistakes in the predictions of the Standard Model to test it. The model suggests that the electron charge is spherical but if there were other particles or forces at play, it might not be.
“If we had discovered that the shape wasn’t round, that would be the biggest headline in physics for the past several decades,” Gerald Gabrielse, who led the research at Northwestern, said in a statement. “But our finding is still just as scientifically significant because it strengthens the Standard Model of particle physics and excludes alternative models.”
“We know the Standard Model is wrong, but we can’t seem to find where it’s wrong. It’s like a huge mystery novel,” he added. “We should be very careful about making assumptions that we’re getting closer to solving the mystery, but I do have considerable hope that we’re getting closer at this level of precision.”
The exclusion of alternative models is a problem. We need a theory that can go beyond the Standard Model, yet almost all of them require the electron to be a little squished. This means any proposed alternative theories need to be rethought to take this new study into account. The precision at which the new measurement has been taken leaves very little room for doubt.
“If an electron were the size of Earth, we could detect if the Earth’s center was off by a distance a million times smaller than a human hair,” Gabrielse explained. “That’s how sensitive our apparatus is.”
There have been hints of particles and phenomenon beyond the Standard Model but so far we are missing some incontrovertible proof.