Protons seem to be a different size depending on how you look at them
Protons contain three quarks that are glued together by particles called gluonsSefa Kart/Alamy
The proton, one of the building blocks for all matter, has a variable size depending on how you look at it. If you are looking at its charge, it will have one radius, but if you look at its mass, you will see a smaller radius because its mass is kept at the centre.
“We have a new picture of the proton. It’s not that we removed information, it’s new in the sense that we’ve added information that wasn’t there,” says Zein-Eddine Meziani at Argonne National Laboratory in Illinois.
In the 1960s, experiments that fired electrons at protons revealed that the latter contained point-like, electrically charged particles, which we now call quarks. A proton has two up quarks and a down o...