Researchers in New York have found antimatter holds together in much the same way as matter. That finding rules out one possible explanation for why antimatter is so rare.

Antimatter was already known to be almost exactly the same as matter, the main differences being that its components (antiparticles) have an opposing charge and quantum spin. The theory of the Big Bang means that in the initial moments of the universe, matter and antimatter should have been created in equal quantities.

Today virtually everything that can be observed from Earth is made of matter and why there’s no longer a symmetry between the two is unclear. The simplest explanation is that the proportions are still the same across the universe as a whole and there are places where almost everything is antimatter.

That doesn’t seem to hold up however: if that were the case, the boundaries between matter-dominated and anti-matter dominated areas should be producing collisions which result in powerful gamma rays that we should be able to detect.

Another possibility is that there’s some significant difference between matter and antimatter that’s caused the imbalance.

Researchers at the Relativistic Heavy Ion Collider in New York have been producing and examining small quantities of antimatter. In particular they’ve been looking at antiprotons, the antimatter equivalent of a proton. They were able to isolate the relationships between pairs of protons from the effects of other particles such as antineutrons.

It turns out that not only do pairs of antiprotons attract one another with a strong enough force to overcome any other repellent forces (in the same way that protons bind together in matter), but the force is exactly as strong as the proton equivalent. In other words, as far as holding together goes, protons and antiprotons are symmetrical.