Are simpler and lighter atoms than hydrogen possible?

If we stick to elements made up of protons and electrons, the answer is obviously no, because you cannot have less than one proton in the nucleus of an atom.

But there is an exotic type of atom, in which one of the ‘normal’ particles is replaced by other types of particles, in which exactly this happens.

It is called a muon, and is formed by an electron orbiting an antimuon.

Muons are particles virtually identical to electrons except for a mass 200 times greater, but which is still 9 times smaller than that of a proton.

Antimuons, which are positively charged, can for all intents and purposes become lighter nuclei than protons, for the very short time they remain stable, and do not annihilate with electrons, since they are different particles.

The element thus made not only has a lower mass than a single proton, but its behavior and orbitals are very similar to those of hydrogen, and is in fact considered its lightest isotope.

It is also one of the simplest atoms that can theoretically exist, as both antimuons and electrons are fundamental particles with no internal structure.

This makes them the easiest atoms for physicists to describe and study, and a useful tool to see where experiments do not…