Physicists suspect they have created the first molecules from atoms that meld matter with antimatter.

Allen Mills of the University of California, Riverside, and his colleagues say they have seen telltale signs of positronium molecules, made from two positronium atoms.

Positronium is an other-worldly mimic of hydrogen… just as hydrogen atoms will combine to form two-atom molecules, so it should be possible in theory to unite two positronium atoms to form a molecule, which would be written as Ps₂.

But positronium does not exist naturally, because matter and antimatter annihilate one another when they meet, releasing a burst of energy. When a positron and electron are combined artificially to create a positronium atom, as was first done in 1951, it quickly self-destructs, emitting energy as a gamma ray…