He is best known for being the discoverer of positronium. Molecules of positronium hydride (PsH) can be made. Exotic molecules such as positronium hydride have also been made. The lifetime of positronium deuteride is indistinguishable from the hydride. Due to its short lifetime, establishing the chemistry of positronium hydride poses difficulties. Natural formation of positronium atoms is predicted to begin in about years. B. Other substances that contain positronium are di-positronium and the ion Ps with two electrons. Positronium could then turn into mirror positronium and then decay into mirror photons. Example&colon; the "positronium" is a bound state electron-positron similar to a hydrogen atom. Electrons and positrons drifting through space will encounter one another and occasionally form positronium atoms. Positronium in the 2S state is metastable having a lifetime of against annihilation. The positronium helide ion PsHe should be formed when positrons encounter helium. R. Pareja, R. Gonzalez from Madrid trapped positronium in hydrogen laden magnesia crystals. Positronium is an "atom" consisting of an electron and a positron.