It's extremely rare and usually exists for just 142 billionths of a second.
Positronium can generate huge amounts of energy. It can shed light on 'antimatter' which existed at the beginning of the Universe, and studying it could revolutionise physics, cancer treatment, and maybe even space travel.
But until now the elusive substance has been almost impossible to analyse because its atoms move around so much.
Now scientists have a workaround - freezing it with lasers.
"Physicists are in love with positronium," said Dr Ruggero Caravita, who led the research at the European Organization for Nuclear Research (Cern), near Geneva. "It is the perfect atom to do experiments with antimatter." READ MORE...
