Fragile particles rarely seen in our Universe have been merged with ordinary electrons to make a new form of matter. Di-positronium, as the new molecule is known, was predicted to exist in 1946 but has remained elusive to science... The discovery, reported in the journal Nature, is a key step in the creation of ultra-powerful lasers known as gamma-ray annihilation lasers. "The difference in the power available from a gamma-ray laser compared to a normal laser is the same as the difference between a nuclear explosion and a chemical explosion," said Dr David Cassidy of the University of California, Riverside, and one of the authors of the paper. "It would have an incredibly high power density." As a result, there is a huge interest in the technology from the military as well as energy researchers who believe the lasers could be used to kick-start nuclear fusion in a reactor.