Now, convert light into matter

Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron - the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

The new research, published in Nature Photonics, shows how Breit and Wheeler's theory could be proven in practise. This 'photon-photon collider', which would convert light directly into matter using technology that is already available, would be a new type of high-energy experiment.

This physics experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts. The scientists had been investigating unrelated problems when they realized what they were working on could be applied to the Breit-Wheeler theory. Demonstrating the Breit-Wheeler theory would provide the final jigsaw piece of a puzzle which describes the simplest ways in which light and matter interact.

"Despite all physicists accepting the theory to be true, when Breit and Wheeler first proposed the theory, they said that they never expected it be shown in the laboratory. Today, nearly 80 years later, we prove them wrong," said Steve Rose from the department of physics at Imperial College.