in brief

Light work | FOR the first time since Einstein said that energy and matter are interchangeable physicists have created particles out of light.

Scientists from the universities of Stanford, Tennessee, Princeton and Rochester first used a powerful laser to create an extremely tightly packed beam of photons. "The density of the photons is a thousand times greater than the number of electrons per cubic centimetre in lead," says Kirk McDonald of Princeton, a member of the team.

They then injected a beam of very high energy electrons from a linear accelerator into the photon beam, slamming some photons backwards into others. The collisions created electrons and their antimatter siblings--positrons.

The experiment is reported in Physical Review Letters(vol 79, p 1626).

From New Scientist, 27 September 1997


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