Oops -- found it. Not too dramatic.

Posted by Sparrow on Jun 02, 2002 at 20:12

Re: Photons. I need some help, if you can and will.... (Sparrow)

Physics News Update

The American Institute of Physics Bulletin of Physics News

Number 337 (Story #2), September 18, 1997 by Phillip F. Schewe and Ben Stein


REAL PHOTONS CREATE MATTER. Einstein's equation E=mc2 formulates the idea that matter can be converted into light and vice versa. The vice-versa part, though, hasn't been so easy to bring about in the lab. But now physicists at SLAC have produced electron-positron pairs from the scattering of two "real" photons (as opposed to the "virtual" photons that mediate the electromagnetic scattering of charged particles). To begin, light from a terawatt laser is sent into SLAC's highly focused beam of 47-GeV electrons. Some of the laser photons are scattered backwards, and in so doing convert into high-energy gamma ray photons. Some of these, in turn, scatter from other laser photons, affording the first ever creation of matter from light-on- light scattering of real photons in a lab. (D.L. Burke et al., Physical Review Letters, 1 September 1997.)

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