They used high-energy electrons traveling near the speed of light, produced by SLAC's two-mile-long accelerator, and photons from a powerful, "tabletop terawatt" glass laser developed at Rochester's Laboratory for Laser Energetics. Physicists accomplished the feat by dumping an incredible amount of power - nearly as much as it takes to run the entire nation but lasting only for a tiny fraction of a second - into an area less than one billionth of a square centimeter, which is far smaller than the period at the end of this sentence. In this experiment scientists observed for the first time the creation of particles from real photons, packets of light that scientists can observe directly in the laboratory. Sometimes this energy burst contains very short-lived packets of light known as "virtual photons" which go on to form new particles. When they smash together particles like protons and anti-protons in high-energy accelerator experiments, the initial particles are destroyed and release a fleeting burst of energy.
Now physicists have succeeded in doing the opposite: converting energy in the form of light into matter - in this experiment, electrons and their anti-matter equivalent, positrons.Ĭonverting energy into matter isn't completely new to physicists. Scientists have long been able to convert matter to energy the most spectacular example is a nuclear explosion, where a small amount of matter creates tremendous energy.
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