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In a novel experiment at the Stanford Linear Accelerator Center, investigators forced light beams to collide with each other in a vacuum and created two tiny specks of matter. The crashing beams conjured up an electron and its antimatter counterpart, a positron.

Physicists had long thought this possible, but no laboratory could pump enough power into the colliding beams of radiation to create matter from nothingness. The Stanford linear acclerator, however, had enough juice to do the job.

One of the light beams used in the experiment was produced by a trillion-watt green laser, but that wasn’t enough. It was the other beam ­ boosted by energy drawn from electrons whizzing down the two-mile-long accelerator ­ that supplied the needed energy. The photons from the laser were allowed to collide almost head on with 47-billion-electron-volt electrons shot from the particle accelerator.

The field created by the electrons colliding was so high, Dr. Adrian C. Melissinos of the University of Rochester said, “that the vacuum within the experiment spontaneously broke down, creating real particles of matter and antimatter.”

The idea of doing something like this is based on Einstein’s special theory of relativity, which showed that matter and energy are equivalent and that one can be transformed into the other through the famous equation E = mc2. This explains the vast energy released by matter in nuclear explosions, but it also means that a huge amount of energy is required to create even the tiniest particles of matter.

While this is all very interesting, the experiment is unlikely to have many practical applications, though it might help in the design of a new generation of research accelerators. A possible future accelerator might work by colliding opposing beams of photons. ST

Colliding Beams (Plain text)

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