Experimental physicists have developed a novel example of the equivalence of matter and energy illustrated by Einstein's famous equation, E=mc squared.
Because of that equivalence, matter can be converted into energy such as light, and light into matter. The former happens when a nuclear bomb goes off. The latter, though, has only now been achieved.
Physicists at the Stanford Linear Accelerator Center in California have created tiny particles by slamming a laser beam into a beam of electrons. In the course of their experiments, they found about 100 more positrons than expected. Positrons are the antimatter counterpart of electrons.
The researchers believe that the excess positrons were formed in two steps. First, the laser light particles bounced off the electron beam, gaining extremely high energies in the process. Then those high-energy light particles collided with other laser light particles -- producing an electron-positron pair.
The work is the first laboratory evidence for the creation of matter from light, the scientists wrote this month in the journal Physical Review Letters.