In the next year, scientists hope to create matter from beams of light. A study published in Nature Photonics on Sunday explains how modern lasers could finally prove an 80-year-old theory of physics.
“We have shown in principle how you can make matter from light,” said Steven Rose at Imperial College, one of the authors of the study. “If you do this experiment, you will be taking light and turning it into matter.”
Albert Einstein’s famous 1905 equation E=mc2 first posited the idea that mass and energy are interchangeable. That means under the right conditions, energy can become matter and vice versa, determined physicists Gregory Breit and John Wheeler in the 1930s. They calculated that on very rare occasions particles of light, called photons, could collide with enough force to create electrons and positrons, the electron’s antimatter equivalent. Electrons, along with protons and neutrons, are the building blocks of atoms that make up everyday objects around us.
Breit and Wheeler believed that proving their hypothesis in a lab was “hopeless.” In the Great Depression and pre-nuclear age, such an experiment was too expensive, and the chances of observing the creation of subatomic particles were too slim, they said.
But Rose and fellow physicists at Imperial College believe that modern lasers, such as the Omega laser at the Laboratory for Laser Energetics in Rochester, New York, could do it. According to the calculations in the recent study, physicists need to squeeze enough photons into a tiny space to create a collision capable of making electrons and positrons. First, they plan to fire a beam of electrons at a slab of gold, creating a high-energy stream of protons. Then they shoot the laser into a centimeter-long gold drum, called a hohlraum, producing light as bright as a star.
Finally, they direct the first beam of photons inside the hohlraum. The authors’ calculate that the collision between the two streams of high-energy photons will create 100,000 pairs of electrons and positrons.
Rose and co-authors Felix Mackenroth, Edward Hill and Oliver Pike plan to pursue such an experiment in the next 12 months. If successful, scientists could use this photon-photon collider to study how subatomic particles interact, Pike said.
“Such a collider could be used to study fundamental physics with a very clean experimental setup: pure light goes in, matter comes out,” he told the Guardian. “The experiment would be the first demonstration of this.”