Physicists at Brookhaven National Laboratory have achieved a groundbreaking experiment, creating matter from light by demonstrating the Breit-Wheeler process. Using the Relativistic Heavy Ion Collider, they accelerated heavy ions to generate nearly real photons, leading to the formation of electron-positron pairs. This experiment showcases Einstein’s E=mc² equation in action, aligning with predictions for transforming energy into matter. While these virtual photons act similarly to real ones, the experiment is a crucial step towards proving the process with real photons when technology advances to create gamma-ray lasers. Don’t forget to comment your thought about this!
Physicists have reportedly created matter from pure light for the first time, showcasing one of Einstein’s most renowned equations in action.
Albert Einstein’s well-known E=mc² equation suggests that by colliding two sufficiently energetic photons, or particles of light, you could produce matter in the form of an electron and its antimatter counterpart, a positron.
This phenomenon, first described by American physicists Gregory Breit and John Wheeler in 1934, has long been one of the most challenging to observe in physics — largely because the photons involved would need to be extremely energetic gamma rays, and gamma ray lasers are not yet available. Alternative experiments have shown matter being formed from multiple photons, but not in the direct one-to-one way necessary to definitively prove the effect.
However, researchers at the Brookhaven National Laboratory in New York now believe they’ve discovered a workaround. Using the lab’s Relativistic Heavy Ion Collider (RHIC), they’ve been able to generate measurements that closely align with predictions for this unusual transformation.
“In their paper, Breit and Wheeler already realized this is almost impossible to do,” Zhangbu Xu, a physicist at Brookhaven Lab, said in a statement. “Lasers didn’t even exist yet! But Breit and Wheeler proposed an alternative: accelerating heavy ions. And their alternative is exactly what we are doing at RHIC.”
Instead of accelerating photons directly, the team accelerated two ions — atomic nuclei that have been stripped of their electrons and thus carry a positive charge — in a large loop, guiding them past each other in a near-collision. Since these ions are charged particles moving at nearly the speed of light, they carry an electromagnetic field with them, filled with not-quite-real ‘virtual’ photons “traveling with [the ion] like a cloud,” Xu explained.
Virtual particles are temporary particles that momentarily appear as disturbances in fields between real particles. They differ from real particles as they can have mass (whereas real photons do not). In this experiment, when the ions nearly collided, their clouds of virtual photons moved so rapidly they behaved as though they were real. These virtually-real photons then collided, resulting in a very real electron-positron pair that the scientists observed.
To verify the Breit-Wheeler process as closely as possible using virtual particles, the researchers needed to confirm that their virtual photons were acting like real ones. They did this by detecting and analyzing the angles between more than 6,000 electron-positron pairs generated in their experiment.
When real particles collide, the resulting products should emerge at different angles compared to collisions of virtual particles. In this experiment, however, the secondary products of the virtual particles scattered at the same angles as those from real particle interactions. This enabled the researchers to confirm that the particles they observed were behaving as if they were generated by a real interaction, successfully demonstrating the Breit-Wheeler process.
The team also measured the energy and mass distribution of the systems. “They are consistent with theory calculations for what would happen with real photons,” Daniel Brandenburg, a physicist at Brookhaven, said in the statement.
Still, despite appearing to act like real particles, the virtual photons in the experiment remain undeniably virtual. This raises the question of whether the experiment truly demonstrated the Breit-Wheeler process, but it remains a crucial first step as physicists work toward developing lasers powerful enough to demonstrate the process with real photons.
The researchers published their findings in the Journal Physical Review Letters.