LIGHTNING “sprites” that dance on top of electrical storm clouds are helping to check whether photons are truly massless.
Theory predicts that photons don’t have any mass, but it has been a struggle to prove this experimentally. A new approach discovered by Martin Füllekrug at the Goethe University in Frankfurt, Germany, could help.
In a paper to be published in Physical Review Letters, Füllekrug describes measuring the ultra-low-frequency radio waves that sprites emit. He tested the method in Antarctica, using copper coils to detect the magnetic field of the radio waves, from which he deduced their speed. This was…
