Astronomers from Chengdu, China have set a new upper limit for the mass of light, challenging our understanding of the universe. Through the study of pulsing stars in the Milky Way and mysterious radio signals from distant galaxies, researchers have determined that a photon, the smallest unit of light, cannot weigh more than 9.52 × 10^-46 kilograms.
The results have major implications for physics and our perception of the cosmos. While photons are commonly believed to be massless, the possibility of even the slightest mass could revolutionize scientific theories, contradicting principles like special relativity and Maxwell’s electromagnetic theory.
Scientists emphasize that the newfound limit does not confirm that photons possess mass, but rather establishes a boundary within which their mass would have to fall if proven present. This groundbreaking research marks the first instance in which the impact of a nonzero photon mass on plasma medium has been considered and quantified as light travels through these conditions.
The team of astronomers from Sichuan University of Science & Engineering, the Chinese Academy of Sciences, and Nanjing University relied on data gathered by the Parkes Pulsar Timing Array and various sources of fast radio bursts to unveil this discovery. By studying the dispersion measure, a key attribute of pulsars and fast radio bursts, researchers could calculate potential delays caused by the mass of photons.
The findings, published in The Astrophysical Journal, highlight the necessity of sophisticated radio telescopes for further investigation. While directly measuring the mass of a photon remains a formidable challenge, continued advancements in data collection and analysis promise to deepen our understanding of this fundamental element of the universe.