A team from Sichuan University of Science and Technology, Chinese Academy of Sciences, and Nanjing University analyzed data collected by the Parkes Pulsar Synchronization Array, as well as data on fast radio bursts from various sources, to determine how heavy the light might be. .

The theory that breaks everything

If we go a little further, we reach a possible upper limit of the mass of light. According to measurements of pulsating stars scattered throughout the Milky Way and mysterious radio signals from other galaxies, a particle of light cannot weigh more than 9.52×10.^-46 kilogram This is a very small limit, but discovering that light has any mass at all would have a profound impact on how we interpret the universe around us and our understanding of physics. Non-zero mass will have profound consequences. This would contradict Einstein’s special theory of relativity and Maxwell’s electromagnetic theory, and would likely lead to a new physics that would answer some huge questions about the universe, but reveal much more in the process.

If a photon had mass, it would have to be extremely small to have no significant effect on the origin of the universe; This means we don’t have the tools to measure it directly. But we can make indirect measurements that would give us an upper limit on this hypothetical mass, and this is exactly what a group of astronomers have done using the Synchronized Pulsar Array.

Synchronization sequence of pulsars It is a collection of radio telescope antennas used to observe neutron stars that send beams of electromagnetic radiation pulsating at extremely precise millisecond pulsars. Fast radio bursts are extremely powerful bursts of light of unknown origin recorded in the vast intergalactic voids of space.

This feature that scientists are studying is known as a measure of dispersion, which is one of the fundamental properties of pulsars and fast radio bursts. It shows how strongly a pulsed beam of radio radiation is scattered by free electrons between us and the light source.

Synchronization sequence of pulsars Looks for delays in the synchronization of pulsar pulses relative to each other. Particularly over an ultra-wide frequency range, dispersion effects can be minimized, allowing researchers to calculate how much delay a hypothetical mass of photons could cause. Meanwhile, scattering of signals from fast radio emissions can also cause a delay proportional to the mass of the photon.

By carefully examining this data, the team managed to determine the upper limit as follows: 9.52×10^-46 kilogram. But don’t rush. The scientists themselves say that this does not mean that light has mass. It just means that we have a new limit to which light can intervene if mass is present.

This is the first time that the interaction between a photon of non-zero mass and a plasma medium has been considered and calculated during the propagation of a photon in a plasma medium.
– the authors write.

According to astronomers, the study reveals the need for high-precision radio telescopes. It’s unlikely we’ll be able to weigh a photon in the near future, but consistently obtaining high-quality data will allow us to further narrow the limits of measurement, and with them their potential impact on the universe around us.