Scientists clarified the value of the fine structure constant

(ORDO NEWS) — French physicists have calculated as accurately as possible the value of the fine structure constant – one of the most important fundamental constants that determines the appearance and properties of the Universe around us. The new value turned out to be about three times more accurate than the previous ones. An article with the results of the calculations was published in the scientific journal Nature.

Scientists are actively arguing about whether the laws of physics were always the same, or during the Big Bang and in the first epochs of the Universe, when its boundaries expanded very quickly, they could be different from modern ones.

In particular, cosmologists want to know if the value of one of the most important physical constants, the fine structure constant, has changed. This dimensionless quantity determines the nature of the interactions between electromagnetic radiation and matter. At last count, it is equal to one divided by 137.035. However, as observations of white dwarfs and distant quasars show, during the youth of the universe, it could have been different.

Physicists from France, under the guidance of a professor at the Sorbonne University Saida Gelatti-Helifa, clarified the value of this constant. To do this, they watched the speed with which a rubidium atom begins to move, illuminated by a laser with a clearly verified power, size and shape.

The value of the fine structure constant can be determined both directly and indirectly using the values ​​of other quantities, which are much easier to measure. In direct experiments, scientists typically cool atoms of rubidium or cesium to near absolute zero and observe how they interact with particles of light.

By illuminating it with a laser, physicists measure how fast this atom is moving. Thanks to this, its mass can be measured very accurately. This value is then used to calculate the mass of the electron, which in turn determines how tightly it is bound to the atom. It is through this ratio that the fine structure constant can be calculated.

Gelatti-Helifa and her colleagues have dealt with most of the noise and uncertainties that arise in such measurements due to imperfections in the laser and measuring instruments. Thanks to this, the scientists tripled the accuracy of the calculations and obtained the value of the fine structure constant with a record low error of 80 parts per trillion. According to their calculations, this value is one divided by 137.035999206 (11).

This value, as scientists note, is consistent with what the Standard Model predicts – a theory that describes most of the interactions of all elementary particles now known to science. This speaks in favor of the fact that the electron is a truly indivisible elementary particle. In addition, the new meaning greatly narrowed the space for the search for hypothetical dark matter particles, which, in theory, could affect the behavior and some properties of electrons.

On the other hand, as physicists write, the new value of the fine structure constant strongly differs from their previous estimates, which were obtained in 2011 and 2012 using two other methods, and also do not coincide with the measurements of their colleagues from the United States, published in 2018. These discrepancies are expressed in the fact that the more accurate value of the fine structure constant turned out to be higher than all earlier estimates.

What is the reason for this discrepancy in values, scientists do not yet know. They suggest that the reason for this was the peculiarities in the operation of lasers and the technique for “removing” noise from the data, and not real physical processes that go beyond the scope of the Standard Model. Physicists hope that further experiments will help to find out what is the reason for this, and will allow scientists to check for the first time whether electrons have the same anomalous magnetic properties as muons, their heavy counterparts.


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