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Scientists find the "magic number" that links forces of the universe

Physicists determined with fantastic accuracy the worth of what's been called "a magic number" and considered one of the greatest mysteries in physics by famous scientists like Richard Feynman. The fine-structure constant (written by the Greek α for "alpha") shows the force of the electromagnetic forces between simple particles like electrons and protons and is used in formulas pertaining to matter and light.


This pure number, with no units and dimensions, is key to the mechanism of the standard model of physics. Scientists were able to change its precision 2.5 times or 81 parts per trillion (p.p.t.), deciding the value of the constant to be α = 1/137.03599920611 (with the last two digits still being doubtful).


As the scientists wrote out in their paper, pinpointing the fine-structure constant with extraordinary exactitude is not just a complex task but holds important importance "because variance between standard-model predictions and experimental observations may supply evidence of new physics." Acquiring a very precise value for a fundamental constant can aid make more accurate predictions and yield new paths and particles, as physicists look to adjust their science with the reality that they still don't fully understand dark matter, dark energy, and the difference between the amounts of matter and antimatter.

In a question with Quanta Magazine, Nobel-Prize-winning physicist Eric Cornell (who was not engaged in the study), explained that there are ratios of bigger objects to smaller ones that appear in "the physics of low-energy matter — atoms, molecules, chemistry, biology." And surprisingly, "those ratios tend to be powers of the fine-structure constant," he said.


The procedure for measuring the fine-structure constant involved a light beam from a laser that caused an atom to recoil. The red and blue colors indicate the light wave's peaks and troughs, respectively. Credit: Nature


For the fresh measurement, the group of four physicists led by Saïda Guellati-Khélifa at the Kastler Brossel Laboratory in Paris, used the method of matter-wave interferometry. This plan involves superimposing electromagnetic waves to produce an interference pattern, which is then studied for new data. In the particular experiment to acquire the new fine-structure constant value, the scientists directed a laser beam at super-cooled rubidium atoms to make them recoil while absorbing and releasing photons. By noting the kinetic energy of the recoil, the scientists deduced the atom's mass, which was then used to solve the electron's mass. The constant α was discovered in the next step, taken from the electron's mass and the binding energy of a hydrogen atom, which was arrived at by spectroscopy.


Check out the new paper published in the journal Nature.

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