Helium atom precision measurements and calculations have a history of nearly a century. In the 1960s, theorists discovered that the fine-structure split (23P0-23P2) of the 23P energy level of helium is the best atomic system for measuring the fine structure constant α (approximately 1/137), which is the key parameter in the Quantum Electrodynamics (QED) theory. QED is the basic theory describing the quantum properties of electromagnetic interactions. It covers almost all physical systems from microscopic particles to macroscopic solids, and is currently the most accurate theory in physics. Such a measurement of α from precision spectroscopy of helium, compared with values determined from totally different methods, presents a perfect test of the consistency of physics. After 50 years of hard work, theorists have develoed different approaches to calculate the QED correction of helium to the 7th power series of α.
from General Physics News - Science News, Physics News, Physics, Material Sciences, Science https://ift.tt/30aM3Ft
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