Scientists tested an electron’s response to a magnetic field with extreme accuracy. Why? Premium
The Hindu
The answer involves one of the most successful theories in the history of physics.
To see a world in a grain of sandAnd a heaven in a wild flower,Hold infinity in the palm of your handAnd eternity in an hour
It’s hard to keep these words, written by the poet William Blake in ‘Auguries of Innocence’, away when we are looking for clues about the fundamental nature of reality in the properties of subatomic particles.
In an astonishing feat of metrology, physicists recently reported measuring the electron’s magnetic moment with a precision of 0.13 parts per trillion (ppt). The resulting measurement is 2.2-times more accurate than the previous best, recorded 14 years ago. More importantly, it’s the most precise test so far of a theory that has both comforted and baffled physicists – the Standard Model of particle physics – and therein lies the rub.
What is the Standard Model?
The Standard Model (SM) is the theory that describes the properties of all subatomic particles, classifies them into different groups, and determines how they’re affected by three of the four fundamental forces of nature: strong-nuclear force, weak-nuclear force, and the electromagnetic force (it can’t explain gravity).
In the 1960s, physicists used SM to predict the existence of a particle called the Higgs boson; it was finally discovered in 2012. Similarly, the SM has allowed physicists to successfully predict the existence and properties of dozens of particles and is considered to be one of the most successful theories in the history of physics.
However, it still can’t explain why the universe has more matter than antimatter, what dark matter is, or what dark energy is. In one strategy to crack these still-open questions, physicists have tested different SM predictions to higher and higher limits and checked whether the predictions agree with observations.
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