Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our
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written by a professional astronomer.
2021 April 13
Confirmed Muon Wobble Remains Unexplained
Image Credit: Fermi National Accelerator Laboratory; Photographer:
Reidar Hahn
Explanation: How fast do elementary particles wobble? A surprising
answer to this seemingly inconsequential question came out of
Brookhaven National Laboratory in New York, USA in 2001, and indicated
that the Standard Model of Particle Physics, adopted widely in physics,
is incomplete. Specifically, the muon, a particle with similarities to
a heavy electron, has had its relatively large wobble under scrutiny in
a series of experiments known as g-2 (gee-minus-two). The Brookhaven
result galvanized other experimental groups around the world to confirm
it, and pressured theorists to better understand it. Reporting in last
week, the most sensitive muon wobble experiment yet, conducted at Fermi
National Accelerator Laboratory (Fermilab) in Illinois and pictured
here, agreed with the Brookhaven result. The unexpected wobble rate may
indicate that an ever-present sea of virtual particles includes types
not currently known. Alternatively, it may indicate that flaws exist in
difficult theoretical prediction calculations. Future runs at
Fermilab's g-2 experiment will further increase precision and,
possibly, the statistical difference between the universe we measure
and the universe we understand.
Tomorrow's picture: supernova shock wave
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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.
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