(Roughly) Daily

Posts Tagged ‘electron

“Protons give an atom its identity, electrons its personality”*…

If an electron were the size of Earth, the experiment could detect a bump the size of a sugar molecule

If the electron’s charge wasn’t perfectly round, it could reveal the existence of hidden particles– and launch a “new physics.” But, as Zack Savitsky reports, a new measurement approaches perfection…

Imagine an electron as a spherical cloud of negative charge. If that ball were ever so slightly less round, it could help explain fundamental gaps in our understanding of physics, including why the universe contains something rather than nothing.

Given the stakes, a small community of physicists has been doggedly hunting for any asymmetry in the shape of the electron for the past few decades. The experiments are now so sensitive that if an electron were the size of Earth, they could detect a bump on the North Pole the height of a single sugar molecule.

The latest results are in: The electron is rounder than that.

The updated measurement disappoints anyone hoping for signs of new physics. But it still helps theorists to constrain their models for what unknown particles and forces may be missing from the current picture…

More at “The Electron Is So Round That It’s Ruling Out Potential New Particles,” from @savagitsky in @QuantaMagazine.

* Bill Bryson

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As we ponder perfection, we might spare a thought for Jean Baptiste Perrin; he died on this date in 1942. A physicist, he studied the Brownian motion of minute particles suspended in liquids (sedimentation equilibrium), and verified Albert Einstein’s explanation of the phenomenon– thereby confirming the atomic nature of matter… for which he was awarded the Nobel Prize for Physics in 1926.

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Written by (Roughly) Daily

April 17, 2023 at 1:00 am

Next to nothing…

Neutinos are so small and so nearly without mass that 50 trillion of them pass unimpeded through a person’s body every second.  Ironically, this nearly nonexistent particle seems poised to start a revolution…

One of the two detectors in the MINOS neutrino experiment sits in the Soudan Underground Laboratory in Minnesota. A recent analysis of MINOS data hints that neutrinos and antineutrinos might not weigh the same-- a challenge to Einstein’s theory of special relativity.

Current theories of particle physics are based on two assumptions: All known forces arise from interactions with neighboring particles and they all obey Einstein’s special relativity theory, which holds that the speed of light and the laws of physics are always the same regardless of a particle’s speed or rotation. For that to hold true, particles and antiparticles—-including neutrinos and their antipartners — must have the same mass.

But new measurements from an experiment called MINOS (for Main Injector Neutrino Oscillation Search) seem to contradict that notion. The three known types of neutrinos —electron, muon and tau — act like chameleons, transforming from one type into another as they travel.

MINOS found that during a 735-kilometer journey from Fermilab to the Soudan Underground Laboratory in Minnesota, about 37 percent of muon antineutrinos disappeared — presumably morphing into one of the other neutrino types — compared with just 19 percent of muon neutrinos, reports MINOS spokesman Robert Plunkett of Fermilab.

That difference in transformation rates suggests a difference in mass between antineutrinos and neutrinos… “One thing is clear — if the masses are different for neutrinos and antineutrinos, then the most sacred symmetry of quantum field theory, CPT (for charge, parity and time), is broken in the neutrino sector,” says Tom Weiler of Vanderbilt University in Nashville.

Read the full story in Science News.

As we wax nostalgic for symmetry, we might send a “Alles Gute zum Geburtstag” to the remarkable Gottfried Wilhelm Leibniz, the philosopher, mathematician, and political adviser, who was important both as a metaphysician and as a logician, but who is probably best remembered for his independent invention of the calculus; he was born on this date in 1646.  Leibniz independently discovered and developed differential and integral calculus, which he published in 1684;  but he became involved in a bitter priority dispute with Isaac Newton, whose ideas on the calculus were developed earlier (1665), but published later (1687).

Leibnitz