Category Archives: Physics

Relativistic Colors

John F. Lindner February 23, 2019 3:04 PM

Metallium, Inc. is attempting to manufacture coins made from as many different metals (and elements) as possible, typically 99 to 99.9% pure. My Metallium coin collection currently includes aluminum, titanium, iron, nickel, copper, zinc, silver, tin, and gold coins. Most … Continue reading →

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720° untangles 360° tangles

John F. Lindner January 27, 2019 11:46 AM

Despite growing up in three dimensions, as a kid I did not recognize one of 3D’s deep and subtle properties: full rotations tangle, but double rotations untangle! Following physicist Paul Dirac, twist a belt one full turn about its length. … Continue reading →

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1+2+3+… = -1/12?

John F. Lindner December 21, 2018 5:52 PM

In quantum electrodynamics, the bare charge of an electron is infinite, but the renormalized dressed charge is finite. The bare electron shields itself by polarizing the virtual electron-positron pairs of the nearby quantum vacuum to reduce its coupling at large distances to in natural … Continue reading →

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A Better Table

John F. Lindner December 12, 2018 8:12 PM

The periodic table of the elements is almost as old as The College of Wooster, and I am a big fan. As we approach next year’s sesquicentennial of Dmitri Mendeleev‘s 1869 periodic table, I present a modest addition to the … Continue reading →

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Math Grenade

John F. Lindner November 30, 2018 10:36 AM

I just bought a new calculator. New to me, that is, but older than me. Inspired by the 1600s Gottfried Leibniz stepped cylinder and the 1800s Thomas de Colmar arithmometer, the Curta mechanical calculator design was developed by Curt Herzstark while … Continue reading →

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Optical Tweezers

John F. Lindner October 21, 2018 11:22 AM

A focused light beam can trap a small particle, such as a micron-sized latex sphere (or biological cell). If the sphere is much larger than the light’s wavelength, ray optics suffices to explain the trapping. Light bends as it passes … Continue reading →

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Dr. Rendezvous

John F. Lindner October 9, 2018 1:23 PM

Edwin Aldrin earned his PhD from MIT in 1963 with a thesis titled, “Line-of-sight guidance techniques for manned orbital rendezvous”. Just three years later in 1966, Aldrin was the pilot of Gemini XII, the last flight of the Gemini program, … Continue reading →

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Anholonomy

John F. Lindner August 10, 2018 2:04 PM

A falling cat’s twisting returns its shape to normal but rotates its body to land feet down. Earth’s spin returns a Foucault pendulum to its initial position in one day but rotates its oscillation plane. Parallel parking cyclically rotates a … Continue reading →

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Norton’s Dome

John F. Lindner July 1, 2018 7:00 PM

Norton’s Dome is a fascinating counterexample in classical mechanics: A frictionless mass balanced at the dome’s top can remain there forever — but can also spontaneously slide down! The Shape Norton’s dome has a cubed square root profile: if the … Continue reading →

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Standard Model at 50

Niklas Manz June 20, 2018 4:48 PM

From Haidar Essili: All I can think of to describe my experience in the Standard model’s 50th anniversary conference is to repeatedly yell the word wow, until I have lost the will to do so. I am at a loss … Continue reading →

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