Author Archives: John F. Lindner

About John F. Lindner

John F. Lindner was born in Sleepy Hollow New York and educated at the University of Vermont and Caltech. He is a professor of physics and astronomy at The College of Wooster. He has enjoyed multiple yearlong sabbaticals at Georgia Tech, University of Portland, and University of Hawai'i. His research interests include nonlinear dynamics, celestial mechanics, and variable stars.

Optical Tweezers

A focussed 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

Edwin Aldrin obtained 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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Saturnday

Ancient cultures everywhere observed seven “wanderers” move against the apparently fixed stars of the night sky: our star the sun, our natural satellite the moon, and the planets Mars, Mercury, Jupiter, Venus, and Saturn. In many languages, these wanderers became … Continue reading
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Anholonomy

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

The Shape In dimensionless coordinates, with the [latex]z[/latex]-axis pointing down, Norton’s dome has the shape [latex display=”true”] z = \frac{2}{3}s^{3/2},[/latex] where [latex]s[/latex] is the arc length along the dome. If [latex]ds^2 = dx^2 + dz^2[/latex], then [latex display=”true”] x = \int dx … Continue reading
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Dancing on Mars

I ran up the stairs to the Studio Art Crit space. Justine was already rolling out the treadmill, so I climbed to the old running track and let down both ends of the steel cable, one end connected to the … Continue reading
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On Mercury One Day Lasts Two Years

Mercury has the most noncircular or eccentric orbit of any non-dwarf planet in the solar system. This eccentricity may have trapped Mercury in a 3:2 spin-orbit resonance, where it rotates three times for every two revolutions. When nearest Sol at … Continue reading
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Dynamo

Stationary electric charges generate radial electric fields, and electric fields push positive charges (and pull negative charges). Moving charges also generate circulating magnetic fields, and magnetic fields deflect moving charges perpendicular to both the fields and their motions. All of electromagnetism follows. In … Continue reading
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Falcon Heavy

I was supervising Jr IS, but as I circulated around the lab, I watched the clock. Everyone was working quietly. Just before launch, I snuck back to my office and closed the door. The SpaceX Falcon Heavy was surrounded by … Continue reading
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The Impossible Problem

In 1969, Hans Freudenthal posed a puzzle that Martin Gardner would later call “The Impossible Problem”. Below is a 2000 version due to Erich Friedman. I have secretly chosen two nonzero digits and have separately told their sum to Sam … Continue reading
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