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 an emeritus professor of physics and astronomy at The College of Wooster and a visiting professor at North Carolina State University. He has enjoyed multiple yearlong sabbaticals at Georgia Tech, University of Portland, University of Hawai'i, and NCSU. His research interests include nonlinear dynamics, celestial mechanics, and neural networks.

After the Moonwalk

Most people are familiar with Neil Armstrong’s iconic photograph of Buzz Aldrin during the first moon walk. Much less well-known are this pair of photographs taken just after the moon walk. To my eyes, Armstrong seems exhausted but happy; Aldrin … Continue reading

Posted in ScotBlogs Contributed | Comments Off on After the Moonwalk

“Contact Light”

Our TV is broken, so Aunt Nora invites us to her apartment. (Aunt Nora isn’t really our aunt, but she introduced our parents to each other, so that’s what we call her.) My brother Jim and I lie on the … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on “Contact Light”

Wooster Epicycles

Just as a vector is the sum of its components, a mechanical motion a combination of its normal mode motions, a quantum state a superposition of its eigenstates, any “nice” function is a Fourier sum of real or complex sinusoids [latex]e^{i … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Wooster Epicycles

Redefining SI

Today the SI (Système international d’unités) base units are redefined. The following are now exact. Memorize these numbers! Cs-133 transition frequency constant [latex]Δν_{\text{Cs}} = 9\,192\,631\,770~\text{s}^{−1}[/latex] defines the second. Then light speed constant [latex]c = 299\,792\,458~\text{m}\cdot\text{s}^{−1}[/latex] defines the meter. Then Planck’s constant [latex]h = 6.626\,070\,15\times … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Redefining SI

Black Hole Radii

I set the alarm for 8:55 AM. Brutal, but I wanted to watch live the National Science Foundation Event Horizon Telescope news conference. I was expecting the first image of a black hole, and the EHT team did not disappoint. … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Black Hole Radii

Black Hole Radii

I set the alarm for 8:55 AM. Brutal, but I wanted to watch live the National Science Foundation Event Horizon Telescope news conference. I was expecting the first image of a black hole, and the EHT team did not disappoint. … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Black Hole Radii

December 22 is the Longest Day

December 22 is the longest day of the year, despite being near the northern hemisphere’s shortest daylight. The sidereal day is the time to rotate 360° with respect to distant stars, about 23 hours and 56 minutes for Earth. The … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on December 22 is the Longest Day

Relativistic Colors

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
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Relativistic Colors

720° untangles 360° tangles

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
Continue reading

Posted in ScotBlogs Contributed | Comments Off on 720° untangles 360° tangles

Luna’s Convex Orbit

Luna orbits Earth and Earth orbits Sol (where Luna is Earth’s moon and Sol is Earth’s star, the sun). As a kid, I thought Luna’s solar orbit formed a loopy spirograph pattern. Instead, Luna’s orbit is convex! Neglecting the eccentricity … Continue reading
Continue reading

Posted in ScotBlogs Contributed | Comments Off on Luna’s Convex Orbit