Author: John F. Lindner

  • The Longest Flight

    John F. Lindner

    As a kid pouring over the Guinness Book of World Records, I was astonished by the record longest flight; instead of lasting hours – as I would have guessed – it lasted more than two months! Today, nearly 65 years later, that amazing achievement remains one of aviation’s most enduring records. For over 64 days…

  • Where Are the Stars?

    John F. Lindner

    When viewing space photography, such as Apollo or International Space Station photos, people often ask, “Where are the stars?” Typically such photos properly expose the bright lunar or space station surfaces and consequently underexpose the dim background stars, rendering space as featureless black. Current ISS astronaut Matthew Dominick has been experimenting with photography, and his…

  • Bertrand’s Postulate

    John F. Lindner

    When searching for prime numbers, the next prime number is no larger than twice the current number. Postulated by Joseph Bertrand, first proved by Pafnuty Chebyshev, I present an elementary proof based on one by the teenage Paul Erdős. Erdős was one of the most prolific twentieth century mathematicians, publishing about 1500 articles with more…

  • Aero thermo dynamics

    John F. Lindner

    Up early this morning to watch the spectacular fourth integrated flight test of SpaceX’s Superheavy Starship, the largest rocket ever built. Each IFT has greatly improved on the previous one, and the fourth was no exception. For the first time, both the booster and the ship softly splashed down in the ocean! Especially impressive was…

  • Stegosaurus Tiling

    John F. Lindner

    John Chase, the head of the Walter Johnson High School Math Department, in Maryland, near Washington DC, liked my Stegosaurus variation of the Spectre monotile so much that he had his students paint it on the wall of their math office! Attached are a couple of photos he shared. Smith, Myers, Kaplan, and Goodman-Strauss recently discovered an infinite…

  • A Better Alphabet

    John F. Lindner

    I still retain the episodic memory of my first encounter with the spelling of people. I was learning to read, and I got cat, mat, pat; I got lot, pot, dot; but I did not get people. Why the o, and why the le instead of el? Soon after I balked at Wednesday; surely that should be something like Wensday (or even Wenzday)? I had…

  • Measuring the Solar System

    John F. Lindner

    Thousands of years ago, ancient astronomers like Aristarchus and Eratosthenes combined careful observations with simple mathematics to measure the solar system, especially the diameters D of Earth, Luna (Earth’s moon), Sol (Earth’s star, the sun), and the radii r of their orbits. You too can do this, but it helps to observe an eclipse or two.…

  • Wooster’s Time Crystals

    John F. Lindner

    Saturday, March 8, 2008. A heavy snow, one of the heaviest I remember, shuts down the city of Wooster. Streets are undriveable, so I walk to Taylor Hall, getting snow in my boots. Taylor is deserted, as the College has begun Spring Break, but like yesterday, Kelly and I work all afternoon and evening in…

  • Venus’s Supercritical Ocean

    John F. Lindner

    The pressure and temperature near the surface of Venus are so high that its carbon dioxide atmosphere is a global ocean of a remarkable state of matter, a supercritical fluid, which fills any container like a gas but is as dense as a liquid. I created a carbon dioxide pressure versus temperature phase diagram using…

  • Percy & Ginny

    John F. Lindner

    A chill went through the spaceflight community last week as NASA reported that it had lost contact with the Ingenuity Mars helicopter. Delivered to Mars underneath the Perseverance rover and intended as a 5-flight 30-sol tech demo, it had vastly exceeded expectations, including the first successful powered flight off Earth, a true Wright brothers moment,…

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