Author: John F. Lindner

  • Shackleton’s Valiant Voyage

    John F. Lindner

    Although a child of the Apollo program, I was gripped by Alfred Lansing‘s 1962 book Shackleton’s Valiant Voyage, a great tale of endurance, leadership, and survival and an inspiring true story from the heroic age of Antarctic exploration. In the 1910s, shortly after Roald Amundsen and Robert Scott separately reached the south pole, Ernest Shackleton organized an expedition…

  • Halo Orbit

    John F. Lindner

    The Webb telescope has fully deployed and arrived at its halo orbit about the second Earth-Sun Lagrange point. But how can it orbit an empty point in space? In the accompanying animated sequence of inertial space diagrams, a star (red) and planet (cyan) orbit their common center of mass (cross). The inward force to pull…

  • Merlin & Raptor

    John F. Lindner

    The turbopump is the heart of most liquid-fueled rocket engines. Gas generator engines tap off and burn a little propellant to drive a turbine, which turns a centrifugal pump, which rapidly pushes the fuel and oxidizer to the combustion chamber, after the cryogenic fuel first circulates around the rocket nozzle to cool it. The combustion generates supersonic exhaust out…

  • Astronomy Christmas Gift

    John F. Lindner

    I awoke early this Christmas morning to watch the successful launch of the James Webb Space Telescope. I remember the genesis of the telescope a quarter of a century ago when it was called the Next Generation Space Telescope. (The telescope’s name is controversial, and I would have preferred an astronomer’s name.) Its development has…

  • Burning Plasma

    John F. Lindner

    In August I received an urgent email from my brother with the title “Fusion”. The National Ignition Facility (NIF) had created a burning plasma — a star on Earth — a major milestone on the long road to controlled nuclear fusion. A plasma is an ionized gas, but in this context “burning” does not mean chemically…

  • Part Science, Part Art, Part Luck

    John F. Lindner

    Launched just last month, Lucy will be the first spacecraft to visit Jupiter’s trojan asteroids, rocky swarms that orbit about 60 degrees ahead and behind Jupiter in its orbit. Hal Levison, Lucy’s Principal Investigator, has described Lucy’s complicated trajectory, which includes an Earth gravity-assist and visits to both trojan swarms, as “part science, part art, and part luck”.…

  • 4D Unknot

    John F. Lindner

    In four dimensions, you can’t tie your shoelaces — because 4D knots don’t work. Any 1D curve in 4D space can be continuously deformed to the unit circle, which is an unknot. The looping animation below demonstrates how to undo a trefoil knot in 4D, where rainbow colors code the 4th dimension. The animation pauses when…

  • Punch it, SpaceX

    John F. Lindner

    She’s not looking up at the sky; she’s looking down at it. I am excitedly following the Inspiration4 spaceflight and its diverse all-private crew of Jared Isaacman, Sian Proctor, Christopher Sembroski, and Hayley Arceneaux. Orbiting higher than any humans this millennium and carrying the largest window ever flown in space, their Crew Dragon Resilience is providing unprecedented and…

  • Dandelin Spheres

    John F. Lindner

    In 1609, Johannes Kepler first described how planets orbit the sun in ellipses. Kepler understood an ellipse as both the locus of points whose distances from two foci sum to a constant and as the intersection of a cone and a plane. But how are these familiar definitions equivalent? In 1822, Germinal Dandelin discovered a beautiful construction that proves this…

  • Grad Schools

    John F. Lindner

    Wooster physics graduates do many things after Wooster, including graduate work. Below is a map of some of the graduate schools they have attended, one dimension of the influence of our department. If you are a recent Wooster physics graduate and don’t see your graduate schools on the map, please contact us, and we will…

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