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For the dinosaurs!
The dinosaurs didn’t have a space program, but we do. I just watched live the first kinetic-impact asteroid-redirection test as NASA’s Double Asteroid Redirection Test spacecraft collided with the asteroid-moon Dimorphos of the asteroid Didymos. Below is the last image DART transmitted, truncated by the impact itself! The goal is to measurably change the speed…
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Science, serendipity, and coincidence
As part of my science history project, the article “Science, serendipity, coincidence, and the Oregonator at the University of Oregon, 1969–1974” has been published in Chaos: An Interdisciplinary Journal of Nonlinear Science. It’s especially exciting because it’s the Feature article in the Focus Issue, From Chemical Oscillations to Applications of Nonlinear Dynamics: Dedicated to Richard…
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Alien Suns Reversing in Exoplanet Skies
Not only can suns stand still in the sky, from some exoplanets their motion can apparently reverse! Wooster physics-math double majors Xinchen (Ariel) Xie ’21 and Hwan (Michelle) Bae ’19 and I just published an article elucidating these apparent solar reversals. Michelle and I began studying the architecture of daylighting terrestrial buildings for energy efficiency as part…
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Black Hole Above the Fold
When grocery shopping, I normally just glance at the newspapers in the newsstand. However, this morning, I was excited to see “above the fold” of the Wall Street Journal a large reproduction of the first image of the supermassive black hole Sagittarius A* at the center of our Milky Way galaxy! The Event Horizon Telescope team…
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Slide Rule Examples
Slide rules were widely used in engineering, science, and mathematics until the early 1970s, including during the Gemini and Apollo space programs. Although rendered largely obsolete by the advent of inexpensive electronic calculators, their descendants continue to have specialized applications, such as backup flight computers. The giant Taylor Bowl slide rule used to be used to…
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Diffraction Limited
Yesterday, Webb optical telescope element manager Lee Feinberg said “We made the right telescope” while reporting that its focus has reached the diffraction limit of 0.7 arcseconds at the infrared wavelength of 2 microns. (For comparison, from Earth, Luna subtends 31 arcminutes, which is about 1/2°.) Unlike the Hubble space telescope, whose primary mirror was…
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Halo Orbit
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…
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50 years later
After MANY months of not traveling, I scheduled a meeting with Robert (Bob) M. Mazo, Professor emeritus from the University of Oregon, now living outside Philadelphia. In 1971/1972 he helped developing the key model to describe chemical reaction-diffusion systems. But, as he stated, he was “only the catalyst” and only accepted to be recognized in…
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Burning Plasma
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…
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Dandelin Spheres
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…
Category: Physics
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Nice post, John! Thanks for writing these. I always enjoy them.
David Smith’s ein stein is an awesome shape!
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Thanks, Mark! I enjoy reading your posts as well.