I was out of town last week, and doing talk prep leading up to that, so it's been a little while since my last collection of Forbes links. Here's the latest from over there:
-- Football Physics: The Forces Behind Those Big Hits: A look at force, momentum, and acceleration in tackling.
-- The Science Of Agents of S.H.I.E.L.D.: What Is Quantum Harmonic Oscillation? A question on Twitter provides an excuse to use some video of The Pip bouncing on playground equipment to discuss the physics of the harmonic oscillator in both classical and quantum forms.
-- The Science Of Alternate Worlds: The Agents of S.H.I.E.L.D thing was prompted by some technobabble about how to move to another dimension, which indirectly led to this post about ideas in modern physics that sorta-kinda look like the alternate worlds of science fiction.
-- Football Physics: What Fantasy Sports Players Have In Common With Planet Hunters: A look at "citizen science" as a possible analogue of fantasy sports for science.
-- Football Physics: Removing The Chains: A look at the physics of GPS with an eye toward improving the spotting of the ball in football.
-- Physics Still Hasn't Solved Some Everyday Mysteries: I got a photo of a "glory" while flying back from California, and was mildly surprised to find the explanation of the effect isn't completely settled. But maybe that shouldn't be a surprise.
I'll also throw in a reminder here that Paige Jarreau is doing a survey of science blog readers, for SCIENCE! (in the form of her postdoctoral research on communication online). If you've got a few minutes, please go over there and help her build up a good data set.
Anyway, that's a bunch of stuff. As usual, some of it is less successful than I'd like, but it was all fun to write, which is the key thing.
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If you Google around a bit to nail down that 34 microsecond GR + SR delay, it's a tough find, especially the GR part, which seems to be based on one paper, referenced numerous times. It's made more complicated because the issue has been taken up by a bunch of relativity denialists. Nonetheless, the relativistic effects seem not to be as great as one would calculate assuming simply that you are comparing your own clock on the ground with that on a satellite orbiting overhead. What your GPS clock is actually interested in is the difference in arrival time of the signals from four satellites whose clocks are synchronized, a problem less susceptible to relativistic error.
Good article about the glory. My recollection is that supernumerary arcs are also produced by surface waves.
Best one I ever saw was on a cloud deck about 20,000' below the plane, with the sun high overhead. There was a contrail behind the plane, so it looked like the glory was burning a dark path (the shadow of the contrail) in the clouds. It was surreal.
I've also seen it when a cloud was illuminated from the side (near sunrise or sunset), but the best ones are on a rather uniform fog bank or cloud deck.