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Comment Threads

• Pigeon commented on Catching Up
  "Google's AI is doing something very interesting that I don't understand." I don't think I've seen that specific behaviour before (probably because I don't allow Google to set cookies or run javascript), but it does definitely look to me like a further manifestation of a class of behaviour of which Google is all too fond, to wit, deliberately being a pain in the arse to try and make sure you see what they want you to see instead of what you want to see. Boogle Gooks is particularly bad in that respect. Far as I'm concerned when I click on...
• Pigeon commented on Catching Up
  I've dropped out of it because the main problem seems to be something in the area of linguistic comprehension, which I can't untangle and it's making my head hurt too much trying. (Taking an opportunity to bash Google is a different matter :))...
• Elderly Cynic commented on Catching Up
  The model that orbits are ellipses is to an understanding of Newtonian mechanics as the Bohr atom is to an understanding of atomic structure. Both were critical steps in the development of the understanding, and both remain useful approximations for teaching. Neither is adequate for practical use....
• Ian Campbell commented on Catching Up
  Regarding the issue of artillery trajectories. The trajectory of a projectile in vacuum is of course an ellipse. However, given that the semi-major axis is 6400km or thereabouts and the width of the ellipse at the relevant point is at most 120km (the Paris Gun mentioned below) a parabola is a reasonable approximation. Why? Because other sources of inaccuracy are vastly more important, given that the idea of artillery is to hit a target. Such things as minor variations in particle size and composition of the propellant, thermal expansion and drooping of the barrel, wear on the barrel (all of...
• Elderly Cynic commented on Catching Up
  The maximum gravitational attraction of the moon on a near-earth object is just under 4 ppm of the earth's attraction. Gravitational anomalies are much larger (up to about 30,000 ppm), but aren't as systematic. I.e. I can't guess, either....