Ever since Isaac Newton first described the laws of gravity in 1687, scientists have known that the quickest route between two points is along a straight line through the Earth’s interior. Through the magic of gravity, any object dropped into such a “chord tunnel” at one end will emerge exactly 42 minutes later at the other end, no matter the distance.I can't be the only one who saw this in an introductory physics class and filed it away as trivia. At one point I'm pretty sure I solved this as a homework problem. It's called a gravity train and here's a proof, not due to me. And somewhat amusingly, the time "42 minutes" depends only on the density of the Earth; if Earth were bigger but made of the same stuff the train would just go faster.
Zero gravity and a ninety-minute orbital day created so many questions for Muslim astronauts that a “Guideline of Performing Ibadah at the International Space Station” was drafted. Rather than require Muslim astronauts to pray five times during each ninety-minute orbit of Earth, the guidelines allowed them to go by the twenty-four-hour cycle of the launch location. Wipes (“not less than 3 pieces”) could be used for preprayer cleansing. And since the orbiting Muslim who began his prayer while facing Mecca was likely, by prayer’s end, to be mooning Mecca, provisions were made allowing him to simply face the Earth or “wherever.” Lastly, instead of lowering the face to the ground, a trying maneuver in zero gravity, prostrating oneself could be approximated by “bringing down the chin closer to the knee,” “using the eye lid as an indicator of the changing of posture” or—in the vein of “wherever”—simply “imagining” the sequence of movements.posted by jeather at 7:59 PM on August 8, 2011 [1 favorite]
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...sandwich...
posted by curious nu at 8:16 AM on August 8, 2011 [7 favorites]