Help me, I'm an amateur! But Newton's 2nd Law, saying force equals mass times acceleration, seems unquestionably true. As a kid riding on a merry-go-round, I loved to get in the center and ride straddling the axis, to see the big outer edge make the circuit in the same time that I made it. But later I learned that a galaxy doesn't spin quite like a carousel: gravitational force toward the outside is weaker,so stars near the center should go around faster, with rotation speed varying precisely in proportion to distance. Wrong! Astronomers detect a "drag" starting about halfway toward the outside, easily explainable by dark matter. But MOND theory tweaks Newton's 2nd Law to explain away dark matter. Weird! WHY?
2006-07-30
19:16:06
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5 answers
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asked by
John (Thurb) McVey
4