Space, Time, & The Illusion Of Gravity (Bryson)
Spacetime is usually explained by asking you to imagine something flat but pliant—a mattress, say, or a sheet of stretched rubber—on which is resting a heavy round object, such as a iron ball. The weight of the iron ball causes the material on which it is sitting to stretch and sag slightly. This is roughly analogous to the effect that a massive object such as the Sun (the iron ball) has on spacetime (the material): it stretches and curves and warps it. Now if you roll a smaller ball across the sheet, it tries to go in a straight line as required by Newton’s laws of motion, but as it nears the massive object and slope of the sagging fabric, it rolls downward, ineluctably drawn to the more massive object. This is gravity--a product of bending of spacetime.
Every object that has mass creates a little depression in the fabric of the cosmos. Thus the universe, as Dennis Overbye has put it, is “the ultimate sagging mattress.” Gravity on this view is no longer so much a thing as an outcome—"not a ‘force’ but a byproduct of the warping of spacetime,” in the words of the physicist Michio Kaku, who goes on: “In some sense, gravity does not exist; what moves the planets and stars is the distortion of space and time.”
— Bill Bryson, A Short History of Nearly Everything (2003, pg. 126)
This entry was posted on Thursday, February 22, 2007 at 6:20am. It has been filed under Media, Books, Quotes, News, Science, Writers, Joshua.
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