A short history of nearly everything - Bill Bryson [273]
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*18How c came to be the symbol for the speed of light is something of a mystery, but David Bodanis suggests it probably came from the Latin celeritas, meaning swiftness. The relevant volume of the Oxford English Dictionary, compiled a decade before Einstein's theory, recognizes c as a symbol for many things, from carbon to cricket, but makes no mention of it as a symbol for light or swiftness.
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*19Named for Johann Christian Doppler, an Austrian physicist, who first noticed the effect in 1842. Briefly, what happens is that as a moving object approaches a stationary one its sound waves become bunched up as they cram up against whatever device is receiving them (your ears, say), just as you would expect of anything that is being pushed from behind toward an immobile object. This bunching is perceived by the listener as a kind of pinched and elevated sound (the yee). As the sound source passes, the sound waves spread out and lengthen, causing the pitch to drop abruptly (the yummm).
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*20The name comes from the same Cavendishes who produced Henry. This one was William Cavendish, seventh Duke of Devonshire, who was a gifted mathematician and steel baron in Victorian England. In 1870, he gave the university £6,300 to build an experimental lab.
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*21Geiger would also later become a loyal Nazi, unhesitatingly betraying Jewish colleagues, including many who had helped him.
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*22There is a little uncertainty about the use of the word uncertainty in regard to Heisenberg's principle. Michael Frayn, in an afterword to his play Copenhagen, notes that several words in German—Unsicherheit, Unschärfe, Unbestimmtheit— have been used by various translators, but that none quite equates to the English uncertainty. Frayn suggests that indeterminacy would be a better word for the principle and indeterminability would be better still.
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*23Or at least that is how it is nearly always rendered. The actual quote was: “It seems hard to sneak a look at God's cards. But that He plays dice and uses ‘telepathic' methods . . . is something that I cannot believe for a single moment.”
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*24If you have ever wondered how the atoms determine which 50 percent will die and which 50 percent will survive for the next session, the answer is that the half-life is really just a statistical convenience—a kind of actuarial table for elemental things. Imagine you had a sample of material with a half-life of 30 seconds. It isn't that every atom in the sample will exist for exactly 30 seconds or 60 seconds or 90 seconds or some other tidily ordained period. Each atom will in fact survive for an entirely random length of time that has nothing to do with multiples of 30; it might last until two seconds from now or it might oscillate away for years or decades or centuries to come. No one can say. But what we can say is that for the sample as a whole the rate of disappearance will be such that half the atoms will disappear every 30 seconds. It's an average rate, in other words, and you can apply it to any large sampling. Someone once worked out, for instance, that dimes have a half-life of about 30 years.
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*25There are practical side effects to all this costly effort. The World Wide Web is a CERN offshoot. It was invented by a CERN scientist, Tim Berners-Lee, in 1989.
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*26You are of course entitled to wonder what is meant exactly by “a constant of 50” or “a constant of 100.” The answer lies in astronomical units of measure. Except conversationally, astronomers don't use light-years. They use a distance called the parsec (a contraction of parallax and second), based on a universal measure called the stellar parallax and equivalent to 3.26 light-years. Really big measures,