Word: ands
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Dates: during 1990-1999
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But such a timepiece would be virtually useless today: computers, communications satellites, global-positioning receivers and telephone-switching systems need a precision beyond anything conceivable even 50 years ago. Time technology long since abandoned mechanical devices and even the hum of quartz crystals. For true precision--accuracy to a billionth...
Behind its barred windows sit 28 atomic clocks, four of them holding atoms of hydrogen and the rest cesium. When excited by lasers or irradiated with microwaves, the atoms begin to dance with an utterly regular vibration that's monitored by computer. Once each second, the results are fed into...
Yet even the most accurate clock in the world can't answer the question of what all these atoms are actually measuring. What is time anyway? According to Isaac Newton, both space and time were fixed attributes of the universe, a God-given stage on which events unfolded. But Albert...
Everything else--including space and time, which he melded into a single entity called space-time--is relative, as malleable as rubber. The Big Bang theory further established that space-time came into existence at a definite point in the past. Talking about what happened "before" the Big Bang is...
This elasticizing of space-time means, for example, that observers might disagree over which of two events happened first--and both could be right. Even more bizarrely, physicists including Stephen Hawking have seriously discussed the possibility that relativity might make it feasible (though not with any technology we know of...