From Sundials to Atomic Clocks: Understanding Time and Frequency, Second Revised Edition

Jespersen, James

ISBN 10: 0486409139 / ISBN 13: 9780486409139

Editore: Dover Publications Inc, 2003

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Dati bibliografici

• Titolo: From Sundials to Atomic Clocks: Understanding Time and Frequency, Second Revised Edition
• Editore: Dover Publications Inc
• Data di pubblicazione: 2003
• Lingua: Inglese
• ISBN 10: 0486409139
• ISBN 13: 9780486409139
• Rilegatura: paperback
• Edizione: seconda edizione
• Condizione: Fine

Descrizione articolo

Riassunto

It's present everywhere but occupies no space. We can spend it, but we can't destroy it or even change it, and there's never any more or less of it. Everyone knows what it is and uses it every day, but no one has been able to define it.
It's time, of course, an elusive concept that has helped unravel some of nature's greatest mysteries, yet remains a mystery itself. This volume, newly revised and updated, offers an unusually clear and accessible introduction to time — its measurement, historic methods of timekeeping, the uses of time information, and the role of time in science and technology. Beginning with a discussion of the nature of time, natural clocks, the relation of time and frequency, and the role of time in navigation, the authors then proceed to a fascinating treatment of man-made clocks and watches — from the sundials and waterclocks of ancient Egypt to today's amazingly precise atomic clocks — accurate to within one second every 370,000 years!
Subsequent chapters offer detailed, yet accessible explanations of the continuing search for more uniform time; the application of time to energy, communication, and transportation; and the role of the world's official timekeepers. Finally, the authors look at time in the context of theoretical science and technology, showing how time has long been a crucial element in theories of the fundamental laws of nature and in astronomy, while improvements in the measurement of time have fostered major developments in the realm of physics. More than 300 drawings and cartoons enliven the pages of this fascinating, coherent, and comprehensive treatment of the age-old enigma of time.

Contenuti

I. THE RIDDLE OF TIME 1. The Riddle of Time The Nature of Time What is Time? "Date, Time Interval, and Synchronization" Ancient Clock Watchers Clocks in Nature Keeping Track of the Sun and Moon Thinking Big and Thinking Small-An Aside on Numbers 2. Everything Swings Getting Time from Frequency What Is a Clock? The Earth-Sun Clock Meter Sticks to Measure Time What Is a Standard? How Time Tells Us Where in the World We Are Building a Clock that Wouldn't Get Seasick II. HAND-BUILT CLOCKS AND WATCHES 3. Early Clocks Sand and Water Clocks Mechanical Clocks The Pendulum Clock The Balance-Wheel Clock Further Refinements The Search for Even Better Clocks 4. "Q" Is for Quality" The Resonance Curve Energy Build-up and the Resonance Curve-An Aside on Q The Resonance Curve and the Decay Time "Accuracy, Stability, and Q" High Q and Accuracy High Q and Stability Waiting to Find the Time Pushing Q to the Limit 5. Building Even Better Clocks The Quartz Clock Atomic Clocks The Ammonia Resonator The Cesium Resonator One Second in 10 000 000 Years Atomic Definition of the Second The Rubidium Resonator The Hydrogen Maser Can We Always Build a Better Clock? 6. A Short History of the Atom Thermodynanics and the Industrial Revolution Count Rumford's Cannon Saturn's Rings and the Atom Bringing Atoms to a Halt Atoms Collide 7. Cooling the Atom Pure Light Shooting at Atoms Optical Molasses Trapping Atoms Penning Traps Paul Traps Real Cool Clocks Capturing Neutral Atoms Atomic Fountains Quantum Mechanics and the Single Atom 8. The Time for Everybody The First Watches Modern Mechanical Watches Electric and Electronic Watches The Quartz-Crystal Watch "How Much Does "The Time" Cost?" III. FINDING AND KEEPING THE TIME 9. Time Scales The Calendar The Solar Day The Stellar or Sidereal Day Earth Rotation The Continuing Search for More Uniform Time: Ephemeris Time How Long Is a Second? "Rubber" Seconds" The New UTC System and the Leap Second The Length of the Year The Keepers of Time World Time Scales Bureau International de Poids et Mesures 10. The Clock behind the Clock Flying Clocks Time on a Radio Beam Time in the Sky Accuracy Coverage Reliability Other Considerations Other Radio Schemes 11. The Time Signal on Its Way Choosing a Frequency Very low Frequencies Low Frequencies Medium Frequencies High Frequencies Very High Frequencies Frequencies above 300 megahertz Noise-Additive and Multiplicative Three Kinds of Time Signals IV. THE USES OF TIME 12. Standard Time Standard Time Zones and Daylight-Saving Time Time as a Standard Is a Second Really a Second? Who Cares about the Time? 13. "Time, The Great Organizer" Electric Power Transportation Navigation by Radio Beacons Navigation by Satellite The Global Positioning System Some Common and Some Far-out Uses of Time and Frequency Technology 14. Ticks and Bits Divide and Conquer "Sending Messages the Old Fashioned Way, One Bit at a Time" Automated Telegraphy Frequency Division Multiplexing Simultaneous Time and Frequency Multiplexing Don't Put All Your Messages in one Basket Keeping the Clocks in Step V. "TIME, SCIENCE, AND TECHNOLOGY" 15. Time and Mathematics A New Direction Taking Apart and Putting Together Slicing up the Past and the Future-Calculus   Conditions and Rules Getting at the Truth with Differential Calculus Newton's Law of Gravitation What's Inside the Differentiating Machine?-An Aside 16. Time and Physics Time is Relative Time Has Direction Time Measurement Is Limited Atomic and Gravitational Clocks The Struggle to Preserve Symmetry The Direction of Time and Time Symmetries-An Aside 17. Time and Astronomy Measuring the Age of the Universe The Expanding Universe-Time Equals Distance Big Bang or Steady State? Stellar Clocks White Dwarfs Neutron Stars Black Holes-Time Comes to a Stop "Time, Distance, and Radio Stars " 18. Until the End of Time Paradoxes Time Is Not Absolute General Theory of Relativity A Bang or a Whimper? 19. "Time's Direction, Free Will, and All That" Time's Direction and Information Disorganization and Information? &nbs