The Science of Time 2016: Time in Astronomy & Society, Past, Present and Future (Astrophysics and Space Science Proceedings Book 50)

The uses of time in astronomy - from pointing telescopes, coordinating and processing observations, predicting ephemerides, cultures, religious practices, history, businesses, determining Earth orientation, analyzing time-series data and in many other ways - represent a broad sample of how time is used throughout human society and in space. Time and its reciprocal, frequency, is the most accurately measurable quantity and often an important path to the frontiers of science. But the future of timekeeping is changing with the development of optical frequency standards and the resulting challenges of distributing time at ever higher precision, with the possibility of timescales based on pulsars, and with the inclusion of higher-order relativistic effects. The definition of the second will likely be changed before the end of this decade, and its realization will increase in accuracy; the definition of the day is no longer obvious. The variability of the Earth's rotation presents challenges of understanding and prediction. In this symposium speakers took a closer look at time in astronomy, other sciences, cultures, and business as a defining element of modern civilization. The symposium aimed to set the stage for future timekeeping standards, infrastructure, and engineering best practices for astronomers and the broader society. At the same time the program was cognizant of the rich history from Harrison's chronometer to today's atomic clocks and pulsar observations. The theoreticians and engineers of time were brought together with the educators and historians of science, enriching the understanding of time among both experts and the public. Front Matter ....Pages i-x Cosmic Time: From the Big Bang to the Eternal Future (Chris Impey)....Pages 1-13 The Proof of the Pudding (William Andrewes)....Pages 15-16 The Role of Ephemerides from Ptolemy to Kepler (Owen Gingerich)....Pages 17-24 How Time Served to Measure the Geographical Position Since Hellenism (Susanne M. Hoffmann)....Pages 25-36 Changing Times in the Nautical Almanac Over 250 Years (Susan Nelmes)....Pages 37-43 Bond Time: The Electric Method of Time Recording (Donald Saff)....Pages 45-45 The Development and Use of the Pilkington and Gibbs Heliochronometer and Sol Horometer (Geoff Parsons)....Pages 47-48 These Are Not Your Mother’s Sundials: Or, Time and Astronomy’s Authority (Sara J. Schechner)....Pages 49-73 The History of Time (Dennis McCarthy)....Pages 75-75 “When?” It’s a Basic Question That We Ask All the Time (Harlan Stenn)....Pages 77-77 Inter-site Alignments of Prehistoric Shrines in Chaco Canyon to the Major Lunar Standstill (Anna Sofaer, Robert Weiner, William Stone)....Pages 79-101 Atomic Time Scales and Their Applications in Astronomy (Felicitas Arias)....Pages 103-104 Relativistic Time at the US Naval Observatory (Matsakis Demetrios)....Pages 105-118 Real-Time Realization of UTC at Observatoire de Paris (G. D. Rovera, S. Bize, B. Chupin, J. Guéna, Ph. Laurent, P. Rosenbusch et al.)....Pages 119-122 Time in Television Systems (Donald Craig)....Pages 123-124 From Computer Time to Legal Civil Time: IANA tz, IETF tzdist, etc. (Steve Allen)....Pages 125-125 The UT1 and UTC Time Services Provided by the National Institute of Standards and Technology (Judah Levine)....Pages 127-139 On a Redefinition of the SI Second (Fritz Riehle)....Pages 141-141 Time Scales Steered by Optical Clocks (T. Ido, H. Hachisu, F. Nakagawa, Y. Hanado)....Pages 143-149 Activities of Time and Frequency Metrology at NICT: Optical and Microwave Frequency Standards and Their Remote Comparisons (T. Ido, M. Fujieda, H. Hachisu, K. Hayasaka, M. Kajita, M. Kumagai et al.)....Pages 151-157 IAU Standards of Fundamental Astronomy (SOFA): Time and Date (Catherine Hohenkerk)....Pages 159-163 Earth’s Variable Clock (L. V. Morrison, F. R. Stephenson, C. Hohenkerk)....Pages 165-165 The Determination of Earth Orientation by VLBI and GNSS: Principles and Results (Nicole Capitaine)....Pages 167-196 Status of the Gaia Mission (François Mignard)....Pages 197-197 Time Synchronization and the Origins of GPS (Richard D. Easton)....Pages 199-202 DASCH for Days to Decades Time Domain Astronomy (Jonathan Grindlay)....Pages 203-204 Mean Solar Time and Its Connection to Universal Time (John H. Seago, P. Kenneth Seidelmann)....Pages 205-226 How Gravity and Continuity in UT1 Moved the Greenwich Meridian (Stephen Malys, John H. Seago, Nikolaos K. Pavlis, P. Kenneth Seidelmann, George H. Kaplan)....Pages 227-241 Aspects of Time as It Relates to Space Geodesy (Ludwig Combrinck)....Pages 243-252 Pulsars: Celestial Clocks (R. N. Manchester, L. Guo, G. Hobbs, W. A. Coles)....Pages 253-265 The Leap Second Debate: Rational Arguments vs. Unspoken Unease (Pavel Gabor)....Pages 267-275 How to Talk to the Public About the Leap Second? The Experience of the IERS Central Bureau (Wolfgang R. Dick)....Pages 277-286 The Problem of Leap Seconds (Bob Frankston)....Pages 287-292 Common Calendar: Fixed-Epoch Deterministic UTC-Based Local Timescales (Brooks Harris)....Pages 293-317 The Transfer of Earth-Time to the Planets (David E. Smith, Maria T. Zuber)....Pages 319-328 Keeping Time with the Asteroids (Rob Seaman, Frank Shelly, Eric Christensen, Alexander Gibbs, Stephen Larson)....Pages 329-330 Long-Term Timekeeping in the Clock of the Long Now (W. Daniel Hillis)....Pages 331-336 Aspects of Time Distribution (Martin Burnicki)....Pages 337-363 Time Critical: Contesting the Measure of the Now (Daniel Wiley)....Pages 365-366 Timescale Pluralism and Sciences of Time (Kevin Birth)....Pages 367-367 Liberating Clocks: Exploring Other Possible Futures (Michelle Bastian)....Pages 369-377 New Technologies and the Future of Timekeeping (Elisa Felicitas Arias)....Pages 379-389 Are Clocks Enough? Science, Philosophy, and Time (Adam Frank)....Pages 391-392 Time Warped: Photography, History, and Temporality (Kris Belden-Adams)....Pages 393-394