Hi Roger, > I received an announcement but cannot attend. Here are a few of my thoughts > on the subject. > > This is important meeting, as important as the meetings before the Gregorian > correction of the calendar and the introduction of standard time. I know > enough about the issue to understand the different agendas. The rotation of > the earth related to the sun lacks the long term precision possible and > required by modern time and location technology. Just like standard time, we > are being railroaded into the modern era. But our sense of time in relation > to the sun is very important, from a historical, cultural, physiological and > psychological perspectives. Read Isaac Asimov's short story "Nightfall" for a > perspective.
Or Edgar Rice Burroughs' Pellucidar, where sundials always read high noon and time is strangely flexible. > Consider SAD, Seasonally Affected Disorder. We are in tune with the sun. We > have an important circadian rhythm tuned to the sun. This is the essence of > time as we experience it. High noon when the sun is at its apex is midday, > halfway between sunrise and sunset, not 13:23:34 DST (Digital Daylight > Standard Mean Civil Clock Time). We cannot get past our innate sense of solar > time, the rhythm and duration of solar cycles. It is part of our being. This > is what sundials show, true solar time. The diurnal rhythm is the most prominent spike in the power spectrum of most any human activity. Adding a secular slope to this rhythm is negligible for many purposes, but is deeply and immediately obvious for others. One second of time is 15 seconds of arc on the sky. Thus one missed leap second will be visible with professional and amateur telescopes world wide. The effect on sundials is (perhaps) less dramatic, but no less evident. Which is to say, the effect isn't just an offset it is a perpetual rate error. > Granted the change to atomic time is a minor adjustment from solar > astronomical time, at this time. But the difference is cumulative. The > difference will accumulate through the centuries. In the future we would be > getting up in the morning at 12:00 or whatever abstract number is defined by > vibrating Cesium atoms. The odd leap second can adjust for the slower > rotation of the earth. Is this better than the riots when an abrupt shift > like the Gregorian correction is required. Computers are easier to reprogram > than people. "Cogito ergo sum". Thinking people rule, technology serves. >From my point of view it is a simply an engineering question. The first step >in system engineering is to understand the problem at hand such that candidate >solutions can be proposed. To understand a problem, one must understand who >is affected. Use cases (such as for sundials and telescopes) are identified >and project requirements discovered. A requirement for civil timekeeping is >that the meaning of the word "day" is "synodic day". How human or computers >implement this is a topic for discussion. Simply pretending that the meaning >of "day" is "86,400 SI-seconds" is an incomplete and incoherent non-solution. >There will thus be side-effects. Rob Seaman National Optical Astronomy Observatory Tucson, AZ --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
