This webpage belongs to www.alexandriancomputus.net, which is a website promoting [Jan Zuidhoek (2019) Reconstructing Metonic 19-year Lunar Cycles (on the basis of NASAs Six Millennium Catalog of Phases of the Moon): Zwolle], and concerns the relation between the fundamental concepts Christian Era and Universal Time.
Christian Era and Universal Time
§ 1 Our era is the Christian Era (see p. 69), but nobody knows precisely when Jesus was born. Nevertheless, in AD 525, more than five centuries after Jesus birth, the first year of our era (referred to as the year AD 1) was retrospectively and implicitly but nevertheless exactly and definitively laid down by the learned Scythian monk Dionysius Exiguus (see p. 69), by means of his Paschal table (see Appendix I p. 103‑105). Therefore most Christians believe that Jesus was born on 25 December 1 BC, that is exactly a week before 1-1-1 = 1 January AD 1 or that He was conceived on 25‑3‑1 = 25 March AD 1 and born on 25‑12‑1 = 25 December AD 1. For example, Charlemagne must have believed that He was born on 25 December 1 BC, because he let himself crown emperor on 25‑12‑800. However, according to modern historians, Jesus was born some years before the beginning of the Christian Era (and died on 3‑4‑33). We conclude that Dionysius Exiguus chronology is only imperfect insofar as its first day is not the day Jesus was born.
§ 2 By simply counting the days and measuring the so called Universal Time UT (see p. 23), we measure accurately the total time elapsed since the beginning of our era. On further consideration, the exact beginning of the Christian Era is nothing but the Greenwich midnight point in time with which 1‑1‑1 began; therefore, the very moment (comprehending date and point in time) of the beginning of our era can be represented by a notation like [1‑1‑1; 00:00:00] or like [1 January AD 1; 00:00]. Similarly not only the beginning of the Christian era but each moment of our era can be represented in terms of date and point in time, for example moment [21 March AD 140; 14:17]. Thus we are provided with a somewhat irregular but nevertheless perfect chronological system based on the Christian Era and the Universal Time UT. For instance, [21‑3‑140; 14:17] represents a moment, called spring equinox, at which in the northern hemisphere spring began (see p. 41). The same applies to [20‑3‑325; 10:02] (see p. 44) and to [20‑3‑415; 05:18] (see p. 45).
§ 3 Nowadays, for practical scientific and economic reasons, extremely accurate atomic clocks are used to generate the so called Coordinated Universal Time UTC, which is continuously such a close approximation of the (real) Universal Time UT that |UT ̶ UTC|, being the absolute value of the (continuously irregularly fluctuating) difference between them, never exceeds 1 second. We establish:
§ 4 By definition, the Central European Time CET is UTC + 1 hour, the Central European Summer Time CEST is CET + 1 hour. This implies that the Central European Summer Time CEST is UTC + 2 hours. Keep in mind that it is nothing but the local Greenwich time which is exactly equal to UT. This implies, for example, that the local Liverpool time is UT ̶ 12 minutes, the local Rome time is UT + 50 minutes, and the local Alexandria time is UT + 120 minutes. Julius Caesar introduced the Julian calendar in 45 BC. He was murdered on 15 March 44BC, it is estimated sometime between 10:30 and 11:50 local Rome time. So he died around [15 March 44BC; 10:20].
§ 5 Keep in mind that in the framework of our era, Thursday 4‑10‑1582 was the very last Julian calendar day, and that that Thursday was immediately followed by Friday 15‑10‑1582 being the very first Gregorian calendar day. As a result, the year AD 1582, that turning point in the history of chronology, had only 355 days. Thus that year is the only calendar year of our era which had a number of days which is not 365 (which is the number of days of any normal calendar year) or 366 (which is the number of days of any leap year). Between the beginning of our era and the year 2021 there were only four calendar years of our era whose year number was divisible by 4 but whose number of days was nevertheless 365, namely the year AD 4 and the years AD 1700, 1800, and 1900. This implies that 1‑1‑1 was a Sunday, because 1‑1‑8 was a Sunday, which simple fact can easily be derived from Annianus 532‑year Paschal cycle (see p. 67‑68) being part of Beda Venerabilis Easter table (see Appendix II p. 106‑120), which is the perfect extension of Dionysius Exiguus Paschal table (see Appendix I p. 103‑105).
§ 6 Keep also in mind that our era consists of the years AD 1, 2, 3, and the years 1, 2, 3, BC, of which the ones after the year AD 1582 are arranged (in principle) according to the Gregorian calendar, that is, according to the principle that any such a year AD x is a leap year only if the number x is an integer divisible by 4 but not by 100 unless by 400, and the ones before the year AD 1582 (in principle) according to the Julian calendar, that is, according to the principle a leap year every four calendar years, on the understanding that:
1) before the leap year 45 BC there was, by retroactive definition, a leap year every four calendar years;
2) between the leap years 45 BC and 9 BC there was, erroneously, a leap year every three calendar years;
3) between the leap years 9 BC and AD 8 there was, in order to adequately compensate for that error, no leap year at all;
4) between the leap year AD 8 and the year AD 1582 there was, in accordance with the principle in question, a leap year every four calendar years.
§ 7 Owing to the prolepticity of the Julian calendar before the year 45 BC, it is only since somewhere in the twelfth century BC that the spring equinox, which marks the beginning of spring in the northern hemisphere, falls in March. As a matter of fact, at the (relatively very abrupt) beginning of the Holocene (around 9700 BC) the spring equinox fell only in June. From somewhere in the ninetieth to somewhere in the fiftieth century BC it fell in May, from somewhere in the fiftieth to somewhere in the twelfth century BC in April.
§ 8 Keep in mind that between the years 1 BC and AD 1 there was no year AD 0 or 0 BC. The first year of our era was the year AD 1, and its first day 1-1-1. The very first turn of the year must have been [1‑1‑2; 00:00:00], because it came one second after [31‑12‑1; 23:59:59]. Analogously, the very first turn of the decade must have been [1‑1‑11; 00:00:00], because it came one second after [31‑12‑10; 23:59:59]. Analogously, the very first turn of the century must have been [1‑1‑101; 00:00:00], the very first turn of the millenium [1‑1‑1001; 00:00:00], the second turn of the millenium [1‑1‑2001; 00:00:00]. As a consequence, the first day of the third millennium was 1‑1‑2001 (not 1‑1‑2000), and its first year the year 2001 (not 2000).
§ 9 We establish that we owe our chronological system to Dionysius Exiguus, who on his turn owed his chronology to Anatolius (see p. 12), the famous third century Alexandrian computist who invented the Metonic structure (see p. 16-17) according to which the 19‑year lunar cycle underlying Dionysius Exiguus Paschal table was composed. The Metonic 19‑year lunar cycle in question is the so called classical Alexandrian cycle the great computist Annianus opted for, and bishop Cyril of Alexandria adopted, in the first half of the fifth century (see p. 59).
© Jan Zuidhoek 2019-2021