The "phantom time hypothesis" is a historical conspiracy theory asserted by Heribert Illig. First published in 1991, the hypothesis proposes a conspiracy by the Holy Roman Emperor Otto III, Pope Sylvester II, and possibly the Byzantine Emperor Constantine VII, to fabricate the Anno Domini dating system retrospectively, so that it placed them at the special year of AD 1000, and to rewrite history to legitimize Otto's claim to the Holy Roman Empire. Illig believed that this was achieved through the alteration, misrepresentation and forgery of documentary and physical evidence. According to this scenario, the entire Carolingian period, including the figure of Charlemagne, is a fabrication, with a "phantom time" of 297 years (AD 614–911) added to the Early Middle Ages. The proposal has found no favour among mainstream medievalists.
The bases of Illig's hypothesis include:
- The scarcity of archaeological evidence that can be reliably dated to the period AD 614–911, the perceived inadequacies of radiometric and dendrochronological methods of dating this period, and the over-reliance of medieval historians on written sources.
- The presence of Romanesque architecture in tenth-century Western Europe, suggesting the Roman era was not as long ago as conventionally thought.
- The relation between the Julian calendar, Gregorian calendar and the underlying astronomical solar or tropical year. The Julian calendar, introduced by Julius Caesar, was long known to introduce a discrepancy from the tropical year of around one day for each century that the calendar was in use. By the time the Gregorian calendar was introduced in AD 1582, Illig alleges that the old Julian calendar should have produced a discrepancy of thirteen days between it and the real (or tropical) calendar. Instead, the astronomers and mathematicians working for Pope Gregory XIII had found that the civil calendar needed to be adjusted by only ten days. (The Julian calendar day Thursday, 4 October 1582 was followed by the first day of the Gregorian calendar, Friday, 15 October 1582). From this, Illig concludes that the AD era had counted roughly three centuries which never existed.
But this theory has interesting skepticism:
The most difficult challenge to the theory is through observations in ancient astronomy, especially those of solar eclipses cited by European sources prior to 600 AD (when phantom time would have distorted the chronology). Besides several others that are perhaps too vague to disprove the phantom time hypothesis, two in particular are dated with enough precision to disprove the hypothesis with a high degree of certainty. One is reported by Pliny the Elder in 59 AD and one by Photius in 418 AD. Both of these dates and times have confirmed eclipses. In addition, observations during the Tang dynasty in China, and Halley's Comet, for example, are consistent with current astronomy with no "phantom time" added.
Archaeological remains and dating methods such as dendrochronology refute, rather than support, "phantom time".
The Gregorian reform was never purported to bring the calendar in line with the Julian calendar as it had existed at the time of its institution in 45 BC, but as it had existed in 325, the time of the Council of Nicaea, which had established a method for determining the date of Easter Sunday by fixing the vernal equinox on March 21 in the Julian calendar. By 1582, the astronomical equinox was occurring on March 10 in the Julian calendar, but Easter was still being calculated from a nominal equinox on March 21. In 45 BC the astronomical vernal equinox took place around March 23. Illig's "three missing centuries" thus correspond to the 369 years between the institution of the Julian calendar in 45 BC, and the fixing of the Easter Date at the Council of Nicaea in AD 325.
If Charlemagne and the Carolingian dynasty were fabricated, there would have to be a corresponding fabrication of the history of the rest of Europe, including Anglo-Saxon England, the Papacy, and the Byzantine Empire. The "phantom time" period also encompasses the life of Muhammad and the Islamic expansion into the areas of the former Roman Empire, including the conquest of Visigothic Iberia. This history too would have to be forged or drastically misdated. It would also have to be reconciled with the history of the Tang dynasty of China and its contact with Islam, such as at the Battle of Talas.