We measure history--its defining moments, landmark documents, and great figures--by dates. The French Revolution began in 1789, the Magna Carta was originally issued in 1215, and Julius Caesar died in the year 44 BC. What makes these dates correct, though? Is it possible that there is a massive gap in the historical record and that the calendar we use today is off by about 1,000 years? Sparked by a chance meeting at a conference in Mexico more...