Makes you wonder how some books get published

A UVic mathematician's new book discusses the extraordinary idea that our calendars are more than 1,000 years off:

Happy 2006! Wait, not so fast. Should we really be saying "Happy 942?"

The thought that we're ahead of ourselves chronologically seems far-fetched, but it's the subject of a new book by University of Victoria mathematician Dr. Florin Diacu...

Diacu admits that an interest in history is unusual for a mathematician, but his research in celestial mechanics—the motion of celestial bodies such as planets and stars—ties the two together. "If you look at planets today you can see where they were in the past. We can tell their movements with good accuracy for about 20 million years in the past and the future."

Not having read the book (or heard the theory) I'm of course not in a position to make any comment on it other than that I'm extremely skeptical. But there are a few points worth making:

1. The modern science of chronology was established by Joseph Scalinger, a harsh critic of the cumbersome Gregorian calendar, in circa ~1600. The Gregorian calendar, whose complexity makes it very difficult to reconstruct chronology accurately, had recently replaced the Julian calendar, one of several times throughout history calendar systems have needed replacement.

2. The assumption that people before us were too stupid to define a working calendar but lived with it for a millennium anyway is universal, but unlikely. There is most likely something else going on that causes our calendars to become outdated every millennium or so.

3. Diacu's idea that our chronology is incorrect is based on an assumption that, "if you look at the planets today, you can see where they were in the past." In other words, planets make a good clock because their motion is predictable and consistent, and he uses that consistency to show that our calendars are incorrect. But all ancient calendars were based on the movement of planets and their moons - most notably ours - yet they all needed replacing at some point.

What does it all mean? Heck if I know. I just wonder how many people would actually pay $25 for a book that tells them we're still in the Dark Ages...