A Passion for Calendars – From the Maya to Mars

  • Nachum Dershowitz | Tel Aviv University

How many days were there in 1752? Is there a year 0? When was there a February 30th? Why did an aluminum company lose $1,000,000 on New Year’s Eve? Who thinks 1900 was a leap year? Why is Passover late? Why does Ramadan end early? Does the Chinese calendar follow a 19 year cycle? Why do the Hindus skip days and months? Who would pay for a Martian calendar?

This talk will answer these ten questions and explain the underpinnings of the major types of calendars: solar (Gregorian, Julian, Persian, Hindu); lunar (Islamic); lunisolar (Chinese, Hebrew, Hindu); cyclical (Mayan, Balinese). It will concentrate on computational features of calendrical calculations, but also dwell on historical and cultural aspects.

Speaker Details

Nachum Dershowitz is a Visiting Researcher with the Foundations of Software Engineering group and a Professor of Computer Science at Tel Aviv University. The third edition of his definitive book, Calendrical Calculations, with Edward Reingold, will be published this summer, and a companion book, Calendrical Tabulations, was published in 2002 (both by Cambridge Univ. Press). His main areas of research are term rewriting, termination proofs, and Boolean satisfiability, in which he has authored or co-authored more than 100 research papers.

Watch Next