We have dog years, financial years and calendar years, but a quest to get geologists and chemists to agree on a scientific year has led to a surprisingly bitter dispute.The official bodies representing the two groups have now settled on the annus as their definition of the year, allowing both groups' data on the half-lives of radioactive elements to be pooled.
Some are still enraged by the decision, however, and a universal scientific definition remains elusive, as the annus differs from the year favoured by astronomers. This changes slightly every year because of the Earth's slowing orbital rate, so the team chose as their reference point the year 2000, when the tropical year lasted 31,556,925.445 seconds. They are using the Latin name for year, annus, which will be denoted by the symbol a, and expressed in terms of kilo-annus (ka), mega-annus (Ma) and so forth.
So far so good. But when a draft proposing the idea came out in early 2009, some members of the Geological Society of America cried foul.
They didn't object to the idea of a precisely defined year, or to the chosen length. Their gripe was with the fact that geologists already use the symbol a (as well as ka and Ma) to denote time in years ago, or "absolute age". Historically, the abbreviations y, ky, and My (or yr, kyr and Myr) have denoted the time interval between two events.
Polistra was named after the original townsite of Manhattan (the one in Kansas). When I was growing up in Manhattan, I spent a lot of time exploring by foot, bike, and car. I discovered the ruins of an old mill along Wildcat Creek, and decided (inaccurately) that it was the remains of the original site of Polistra. Accurate or not, I've always liked the name, with its echoes of Poland (an under-appreciated friend of freedom) and stars. ==== The title icon is explained here. ==== Switchover: This 2007 entry marks a sharp change in worldview from neocon to pure populist. ===== The long illustrated story of Polistra's Dream is a time-travel fable, attempting to answer the dangerous revision of New Deal history propagated by Amity Shlaes. The Dream has 8 episodes, linked in a chain from the first. This entry explains the Shlaes connection.