A recent NPR article reported on the team of craftsmen and technicians who are grinding the mirrors for the Giant Magellan Telescope. While the entire article is interesting, what is particularly interesting to me is that it reveals the importance of tacit knowledge in making even the most technical instruments.
The astrolabe is a fascinating medieval astronomical/astrological instrument. The replica I have always attracts students’ attention when I bring it into class and we talk about how scientific knowledge is embodied in technical instruments. We work through how use the astrolabe to tell time, find the positions of stars, the elevation of buildings. We also spend time thinking seriously about astrolabes as objects of artistic value. By then end of even my introductory course students have a good idea of the history of astrolabes and how they were used.
Consequently, I am particularly sensitive to erroneous and problematic stories about the astrolabe. Unfortunately, that is precisely what a reporter over at Curiosity.com did in a recent article: “10 Astronomical Discoveries Made Without A Telescope.” While there are a number of problems this post, I concentrate on the errors about the history of the astrolabe.
The last couple of days have seen a number of articles on the “leap second,” this otherwise unremarkable second that we agree to insert every now and then to keep atomic clocks in sync with the rotation of the earth. The decision yesterday to postpone making a decision sounds a lot like early modern efforts to reform the calendar. Then they were concerned about keeping the calendar in sync with planetary motions—in particular, they worried that the spring equinox was drifting too far from the established date.
For more than 300 years astronomers, mathematicians, and astrologers argued about how best to fix the problem. It wasn’t until 1582 that Pope Gregory issued a papal bull establishing a new, reformed, and more accurate calendar. Still, it took some countries centuries to adopt this new calendar.
Teaching a course on plagues and epidemics in history makes me more aware than normal of press reports about some group of scientists trying to retro-diagnose some historical plague or epidemic (Find a description of this course and a link to the syllabus on my Recent Courses page). There seems to have been a rash of them lately — paradigmatic studies arguing that the “Black Death” was caused by yersinia pestis and further efforts to find the origins of syphilis. While these might be good science, though I’m not convinced, they are bad history. And I confess, I don’t really understand the benefit of such research.
Recent research, however, has crossed the line from possibly useful to absurd. A group of physicians has retro-diagnosed a fictional plague, the plague in Sophocles’ Oedipus Rex.