Visualization of Ancient Cosmological Models: a presentation of completed work and some difficulties

Posted on 28 January 2014

Talk: Henry Mendell (California State University, USA), “Visualization of Ancient Cosmological Models: a presentation of completed work and some difficulties”.


Date: Tuesday, 28 January 2014

Time: starting at 18:00 c.t. (i.e. 18:15)

Venue: TOPOI Building Dahlem, Hittorfstraße 18, Freie Universität Berlin, 14195 Berlin (map)


As part of Topoi 1, Group-D, Sebastian Szczepanski and I developed software for the visualization of ancient cosmological theories. These included the 4th cent. BCE planetary models of Eudoxus, Aristotle, and Calippus, as well as the basic planetary models of Ptolemy’s Almagest. Because the visualizations are open source and written in HTML-5, they have a higher likelihood of surviving than many other potential platforms. Most important is the flexibility of the program that allows the user to modify all the parameters, to reveal or hide or even eliminate components of a model, to focus in on certain features of the model, or to change views. In the Ptolemaic models, which are coordinated to Julian, Gregorian, and Egyptian calendars, one may set the clock to where one wishes and see the results.

As a research tool, it allows the user to get a clearer picture of how ancient models work. For example, in the case of the 4th cent. BCE models, the models allow one to see, for example, how well they represent retrograde motion, latitude variation on the horizon, or anomally in invisibility appearances, the three main candidates in modern scholarship for the motivations for the third and fourth sphere of the slow planets in the Eudoxan model. The main value, however, is as a pedagogical tool for anyone wishing to get a deeper understanding of the models or to present it to others.

In the first, main part of my talk, I will present the software and will indicate areas where it can be developed and improved to make it more user friendly. In the second part, I will discuss problems of integrating the visualizations with texts associated with scholarship on them, I will then turn to two features that we did not integrate into the visualizations. The first is coordinating the visualiztions to modern trackings of bodies. This is important for all models. I will argue that even for theories of dubious empirical foundations, it is important to see how well or poorly they preserve the phenomena. The second issue is the construction of tables. An equally important part of the visualization is to be able to coordinate the visualizations with astronomical tables. Yet, tables themselves are a form of visualization. So, for example, Babylonian models, which are table based, are best presented through flexible spread sheets. I shall illustrate this with a simple example. Here is where software advances have been most detrimental. We should employ a standard spread sheet Program such as Excel but modified to present different versions of sexagesimal numbers, including whole number decimal/fraction sexagesimal, base 30 for the first fraction, etc. Unfortunately, software developers have not been kind here. Microsoft no longer, for example, allows DLL’s. So my example will have to use Mac System 9! Hence, I will conclude with a question about how to proceed in this issue.


Or you can download the slides from here.




Or you can just download the video files (.mp4): talk (412 MB) ; discussion (223 MB).