Goethe's Farbenlehre and Photochemical Experiments by J. Ritter

• Applicant: Professor Dr. Olaf Müller
• Subject Area: Theoretical Philosophy ; History of Science
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 279702699

In his research on optics, Goethe discovered a symmetry between light and darkness that pervades the whole of geometrical optics. Goethe construed this symmetry as a kind of polarity and suggested that scientists in other areas should proceed by actively looking for polarities in the phenomena and in their experiments. Goethe's guiding principle soon led to its first success: it enabled the physicist J. Ritter to discover the photochemical effects of what we now know to be ultraviolet light. Ritter used various other photochemical experiments to demonstrate symmetries between light and darkness. These experiments are hard to interpret and evaluate from our current perspective. Many theorists have taken them to be deficient and consequently have not examined them in detail, but we think Ritter's experimental abilities and results deserve a more charitable interpretation. After all, Ritter was an important and reputable experimenter of his time. We will use a detailed analysis of Ritter's extensive writings on photochemistry to provide a theoretical reconstruction of his experiments, from a current perspective and with current terminology. Then we will use modern means to replicate his experiments. And finally we will try to replicate the experiments as Ritter would have conducted them, using sunlight instead of artificial light, flawed prisms and chemicals of Ritter's time instead of their modern counterparts. This part of the project will be carried out by A. Reinacher, and will result in a detailed case study. O. Mueller will use this case study, on the one hand, to examine questions in the philosophy of nature. Here, his aim is to explicate, and possibly defend, the notion of polarity, which has played an important role in German philosophy of the time. Ritter sided with Goethe in criticising Newton's optics, and he took his experiments to substantiate this criticism. We hope to find out whether this ambition was reasonable - from Ritter's own point of view and from our current perspective. Was there a tenable alternative to Newton's historically successful view, one that was not only compatible with the phenomena of geometrical optics but also with early photochemistry? By answering this question, we hope to find out which potential Goethe's guiding principle of polarity held for the scientists of his time. On the other hand, O. Mueller's goal is to provide a double biography of the collaboration between Goethe and Ritter.

• DFG Programme: Research Grants