Jena is celebrating 225 years of UV radiation
The University of Jena commemorates the discovery of UV radiation and its significance for modern key technologies.
In a darkened room, minerals can be seen under ultraviolet light at the Mineralogical Collection of the University of Jena.
- Light
- Life
- Liberty
Published: | By: Irena Walinda
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225 years ago, on 22 February 1801, natural scientist Johann Wilhelm Ritter (1776–1810) conducted an experiment in Jena that fundamentally changed our understanding of light: he proved the existence of invisible radiation beyond violet light. To mark this anniversary, Friedrich Schiller University Jena is hosting an interdisciplinary symposium from 21 to 22 February 2026.
Entitled ?The Discovery and Application of UV Radiation?, the conference combines the history of science with current developments—from early UV microscopy to extreme ultraviolet lithography (EUV), the key technology in modern chip production. A highlight of the conference will be the re-enactment of Ritter’s historical experiment by Professors Holger Cartarius (University of Jena), Timo Mappes (German Optical Museum and University of Jena) and Tom Wagner (University of Jena).
From thinking in polarities to discovering the invisible
Portrait of natural scientist Johann Wilhelm Ritter (1776–1810)
Picture: Wikimedia CommonsWhen Johann Wilhelm Ritter was experimenting in Jena in 1801, he was working at the intersection between physics, chemistry and natural philosophy. Inspired by William Herschel’s recent successful detection of infrared radiation, Ritter set out to find a ?counterpole? in the light spectrum. Using a prism and light-sensitive silver chloride papers, he demonstrated that beyond the visible violet light there is radiation that has a particularly strong chemical effect – what is known today as ultraviolet radiation.
The intellectual exchange with Johann Wolfgang von Goethe, who was intensively studying optical phenomena in Jena, among other things, was decisive for this leap in knowledge. Goethe’s reflections on the polarity of light provided Ritter with important impulses to not consider the spectrum as closed. The discovery of UV radiation is therefore also an example of the productive interaction between experimental natural science and humanities-influenced natural thinking.
?Ritter understood the art of what we call exploratory experimentation. His discovery was guided by expectation. It impressively demonstrates how new insights can arise from the interplay of different ways of thinking—a hallmark of Jena as a centre of science to this day?, says philosopher Dr Helmut Hühn, who rganized the symposium.
The symposium is part of the L? event series, which is linked to the University’s profile areas—LIGHT, LIFE and LIBERTY—and combines historical, scientific and technological perspectives on UV radiation with questions about health, the environment, radiation protection and social responsibility. In lectures and discussions, researchers from various faculties of the University of Jena, together with external experts, highlight the University's interdisciplinary research profile.
From UV microscopy to a key technology of the 21st century
The conference combines history with the present. Important milestones from the discovery to the application of UV radiation have a strong connection to Jena. At the beginning of the 20th century, UV microscopy was introduced in the city on the Saale river to increase resolution, which led to the discovery of fluorescence in microscopy.
One focus of the symposium is on current technological applications, in particular extreme ultraviolet lithography (EUV). Only with this technology can structures in the nanometre range be produced economically—a prerequisite for modern high-performance chips. The development of this technology in Jena was honoured with the German Future Prize in 2020 and is an example of the long journey from a historic discovery to a globally relevant key technology.
?The close collaboration between university and non-university research with industrial research and development is the reason why we find the highest density of innovation in Germany in Jena. We can illustrate this well using the example of the benefits of UV radiation?, says Prof. Dr Timo Mappes from the German Optical Museum.
A programme between the history of science and the present
The symposium opens on Saturday with a guided tour of the UV Cabinet of the Mineralogical Collection at the University of Jena. This will be followed by the scientific conference with presentations by researchers from the fields of history and theory of science, physics, chemistry, technology and cultural studies. The Association for Radiation Protection will declare UV radiation the ?Radiation of the Year 2026? during the conference. On Sunday, a cultural walk entitled ?In the Footsteps of Goethe and Ritter? will not only take participants to important locations in Jena’s scientific and intellectual history, but it will also bring to life the close connection between scientific research, technological application and culture in the city that continues to this day.
The L? Symposium is organized by the Center for Romanticism Research at Friedrich Schiller University Jena, the German Optical Museum, the Association for Radiation Protection and the Romantikerhaus Jena. Registration for all programme items is required by 14 February 2026 by e-mail to h.huehn@uni-jena.de.
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21—22 February 202621—22 February 2026
Contact:
Helmut Hühn, Dr
Professur neuere Kunstgeschichte