"Radiation of the year 2026". The discovery and application of UV radiation

Symposium on the history of science

On February 22, 1801, the romantic experimental physicist Johann Wilhelm Ritter (1776-1810) discovered UV radiation in Jena. Ultraviolet radiation is part of the electromagnetic spectrum and is in the wavelength range between X-rays and visible optical radiation (light). Shortly before, Friedrich Wilhelm Herschel (1738-1822) had discovered infrared radiation as a form of energy beyond the visible red spectral range using highly sensitive thermometers. After Ritter had discussed the color theory of Johann Wolfgang von Goethe (1749-1832) and the "polarity" or symmetry of light spectra postulated therein, the latter postulated the existence of another form of radiation at the other end of the visible spectrum for reasons of symmetry.

The young physicist was thus motivated by Goethe's influence to search for this radiation. He split the solar radiation with a glass prism and used it to expose silver chloride, which then showed a photochemical reaction and turned black. The silver chloride changed color particularly strongly beyond the violet spectral range of visible light. There must therefore be radiation in this range that is not visible to the human eye.

On Saturday, 21 February 2026, the eve of the discovery 225 years ago, the Jena Centre for Romanticism Research, together with the German Optical Museum, the Professional Association for Radiation Protection and the Romantikerhaus Jena, is organizing a symposium on the history of science. Scientists from four faculties of the University of Jena (Faculty of Philosophy, Faculty of Physics and Astronomy, Faculty of Chemistry and Earth Sciences, Faculty of Biosciences) are taking part. The lectures will not only focus on the heuristics of romantic experimental physics. Current knowledge about the benefits and dangers of radiation, which will be proclaimed "Radiation of the Year 2026" by the Association for Radiation Protection, will also be conveyed.

Other 'milestones' in the research and application of ultraviolet radiation that were achieved in Jena will also be highlighted: the first application of UV microscopy with the discovery of fluorescence in microscopy (1904) and the development of the technical solution of lithography in the extreme ultraviolet (EUV lithography), which was awarded the German Future Prize in 2020. A cultural, scientific and technological history city walk will conclude the interdisciplinary meeting on Sunday, February 22, 2026.

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The symposium takes up the guiding principle of "Light, Life & Liberty" and links the university's profile areas with one another: 

• Light: historical and physical fundamentals as well as technological innovations relating to UV radiation 
• Life: benefits, risks, and significance for health, the environment, and radiation protection
• Liberty: interdisciplinary exchange, open science, historical knowledge, and social communication 

This orientation reflects the university's profile-building research and guiding principle.

Program

Saturday, February 21, 2026, 10:00–11:30 a.m. 
Sellierstraße 6, 07745 Jena 

• the university's mineralogical collection will be open and visitors will be able to view the UV cabinet (guided tour by Dr. Birgit Kreher-Hartmann).
   

Saturday, February 21, 2026, 1:30-6:00 p.m.
Rosensäle of the Friedrich Schiller University Jena, Fürstengraben 27, 07743 Jena

• Welcome, introduction of the co-organizers, introduction to the conference
  • Dr. Helmut Hühn (Friedrich Schiller University Jena)
  • Prof. Dr. Timo Mappes (German Optical Museum)
• Greetings
  • Prof. Dr. Thomas Pertsch (Vice President for Research and Innovation at Friedrich Schiller University Jena)
  • Dipl.-Ing. Martina Froning (Vice President of the German Radiation Protection Association)
• Lecture: Ultraviolet. On the discovery of UV radiation in Jena
  • Prof. Dr. Olaf L. Müller (Humboldt University of Berlin)
• with re-enactment of a experiment by Johann Wilhelm Ritter
  • Prof. Dr. Holger Cartarius (Friedrich Schiller University Jena)
  • Prof. Dr. Timo Mappes (German Optical Museum)
  • Prof. Dr. Tom Wagner (Friedrich Schiller University Jena)
     
• Break
   
• Lecture: What do we know about UV radiation today? Dangers and benefits
  • Dr. Birgit Keller (Non-ionizing Radiation Working Group of the German Radiation Protection Association)
• Lecture: The beginning of UV microscopy and the discovery of fluorescence in microscopy in Jena in 1904
  • Prof. Dr. Timo Mappes (German Optical Museum)
     
• Break
   
• Lecture: DUV lithography optics from ZEISS - resolution and precision as drivers of innovation
  • Dr. Bernhard Kneer (ZEISS Semiconductor Manufacturing Optics, ZEISS SMT)
• Lecture: EUV lithography - light for the digital age
  • Dr. Jörg Petschulat (ZEISS Semiconductor Manufacturing Optics, ZEISS SMT):
• Lecture: The "Radiation of the year 2026"

  • Matthias Bothe (German Radiation Protection Association)

     

Sunday, February 22, 2026, 10.00-12.00 a.m.
City walk (meeting point: Goethe Laboratory of the Friedrich Schiller University Jena, Fürstengraben 26, 07743 Jena)

An event organized by the Friedrich Schiller University, the Jena Centre for Romanticism Research, the Deutsches Optisches Museum, the Radiation Protection Association and the Romantikerhaus Jena.