Shadow projections – illustrative history of physics on the occasion of World Audiovisual Heritage Day 2022

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Every year on 27 October, UNESCO celebrates the „World Day for Audiovisual Heritage“ – in 2022 especially with the motto „Enlisting documentary heritage to promote inclusive, just and peaceful societies“ in connection with the 30th anniversary of the Memory of the World Programme. From TIB’s perspective, this World Day is always a fitting occasion to honour the film heritage of former Göttingen based IWF Wissen und Medien gGmbH (formerly the Institute for Scientific Film – IWF) and its preservation, as well as historical scientific film as a whole. Last year there was the unique ethnological film collection to discover, this year there is a detour into experimental physics and physics history for a special occasion:

Professor Robert Wichard Pohl (1884 to 1976), primarily resident and active at Göttingen University from 1919 to 1952, is considered a pioneer of solid-state physics and was especially known for his experimental physics lectures, which also appeared in many editions as a textbook. His teaching concept for physics at school and university influenced generations far beyond Göttingen, Germany and Europe. Among other things, Pohl constructed special set-ups for demonstration experiments that were projected as (shadow) projections onto the lecture hall wall and he also developed other instructive experiments. A large number of these experiments were reconstructed and repeated in an impressive video series of a total of 62 experiments under the editorship of the IWF at the I. Physikalisches Institut of the University of Göttingen with the prominent participation of Pohl’s son Robert Otto, also a solid-state physicist, using original equipment in the historic lecture hall between 2003 and 2005. For years, these have been freely viewable on the TIB AV portal, whether as individual videos or as a compilation cut together in one piece.

Pohl experiment: Stabilisation using a spinning top
Example: Robert Otto Pohl and Klaus Lüders demonstrate the phenomenon of precession in an experiment – „Stabilisation using a Spinning Top“ (2003).WF-Video:

The videos, which illustrate Pohl’s joy in experimentation and the clarity of his teaching concept, are among the most popular on the AV-Portal, with several thousand views in some cases. This alone is worthy of appreciation, as the experimental videos themselves are a testimony to the times and audiovisual heritage. And what’s more, they are part of a unique academic teaching tradition. But that is by no means all: in the recent past, it has been possible to give these experimental films, which are linked to textbook chapters in the AV-Portal but also stand on their own, more background and context in the history of science with two special documentaries on Pohl’s life and work. These are presented here:

Behind the Shadows – Lectures on Experimental Physics in the Tradition of Göttingen Physicist Robert Wichard Pohl (2022)

The research project „Projektionen. Die Lehrsammlung Robert Wichard Pohl“ („Projections. The Robert Wichard Pohl Teaching Collection“) was dedicated to an impressive reappraisal of the success of Pohl’s teaching system and the worldwide dissemination and use of his experimental set-ups to this day. Under the aegis of the science historian Dr. Michael Markert, the detailed blog accompanying the project named „Shadow Projections“ (only available in German), also reports in detail on the occasion and circumstances that led to the aforementioned experiment videos at the beginning of the 2000s – a (not entirely straightforward) textbook re-edition of the „Introduction to Physics“. Finally, a fantastic documentary (german with english subtitles) was created, which was also published on the AV-Portal in the course of the project’s conclusion in spring this year. The film focuses on “ the use of Pohl ideas and apparatuses in modern basic lectures on experimental physics in Göttingen. The film depicts the work of the lecturers and lecture hall technicians which is complemented with interviews. It was realized within of the research project „Projektionen. Die Lehrsammlung Robert Wichard Pohl“.“

Example of current replica of a Pohl experiment - demonstration of oscillations in shadow casting
Example of current use of a Pohl experiment at the University of Göttingen – demonstration of oscillations in shadow casting in documentary „Behind the Shadows“ (2022):

Simplicity is a Sign of the Truth – The Life and Work of the Physicist Robert Wichard Pohl (2005).

The film produced by Michael Markert and Sofia Leikam perfectly complements a no less interesting documentary by Ekkehard Sieker about Robert Wichard Pohl, which was made at the same time but independently of the experimental videos. In this documentary, Pohl’s career, especially his enthusiasm and importance for (Göttingen) experimental physics, is made clear with the help of valuable contemporary images and film material as well as interviews with contemporary witnesses. Original images and sound recordings also illustrate Pohl’s context of influence, for example the importance and reputation of Göttingen University as a centre of science, especially in and for physics, with luminaries such as Max Born and Ernest Rutherford also commenting.

Es konnte schließlich mit einigen Mühen, aber erfolgreich vor wenigen Tagen gelingen, Siekers Dokumentation ebenso langzeitarchiviert und frei verfügbar im AV-Portal erscheinen zu lassen. Michael Markert, Robert Otto Pohl und Ekkehard Sieker ermöglichten unter anderem als Hinweisgeber und „Türöffner“ Kontakte zu an der Dokumentation beteiligten Personen bzw. zu deren Nachkommen, um die notwendigen Veröffentlichungsrechte zu klären. Dankeschön!

Finally, with some effort, but successfully, a few days ago, Sieker’s documentary  „Einfachheit ist ein Zeichen des Wahren“ (freely translated „Simplicity is a sign of the truth“) was able to be published in the AV-Portal, also archived for a long time and freely available. Michael Markert, Robert Otto Pohl and Ekkehard Sieker, among others, acted as informers and „door-openers“, facilitating contacts with people involved in the documentation or their descendants in order to clarify the necessary publication rights. Thank you!

Excerpt from a Pohl lecture and demonstration from 1952 in the documentary "Einfachheit ist ein Zeichen des Wahren" (2005)
Excerpt from a Pohl lecture and demonstration from 1952 in the documentary „Einfachheit ist ein Zeichen des Wahren“ (2005):

Michael Markert writes aptly in the project blog (translated):

In combination with the experimental films, historical footage and the documentary, the result shortly after the turn of the millennium – and shortly before the Göttingen Physics Department moved out of the building already used by Pohl – was not only a new edition of the „Introduction to Physics“, expanded in terms of media, but also a comprehensive documentation project. With demonstrations such as the one on „Stabilization Using a Spinning Top“, it also saved for posterity such set-ups that have not been shown in lectures even in Göttingen for a long time. Demonstrated with historical equipment in the historical lecture hall by teachers with decades of Pohl experience, the media compound is not only a particularly unmediated but also very personal approach to the work of Robert Wichard Pohl.

He, Sofia Leikam and all those involved have impressively broadened the horizon on the work and aftermath of Robert Wichard Pohl with this new documentary and with the entire research project on the special teaching concept. It is fantastic to be able to make this freely accessible long term preserved and citable together with the experimental videos and now, quite recently, also with Sieker’s documentary in the AV-Portal. In this way, scientific film heritage is not only preserved, but receives new impetus, appreciation and also added value.

The efforts for the documentaries also repeatedly show that the preservation and accessibility of historical (scientific) film, beyond the technical and preservation aspects, is especially a sometimes lengthy and challenging clarification of rights. This should be extraordinarily appreciated on this special day. It is – once again – a wonderful opportunity to show gratitude, respect and high esteem to the people who, in many years of intensive (micro) work, make possible and secure the preservation, indexing and low-threshold access to these and other historical, scientific films. Many thanks!

... arbeitet seit Mai 2020 an der TIB mit Schwerpunkt Wissenschaftskommunikation besonders als Community Manager für das TIB AV-Portal. // ... has been working at the TIB since May 2020, specialising in science communication, especially as Community Manager for the TIB AV-Portal.