Establish whether the surviving transparency was created before the Cologne lecture

Determine whether Hermann Minkowski created the surviving colored space-time transparency for an earlier Ferienkurs presentation rather than exclusively for his later Cologne lecture.

Background

The surviving colored transparency depicts the primed and unprimed coordinate systems and the geometric derivation of Lorentz contraction. Although it appears likely to have been used in Minkowski’s Cologne lecture, the paper observes that the absence of further explicit drawings in the earlier manuscripts and the reference to a missing “Figur” may indicate an earlier origin. The precise date and occasion of its production therefore remain unresolved.

References

While it seems safe to assume that Fig.\,\ref{fig:Figur-colored} shows the transparency shown during his talk in Cologne, we can now also conjecture that the same transparency may well have been created quite a bit earlier, perhaps already for the presentation during the Ferienkurse.

— Minkowski's Geometric Explanation of Lorentz Contraction  (2608.20138 - Sauer, 20 Aug 2026) in Section 4, paragraph beginning “The full colored transparency is shown”