There are at least two stories in circulation regarding the photograph of Lorentz and Einstein. Some sources claim that the photograph was taken in the doorway to Ehrenfest’s house on the Witte Rozenstraat in Leiden. This is reported by the Museum Boerhaave  as well as various other secondary sources. Other sources, such as Vincent Icke on the Dutch television program DWDD (4 Nov 2015), claim that the photograph was taken in front of Leiden Observatory.

There is a second misunderstanding regarding the positions of Einstein and Lorentz in the photograph. The original photograph is in the possession of the Museum Boerhaave. I received this original after paying for the right to use it as a cover. In the original I received, Lorentz is standing on the left and Einstein is standing on the right. However, on all the photographs I had previously seen – in books, on the internet and even at the Museum Boerhaave itself – Lorentz was always on the right hand side and Einstein was on the left. How could this be?

Further inquiry at the museum revealed that the original I had received was most likely the correct version (i.e. with Lorentz on the left hand side). However, the original was mirrored because the prevailing etiquette at that time dictated that the more senior individual should stand on the right of the photograph, according to the museum. Consequently, there are ‘two originals’ in circulation: the ‘true’ original – as printed on my book – and the mirrored version that one more commonly sees. The version printed on my book is probably the correct version, since it is unlikely that anyone would mirror a photograph to contradict prevailing etiquette.

I have used this photograph as a cover, because the new photon model provides answers to unresolved discussions between Einstein and Lorentz. This does not just concern the subject ‘the radiation problem’, but also the question of how Newton, Einstein and Lorentz’s world views regarding space and time can be described in a coherent manner. The cover photo reminds us of some theoretical problems of the period 1895-1920 that are still unresolved.