At the turn of the previous century, this Leiden building was a major physics hub. Here, Heike Kamerlingh Onnes produced liquid nitrogen and, later, liquefied helium – feats that confirmed significant theories explaining how matter works. He was awarded the Nobel Prize for his accomplishments in 1913. His colleagues Hendrik Lorentz and Pieter Zeeman also won a shared Nobel Prize for their work here: the discovery of the Zeeman Effect, which indirectly proved the existence of electrons.
The KOG is the first place in the Netherlands to be awarded the title of “Historic Site” by the European Physical Society. There are now eighteen sites, including a particle accelerator at CERN in Geneva and the Niels Bohr Institute in Copenhagen.
However, the present plaque next to the bust of Kamerlingh Onnes is a temporary version. According to some physics historians, its current wording gives too much credit to Lorentz en Zeeman, passing over the work of British physicist, Joseph John Thomson, who provided direct proof of electrons.BB