Zamenhof Day Zamenhof Day Zamenhof Day (), also called Esperanto Book Day, is celebrated on 15 December, the birthday of Esperanto creator L. L. Zamenhof. It is the most widely celebrated day in Esperanto culture. On this day, Esperantists hold information sessions and cultural gatherings to promote literature in Esperanto. The history of celebrating Esperanto on Zamenhof's birthday can be traced back to 17 December 1878, when at a birthday party for his 19th birthday he presented to his friends his "Lingwe uniwersala", the first version of his international language. By 1887, this language had evolved into what is now recognized as
Ludwik Rajchman the first cousin of Ludwik Hirszfeld, a Polish microbiologist. Ludwik Rajchman is the father of Jan A. Rajchman, a Polish computer scientist, inventor of magnetic-core memory. Rajchman grew up in Warsaw in the difficult conditions of the Russian occupation. At an early age, he and his sister Helena became keenly aware of the social injustices in their "country" (Poland did not officially exist at the time) and were involved as teenagers in teaching young workers. As an adult, he joined the Polish socialist party (PPS) and was involved in the 1905 uprising and even arrested. After several months in prison