Progress in the exact and natural sciences

In the late 19th and early 20th centuries the natural sciences developed quickly and new fields (physical chemistry, engineering sciences, genetics) appeared. In chemistry D. I. Mendeleev created the periodic table of elements in 1869, and S. Arrhenius proposed the theory of electrolytic dissociation in 1887. In physics W. Röntgen discovered invisible rays (“X-rays”) in 1895 (the first Nobel Prize in physics, 1901), A. Becquerel found the radiation of uranium in 1896, and Marie and Pierre Curie isolated polonium and radium in 1898; Marie Curie introduced the term “radioactivity”. In 1897 J. J. Thomson discovered the electron, in 1911 E. Rutherford proposed the nuclear model of the atom, in 1913 N. Bohr refined it, and in 1900 M. Planck introduced the idea of the quantum. In 1905 A. Einstein published his special theory of relativity. In biology Charles Darwin argued for evolution by natural selection in On the Origin of Species (1859); Gregor Mendel’s laws of heredity (1866) were rediscovered in 1900 and founded genetics; I. P. Pavlov studied higher nervous activity. In microbiology L. Pasteur worked on fermentation and the role of microbes, pasteurisation and rabies vaccination; R. Koch found the tuberculosis bacillus in 1882, and I. I. Mechnikov received the 1908 Nobel Prize for his work on immunity. These discoveries brought X-rays, sterilisation and vaccination into medicine and laid the basis for 20th-century scientific and technical progress.