Walter Baade and Fritz Zwicky invent the concept of the neutron star, a new type of celestial object, suggesting that supernovae might be created by the collapse of a normal star to form a neutron star.
Sir Arthur Eddington publishes The Expanding Universe: Astronomy's 'Great Debate', 1900–1931 in Cambridge.
April 3 – First attempted human kidney transplant, by Dr Yuri Voronoy in the Soviet city of Kherson; the recipient dies 2 days later due to incompatibility of blood type with the (cadaveric) donor.[12][13][14][15]
^Kharasch, M. S.; Mayo, Frank R. (1933). "The Peroxide Effect in the Addition of Reagents to Unsaturated Compounds. I. The Addition of Hydrogen Bromide to Allyl Bromide". Journal of the American Chemical Society. 55 (6): 2468–2496. doi:10.1021/ja01333a041.
^Crilly, Tony (2007). 50 Mathematical Ideas you really need to know. London: Quercus. p. 125. ISBN 978-1-84724-008-8.
^Champernowne, D. G. (1933). "The construction of decimals normal in the scale of ten". Journal of the London Mathematical Society. 8 (4): 254–260. doi:10.1112/jlms/s1-8.4.254.
^Matevossian, Edouard; et al. (2009). "Surgeon Yurii Voronoy (1895–1961) – a pioneer in the history of clinical transplantation: in Memoriam at the 75th Anniversary of the First Human Kidney Transplantation". Transplant International. 22 (12). European Society for Organ Transplantation: 1132–1139. doi:10.1111/j.1432-2277.2009.00986.x. ISSN0934-0874. PMID19874569. S2CID12087935.
^Klein, Andrew; et al. (2011). Organ Transplantation: A Clinical Guide. Cambridge University Press. p. 2.
^Humar, Abhinav; et al. (2009). Atlas of Organ Transplantation. Springer. p. 1.