1906 in science

Chemistry

• Charles Barkla discovers that each element has a characteristic X-ray and that the degree of penetration of these X-rays is related to the atomic weight of the element.
• Mikhail Tsvet first names the chromatography technique for organic compound separation, in the course of demonstrating that chlorophyll is not a single chemical compound.

  Geology

• April 18 – The San Francisco earthquake, an estimated 7.9 on the Richter scale and centered on the San Andreas fault, strikes near San Francisco, California. The earthquake and fire destroy over 80% of the buildings in the city, and kill as many as 6,000 people. Harry Fielding Reid devises the elastic-rebound theory to account for earthquake mechanism.
• Richard Oldham argues that the Earth has a molten interior.

  Mathematics

• Andrey Markov produces his first theories on Markov chain processes.
• Axel Thue uses the Thue–Morse sequence to found the study of combinatorics on words.

  Medicine

• September – Last death from yellow fever in the Panama Canal Zone following a mosquito eradication program led by William C. Gorgas.
• October–December – Martha Baer undergoes sex reassignment surgery to become Karl M. Baer in Germany.
• November 3 – A speech given by Alois Alzheimer for the first time presents the pathology and clinical symptoms of pre-senile dementia together; the condition will rapidly become known as Alzheimer's disease.
• BCG immunization for Tuberculosis first developed.
• Transmission of dengue fever by the Aedes mosquito is confirmed.
• Frederick Hopkins proposes the existence of vitamins and suggests that a lack of them causes scurvy and rickets.
• Charles Sherrington publishes The Integrative Action of the Nervous System.
• Clemens Peter von Pirquet, with Béla Schick, coins the term "allergy" to describe hypersensitive reactions.
• Royal Victoria Hospital, Belfast, is completed, the first such air conditioned building in the world.
• George Newman publishes Infant Mortality: a Social Problem in England.
• August von Wassermann develops a complement fixation test for the diagnosis of syphilis.

  Physics

• Walther Nernst presents a formulation of the third law of thermodynamics.

  Technology

• January – Lee De Forest files a patent for the Audion vacuum tube, which helps usher in the age of electronics.
• February 10 – Launch of British battleship HMS Dreadnought.
• March 18 – At Montesson in France, Romanian inventor Traian Vuia becomes the first person to achieve an unassisted takeoff in a heavier-than-air powered monoplane, but it is incapable of sustained flight.
• October 18 – German inventor Arthur Korn demonstrates the transmission of a photograph electronically over a distance of 1800 km using his Bildetelegraph or phototelautograph system.
• December 24 – Reginald Fessenden makes the first radio broadcast, including a musical recording, a violin solo, and readings, from Brant Rock, Massachusetts.
• The first practicable gyrocompass is invented by Hermann Anschütz-Kaempfe in Germany.

  Events

• November 12 – First displays of the Deutsches Museum open to the public in Munich.

  Publications

• African Invertebrates begins publication as Annals of the Natal Government Museum; it will be continuing publication more than a century later.

  Awards

• Nobel Prizes
• * Physics – Sir J. J. Thomson
• * Chemistry – Henri Moissan
• * Medicine – Camillo Golgi, Santiago Ramón y Cajal
• Hughes Medal – Hertha Ayrton

  Births

• January 6 – G. Ledyard Stebbins, American botanist and geneticist.
• January 10 – Grigore Moisil, Romanian mathematician.
• January 11 – Albert Hofmann, Swiss chemist.
• February 3 – George Adamson, Indian-born wildlife conservationist.
• February 4 – Clyde Tombaugh, American astronomer.
• February 17 – Elizabeth M. Ramsey, American research physician.
• February 18 – Hans Asperger, Austrian pediatrician.
• April 28 – Kurt Gödel, Austrian mathematician.
• June 13 – Bruno de Finetti, Italian statistician.
• June 18 – Orvan Hess, American obstetrician.
• June 23 – Derek Jackson, Swiss-born British spectroscopist and steeplechase rider.
• July 2 – Hans Bethe, German-born physicist, recipient of the Nobel Prize in Physics.
• August 19 – Philo Farnsworth, American television pioneer.
• September 1 – Karl August Folkers, American biochemist.
• September 4 – Max Delbrück, German-born biologist.
• September 30 – Vera Faddeeva, Soviet mathematician.
• October 2 – Willy Ley, German-born scientific populariser.
• November 3 – Carl Benjamin Boyer, American historian of mathematics.
• November 5 – Fred Lawrence Whipple, American astronomer, coins the term "dirty snowball" to explain the nature of comets.
• November 18 – George Wald, American scientist.
• December 9 – Grace Hopper, American computer scientist.
• December 25 – Ernst Ruska, German physicist, recipient of the Nobel Prize in Physics.

  Deaths

• January 13 – Alexander Stepanovich Popov, Russian physicist.
• January 14 – Hermann Sprengel, German-born British chemist.
• February 27 – Samuel Pierpont Langley, American astronomer.
• March 8 – Henry Baker Tristram, English ornithologist.
• April 19 – Pierre Curie, French winner of the Nobel Prize in Physics.
• May 15 – James Blyth, Scottish electrical engineer.
• July 5 – Paul Drude, German physicist.
• September 5 – Ludwig Boltzmann, Austrian physicist.