Willem de Sitter


Willem de Sitter was a Dutch mathematician, physicist, and astronomer. He is known for the de Sitter universe, which is a cosmological model that was named after him.

Life and work

Born in Sneek, Netherlands, de Sitter studied mathematics at the University of Groningen and then joined the Groningen astronomical laboratory. He worked at the Cape Observatory in South Africa. Then, in 1908, De Sitter was appointed to the chair of astronomy at Leiden University. He was director of the Leiden Observatory from 1919 until his death.
De Sitter made major contributions to the field of physical cosmology. In 1916-17, he published a series of papers describing the consequences of Albert Einstein's theory of relativity to the understanding of astronomy, which were directly affected Arthur Eddington's 1919 findings in the famous experiment of the solar eclipse. He co-authored a paper with Einstein in 1932, with whom he had a lengthy correspondence, in which they discussed the implications of cosmological data for the curvature of the universe, comparing "space to a cloth". He also came up with the concept of the De Sitter space and De Sitter universe, a solution for Einstein's general relativity in which there is no matter and a positive cosmological constant. This results in an exponentially expanding, empty universe. De Sitter was also well-known for his research on the motions of the moons of Jupiter, and was invited to give the George Darwin Lecture at the Royal Astronomical Society in 1931. His research helped to launch inquiries into relativistic cosmology.
Willem de Sitter died after a brief illness in November 1934.

Honours

In 1912, he became a member of the Royal Netherlands Academy of Arts and Sciences.

Awards

  • James Craig Watson Medal
  • Bruce Medal
  • Gold Medal of the Royal Astronomical Society
  • Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society

    Named after him

  • The crater De Sitter on the Moon
  • Asteroid 1686 De Sitter
  • De Sitter universe
  • De Sitter space
  • Anti-de Sitter space
  • De Sitter invariant special relativity
  • Einstein–de Sitter universe
  • De Sitter double star experiment
  • De Sitter precession
  • De Sitter–Schwarzschild metric

    Family

One of his sons, Ulbo de Sitter, was a Dutch geologist, and one of Ulbo's sons was a Dutch sociologist Ulbo de Sitter.
Another son of Willem, Aernout de Sitter, was the director of the Bosscha Observatory in Lembang, Indonesia, where he studied the Messier 4 globular cluster.

Selected publications

Category:1872 births
Category:1934 deaths
Category:19th-century Dutch astronomers
Category:19th-century Dutch mathematicians
Category:20th-century Dutch astronomers
Category:Dutch relativity theorists
Category:20th-century Dutch mathematicians
Category:Cosmologists
Category:People from Sneek
Category:Academic staff of Leiden University
Category:University of Groningen alumni
Category:Members of the Royal Netherlands Academy of Arts and Sciences
Category:Foreign associates of the National Academy of Sciences
Category:Recipients of the Gold Medal of the Royal Astronomical Society
Category:Presidents of the International Astronomical Union