Willem de Sitter

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Sitter, Willem de

 

Born May 6, 1872, in Sneek; died Nov. 19, 1934, in Leiden. Dutch astronomer.

De Sitter graduated from the University of Groningen. In 1897 he began work in photometry at the observatory on the Cape of Good Hope, where he developed a theory for the motion of the first four satellites of Jupiter. In 1908 he became a professor of astronomy and in 1919, director of the observatory of the University of Leiden. De Sitter created his own fundamental system of astronomical and geodetic constants. His works on the theory of relativity served as an impetus for the organization of an expedition to observe the solar eclipse of 1919. It was during this eclipse that the deviation of light rays passing near the sun was detected, a phenomenon that had been predicted by Einstein.

WORKS

“The Expanding Universe.” Bulletin of the Astronomical Institutes of the Netherlands, 1930, vol. 5.

REFERENCE

“Willem de Sitter.” Monthly Notices of the Royal Astronomical Society, 1935, vol. 95, no. 4.
References in periodicals archive ?
Spencer had already reasoned along similar lines in response to de Sitters objection [31-35].
represents the rotating de Sitter vacuum in the corotating frame [25].
Zhai, On spacelike hypersurfaces with constant scalar curvature in the de Sitter space, Diff.
In Section 3, we deal with Smarandache curves on de Sitter and hyperbolic spaces for timelike curves.
are locally the catenoid of the 1st kind, the catenoid of the 3rd kind, the de Sitter pseudosphere, or the hyperbolic pseudosphere.
Markkanen, "De Sitter Stability and Coarse Graining," European Physical Journal C, vol.
On the other hand, proceeding from the aforementioned theoretical results [1-3] we can now state that the observed redshift in the spectra of galaxies and quazars has no relation to cosmology but is the "effect of distance" in the stationary universe of the de Sitter metric.
Moreover, in the sense of de Sitter and hyperbolic shape operator in [H.sup.3], we study extrinsic differential geometry of these invariant surfaces by using notations in [7, 8].
There exist some special submanifolds in [R.sup.n + 1.sub.2], such as unit pseudo-n-sphere [S.sup.n.sub.2], anti de Sitter n-space [H.sup.n.sub.1], null cone [[LAMBDA].sup.n.sub.1], and Lorentz torus [S.sup.1.sub.t] x [S.sup.n - 1.sub.s], which have the same definitions as in [17].
Aiyama [1] had proved that a compact spacelike submanifold with parallel mean curvature vector and flat normal bundle in de Sitter space [S.sup.n+p.sub.p](c) is totally umbilical.
Later work by Willem de Sitter and independently by Aleksandr Friedmann implies the possibility that the universe is expanding.