Marcus Sparnaay

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Marcus Johannes Sparnaay (* 1923 ; † February 11, 2015 ) was a Dutch physicist.

Sparnaay received his doctorate in 1952 from the University of Utrecht ( Direct measurement of Van der Waals forces , Directe metingen van Van der Waals-krachten ). He was a physicist at the Philips laboratories (Nat-Lab) in Eindhoven . He stayed there until 1983 and also taught at the University of Twente.

He is known for the experimental confirmation of the Casimir effect . Hendrik Casimir , one of the three directors of the Philips laboratory since 1946, had predicted the effect in the 1940s and made the first experiments with his student Dirk Polder in 1948 on the attraction of two metal plates with a distance of 1 micrometer, but they were still too imprecise. Sparnaay - who had already undertaken experiments with Theodoor Overbeek in 1954 , between quartz and glass plates - was able to confirm the effect on metal plates much better in 1958 (like the Russian physicists Boris Derjagin , Evgeni Lifschitz and I. Abrikosova earlier in 1956 ). He constructed an ingenious lever device with which the lower metal plate could be moved with a step size in the 5 nanometer range. The top metal plate was attached to a spring which was used to measure the force exerted on the plates. Casimir's calculation predicted a drop to the fourth power of the distance.

At that time, the accuracy was still in the range of 15% of the predicted value (in 1996 Steve Lamoreaux at the University of Washington confirmed the effect with 5% accuracy).

Fonts

  • The electrical double layer , Oxford, Pergamon Press 1972
  • Van spierkracht tot warmtedood: een geschiedenis van de energie , s´Hertogenbosch, Voltaire 2002
  • as editor with Andries Sarlemijn Physics in the Making. Essays in Honor of HBGCasimir , North Holland 1989

Web links

Individual evidence

  1. ↑ Sparnaay Measurements of Attractive Forces Between Flat Plates , Physica, Volume 24, 1958, pp. 751-764
  2. ^ Sparnaay, "Attractive Forces between Flat Plates", Nature, Volume 180, 1957, p. 334
personal data
SURNAME Sparnaay, Marcus
ALTERNATIVE NAMES Sparnaay, Marcus Johannes
BRIEF DESCRIPTION Dutch physicist
DATE OF BIRTH 1923
DATE OF DEATH February 11, 2015