Louis Essen

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Louis Essen

OBE FRS[1](6 September 1908 – 24 August 1997) was an English physicist whose most notable achievements were in the precise measurement of time and the determination of the speed of light. He was a critic of Albert Einstein's theory of relativity, particularly as it related to time dilation
.

Louis Essen
Born(1908-09-06)6 September 1908
D. W. Dye

Early work

Born in

D. W. Dye, investigating the potential of tuning forks and quartz crystal oscillators for precise time measurement. His research led to his development of the quartz ring clock in 1938, the clock soon becoming a standard for time measurement at observatories
throughout the world.

The speed of light

During

Conférence Générale des Poids et Mesures
adopted the standard value, 299,792.458 km/s for the speed of light.

Atomic clocks

Louis Essen (right) and Jack Parry (left) standing next to the world's first caesium-133 atomic clock.

Essen earned his

National Bureau of Standards. In 1955, he developed,[2] in collaboration with Jack Parry, the first practical atomic clock
by integrating the caesium atomic standard with conventional quartz crystal oscillators to allow calibration of existing time-keeping.

Time standards

This work led Essen to champion the caesium spectrum as an international time

Gerald Clemence defining the time unit in terms of the Earth's motion round the sun. The ephemeris second, based on a fraction of the tropical year derived from Simon Newcomb's expression for the mean solar motion, became a standard in 1960, but in 1967, at the 13th Conférence Générale des Poids et Mesures, the second was redefined in terms of a value for the ephemeris second that had been precisely measured by Essen in collaboration with William Markowitz of the United States Naval Observatory
in terms of the frequency of a chosen line from the spectrum of caesium.

Later life

Essen spent all his working life at the National Physical Laboratory.

In 1971 he published The Special Theory of Relativity: A Critical Analysis,[3] questioning Special relativity, which apparently was not appreciated by his employers. Essen said in 1978:[4]

No one has attempted to refute my arguments, but I was warned that if I persisted I was likely to spoil my career prospects.

He retired in 1972 and died in Great Bookham, Surrey in 1997.

Awards and honours

References

  1. ^
    doi:10.1098/rsbm.1998.0010
    .
  2. S2CID 4191481
    . p.280.
  3. ^ Essen, L. (1971) The Special Theory of Relativity: A Critical Analysis, Oxford University Press (Oxford science research papers, 5)
  4. Electronics and Wireless World: 126–127. Archived from the original on 20 December 2013.. A number of responses to both articles from other scientists can be found on this page
    .
  5. ^ Золотая медаль имени А.С.Попова [Gold Medal A.S. Popov] (in Russian). Russian Academy of Sciences. Retrieved 30 August 2011.
  6. IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society. Archived from the original
    on 6 September 2011. Retrieved 27 August 2011.

External links
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