Udo Adelsberger

Udo Adelsberger (born June 7, 1904 in Königsberg , Prussia ; † January 6, 1992 in Neckargemünd ) is the developer of the quartz clock in Germany with Adolf Scheibe and the discoverer of the inconsistency of the earth's rotation speed with Scheibe .

After graduating from secondary school in Königsberg, Udo Adelsberger studied mathematics, chemistry and physics at the Albertina in Königsberg and graduated with a state examination. His wife was a mathematician. After completing his doctorate with Richard Gans , Adelsberger joined the Physikalisch-Technische Reichsanstalt (PTR) in Berlin in 1927 . In 1931 he moved to the PTR high-frequency laboratory under Adolf Scheibe. When the Physikalisch-Technische Anstalt was established, the forerunner of the Physikalisch-Technische Bundesanstalt (PTB), he became head of the laboratory for time and frequency measurement. In 1953 Adelsberger became director of the IA subdivision and official professor of the PTB. Until his retirement in 1953 he was entrusted with many international tasks, including a. Committee for the definition of the second and worked in the Apollo program of NASA (u. A. Determining the appropriate time slot for re-entry of the capsule).

The PTR quartz watches

From 1930, Scheibe developed the PTR quartz watches together with Udo Adelsberger. After a lengthy trial run, the »Quartzuhr I« (QI) was put into continuous operation in January 1932 , followed by an identically constructed QII in February. The technical structure consisted of two laboratory tables on a floor space

• inner and outer thermostat
• Control quartz (60 kHz, quartz rod with rectangular cross-section and four diagonal excitation electrodes) in a highly evacuated glass tube
• 60 kHz quartz generator as exciter in Pierce circuit without additional grid resistance
• two-stage 60 kHz tube amplifier
• three-stage frequency divider from inductively fed back tube transmitters (on 10 kHz, 1 kHz, 333 Hz)
• Synchronous motor driven by a coupling coil (5 revolutions per second) for actuating the time contact on the timer
• High-speed writer that writes time stamps on paper with a precisely controlled feed rate (a measurable time stamp of 0.1 mm corresponds to 0.001 s)

In June 1933 the QIII and QIV went into operation. They were improved in many details, but above all in the lower dependence of the control crystals on the ambient temperature. Quartz rods of larger mass with a square cross-section and three box-shaped excitation electrodes. The clock group became a public time and frequency measure from autumn 1933.

As early as the spring of 1934, there were significant changes in the rate of both QI and QII. In June 1934 a similar change in gear occurred on the completely differently built QIII. In 1935, Scheibe and Adelsberger shocked the experts at the time with the conclusion that it was not their clocks that went wrong, but that the astronomical day length used as a comparison and as the time standard to date was inconsistent. This is due to the fact that the rotation speed of the earth changes with the seasons. In 1938 they met the evidence. It was not until 1948 that the claim was verified by a third party. So the rotation of the earth is not uniform. It is also steadily slowed down by various influences (including the moon). From time to time all clocks need to be adjusted accordingly. The turn of the year is chosen as the point in time for the equalization second. Natural time systems such as the astronomical day length are unsuitable for exact time measurement. From this follows the current stipulation that time should never be derived from position determinations, but rather, conversely, to define the second in terms of atomic physics and thus to determine positions.

Web links

• http://www.chronos-ev.de/vortrag/vortraege.htm Horst Hassler: A. Scheibe and U. Adelsberger - physicists and clockmakers from Germany (PDF file; 416 kB)