Qualla: Physikalisch-Technische Bundesanstalt

Physikalisch-Technische Bundesanstalt: Introduction

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit Photo taken on April 11, 2005, by Magnus Manske, in Braunschweig, Germany., CC BY-SA 3.0. When a radio-controlled clock in a German kitchen jumps to the top of the hour, it is obeying a number that began as a count of caesium atoms in a low building on the western edge of Braunschweig. The Physikalisch-Technische Bundesanstalt is where the Federal Republic keeps its second — and its metre, its kilogram, its ampere and its volt. Every scale in every supermarket, every fuel pump, every hospital dosimeter in the country is, through a chain of calibrations, checked against something in this compound.

Image: Photo taken on April 11, 2005, by Magnus Manske, in Braunschweig, Germany. | CC BY-SA 3.0

Physikalisch-Technische Bundesanstalt: The Second Lives Here

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit Wusel007, CC BY-SA 3.0. German law is unusually direct about this. The Units and Time Act names the PTB as the country's sole authority for realising and disseminating the legal units, and specifically entrusts it with the legal time. There is no committee, no vote. There are four primary caesium clocks...

Image: Wusel007 | CC BY-SA 3.0

Physikalisch-Technische Bundesanstalt: Seventy-Seven and a Half Kilohertz

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit User:Mattes, Public domain. The time gets out of Braunschweig by longwave. DCF77 transmits from Mainflingen, about 27 km southeast of Frankfurt am Main, on 77.5 kHz, its carrier steered by the Braunschweig clocks; Media Broadcast runs the mast on the PTB's behalf. The nominal service radius is 2,000 km, whi...

Image: User:Mattes | Public domain

Physikalisch-Technische Bundesanstalt: The Business of Being Sure

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit PTB, CC BY-SA 3.0 de. Time is the famous part. The institute is much larger than that: nine technical-scientific divisions, around sixty departments, more than two hundred working groups, split between Braunschweig and two Berlin sites. In Berlin-Adlershof it operates its own electron storage ring, th...

Image: PTB | CC BY-SA 3.0 de

Physikalisch-Technische Bundesanstalt: Helmholtz Takes the Job

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit PTB, CC BY-SA 3.0 de. The lineage runs back to 1887 and the founding of the Physikalisch-Technische Reichsanstalt, an institution built on the argument that a newly industrial Germany could not compete without agreed standards. Werner von Siemens supplied private land in Berlin-Charlottenburg. Hermann...

Image: PTB | CC BY-SA 3.0 de

Physikalisch-Technische Bundesanstalt: From Charlottenburg to Watenbüttel

Tue, 04 Aug 2026 00:00:00 GMT

Photo credit User:Brunswyk, CC BY-SA 3.0. The record is not clean. Johannes Stark, awarded the Nobel Prize in 1919 and by the 1930s the loudest advocate of a racially defined "German physics," ran the Reichsanstalt from 1933 to 1939; Abraham Esau led it from then until the end of the war. The PTR was dissolved with the R...

Image: User:Brunswyk | CC BY-SA 3.0