The Physikalisch-Technische Bundesanstalt (PTB) is the national metrology institute of the Federal Republic of Germany, with scientific and technical service tasks.

PTB's tasks are as follows: the determination of fundamental and natural constants; the realization, maintenance and dissemination of the legal units of the SI; and safety technology.

[5] In Berlin-Adlershof, PTB operates the MLS (Metrology Light Source) electron storage ring for calibrations in the field from the infrared (THz) to the extreme ultraviolet (EUV).

PTB is composed of the following nine divisions:[9][10] Two essential factors which led to the founding of the Physikalisch-Technische Reichsanstalt (Imperial Physical Technical Institute – PTR) were the determination of internationally valid, uniform measures in the Meter Convention of 1875 and the dynamic industrial development in Germany in the 19th century.

A considerable impact on the initiative for the founding of a state institute for metrology in order to promote the national interests of the economy, of trade and of the military was made – in particular – by the upcoming electrical industry under the direction of the inventor and industrialist Werner von Siemens.

To decide whether electricity or gas would be more economic for street lighting in Berlin, the PTR was to develop a more precise standard for luminous intensity.

The measurements prompted a decisive impulse on the part of Max Planck to divide thermal radiation – in an "act of despair", as he later declared – into separate portions.

Under Warburg's successor Walther Nernst, the Reichsanstalt für Maß und Gewicht (Imperial Institute for Weights and Measures – RMG) was, in addition, integrated into the PTR.

This included, among other things, research on the newly discovered X-rays, new atomic models, Einstein's Special Theory of Relativity, quantum physics (based on the already mentioned work on the black-body radiator), and the investigation of the properties of the electron.

In this connection, he recognized some years later – together with his colleague Robert Ochsenfeld – that superconductors have the property of displacing from their interior a magnetic field which has been applied from the outside – the Meißner-Ochsenfeld Effect.

In addition, researchers of PTR developed acoustic mines and a steering system for torpedoes which orientated itself on the sound field of traveling ships.

Since exact measures are a basic requirement for the manufacture of military equipment, the PTR gained a key role in armament production and defense.

Esau received the title "Authorized Representative of the Reichsmarschall for Nuclear Physics", a post which he, however, ceded to Walther Gerlach already at the end of 1943.

[16] To escape the bombing raids of the allies, the PTR was, in 1943, relocated at the initiative of the president and Thuringian privy councillor Abraham Esau[17] to different places in Germany (for example to Weida and Ronneburg in Thuringia and to Bad Warmbrunn in Lower Silesia).

Approximately from 1947 on, successor institutes were developed in addition to the PTR in Berlin-Charlottenburg, i.e. one in East Berlin – for the Soviet Occupation Zone – and one in the Bizone – and later Trizone.

The idea for this re-founding had been developed by the former PTR advisor for theoretical physics, Max von Laue, already during his internment in Farm Hall.

In 1947, he succeeded in convincing the British authorities to make the former Luftfahrtforschungsanstalt (Aeronautical Research Institute) in Völkenrode near Braunschweig available to the PTR successor.

In the German Democratic Republic (GDR), the Deutsches Amt für Maß und Gewicht (DAMG) had established itself with its principle seat in Berlin.

After several renamings, this institute was designated Amt für Standardisierung, Meßwesen und Warenprüfung (Office for Standardization, Metrology and Quality Control – ASMW) during the last GDR years; the name already indicates that this office of the GDR had more extensive tasks than PTB in the Federal Republic of Germany (FRG), namely additional tasks in the field of standardization and quality assurance and in the area of activity of the Bundesanstalt für Materialforschung und -prüfung (BAM).

Not only its scientific metrological profile was extended, but also its palette of services rendered to industry, in particular in the form of calibrations of measuring instruments.

PTB dealt with this controversial subject from 1977 to 1989, above all due to the fact that the task "long-term management and disposal of radioactive waste"[18] had been assigned to it.

This also includes a highly sensitive trace survey station for radionuclides which has been measuring radioactive substances in ground-level air for more than 50 years.

Despite a phase of staff reductions – after the strong expansion following reunification – PTB ranks today among the largest national metrology institutes in the world.

As an official information bulletin, the journal stands in a long tradition which goes back to the beginnings of the Physikalisch-Technische Reichsanstalt (Imperial Technical Physical Institute - PTR, founded in 1887).

[22] Presidents of PTB and of the Physikalisch-Technische Reichsanstalt Berlin-Charlottenburg:[23] Employees of PTR and PTB were, among others: Udo Adelsberger, Walther Bothe, Kurt Diebner, Gerhard Wilhelm Becker, Ernst Engelhard, Abraham Esau, Ernst Gehrcke, Hans Geiger, Werner Gitt, Eugen Goldstein, Ernst Carl Adolph Gumlich, Hermann von Helmholtz, Fritz Hennin, Friedrich Georg Houtermans, Max Jakob, Hellmut Keiter, Dieter Kind, Hans Otto Kneser, Friedrich Wilhelm Kohlrausch, Wilhelm Kösters, Bernhard Anton Ernst Kramer, Johannes Kramer, August Kundt, Max von Laue, Carl von Linde, Leopold Loewenherz, Otto Lummer, Walter Meidinger, Walther Meißner, Franz Mylius, Walther Hermann Nernst, Robert Ochsenfeld, Friedrich Paschen, Matthias Scheffler, Adolf Scheibe, Harald Schering, Reinhard Scherm, Johannes Stark, Ulrich Stille, Ida Tacke, Gotthold Richard Vieweg, Richard Wachsmuth, Emil Warburg, Wilhelm Wien.