Seven units determined the basis of all measurement. But this basis of the International System of Units was conversed – via the tracing back of the units to fundamental constants of nature. The scientific challenge was to place the base units on a solid and permanent basis, as had already been successfully accomplished for the "second" and the "meter" with reference to atomic excitations and the speed of light.  PTB was decisively involved in this current restructuring of the system of units: for example with the Avogadro project for the redefinition of the kilogram and the mole and with the "Boltzmann constant" project for the kelvin.

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In the Units and Time Act, the realization and the dissemination of the units are assigned to PTB. To realize a physical unit means to develop, to operate and to maintain a national standard for the unit in question (or national standards for the whole scale of this unit). To disseminate the units means to build bridges between this island of highest accuracy and the world of application, for example to industry with its manifold metrological requirements. This is achieved by calibrations, whereby the tasks of PTB – being at the top of the metrological hierarchy – are limited to calibrations for which actually highest accuracy requirements must be met. Here, PTB works in accordance with a principle of subsidiarity: If an external calibration laboratory can meet the requirements of the measurement tasks as well as required, PTB gives precedence to it. For that reason, industrial enterprises from high- technology branches, on the one hand, contact PTB with special calibration requests and, on the other hand, in particular accredited calibration laboratories which must submit their own reference standards for calibration at regular intervals, to obtain traceability to the national standards, as required by the relevant norms of the quality management systems. 

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How high is the current radiation burden of the environment by natural and artificial radioactivity? Which substances do we blow – and in what concentration – into the air from exhausts and factory chimneys?  Which measures can we take to confine the noise in our working environment and in our world of mobility?  How can explosions in chemical production plants, gas pipelines or in other ignition-capable atmospheres be avoided or confined? The possibilities of precise and reliable measurement are the prerequisite to quantify these risks. Therefore, in Germany, PTB provides the metrological basis for the surveillance of the environment and the protection of the citizens, for example, with its trace survey station for radioactive substances in the air, with the type examinations of exhaust meters and their chemical analysis, with its standards for sound and ultrasound measurements, or with its know-how in physical safety technology and explosion protection.

If two people want to communicate with each other, they should speak the same language.  In the scientific-technical world, in which objects are produced, quantified, and evaluated based on a division of labor, measurement results represent such a language.  Thus, a measuring system which is uniform worldwide is indispensable, especially for globalization in our times.  In practical applications, worldwide uniformity is achieved only by concrete cooperations, a great number of confidence-building measures and transparent measurement results. PTB cooperates with the National Metrology Institutes (NMIs) in a great number of joint research and development projects and it is – on an international scale – firmly involved in the metrological structures.

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PTB is active in a great number of developing countries and newly industrialized countries and promotes projects for the establishment of a quality infrastructure within the scope of the German development coopperation. In the 1960s, technology transfer and the establishment of metrological partner organizations still were in the foreground. Today, the cooperation mainly relates to the establishment and development – according to the market needs – of all relevant institutions of the quality infrastructure in the partner countries as well as to their interconnection and the use of QI services by the users. PTB advises partner governments and ministries, promotes the institutions of the quality infrastructure and also supports small and medium-sized enterprises – work which is highly appreciated worldwide and whose success is also reflected by the fact that many partner countries from the first years –such as Argentina, Brazil, China, India, Mexico, South Korea, and later also Kenya and South Africa – today represent their interests as full members in the respective international technical organizations.

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