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Wrong or inaccurate measurements can lead to wrong decisions, which can have serious consequences, costing money and even lives. The human and financial consequences of wrong decisions based on poor measurement being taken in matters as important as environmental change and pollution are almost incalculable. It is important therefore to have reliable and accurate measurements which are agreed and accepted by the relevant authorities worldwide. Metrologists are therefore continuously involved in the development of new measurement techniques, instrumentation and procedures, to satisfy the ever-increasing demand for greater accuracy, increased reliability and rapidity of measurements.
| When you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind. It may be the beginning of knowledge, but you have scarcely, in your thoughts, advanced to the stage of science. |
| Lord Kelvin |
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For individuals not directly involved in science to have confidence in the reliability and accuracy of the measurements made by scientists and metrologists, it is essential that instruments used within any local or national measuring system are calibrated, and that the calibration may be traced to an internationally accepted system of standards or reference materials. For example, that the weighing scales in a local supermarket are calibrated against national standard weights and that these standards are themselves calibrated against an international standard of mass. One can thus create a chain of calibrations, which allows the measurements in the supermarket to be traced to an internationally accepted and accredited set of standards. The consumer can therefore have confidence and trust in the local systems of weights and measures. A confidence that is reinforced when they are able to see that the weights and measures used in their own country are equivalent to the weights and measures used in other countries, and that all are based on a single international standard.
| Immersion in water makes the straight seem bent; but reason, thus confused by false appearance, is beautifully restored by measuring, numbering and weighing; these drive vague notions of greater or less or more or heavier right out of the minds of the surveyor, the computer, and the clerk of the scales. Surely it is the better part of thought that relies on measurement and calculation. |
| Plato (The Republic) |
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Metrology is an old science, which has evolved over many centuries but is today often distinguished by the development towards scientific metrology and legal metrology. Whereas scientific metrology is essential to all those engaged in the various chains of measurement, calibration and accreditation, legal metrology's primary focus is on measurements that directly affect consumers. So while the physicists who maintain the International Prototype of the kilogram (the last physical artifact which defines a base unit and against which all other measuring systems in the world are calibrated) at the BIPM, Sèvres, can be thought of as scientific metrologists, they are not directly connected with the concerns of legal metrology in their daily work. On the other hand, the technicians who calibrate weighing scales in shops and markets are directly concerned with legal metrology, and are of course also metrologists.
However much scientific metrology and legal metrology may and can deal with very different levels of precision, they both deal with closely related problems. Both scientific metrology and legal metrology being essential in ensuring that as wide a constituency as possible has confidence in, and is protected by precision measurements. The potential consequences of inaccurate data related to commerce and medicine will affect us all, demonstrating that metrology is one of today's key sciences.
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Summary
