On Monday, Stock and other 20 measures in Europe and US experts met in London to plan a redefinition of the kilo will have to accept the 54 countries, including Spain, that use the international system of units. We need a definition that is stable and accessible to all, says Stock, under the command of one of the most precise scales in the world with which is repesando per kilo to express its value depending on a universal constant, instead of with a nineteenth-century weighs. Each year, three men descend into the basement where kg is located, open the gate and check that it is still intact. They are the director of the BIPM, the President of the International Committee of weights and measures and the director of the archives of France. Each holds one of the three keys which open the door. The first time I saw that process I thought it was very funny, explains Ian Mills, expert in microscopy at the University of Reading (United Kingdom) and one of the organizers of the meeting of last week.
Only in three occasions has been removed per kilo of your camera. It was to check his weight remained the same. The results of the two recent reweighing, in 1946 and 1989, threw a disturbing result: kilo had thinned about 0.00005 grams. Planck against Avogadro do not know what has happened to the weight during the last century, recognized Stock. Like him, other teams from USA, Switzerland, Canada, China and six other countries are making their own calculations based on universal constants. The efforts are intended to advise political delegates of the General Conference of weights and measures (GFCM), which brings together 54 countries of the Metro Convention. Signed in 1875, the Convention was designed to standardize weight (kg) time (second), length (meter), intensity of a current (amp), temperature (kelvin), amount of a substance (mol) and luminous intensity (candela).