Is Paris Worth a Mass?; Measurement  

Oleh:

[s.n]

Jenis: Article from Bulletin/Magazine
Dalam koleksi: The Economist (http://search.proquest.com/) vol. 406 no. 8818 (Jan. 2013), page 12.
Topik: Standards; Measurement; Weights & Measures; Physics; Scientific Apparatus & Instruments

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Perpustakaan Pusat (Semanggi) Nomor Panggil: EE29.75 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

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In the 19th century, the heyday of European colonialism, those two great imperial rivals, Britain and France, agreed to carve up not merely the world, but the universe. The capacity to describe that universe depends on the ability of scientists to relate their discoveries to the fundamental quantities of length, time and mass. The British gained control of time, which is why the Earth's prime meridian--from which the planet's rotation and thus the lengths of the day, the hour, the minute and the second were then calibrated--runs through Greenwich, a suburb of London. The French annexed length and mass. They kept them, in the form of two lumps of metal, in sealed jars in the Bureau International des Poids et Mesures in Sevres, a suburb of Paris. Time is now defined by readily available clocks that use caesium atoms as their pendulums, while distance is specified in terms of the speed of light in metres per second. Mass, however, remains stubbornly stuck in Paris, under three concentric glass lids (pictured) strangely reminiscent of cheese covers, which are intended to stop it either absorbing or shedding matter and thus changing in value. Unfortunately, the cheese covers have not worked. Over the years the standard kilogram has put on weight, or possibly lost it. Nobody quite knows which . But they do know that it is not the same kilo that went under the lids in 1889.

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