Solution to precision weighing challenge
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The winner of the precision weighing challenge (published in issue 393/2) is:
Paolo Oliveri, University of Genoa, Genoa, Italy
The award entitles the winner to select a Springer book of his choice up to a value of € 75.
Although “Lhasa” literally means “place of the gods,” the reversal of the balance tip is not really a sign of their omnipotence. It all comes down to thin air, so next time you trade those valuable pearls high up in the mountains, remember the fancies of weighing in alps.
As the air density is reduced, the apparent mass of the stainless steel weight increases relative to that of the platinum weight. We know this from the difference in balance readings between Paris (near sea level) and Lhasa (at very high elevation). In Tibet, the stainless steel weight already appears to be “heavier” than the platinum weight. Reducing the air density even further, all the way to zero in fact, would only make this difference grow larger. But, at zero air density as...
KeywordsNobel Laureate Apparent Mass Moon System Primary Mass Reference Weight
Author thanks Richard Davis of the Bureau International des Poids et Mesures for insightful discussions during the BIPM Metrology Summer School 2008, and for sharing his knowledge of the international prototype of the kilogram, which is not open to public viewing as mandated by the 1875 Metre Convention (http://www.bipm.org/en/convention/).