Kilo will soon lose its physical gain, so humans better shed weigh-ward ways

If the 41 official chunks of metal that are the standard for the unit of weight called the kilogramme cannot keep themselves in check, what of mortal humans faced with the temptations of the festive season? Of course, the platinum-iridium alloy International Prototype Kilogramme ( IPK) and its 40 replicas in different countries have only gained an infinitesimal amount since the first was cast in 1875 — a few micrograms in 137 years compared to what the average binged-out humans put on in a month — but the phenomenon may have wider ramifications. Considering these units have all gained varied amounts of weight, apparently according to their surroundings — a tendency seen in human beings too — it could spell trouble for scientific experiments as well trade in items restricted by weight such as radioactive materials, both of which demand extreme precision.

The revelation of this gain, however, will afford some comfort to those who have been anxiously watching weighing machines notching up ever higher numbers. If the standard measure itself weighs more — but, by definition, remains a kilo officially — all readings can be deemed at least partially understated. The notso-good news is that while the weight build up on the IPK will probably be scraped off using ozone and ultraviolet light, shedding the excesses of seasonal overindulgence will be tougher. In any case, any euphoria about even that small offset on weighing machine readings will be relatively short-lived as the IPK, the only physical measure left of the seven components of the international system of units, will soon be brought in line with the metre, second, kelvin, ampere, mole and candela, which are already based on Planck’s fundamental constants of nature. So, better scale down weigh-ward ways fast.