Overindulged at Christmas You're lighter than you think: Official weight of a kilo is changed (by a fraction of a gram)
00:07 GMT, 7 January 2013
00:07 GMT, 7 January 2013
You may be lighter than you think, even if you have overindulged this Christmas
It will come as welcome news to those who overindulged over the festive period – we are all a little bit lighter than we think.
Scientists have found that the original kilogram, the standard by which all weight is measured and by which our home scales are set, has become ever so slightly heavier since it was created in the 19th century.
As a result, everything else has become lighter, although only by a fraction of a gram.
The original matchbox-sized platinum weight – known as International Prototype Kilogram – was created in 1875 and is kept in the International Bureau of Weights and Measures in Paris.
Another 40 official replicas were also distributed around the globe, with Britain’s being held at the National Physical Laboratory.
These original kilograms are the standard against which all other measurements of mass are made. But their surfaces have picked up small amounts of pollution making them fractionally heavier.
Peter Cumpson, professor of MicroElectroMechanical systems at Newcastle University, told the journal Metrologia: ‘It is a really tiny effect, but strictly speaking we are all slightly lighter than we were in the late 1800s.
‘The kilogram held in Paris is the original by which all weight is defined. However it changes, its weight will still always be a kilogram. So if it gets heavier, then everything else becomes just a little bit lighter, including us.
‘We’re only talking about a very small change – less than 100 micrograms – so, unfortunately, we can’t all take a couple of kilograms off our weight and pretend the Christmas over-indulgence never happened.’
Using a probe similar to an MRI scanner, the team found that atmospheric pollutants from cars and even trees had attached to the surface of the weights.
Tiny amounts of mercury, from broken instruments kept in labs to measure temperature, had also fused with the metal.
Now the team led by Professor Cumpson have found that treating the metal can remove the pollutants. They developed a technique using UV-light and ozone to remove contamination from the weights.
‘What we have done is effectively give these surfaces a suntan,’ said Professor Cumpson.
Everything else has become lighter after scientists discovered the original kilogram, by which all weight is measured, has become slightly heavier