The kilogram is the only metric measure that still relies on a physical object - a metal cylinder called the International Prototype Kilogram (IPK). It was first made in 1799 and designed in London’s Hatton Garden to have the same mass as a litre of water. A litre is a thousandth of a cubic metre, and a metre is one ten-millionth of the distance from the Equator to the North Pole.
The current IPK dates from 1879. It’s made of a platinum-iridium alloy twice as dense as lead and kept under heavy security in Sèvres, on the outskirts of Paris.
By definition, the IPK always has a mass of 1kg. But, in practice, it has to be continually cleaned and compared to other replicas to make sure it hasn’t gained weight from dust or lost weight from wear and tear. The IPK is thought to have changed over the last 100 years by the mass of a small grain of sand. In a world increasingly dependent on precise measurements, this is problematic. In 2014 it is likely to be replaced by a definition based on Planck's Constant - the tiny but unchanging fundamental constant of quantum physics.
A bird’s feathers weigh more than its entire skeleton.
We come into the world laden with the weight of an infinite necessity.
The total weight of all the ants in the world is roughly three times more than the weight of all the human beings in the world.
There is no easy way to weigh your head but you could try any of the following methods:1. Cut it off and place on scales. (This is accurate, but you’ll be dead.)
From birth, man carries the weight of gravity on his shoulders. He is bolted to earth. But man has only to sink beneath the surface and he is free.
The world's most sensitive scales (at Caltech) can detect a cluster of xenon atoms a billion, trillion times lighter than a gram. A zeptogram (10-21g) is roughly the mass of a single protein molecule. But to identify proteins by weight, the scales will have to become another 1,000 times more precise, capable of weighing yoctograms (10-24g), or individual hydrogen atoms. If this can be achieved, such devices could be used to diagnose diseases very early by detecting single marker molecules found in a drop of blood.
A newborn blue whale puts on 14 stone in weight every day.
The International Space Station has cost more than 30 times its own weight in gold.