Sir, Your report (February 15) on redefinition of the kilogram, the international standard for mass, perpetuated the common misconception that mass and weight mean the same thing.
Mass is purely a property of an object whilst weight is the pull of the local gravitational field on the object. Since this field varies from place to place, so will the weight. In the International Space Station, a 1kg block will still have the same mass but it will be weightless.
Yours sincerely,
JON LAYNE,
11 Rowan Drive,
Selston, Nottingham NG16 6GL.
February 15.