Re: [Phys-l] Physics Grammar

["John Clement" <clement@hal-pc.org>]

All units are actually defined in terms of a human scale, or perception.
The decibel is defined in terms of the human hearing threshold and accuracy
of volume perception.  While they have been decoupled from a particular
king's foot, the SI base units are still defined as to be on a human scale.
And this is actually reasonable, because it makes them more easily
understandable.  The dB scale should be defined in terms of human perception
because it is generally used for things involving human hearing.

John M. Clement
Houston, TX

> I quite agree most physical quantities should not be defined in terms of
> human perception, e.g. force, entropy, length (tho here at one time it
> was measured by a certain king's digits), etc.  However, there is at
> least one quantity that is measured (defined) by human perception.  And,
> wow, it's LIGHT; how ironic.  Yes, the lumen is defined by the standard
> eye's perception of flux, and it's an SI unit.