PhySy Foundation

Submitted by grandinetti on Tue, 11/08/2011 - 16:45

The PhySy Foundation framework provides support for the SI Units of quantities in the physical sciences.

An important characteristic of physical quantities is that any given physical quantity can be derived from other physical quantities through physical laws. For example, the physical quantity of speed is calculated as a ratio of distance traveled to time elapsed. The volume of a box is calculated as the product of three quantities of length: i.e., height, width, and depth of the box. Any physical quantity can always be related back through physical laws to a smaller set of reference physical quantities. This idea was originally proposed by Joseph Fourier in his book Théorie analytique de la chaleur (The Analytic Theory of heat). In fact, as the laws of physics become unified it has been argued that this smaller set can be reduced to simply the Planck length and the speed of light. At the level of theory employed by most scientists and engineers, however, there is a practical agreement that seven physical quantities should serve as fundamental reference quantities from which all other physical quantities can be derived. These reference quantities are (1) length, (2) mass, (3) time, (4) electric current, (5) thermodynamic temperature, (6) amount of substance, and (7) luminous intensity.

In the next parts we examine the three important types in PhySy Foundation: PSScalar, PSUnit, and PSDimensionality. Ultimately, programmers will have more significant interactions with a type like PSScalar than PSUnit, and even less than with PSDimensionality. Therefore, we begin this tutorial with the PSScalar type.