[boost] Re: Physical quantities

From: Dan W. (danw_at_[hidden])
Date: 2004-01-09 17:28:01

Kevin Lynch wrote:
> 3) From a fundamental physics standpoint, length and time are "the same 
> thing", in a rigorous sense, since special relativity relates them, and 
> in many applications to particle physics, you would want them to have 
> the same dimensionality, because they do.  Ditto mass and energy ... 
> energy is no longer a derived unit, but has the same fundamental 
> dimension as mass.  And it happens to have the same units as inverse 
> length..... so this case also shows that different physical dimensions 
> can have the same units in certain problem domains.

And if in some domains,

         (wave)length^(-1) == energy == mass

then perhaps is not so much what "unit system" a particular unit should 
be a member of, --which to me is a useless membership in the first 
place, since I would not care to respect any particular 'system' in my 
programming--, as much as what domain it is currently a member of, 
which, unlike a unit system, has *semantic* meaning.