[boost] Re: runtime unit-modifiablephysical-quantitiesusingpqs1-00-01

From: David B. Held (dheld_at_[hidden])
Date: 2004-01-04 19:58:50

"Andy Little" <andy_at_[hidden]> wrote in message
news:bta7us$bkg$1_at_sea.gmane.org...
> [...]
> A physical-quantity is made of powers of  The Seven dimensions:
> length, mass, time, temperature, current, amount-of-substance,
> luminous intensity.
> (aside  -please not lets get complicated :-) )
> [...]
> There are only 7 dimensions. Thats it.
> [...]

Surely this is ridiculous?  I can see an extreme reductionist arguing
that you only need dimensions for space, time, and the fundamental
forces.  And if you really want to get anal, then you could equate
space and time, and end up with four dimensions (distance, mass,
electroweak charge, strong charge).  Everything else is derived,
right?  And if you buy superstring theory or quantum gravity, then
you could probably get away with just one or two dimensions, right?
But how useful is that?  Who cares if luminous intensity is really
just photons/area?  It's still a useful dimension, right?  And even
though temperature and energy are related, I think there's a lot of
physicists that would be unhappy to not have a natural energy
dimension without having to state it in derived terms.  Isn't it about
expressing the solution in the problem domain?  Physicists write
equations with Joules and Watts, not just N m and lbs.-ft./s.

Dave

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