Re: Constant 'c'?

George Murphy (
Wed, 05 Nov 1997 09:32:30 -0500

Moorad Alexanian wrote:

> I think I made it very clear in my previous posts that the constancy of the
> speed of light is a fundamental feature of nature and has nothing to do with
> what units we use in physics. The relation between calorie and joule is
> precisely the same as the relation between inch and centimeter.

Not exactly. People always knew that inches & centimeters were
units for measuring the same physical quantity, length. Until the
discovery of conservation of energy ~150 years ago, people didn't know
that heat and mechanical work were different forms of the same thing,
energy, & used different units for measuring them. What I'm arguing is
that Minkowski's formulation of relativity in terms of space-time is
analogous to the latter discovery, & thus that c is analogous to the
mechanical equivalent of heat.

> For the same reason, Planck's E = h f and de Broglie's p =
> h/ lambda are fundamental features of nature (or our understanding of nature
> if you like) and not mere conversion factors. These findings of Planck and
> de Broglie indicate the fundamental particle/wave duality of nature (or our
> understanding of nature if you like).
You point out here something that I've puzzled about. Of the 3
basic constants c, G, & h (which can be combined to give "natural"
Planck units for length, time, & mass), the first 2 can be seen as
conversion factors: From special relativity, c converts space units to
time units, & from general relativity G converts inertial mass units to
gravitational mass units. But h can't be seen as such a conversion
factor: Quantum theory (at least in versions I know) doesn't say that
energy & frequency are really the same thing in different units. Any
George Murphy