Re: SI and nothing else

[Hugh Haskell <hhaskell@mindspring.com>]

> On 15 Oct 1997 Bob Sciamanda was responding to:
>
> > > ... For example, for TIME one could say: "one GeV^(-1) is a time interval
> > >   between two maxima of E(t) for an e.m. wave at a fixed vacuum location.
>
> He wrote:
>
> > But this doesn't define a definite interval of time unless the frequency
> > of the e.m. wave is specified.  Or do I mis-interpret. (I never could make
> > sense out of this h=c=1 system!)
>
> I did goof on the verbal interpretation of the TIME line. Perhaps somebody
> will come with a correct interpretation. The relation, T=1/f, which I should
> have accounted for, has nothing to do with the system of units.
>
> Forget about h=c=1 and think in terms of common units. Or refer to harmonic
> waves traveling from left to right along a tight rope. The f is imposed by
> the source and v is imposed by the tension in the rope. A higher f always
> corresponds to a shorter L (wavelength) because v=L*f=const. The time
> interval
> between two maxima passing me is different for each f.
>
> Suppose I declare that v is dimensionless and equal to one. Why? Because
> I am a spider who lives on this rope and v is my "universal constant". And
> I want to simplify things as much as possible. What can be more simple that
> a system with only one fundamental unit?
>
> Is c=h=1 an example of a simplification which makes things more difficult?
>
>                                               Ludwik Kowalski

Having worked some years ago on problems in which that set of units was
practical, I would say that the answer to Ludwik's question is "Yes and
no." Yes if you are a student just getting used to some of the wierdness of
quantum mechanics and are having enough trouble dealing with the complex
mathematics. A resounding "No!" is you are employed in the field where you
work with the ideas every day. The simplification of the equations you deal
with is considerable when you work with them all the time, but this very
simplification makes them almost incomprehensible to the beginner who is
used to having all this extra baggage of dimensions on their favorite
universal constants. It is perhaps analagous to the problems beginning
students who have grown up in the archaic American system of units have
when they find themselves suddenly immersed in SI units. The culture shock
can be considerable. For this reason, I would not recommend using c=h=1
before a student is starting on a thesis research project and actually has
the time to get used to the ideas or at the earliest, when they are taking
their highest level courses in particle physics and field theiry.

Hugh

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Hugh Haskell <mailto://hhaskell@mindspring.com>

The box said "Requires Windows 95 or better." So I bought a Macintosh.
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