sci.physics.research

On 10 Aug., 00:58, Igor Khavkine wrote:
> On 2007-08-09, JohnMS wrote:
>
> > I challenge Igor to provide any experiment where an action value
> > smaller than h has been measured. (I am not talking about
> > experiments where large action values are divided by particle numbers;
> > the large action value is always an integer multiple of h.)
>
> If by the word "action" you mean "integral of the Lagrangian over some
> path", what I called the "action functional" in my previous post, then I
> don't know of any experiments that measure it, in whatsoever continuous
> or discrete units. If you think that such experiments exist, then I
> invite you to give an example.
>
> If you can provide such an example, then we can discuss whether the
> quantum mechanical operator corresponding to the same measurement has
> discrete or continuous spectrum.
>
> Igor

Well, if action could not be measured, it would not be a
pysical quantity and would be part of theology, not
of physics. So I hope everybody agrees that action can be
measured (yes, the integral of the Lagrangian).

I am confused somewhat; you said that J is
sometimes given by an expansion in h; so why do you
say now that it cannot be measured? (Or do I misunderstand)?
The expansion formula must have been checked with
experiment?

But honestly, I am also confused by this whole topic.
It has always disturbed me, and I do not have answers
to all issues. Could it be this way:

If you measure an object moving along its path, say a freely
moving object, to determine L, you must measure position (to
determine the path) and velocity (to determine the
Lagrangian). Imagine you do it by illuminating the object.

First, measuring the path could be done
by counting photons; the result is an integer times h.

Second, measuring is limited by the uncertainty principle, so
that a smaller value than h is not possible.

Third, measuring values are always uncertain by h, so that
values between integer multiples do not make real sense.

This is not a proof that action is an integer multiple of h,
but they do seem strong hints.

John