Re: Only some energy has mass?

From: Pmb (someone_at_somewhere.com)
Date: 12/18/04 

Date: Sat, 18 Dec 2004 18:13:15 -0500

<globarr@yahoo.com> wrote in message
news:1103398639.799364.142030@c13g2000cwb.googlegroups.com...
> In <raidnbpgw8Kdtl7cRVn-qA@comcast.com>
> Pmb <some...@somewhere.com> wrote:
> >In <1103305852.634561.320210@z14g2000cwz.googlegroups.com>
> >Gerald L. O'Barr <globarr...@yahoo.com> wrote:
> >> N:dlzc D:aol T:com \(dlzc\) <N: dlzc1 D:cox T:n...@nospam.com>
> >>>No. The role of the physicist is to TEST the limits.
> >>>The limits are known, and are clearly defined in the postulates,
> >>>or in the mathematics applied to arrive at a solution. For
> >>>example, SR is limited to "flat space". A theoretician is
> >>>to make new hypotheses, new limits, new tests.
> >
> >> Gerald L. O'Barr <globarr...@yahoo.com> comments:
> >> ----- (remove 3 dots for e-mail)
> >> What is the limit for PV = nRT?
> >> The limit for PV = nRT is not a math limit!
> >> Its limit is not and cannot be determind by math!
> >> Its limit is a physical limit, dealing with
> >> the physical size of atoms or molecules, etc.
> >> Why do I get the feeling that you are only
> >> a mathematician?
> >> Please note, I am not disagreeing with everything
> >> you say above. Just seeking clarification.
>
> Pmb <some...@somewhere.com> wrote:
> >What SR is limited to depends on what one means by
> >"SR". Some (e.g. Pauli/Schutz, etc) speak of SR to
> >mean "relativistic physics in an inertial frame"
>
> Gerald L. O'Barr <globarr...@yahoo.com> comments:
> ----- (remove 3 dots for e-mail)
> SR is a simple math theory.

A theory is its postulates. The postulates of SR are

(1) The laws of physic are the same in all inertial frames (i.e. are Lorentz
covariant)
(2) The speed of light is invariant.

The first one means its a law about the laws of physics. The second states
that the speed of light will always be measured to be "c" in all inertial
frames of reference.

> That is, it does not
> tell us what physically occurs, ...

Sure it does.

> ...and then develop the
> math that is being controlled by these physical acts.
> SR starts and ends with math. It says that the
> measurement of light is a math constant, c, ...

The language of physics is math. If you're going to say this about SR then
you're saying it about all of physics and that I have to disagree with.

> It at no time explains why or how light is a constant,

That's why its a postulate and not a derived quantity (if one postulates
that the photon's proper mass is zero then one can derive the constancy of
light on the first postulate and Maxwell's equations).

> It at no
> time explains how the math forms for all these
> equations can remain of the same form.

Hence the first postulate

> Now obviously, it does not have to explain any of
> these things.

No law of physics explains anything per se.

> Now I am not sure if I answered your question, but
> I will be happy to try again, if you see something
> that was missed!

I don't recall having a question. The only question I recall is you asking
me if I was a mathematician. I assumed that was a rhetorical question. To
answer your question - I had two majors in college. My primary major was
physics in both undergrad and in grad school. My secondary major as an
undergrad was math. Its useful in physics to know as much math as possible.

Pmb

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