Re: .Re: Why all the fascination with E = mc^2 ??

From: John C. Polasek (jpolasek_at_cfl.rr.com)
Date: 06/14/04 

Date: Mon, 14 Jun 2004 00:46:59 GMT

On 9 Jun 2004 03:25:26 GMT, D.McAnally@i'm_a_gnu.uq.net.au (David
McAnally) wrote:

>leoppard@MailAndNews.com (Leonard Pardin) writes:
>
>>Bjoern Feuerbacher <feuerbac@thphys.uni-heidelberg.de> wrote in message news:<ca4dg0$m1s$1@news.urz.uni-heidelberg.de>...
>>> Leonard Pardin wrote:
>>> > For example, Einstein
>>> > simply states that the loss of radiation energy of the body can be
>>> > converted into a loss of kinetic energy by simply adding a constant.
>>> > That statement is not mathematically derived: it is just stated.
>>> >
>>> > Here is a quote from Einstein's 1905b article:
>>> >
>>> > "Thus it is clear that the difference H - E [the difference in
>>> > measured radiation energy of the body from the stationary and the
>>> > moving reference frame]can differ from the kinetic energy K of the
>>> > body, with respect to the other system (x, h, z), only by an additive
>>> > constant C, which depends on the choice of the arbitrary additive
>>> > constants of the energies H and E."
>>>
>>> Err, didn't you notice the word "thus" at the beginning of this
>>> sentence? Hint: "thus" indicates that this is a conclusion from what
>>> followed before.
>>>
>>> What followed before was:
>>>
>>> "H and E are energy values of the same body referred to two systems of
>>> co-ordinates which are in motion relatively to each other, the body
>>> being at rest in one of the two systems (system (x, y, z))."
>>>
>>> Don't you understand why this implied that H-E = K + C, or did you
>>> simply miss that sentence???
>
>> Well, let's see...Einstein tells us (and I quote):
>
>>"Let there be a stationary body in the system (x, y, z), and let its
>>energy - referred to the system (x, y, z) - be E0. Let the energy of
>>the body relative to the system (x, h, z), moving as above with the
>>velocity v, be H0."
>
>>(Einstein doesn't define the TYPE of "internal" energy possessed by
>>this body, but the emitted light energy is the stuff measured)
>
>Which tells us how much the energy of the body CHANGES.
>
>> Later Einstein informs us:
>
>>"H and E are energy values of the same body referred to two systems of
>>co-ordinates which are in motion relatively to each other, the body
>>being at rest in one of the two systems (system (x, y, z))."
>
>> Einstein must be referring to "light" energy, simply because that
>>is the only energy that is measured anywhere in the article.
>
>That is an invalid conclusion. By what line of reasoning do you come
>to the conclusion that Einstein was referring to "light" energy? I
>have not seen you logically and rigourously work towards that conclusion.
>
>And what do you mean by the "light" energy of a body, anyway?
>
>>So, we have the following situation:
>
>>E is the light energy of the body measured from the stationary frame;
>>H is the light energy of the body measured from the moving frame.
>
>Based on your unproven assumption that Einstein was referring to "light"
>energy of the body, whatever you mean by that.
>
>>So Einstein says that (light energy from the body measured in the
>>moving frame "H") less (the light energy from the body measured in the
>>stationary frame "E") must equal some change in the kinetic (motion
>>energy) of the body.
>
>Einstein said that the decrease in the energy of the body relative to
>the second frame minus the decrease in the energy of the body relative
>to the stationary frame is equal to the decrease in the kinetic energy
>relative to the second frame. This comes from the definition of the
>kinetic energy, as the difference between the energy of the body and
>its energy relative to its rest frame.
>
>> That's very clever: Presto! Chango! light energy is converted to
>>Kinetic energy.
>
>That is based on your loose interpretation of what Einstein wrote, and
>your unproven assumption that he was discussing the "light" energy of
>the body, whatever that is. Do you know anything about conservation
>of energy? The radiation energy comes from the body. Where else
>could it have come from? This means that some of the energy of the
>body is converted into radiation energy, including part of the kinetic
>energy when working in the frame with respect to which the body is moving
>(which is the reverse of your claim above that radiation energy is
>converted to kinetic energy, thus showing that you have not understood
>anything).
>
>>> > So my question is: what is the relationship between kinetic
>>> > energy and radiation energy?
>>>
>>> I don't think there is a *general* answer for that. However, in the
>>> *specific* case above, the answer is quite clear.
>
>> What? Is there no complicated mathematical formula to show us how
>>light energy can be converted to kinetic energy?
>
>Well, considering that this question is based on your unproven assumptions
>and your faulty reasoning to get to your point above, then the question
>here can be safely disregarded as not having enough of a logical
>foundation to be worthwhile enough to deem any worry about answering.
>
>>Surely there must be
>>something or someone we can call up to support Einstein's statement
>>that "it is clear that the difference H - E can differ from the
>>kinetic energy K of the body, with respect to the other system (x, h,
>>z), only by an additive constant C, which depends on the choice of the
>>arbitrary additive constants of the energies H
>>and E." If it so clear, shouldn't it be simple to demonstrate?
>
>It is, if a person understands what is going on. I have told you SEVERAL
>TIMES that H is greater than E by an amount equal to the kinetic energy
>relative to the frame in which the body is moving. The constant C was
>introduced in order to account for the arbitrary placement of the datum
>for H and the datum for E. Einstein actually points out, himself, that
>C depends on the datum for H and the datum for E, which can be
>arbitrarily placed. If you aren't going to pay attention when somebody
>points that out to you, then what is the point of trying to tell you
>anything?
>
>>> > Whence comes Einstein's statement that
>>> > the difference in measurements of the body's radiation energy can be
>>> > equated to a loss of the body's kinetic energy and therefore a loss of
>>> > mass?
>>>
>>> From his gedanken experiment in which he views the same process in two
>>> different frames. In one frame, the body has kinetic energy, in the
>>> other, he has not.
>
>> Well Einstein should have thought up another "gedanken experiment"
>>that wouldn't have required him to make up nonexistent relationships
>>between radiation energy and motion energy.
>
>No. The relationships of the energy are based exclusively on the
>established physical principle of conservation of energy. The entire
>paper is based on conservation of energy and the Principle of Relativity.
>This means that the conclusions that he draws are a necessary consequence
>of treating conservation of energy as a physical law in the Special Theory
>of Relativity. The set-up that Einstein introduced may have been
>artificial, but the physics was not.
>
>>> Additionally, where *should* the radiation energy come from, if *not*
>>> from a change in kinetic energy of the body??? Ever heard of
>>> conservation of energy?
>
>> Where does the radiation energy from a stationary chunk of radium
>>come from?
>
>That is a question for quantum mechanics and nuclear physics, and outside
>the scope of the present discussion.
>
>>Einstein was supposed to be deriving a formula showing that
>>mass was converted into energy.
>
>Which he did to the satisfaction of all those people whose minds are not
>prejudiced by their own opinions.
>
>>If we just assume that loss of energy
>>equals loss of mass, that's called begging the question in nice
>>circles.
>
>But he did not assume that loss of energy equals loss of mass. That
>loss of energy equals loss of mass follows as a consequence of the
>fact that, relative to the moving frame, the body loses kinetic energy
>and its velocity is unchanged, so that the only way in which kinetic
>energy can decrease is that there is a decrease of mass.
>
>>In more mundane circles (like the ones I travel in) it's
>>called "doubletalk."
>
>Only by those who lack the intelligence and understanding to comprehend
>what is going on, including those who are resolutely opposed to doing
>any mathematics, and who therefore can't be bothered to follow the
>arguments because the arguments are too mathematical for them.
>
>How can you possibly think that you can challenge the results of arguments
>if you won't bother reading the arguments because they are too
>mathematical for you? If you don't know the logical steps used in an
>argument, then you can't challenge the logic that is used.
>
>If you want to discuss relativity, then you should at least make the
>effort to actually learn about it. Even better, forget about doing
>relativity at present, and then come back to it later, after you have
>familiarised yourself with Newtonian mechanics. It is evident from your
>problems and questions here that you are unfamiliar with such Newtonian
>concepts as kinetic energy and conservation of energy. And since you
>don't even understand kinetic energy and conservation of energy in the
>Newtonian context, how can you hope to understand them in the relativistic
>context?
>
>David
>
> "Men were real men, women were real women, and
> small furry creatures from Alpha Centauri were
> real small furry creatures from Alpha Centauri."
>
At last count we have 116 essays on the topic of the derivation of E =
mc^2, with nary a derivation to be seen.

Radiation, from masses, radiation ??? Is that the best we/Einstein can
do?
To our rescue we recite the old adage: "The half of science is knowing
the name of everything".

Here our savior is Phlogiston!! Phlogiston, of course! Phlogiston
provides the radiation! I'm sure everyone knew this, and just forgot
it, or were too shy to go into print about it.

But,--- the other half is still the derivation.

Mr. Dual Space
(If you have something to say, write an equation.
 If you have nothing to say, write an essay).

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