Re: Electron-positron annihilation

From: Bjoern Feuerbacher (feuerbac_at_thphys.uni-heidelberg.de)
Date: 06/07/04 

Date: Mon, 07 Jun 2004 16:20:16 +0200

John Kennaugh wrote:
> Bjoern Feuerbacher writes
>
>>John Kennaugh wrote:
>>
>>>Franz Heymann writes
>
>
>
>>> OTOH it predicts that a clock, or rather time, goes slower at the
>>>equator than at the poles while I understand that this in fact is not
>>>the case.
>>
>>Please provide a reference to both the calculation predicting this
>
>
> "Thence we conclude that a balance clock at the equator must go more
> slowly by a very small amount than a precisely similar clock situated at
> one of the poles under otherwise identical conditions" Albert Einstein
> 1905

BFD. This was before the advent of GR - no one had ever until then
imagined that gravity could have an effect of time, too.

Oh, BTW, you didn't gave the reference for this quote.

>>and to the observations contradicting this
>
>
> I don't need to there would be massive headlines saying "relativity
> vindicated" if there had have been a difference.

Perhaps no one ever bothered to do the experiments when the clocks
necessary to do it were finally available? E.g. the experiment
bay Haefele and Keating was considered by many physicists to be
unnecessary, since relativity was already firmly established.

> The silence is
> deafening. There have existed clocks accurate enough since 1971 with a
> time difference of 104ns per day.

And the experiment by Haefele & Keating was done not long after that,
confirming the predictions of SR and GR. So, why do you think one should
have done yet another quite similar experiment? As I said, relativity
was already firmly established then.

>>(the calculations aren't that
>>easy, since one has to take both the GR and SR effects into account...)
>
>
>>>It was claimed that this was because the earth is flatter at
>>>the poles, that the SR term is conveniently cancelled by the GR term.
>
>
>>Reference, please. Calculations, please.
>
>
> Ref "Relativistic corrections for terrestrial clock synchronization"
> Cocke Phy.Rev.Lett Vol16 1966 p662

This was done only that later? Strange.

Anyway, thanks for the reference. I'll try to look at it when
I have time.

>>>Then someone pointed out that mean sea level is a surface of constant
>>>gravity potential by definition and there is no GR effect for two points
>>>an equal distance above MSL leaving an experimental result which
>>>contradicts SR.
>
>
>>Well, *were* both clocks at mean sea level?
>
>
> It doesn't have to be pole and equator any pair of clocks at the same
> height above sea level at different latitudes will do. The difference
> would be less than 104ns per day but should be significant over the 20
> years which have elapsed.

Well, why do you think that no such difference were observed? Did you
scan the scientific literature on this?

>>The gravitational potential *is* different at the poles than at the
>>equator, if you didn't know.

Do you know that?

>>Maybe you would like to give references for your assertions.
>
> "If you want to know the time ..." W.A.Scott Murray. Electronics and
> Wireless World Dec 1986 P28 to 31.

Oh no, not Scott Murray again! Judging from what you quoted from that man
so far, he isn't very reliable when it comes to physics.

>>The postulate by SR that light speed is independent of the motion of
>>the emitter and of the observer is based on Maxwell's equations, which
>>were well known and accepted in 1905, and thus in no way absurd. How
>>often do I need to repeat that?
>
>
> You can repeat it as often as you damn well like it isn't true.

Well, then please show me how one can derive from Maxwell's
equation any other speed for electromagnetic waves than c.

> You have
> been taken in by a ruse used in text books.

Err, no. I know myself how to calculate the speed of electromagnetic
waves from Maxwell's equations, and thus I've seen myself that it does
not depend on the motion of the emitter.

> Basically text books are not
> so much written as compiled and a 'good' idea found in one text book
> will find its way into others. A text book has to satisfy the needs of
> the lecturer. He won't recommend it otherwise. The problem is that there
> isn't any legitimate justification for Einstein's second postulate

There is. Again: please show me how one can derive from Maxwell's
equation any other speed for electromagnetic waves than c.

> and
> if students become aware of this they are likely to give their lecturer
> a hard time and the time scale will slip. There are two techniques I
> have noticed.
>
> The first is to use MMX. What MMX actually showed is that the speed of
> light from a source *stationary w.r.t the observer* is always constant
> independent of the speed of the apparatus relative to the rest of the
> universe.

Yes. This ruled out the idea that light propagates in an ether, relative
to which the earth is moving. This is usually pointed out quite
explicitly in lectures on SR.

> This is however expressed as "... and hence the speed of light
> was shown to be constant independent of the motion of the observer"

No. Why on earth do you think so? In general lecturers are quite
explicit to point out that the MMX simply showed that light does not
propagate in an ether in which the earth is moving.

> - in context not untrue. Then there is an intervening chapter to allow the
> student to forget the context before the chapter on relativity.

Huh? What on earth are you talking about? The MMX is mentioned right
at the beginning of lectures about relativity - as one of several pieces
of evidence.

> Which
> starts with "as it was shown that the speed of light is constant
> independent of the motion of the observer....".

This statement is *not* (only) based on the MMX, and that is usually
made quite clear in lectures on SR.

> They then state the
> second postulate in a form which says nothing specific about moving
> sources e.g. "All observers must find the same value of the free space
> velocity of light regardless of any motion they have"

Huh? *Obviously* this says something about sources - namely, that the
speed of the source relative to the observer has no influence on the
measured speed of light.

> and then crack on
> with the maths and it is only when writing the actual equations that it
> is used to mean "All observers must find the same value of the free
> space velocity of light regardless of any motion they have relative to
> the source".

Err, the second statement you give here is *included* already in the
first one. Are you incapable of understanding that simple logic?

> Sneaky what?

There is nothing sneaky here. Only your inability to understand plain
statements.

> The second fiddle is to say that Maxwell's equations show that the speed
> of light is c.

They do. If you think otherwise, please show how one could get any other
speed from them.

> They do not say that the speed is c+Vs where Vs is the
> speed of the source so they show that the speed of light is independent
> of the source.

Yes, exactly right.

> Utter rubbish.

Well, then please show me how one gets from Maxwell's equations that if
the source moves with v, the speed of light will be c+v. I'm waiting.....

> What Maxwell believed his equations showed
> is that the speed of light is c relative to the ether.

What Maxwell believed is rather irrelevant to what the equations plainly
say.

> He would have
> predicted that the speed of light relative to a source travelling at v
> relative to the ether would be c-v in the direction of travel.

He couldn't have gotten such a predictions from his equations.

If you think otherwise, please show me the calculation.

> Likewise
> he would predict that the speed of light measured by an observer
> travelling at v relative to the ether would measure the speed as c+v
> from a source directly ahead.

Same comment.

> Maxwell's own interpretation of his
> equations put both observer and source in the same position.

Maxwell's interpretation is rather irrelevant here. What is relevant
is what the equations plainly say.

> The speed
> relative to either is not c because it is c relative to the ether and
> they have velocity relative to the ether.

That contradicts what the equations plainly say.

> If you take away the ether,
> i.e. you decide that it doesn't exist then there is nothing in Maxwell's
> equations which then indicates what c is a speed relative to.

Wrong. Maxwell's equations tell you what you will measure. They tell you
that you will measure c for the speed of light. They say that
every observer will measure c, regardless of his motion relative to the
source or whatever. Hence *obviously* they say that the speed c is
relative to the observer!

> The most
> logical is that c is relative to the source producing the light.

Well, then please show me how one can derive from Maxwell's
equation any other speed for electromagnetic waves than c.

> It cannot be constant w.r.t the observer

Why not?

> there might not be one

So what????????????????? It is constant wrt any *hypothetical* observer.
If there is an observer in *any* frame, he will measure c. What on earth
is your problem with that?

Do you also say that if there is no observer to look, the length of a
rod is undetermined?????

> and in any case you have a problem with causality. i.e. what possible physical
> process could result in the light travelling at c relative to each and
> every observer.

Why on earth would that pose any problems with causality???

> [.....]
>
>
>>>Superficially the experiment fires high energy protons at a fixed target
>>>and photons are produced which have a speed of c relative to the target
>>>as would be expected by both relativity and ballistic theory.
>>
>>Err, the photons come from the decay of *pions*, which are *moving* wrt
>>the target.
>
>
> Try reading a post before jumping in with irrelevant comments.

I read it. The comment is in no way irrelevant.

>>>The belief that the experiment supports the second postulate is based on
>>>a predicted by science, based itself on relativity, that a neutral pion
>>>(pi-meson) is first produced,
>
>
>>So you want to claim that pions don't exist, or what???

Hello?

>>>that this is moving at 0.999c
>
>
>>If pions exist, then this speeds follows quite simply from conservation
>>of momentum. Do you dispute this conservation, too?

Hello?

>>>and it is
>>>this which decays. Unless it has been shown theoretically that if the
>>>ballistic theory were correct the neutral pion would still be predicted
>>>as being involved it hasn't really proved anything.
>>
>>You *really* want to claim that the existence of neutral pions has never
>>been shown???
>
>
> How can you *show* the existence of a particle which decays in
> 8.4 x 10^-17 s ? You can't.

Ever heard of such things as "decay width", "invariant mass" etc.?

Thanks for showing yet again that you have no clue what you are talking
about.

> Theory predicts it

AFAIK, the particle was observed before any theory predicted its
existence. If you think otherwise, give a reference, please.

> and its existence is then
> *confirmed* by viewing its decay products.

And what problem do you have with such a confirmation?

> Or alternatively the decay
> products are noted and theory used to predict the particle. If the
> theory is wrong...

What's your basis for assuming that the quark model might be wrong?

>>>Even if one accepts the existence of the neutral pion it has a lifetime
>>>of about 10^-15s
>>
>>Err, no. (8.4 +- 0.6) * 10^(-17) s.
>><http://pdg.lbl.gov/2002/mxxxlight.pdf>
>
>
> You are forgetting time dilation.

You were talking about the life time of the pion above. Not about the
*observed* time until it decays. The life time itself is a Lorentz
invariant.

> If you read up on the experiment it is
> travelling at 0.99975c.

Nice, but totally irrelevant.

> I thought I was the one who didn't know anything about physics.

Yes, and you have demonstrated that again here by confusing the life time
of a particle with the observed time it takes to decay when moving at
high speeds.

>>>so it will only travel 0.003mm before decaying so
>>
>>Even less.
>
> Considerably less if the theory it is trying to disprove is correct.

Huh?

>>>unless it is a very thin target the decay will still take place within
>>>the target
>>
>>Yes.
>
>
>>>and no matter how thin, within the near field of the target
>>>making the stationary target the affective source.
>>
>>Absolute total non sequitur. The photons come from the pion. What on
>>earth has the near field of the target to do with that???

I notice that you did not answer that question below.

> If the second postulate of relativity is wrong then light is ballistic

What is "ballistic" supposed to mean? And how does this follow from
the second postulate being wrong?

> where c is the speed at which photons relative to the source.

Contradicts Maxwell's equations.

If you think otherwise, please tell me how one gets a light speed of
c+v from Maxwell's equations for a source which is moving towards the
observer.

> Unlike ether based theories such as relativity

SR is not ether based.

> there is nothing which says that
> the speed of the photons will remain at c come hell or high water.

There is also nothing which tells Planck's constant to remain at
its value. What's your point?????

> On the contrary. As H.Aspden pointed out to Waldron if a photon was
> emitted by an atom at c relative to the atom it would travel at the
> velocity c plus the thermal agitation velocity of the atom

What's that?

And how on earth would that follow?

> and that does not appear to be the case.

In other words: yet another piece of evidence that the speed of light
is not source-dependent.

> One has to assume therefore that c is the
> natural interaction speed of a photon

What on earth is "interaction speed" supposed to mean?

> and an em field

Huh? There are also static fields, if you didn't know.

> and that a photons
> speed leaving a source is at a speed relative to the average field
> produced by many atoms at the surface.

Please show me how that follows from Maxwell's equations.

> i.e. there is a near field effect
> producing the final velocity.

How on earth would that work?

> Photons from the pion, if still within the
> near field of the target will therefore be affected by the near field
> effect and have a speed c relative to the target, and not relative to
> the pion. Look up 'extinction' ref Tolman or Ewald-Oseen.

That reference is rather vague.

>>>There are other
>>>things which could influence the result like a strong magnetic field.
>>
>>How would the result?
>>
>>And why do you think there was such a field?
>
>
> You don't seem to have read up on the experiment.

No. I freely admit that. Franz' description looked already quite nicely.

> There was a magnetic
> field after the target to deflect any charged particles.

Nice. How would such a field influence the results?

> You don't hit a
> beryllium target with high speed protons and expect only pions to be
> produced. They assumed that it would not have any affect on the photons.

If you have any evidence that magnetic fields have an influence on the
photons, feel free to provide it. Oh, you could also show how that
follows from Maxwell's equations, BTW.

So far, you are very good on assertions, but have not shown even *one*
calculation...

[snip]

>>> It is even more absurd if one tries to deny the existence of the
>>>ether.
>
>
>>Care to suggest an experiment which would observe it?
>
>
> Any experiment which shows source independence shows the existence of
> the ether.

Total non sequitur.

> It is the only explanation of source independence.

SR does not need an ether and nevertheless explains source independence.

>>>If a source is surrounded by nothing which can effect the speed of light
>>>(no ether)
>>
>>Space?
>>
>>
>>
>>>there is nothing c can be referenced to other than the
>>>source.
>>
>>Why?
>
>
> D'oh! You have a source surrounded by billions of miles of space in all
> directions. If there is no ether then there is nothing which can affect
> the speed of light for billions of miles in all directions.

Why *should* anything be needed to "affect" it? Why can't the structure
of space itself "tell" it how fast it has to move? That's exactly what
SR says, essentially: that the speed of light is inherent of the
geometry of space-time.

> c is a speed. A speed is meaningless unless it is a speed relative to something

It is relative to every (hypothetical) observer.

Do you also say that a length is meaningless as long as no one observes it?

> and the only 'something' there is, is the source. But then you have it
> wrong anyway.

Well, then please show me how one can derive from Maxwell's
equation any other speed for electromagnetic waves than c.

> [....]
>
>
>
>>>If you apply the postulate directly:
>>> A S
>>> B-->v
>>> Then light leaves the source at c to go to A and leaves the source
>>>at
>>>c-v to go to B (because that is c relative to B)#.
>>
>>Err, no. If you apply the postulate directly, the light leaves the
>>source at c to go *both* to A and B.
>
>
> No that cannot be

Why not?

And I notice that you didn't bother to explain how one would get *your*
claims from applying the postulate directly. Hint: this isn't possible
- your claims *contradict* the postulate.

>>># Note if a wave passes both A and B going at c relative to each then
>>>the only way you can explain Doppler shift is if the light left the
>>>source at a different speeds for A and B.
>
>
>>Nonsense again. The Doppler shift is explained by the motion of the
>>source relative to A and B.
>
>
> This is another little fiddle used by text books which has taken you in.
> What the book will say is that the speed is c but that distance changes
> with time. Spotted it? Distance changing with time is speed.

Yes. And where on earth is your problem now???

> I am
> applying the second postulate totally correctly. It requires the speed
> of light be c everywhere in an observers frame of reference whether it
> is going away from him, towards him or across his line of sight.

Then why on earth did you say that for the observer B, the speed of
light is c-v? Hint: c-v is not the same as c.

Another hint: your sentence "because that is c relative to B" did not
make any sense at all. c-v is not the same as c only because it
is relative to B.

> In his
> FoR it leaves the source a c relative to him whatever that happens to be
> relative to the source.

This sentence didn't even make sense grammatically. I have no clue what
it is supposed to mean.

> "But the ray moves relatively to the initial point of k [moving source],
> when measured in the stationary system, with the velocity c-v, " - ON
> THE ELECTRODYNAMICS OF MOVING BODIES By A. Einstein June 30, 1905

You totally misunderstand Einstein here.

> Of course an observer at the source travelling with the source will see
> it leave the source at c but that is a different FoR.

*Any* observer will see the light travelling at c.

>>"c relative to B" makes no sense. You would know that if you had
>>understood anything about SR.

Hello?

>>>If it arrives just as
>>>A and B coincide it means that it set out at different speeds
>>
>>No, it doesn't mean anything like that.
>>
>>
>>
>>>arrived at
>>>the same time so must have set out at different times
>>
>>False premise ==> false conclusion.
>
>
> No absolutely standard relativity.

No. You applied it totally incorrectly, nicely showing that you don't
understand it.

> Look up 'ascribing times to distant events'

That has nothing to do with the nonsense you presented above.

> I am not presenting anything non standard I am just not using
> the usual carefully chosen wording.

Hint: the wording was chosen in order to make *sense*. In contrast,
*your* wording does *not* make sense.

[snip a bit]

>>>So what the second
>>>postulate says is that the same light *appears* to leave the source at
>>>two different times setting out at two different speeds.
>>
>
>>No, it says nothing like that. Why on earth do you think so?
>
>
> I have just shown that to be the case based on the normal
> interpretation of the second postulate.

No. You applied the postulate in a totally wrong way by claiming
that for B, the speed of light is c-v - whereas according to the
postulate, it is c!!!

> I am not presenting anything non
> standard I am just not using the usual carefully chosen wording or
> deriving things using Lorentz transforms.

See above.

>>>SR and LET are very similar but if you insist SR is not LET,
>>>and most relativists do,
>>
>>Yes. SR explains the effects by essentially postulating
>
>
> You do not *explain* something by postulating.

Why on earth do you think so???

Almost any explanation in physics starts by either postulating something
new or by relying on a postulate which was made sometime earlier and is
widely accepted now.

> SR explains nothing.

Says the one who doesn't understand ot.

> Quite the contrary. You are obviously a beginner.

ROTFL!!!

Hints: I've got a PhD in physics. I passed several exams about SR.
I even *wrote* a bit on SR for other students, which was greatly
appreciated!

> Relativity was
> declared to be a 'principle theory' i.e. little more than a mathematical
> model by AE.

Nice for him.

> The standard answer is "Relativity does not attempt to
> answer those sorts of question".

Which sort, specifically?

> You have to watch relativists they are
> a sneaky bunch they say things like "relativity has nothing to do with
> the ether"

That's right.

> when actually it means "relativity has nothing to say on the
> subject of whether there is an ether or not, it isn't the sort of theory
> which deals with such matters".

Well, how is that different from "it has nothing to do with the ether"?????

> SR does not rule out LET because LET is mathematically compatible with SR.

Agreed. So what??? The ether simply is not *necessary*. Ever heard of
Occam's razor?

>>that the same effects are observed differently in frames which are
>>moving wrt each other, whereas LET says that there is an ether, an
>>absolute speed (the speed wrt the ether) can be defined, and this
>>absolute speed causes actual time dilations, length contractions etc.
>
>
> I note the implication that in SR Time and length dilation is not
> *actual* but the result of observational differences.

Depends on what you mean by "actual". Time dilation and lenght
contraction (not length dilation!!!) are measured in *any* *possible*
observation. How much more actual can you get?

> You don't accept
> the standard result of the twin paradox then? That requires actual time
> difference.

That requires a time difference *measured* by any possible observation.
That does essentially imply that the time difference is "actual".

> A S
> B-->v
>
> What Lorentz says is that light leaves S at c relative to the ether. It
> is travelling at different speeds relative to A and B because it is
> travelling at c relative to the ether. A and B's measuring rods and
> clocks are differently affected by their motion through the ether in
> accordance with Lorentz transforms with the result that they end up
> getting the same value c for the speed of light. They calculate the time
> of the distant event as being different because there rods and clocks
> are differently affected by their different speeds relative to the
> ether.

Nice, but not in any way relevant here.

>>If you can't see the difference between SR and LET, then you haven't
>>understood SR, plain and simple.
>
>
>
> In order to overcome the "relativity does not attempt to answer those
> sorts of question I have developed a technique where I say "If we assume
> that SR is not LET then ...." as I effectively did as follows

Nevertheless, you have nicely demonstrated that you don't understand
what SR really says.

>>>SR and LET are very similar but if you insist SR is not LET,
>>>and most relativists do,
>>>then I have to amend my statement to say 'What the
>>>second postulate says is that the same light *actually* leaves the
>>>source at two different times setting out at two different speeds'.
>>
>>No. The second postulate says nothing like that. How could a postulate
>>which says that the speed of light is the same for every observer say
>>that light leaves the source at two different speeds??????????
>
>
> In A's FoR the source is stationary. In his FoR light travels at c so
> leaves the source at c relative to the source. In Bs FoR the source is
> moving but in B's FoR light still travels at c relative to his FoR but
> the source is travelling relative to the FoR

Right so far.

> so light speed relative to the source is c-v

Wrong. B would *say* that the speed of light relative to the source
*should* be c - *IF* the usual addition of velocities would hold!!!
Since that addition does *not* hold, B simply would be wrong in saying
that the speed of light relative to the source is c-v. The speed of
light relative to the source is c. That the source is moving relative to
B does not change that, and that B measures that the speed of light
relative to him is c does not change that, too.

> because that is c relative to the FoR of B.

"c relative to the FoR of B" makes no sense at all. c is c.

[snip repetition]

Bye,
Bjoern

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