Re: What is the history of relativity theory? (continuation of Poincare thread)
- From: "Harry" <harald.vanlintel@xxxxxxx>
- Date: Tue, 4 Oct 2005 20:38:26 +0000 (UTC)
"Javier Bezos" <see_below_no_spam@xxxxxxxx> wrote in message
news:1128252445.262634.245790@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Harry:
>
> [btw, Harry or Harald?]
Harry is my newsgroup nickname.
> > As far as physics is concerned, those physical concepts are just
> different
> > models for the same theory of physics: they don't change the relativity
> > laws. Also with Poincare, c is the same for all "observers", no matter
> > how they are moving wrt to the emitting body.
>
> No citation has been given yet to support the latter,
> except it's "implicit".
See the recent reply by Homo Lykos to me in the "why Einstein" thread:
Poincare introduced the fashion to give light speed the value "1". That's
both implicit and very clear.
And certainly citations have been given to support the latter - but I'm not
going to look them up again.
> > > it's in clear contradiction with SR since he clearly
> > > states that c is different for two observers _in the same
> > > frame_ ("dans une translation commune", p. 564; they are
> > > even fixed w.r.t the clocks) -- this is one of the reasons
> > > I think Poincar=E9 was answering the Einstein's ideas, but
> > > this is just a personal opinion.
> >
> > I don't have that one, so I can't examine it. But I do have Science et
> > Methode and I have not noticed something strange like that. Which chapt=
> er?
> You can download the 1908 paper from the Homo Lykos site
> (you can find the url on several of his posts; by the
> way, Homo Lykos, thanks!). I would recommend to
> download all the papers, since they all are fascinating
> readings.
OK, I'll now search for it.
> > It's similar with Einstein's papers; what do you think of Einstein 1905=
> :
> > "But the [light] ray moves relatively to the initial point of k, when
> > measured in the stationary system, with the velocity c-v" ?
>
> He's not making assumptions about v.
He correctly stated that the velocity of light relative to a point that
moves with a velocity v is c-v.
But those who don't understand "relative velocity" get confused and claim
that that is against SRT.
Similarly, you have misunderstood Poincare.
> Einstein first uses
> the PoR and then the constancy of c. The citation you give
> is in the middle of these two (rough) steps, when Einstein
> is concerned with a general form of LT containing a certain
> parameter phi(v) whose value has still to be determined.
> Then he continues -- "for we have not as yet furnished the
> proof that the principle of the constancy of the velocity
> of light is compatible with the principle of relativity"
> -- with the second step of the proof and finds that
> phi(v)=3Dphi(-v), so that the parameter has to be always 1.
>
> The method followed by Einstein (namely, to introduce a
> parameter without making assumptions and to see what
> happens afterwards) is fairly frequent in both mathematics
> and physics, as you very likely know. Admittedly, this
> method is a lot more convoluted than the ones developed
> later, but it was the very first time the proof was
> done, after all...
Fine although that wasn't my point.
Now I found the text by Poincare: you meant La dynamique de l'electron in
http://www.soso.ch/wissen/hist/SRT/P-1908.pdf
- Reading through the whole page 564, I can find nothing wrong with it.
Which sentence is the one you misunderstand? He accounts wrt the ether
frame, thus wrt an unknown "stationary" frame. Put in my words: in that
frame the speed of light relative to the moving observer is c-v, but the
moving observer isn't aware of being in motion so that in his reference
frame his own speed v=0 and he only finds c. By chance the example I gave of
the paper by Einstein is similar.
BTW, I had not noticed that you referred to a paper of which I already
discussed the thereon following pages with Ouwehand: Poincare made a
calculation error at the top of p. 566.
Best regards,
Harald
.
- References:
- Prev by Date: Re: Cracked glass
- Next by Date: Re: Derivation of Lorentz Transformation
- Previous by thread: Re: What is the history of relativity theory? (continuation of Poincare thread)
- Next by thread: metastability
- Index(es):
Relevant Pages
|
