Re: Q question about relativity
From: Andr? Michaud (srp_at_microtec.net)
Date: 09/04/04
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Date: 3 Sep 2004 17:52:50 -0700
"Harry" <harald.vanlintel@epfl.ch> wrote in message news:<41388cd0$1@epflnews.epfl.ch>...
> "N:dlzc D:aol T:com (dlzc)" <N: dlzc1 D:cox T:net@nospam.com> wrote in
> message news:fH_Zc.84899$4o.84201@fed1read01...
> > Dear Harry:
> >
> > "Harry" <harald.vanlintel@epfl.ch> wrote in message
> > news:4138415c$1@epflnews.epfl.ch...
> > >
> > > "Uncle Al" <UncleAl0@hate.spam.net> wrote in message
> > > news:41374702.5559C306@hate.spam.net...
> > >> Ohad wrote:
> > ...
> > >> > Einstein said that a proof of his theory, about changing the
> > >> > space, is seeing that even light is bent according to gravitation.
> > >>
> > >> Learn something,
> > >>
> > >> http://arXiv.org/abs/gr-qc/9909014
> > >> Phys. Rev. Lett. 92 (2004) 121101
> > >> falling light
> > >
> > > Einstein was dead in 2004. He certainly did not write that. Learn
> > > something:
> > >
> > > "We easily recognize that the course of the light-rays must be bent with
> > > regard to the system of co-ordinates" - in "The foundation of the
> > > general
> > > theory of relativity", A. Einstein
> >
> > Harald, Einstein indeed died in 1955. I think Uncle Al's point is that
> > the OP wasn't aware that Einstein is not the last word in relativity.
> > Even at the time of the formulation of the GTR, Einstein was not the
> > only person working on the math. And it is even being reformulated
> > and tested even today.
> >
> > Even Einstein chose some sloppy wording. Maybe he wasn't aware of those
> > multitudes that would come after him, that would remember the *wrong*
> > syllogism, and not retain the bigger picture.
>
> Fine. Maybe I overreacted a bit to the "correction" that "light falls".
> What I object to is the mistreatment claiming that light "falls" in the
> sense that its frequency increases, as also some others have remarked (and
> even Einstein, although IMO inconsistently, in 1911).
> "the [redshift] phenomenon is alternatively discussed (even in some
> authoritative texts) in terms of an energy loss of a photon as it overcomes
> the gravitational attraction of the massive body. This second approach [...]
> we assert that it is misleading."
> http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=AJPIAS000068000002000115000001&idtype=cvips&gifs=yes&jsessionid=3051831093837402530
>
> > If you'll note the choice of Einstein's words, you'll see the words
> > "course" and "system of co-ordinates" being used, as if the photon were
> > barely involved. The "course" or path is bent in the chosen "system of
> > co-ordinates". The photon is unaffected, and simply follows this path.
>
> The same can be said for a satellite in orbit around earth. Still we say
> that its path is bended - in our reference system.
Not really. All satellites launched to orbit the Earth are affected. They
all are imperceptibly slowly spiralling down. No really stable orbit that
close to the Earth can apparently be established.
All those that are not re-boosted back in a timely manner the desired
orbit eventually end up reintering the atmosphere and burning up.
> > The path is different than one a massive particle, even travelling at
> > 0.9999999999999c, would take. Null geodesics are like that.
>
> That's interesting! Do you mean that particles still follow (neo-)Newton,
> while light bends twice that amount?
Exactly right. Confirmed by all experiments. But even concluding that
Newton's theory was falsified by it is somewhat of a stretch since
simply dividing the pseudo-mass by two will get the right angle with
simple Newtonian mechanics.
The very same technique has been used for over a century with the Coulomb
equation to get the value required to account for the ionization energy
of the hydrogen atom from rest state without anyone growing pimples about
it and saying that the Coulomb equation had been falsified.
Newton's mechanics still is precise enough (and is still in use) to account
for just about all motion involving masses in the known universe. The
exceptions: Mercury's precession and the Pioneer 10/11 trajectories. But
on that last count, even GR fails.
> Then I misunderstood the paper of Carlip... Please clarify!
Yes. I too am interested in your explanation.
André Michaud
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