A constant speed of light in all reference frames? Surely you can't be serious. [Physics]

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From: harald on 10 Mar 2010 13:56

On Mar 5, 5:33 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> On Mar 4, 10:48 am, PD <thedraperfam...(a)gmail.com> wrote:
>
>
>
> > On Mar 3, 10:59 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > > > It is not a function of finite propagation speeds, this we know,
> > > > > > because we took into account the finite propagation speeds in our
> > > > > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > > > > remember that?
>
> > > > > I beg to differ. It is not a "mere" or "simple" function of finite
> > > > > propagation speed, but it *is* a function of it IMO. RoS only took it
> > > > > into account by allowing us to use different time coordinates in each
> > > > > frame. If the speed of light was infinite there would be no RoS.
>
> > > > I disagree. All that is needed in relativity of simultaneity is a
> > > > signal speed that can be VERIFIED to be the same from both events by
> > > > either observer.
>
> > > Well you are going to have problems with that. There is no way to
> > > *know* that the speed is the same both ways.
>
> > Yes, there is. That's what isotropy experiments have determined. I'm
> > surprised you weren't aware of this.
>
> Do you mean like this one?
>
> http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988...
>
> The author is kind enough to point out problems in some similar
> experiments, while failing to notice any in his own.

Yes that paper is amazing - shocking, what a blunder of Physical
Review!
In a nutshell, although they claim to haves obtained results that are
"consistent with the special theory of relativity", they claim in fact
(but unwittingly) to have disproved SRT's postulates:

1. "A clear null result is obtained for a hypothesis in which
anisotropy of the cosmic background radiation is used to define a
preferred reference frame [...] in which light propagates
isotropically at a fixed speed." -> according to SRT, one may pretend
ANY inertial reference to be such a "rest frame"; and contrary to
their assertions, according to SRT such a claim cannot be disproved
with measurements.

> For example, has he made any assumption about contraction of his
> equipment in the direction of motion? Tom Roberts has written posts
> in this group showing where some of these experiments are in effect
> two way measurements.
>
>
> > > That is why Einstein
> > > wrote, "But it is not possible without further assumption to compare,
> > > in respect of time, an event at A with an event at B. We have so far
> > > defined only an ``A time'' and a ``B time.'' We have not defined a
> > > common ``time'' for A and B, for the latter cannot be defined at all
> > > unless we establish by definition that the ``time'' required by light
> > > to travel from A to B equals the ``time'' it requires to travel from B
> > > to A."
>
> > > > Since the distance from the events to the observer is
> > > > equal, as verifiable at any time by each observer, we learn from this
> > > > that each observer KNOWS the propagation delays from each event to the
> > > > observer are equal. This acknowledges the propagation delays
> > > > completely, but simply allows for verification that they are the same.
>
> > > Assuming the speed of light is the same in both directions.
>
> > Which is an experimentally confirmed fact. Done well after Einstein's
> > comments on the matter, by the way.

That would contradict SRT - people who are discussing here for years
SHOULD know better!

> Provide a link to an experiment and I'll take a look.
>
>
> > > > Then the determination of simultaneity or nonsimultaneity of the
> > > > original events is completely unambiguous: If the observer receives
> > > > both signals at the same time, then (because the propagation delays
> > > > are the same) the original events were simultaneous; if the observer
> > > > receives both signals at different times, then (because the
> > > > propagation delays are the same) the original events were
> > > > nonsimultaneous.
>
> > > > Then the frame-dependence of simultaneity follows directly from the
> > > > experimental *observation* that for the same pair of events, one
> > > > observer correctly and unambiguously concludes the events were
> > > > simultaneous, and the other observer correctly and unambiguously
> > > > concludes the events were nonsimultaneous.
>
> > > > You've mentioned in the past that you found your disbelief in
> > > > relativity stems from being unable to find a good, understandable
> > > > explanation of it. I invite you to read back on this thread where I
> > > > was trying to explain to Ste (who has a similar complaint) how this
> > > > comes about.
>
> > > No need. Lorentz showed how all frames could measure the speed of
> > > light to be c. That in effect confirms the second postulate, which is
> > > the stumbling block for many.

Not exactly: it confirms the FIRST postulate. In contrast, the second
postulate is valid for a single "frame", and as Einstein wrote, it
appears to be in conflict with the first. ;-)

> > Well then, you are just *choosing* what you would like to believe. In
> > this case, lodging a complaint against relativity that it is not well
> > explained, when you are not interested in pursuing a better
> > explanation, having settled on LET instead, is a bit on the
> > disingenuous side.
>
> You are reading more into that than what I wrote. I am not choosing
> LET over SR. They use the same math and I consider them two
> interpertations of the same thing. The LET interpertation had the
> advantage, for me, of showing how c + or - v could end up being
> measured c in all frames. Given that was possible I no longer had any
> problem accepting the second postulate. Eventually I became aware
> that the second postulate wasn't so much an assumption as a
> stipulation. We will consider the speed of light to be our standard.
>
> Recently I have been going back and re-reading some of the books I
> have bought over the years to see if I can come to grips with some of
> the modern interpertations of SR. After thinking about it for awhile
> I have realized that my objections about the changing definition of c
> were petty/anal. An analogy would be that there used to be 24 hours
> in a day, 60 minutes in an hour, and 60 seconds in a minute. Now we
> have defined a second as so many transitions of an atom, and can
> measure the variation in the length of a day. The new way is better.
> That it is not in perfect agreement with the old doesn't change much.
> There was nothing sacred about the old. So yes, an old dog can be
> taught new tricks :)
>
> Bruce

Indeed, as you indicated, "speed" as defined in SRT is simply the
ratio of measured distance over time; and common one-way measurements
are merely averaged two-way measurements - as also made clear in the
FAQ. RoS simply (and artificially) makes light speed look isotropic
and with SRT's definition of speed, that speed "is" isotropic.

Some experiments show smart attempts to sidestep that problem by
basing themselves on physical effects that are consistent with
"Einstein synchronization"; and some less smart experiments (such as
by Gagnon et al) are based on faulty reasoning.

Regards,
Harald

From: Dono. on 10 Mar 2010 14:07

From: Dono. on 10 Mar 2010 14:10

On Mar 10, 10:56 am, harald <h...(a)swissonline.ch> wrote:
> On Mar 5, 5:33 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
>
>
>
>
> > On Mar 4, 10:48 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > On Mar 3, 10:59 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > > > > It is not a function of finite propagation speeds, this we know,
> > > > > > > because we took into account the finite propagation speeds in our
> > > > > > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > > > > > remember that?
>
> > > > > > I beg to differ. It is not a "mere" or "simple" function of finite
> > > > > > propagation speed, but it *is* a function of it IMO. RoS only took it
> > > > > > into account by allowing us to use different time coordinates in each
> > > > > > frame. If the speed of light was infinite there would be no RoS.
>
> > > > > I disagree. All that is needed in relativity of simultaneity is a
> > > > > signal speed that can be VERIFIED to be the same from both events by
> > > > > either observer.
>
> > > > Well you are going to have problems with that. There is no way to
> > > > *know* that the speed is the same both ways.
>
> > > Yes, there is. That's what isotropy experiments have determined. I'm
> > > surprised you weren't aware of this.
>
> > Do you mean like this one?
>
> >http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988...
>
> > The author is kind enough to point out problems in some similar
> > experiments, while failing to notice any in his own.
>
> Yes that paper is amazing - shocking, what a blunder of Physical
> Review!
> In a nutshell, although they claim to haves obtained results that are
> "consistent with the special theory of relativity", they claim in fact
> (but unwittingly) to have disproved SRT's postulates:
>
> 1. "A clear null result is obtained for a hypothesis in which
> anisotropy of the cosmic background radiation is used to define a
> preferred reference frame [...] in which light propagates
> isotropically at a fixed speed." -> according to SRT, one may pretend
> ANY inertial reference to be such a "rest frame"; and contrary to
> their assertions, according to SRT such a claim cannot be disproved
> with measurements.
>
>
>
>
>
> > For example, has he made any assumption about contraction of his
> > equipment in the direction of motion? Tom Roberts has written posts
> > in this group showing where some of these experiments are in effect
> > two way measurements.
>
> > > > That is why Einstein
> > > > wrote, "But it is not possible without further assumption to compare,
> > > > in respect of time, an event at A with an event at B. We have so far
> > > > defined only an ``A time'' and a ``B time.'' We have not defined a
> > > > common ``time'' for A and B, for the latter cannot be defined at all
> > > > unless we establish by definition that the ``time'' required by light
> > > > to travel from A to B equals the ``time'' it requires to travel from B
> > > > to A."
>
> > > > > Since the distance from the events to the observer is
> > > > > equal, as verifiable at any time by each observer, we learn from this
> > > > > that each observer KNOWS the propagation delays from each event to the
> > > > > observer are equal. This acknowledges the propagation delays
> > > > > completely, but simply allows for verification that they are the same.
>
> > > > Assuming the speed of light is the same in both directions.
>
> > > Which is an experimentally confirmed fact. Done well after Einstein's
> > > comments on the matter, by the way.
>
> That would contradict SRT - people who are discussing here for years
> SHOULD know better!
>

Check this out:

http://groups.google.com/group/sci.physics.relativity/browse_thread/thread/d510e92359d833ab/352a087c626bf49f?lnk=gst&q=Surfer#352a087c626bf49f

From: harald on 10 Mar 2010 14:13

On Mar 6, 7:15 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote:

[..]

> Read what I actually wrote, not what you think I wrote. I wrote, "I
> consider them two interpertations of the same thing." The events are
> the same. The predictions are the same. The interpertation of why
> things appear the way they do is different.
>
> > > The LET interpertation had the
> > > advantage, for me, of showing how c + or - v could end up being
> > > measured c in all frames.
>
> > In SR there is no c+v or c-v, because there is no fixed absolute aether
> > frame in which light really travels at c.
>
> There most certainly is a c+v and c-v in SR. They are called closing
> speed. And one of the most difficult things for a new student to
> understand is why unlike anything else EM waves have the same speed in
> all frames. I will probably screw up how I put this but IMO it is
> because we made it that way. Nature does what it wants to, but we
> still have some choice in how we write the equations that describe
> what nature is doing.
>
> Say you have a cannon that launches a projectile using a spring.
> Given the strength of the spring, how far it is compressed, the weight
> of the projectile and the inclination of the barrel, you could
> calculate the trajectory of the projectile. Put the cannon on a
> flatbed of a moving train and it would be easiest to calculate the
> trajectory relative to the train, and then add the velocity of the
> train to get the position of the projectile relative to the ground at
> any given instant. But it is possible to work things out directly
> from the FoR of the ground, so long as you are consistant. For
> example, the spring may only expand a foot in the barrel of the
> cannon, but in doing so it pushes the projectilie six feet relative to
> the ground.
>
> When we make a calculation from the track FoR that involves the train
> we use the closing speed of c+v and get a correct answer. There is
> nothing stopping a rider on the train from using the same track
> coordinates and the same c+v to get the same answer. It just makes
> things a whole lot easier if he uses coordinates from his rest frame.
> Maxwell had found that the speed of light always seemed to be c, as
> measured using clocks synchronized in the rest frame the measurement
> was made in. I don't know if he was aware of RoS or not, but it
> certainly made the writing of his equations easier to keep the speed
> of light a constant.

Actually, Maxwell assumed that Newton's theory would hold accurately,
and thus he expected the MMX to permit finding a value for "absolute
speed".

> > > Given that was possible I no longer had any
> > > problem accepting the second postulate. Eventually I became aware
> > > that the second postulate wasn't so much an assumption as a
> > > stipulation. We will consider the speed of light to be our standard.
>
> > No .. it is an observed fact. Not a stipulation
>
> It was an observed fact in part because of the proceedures used to
> observe it. As I have said before, light behaved differently than
> anything else and it wasn't clear how it could do so.
>
> > > Recently I have been going back and re-reading some of the books I
> > > have bought over the years to see if I can come to grips with some of
> > > the modern interpertations of SR. After thinking about it for awhile
> > > I have realized that my objections about the changing definition of c
> > > were petty/anal.
>
> > :) Always a good conclusion to reach .. it shows you really are thinking
> > and learning and advancing.
>
> Reading Bondi he gave a good explaination for why time is considered a
> fourth dimension and how rotations fit in. I wont say any more at
> this point because I would probably screw it up. Sometimes it is
> easier to understand things than it is to express the ideas to
> others. Then again, it could be because I don't really understand it
> that well yet.

Evidently (and in contrast to many self-proclaimed "relativists",) you
understand the PoR rather well! Don't let them confuse you. ;-)

Cheers,
Harald

From: Dono. on 10 Mar 2010 14:13

On Mar 10, 11:10 am, "Dono." <sa...(a)comcast.net> wrote:
> On Mar 10, 10:56 am, harald <h...(a)swissonline.ch> wrote:
>
>
>
>
>
> > On Mar 5, 5:33 am, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > On Mar 4, 10:48 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > On Mar 3, 10:59 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > > On Mar 3, 11:21 am, PD <thedraperfam...(a)gmail.com> wrote:
>
> > > > > > On Mar 2, 8:12 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > > > > > > It is not a function of finite propagation speeds, this we know,
> > > > > > > > because we took into account the finite propagation speeds in our
> > > > > > > > procedure for determining simultaneity/nonsimultaneity. Do you not
> > > > > > > > remember that?
>
> > > > > > > I beg to differ. It is not a "mere" or "simple" function of finite
> > > > > > > propagation speed, but it *is* a function of it IMO. RoS only took it
> > > > > > > into account by allowing us to use different time coordinates in each
> > > > > > > frame. If the speed of light was infinite there would be no RoS.
>
> > > > > > I disagree. All that is needed in relativity of simultaneity is a
> > > > > > signal speed that can be VERIFIED to be the same from both events by
> > > > > > either observer.
>
> > > > > Well you are going to have problems with that. There is no way to
> > > > > *know* that the speed is the same both ways.
>
> > > > Yes, there is. That's what isotropy experiments have determined. I'm
> > > > surprised you weren't aware of this.
>
> > > Do you mean like this one?
>
> > >http://mysite.verizon.net/cephalobus_alienus/papers/Gagnon_et_al_1988....
>
> > > The author is kind enough to point out problems in some similar
> > > experiments, while failing to notice any in his own.
>
> > Yes that paper is amazing - shocking, what a blunder of Physical
> > Review!
> > In a nutshell, although they claim to haves obtained results that are
> > "consistent with the special theory of relativity", they claim in fact
> > (but unwittingly) to have disproved SRT's postulates:
>
> > 1. "A clear null result is obtained for a hypothesis in which
> > anisotropy of the cosmic background radiation is used to define a
> > preferred reference frame [...] in which light propagates
> > isotropically at a fixed speed." -> according to SRT, one may pretend
> > ANY inertial reference to be such a "rest frame"; and contrary to
> > their assertions, according to SRT such a claim cannot be disproved
> > with measurements.
>
> > > For example, has he made any assumption about contraction of his
> > > equipment in the direction of motion? Tom Roberts has written posts
> > > in this group showing where some of these experiments are in effect
> > > two way measurements.
>
> > > > > That is why Einstein
> > > > > wrote, "But it is not possible without further assumption to compare,
> > > > > in respect of time, an event at A with an event at B. We have so far
> > > > > defined only an ``A time'' and a ``B time.'' We have not defined a
> > > > > common ``time'' for A and B, for the latter cannot be defined at all
> > > > > unless we establish by definition that the ``time'' required by light
> > > > > to travel from A to B equals the ``time'' it requires to travel from B
> > > > > to A."
>
> > > > > > Since the distance from the events to the observer is
> > > > > > equal, as verifiable at any time by each observer, we learn from this
> > > > > > that each observer KNOWS the propagation delays from each event to the
> > > > > > observer are equal. This acknowledges the propagation delays
> > > > > > completely, but simply allows for verification that they are the same.
>
> > > > > Assuming the speed of light is the same in both directions.
>
> > > > Which is an experimentally confirmed fact. Done well after Einstein's
> > > > comments on the matter, by the way.
>
> > That would contradict SRT - people who are discussing here for years
> > SHOULD know better!
>
> Check this out:
>
> http://groups.google.com/group/sci.physics.relativity/browse_thread/t...- Hide quoted text -
>

...and here is the link to the published paper: http://arxiv.org/abs/0910.5658