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

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From: Ste on 19 Feb 2010 23:25

On 18 Feb, 21:48, PD <thedraperfam...(a)gmail.com> wrote:
> On Feb 18, 3:12 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
> > On 18 Feb, 16:35, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > On Feb 18, 9:43 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > I'm confused Mark.
>
> > > > My position is that someone must hold a priori that alternate
> > > > dimensions are a real possibility, in order to hold that any theory
> > > > that employs alternate dimensions is credible. Some here do hold that
> > > > alternate dimensions are a real possibility, so of course they hold
> > > > theories that employ them as credible.
>
> > > > I don't hold that alternate dimensions are a real possibility, so of
> > > > course I don't accept that theories that employ them are credible.
>
> > > The problem is, you act like everybody in this group went into physics
> > > classes knowing and believing everything that was taught in the
> > > physics classes.
>
> > No, I'm basically saying that the only people who came *out* of those
> > classes, and went into theoretical or experimental physics, are the
> > people who by the end believed any of that nonsense.
>
> Hmmm. So there appears to be two models for what has happened in such
> cases:
> 1) the student who went through those classes had reason and good
> sense *stripped* of them to the point where they would believe
> nonsense, and this result is inherent to the process undergone.
> 2) the student who went through those classes learned something new,
> including how to test unambiguously for extra dimensions (regardless
> whether it has been yet determined by test) and what the motivations
> for even considering them might be, so that what seems like nonsense
> to the novice no longer seems like nonsense.

I dare say there is a third. The student went into the class without
having any "good sense" in the first place, and therefore they were
willing to accept anything that they were told there.

Of course I'd rather avoid saying that these students have "no sense".
I'm much more willing to believe that they are simply not concerned
with a practical-mechanical explanation, possibly because beforehand
they don't have any well-developed intuitions for it, and secondly
it's vogue in science at the moment to emphasise purely mathematical
explanations over practical-mechanical explanations.

> Now, how might one test which of these two claims is what has really
> happened?
>
> Let me suggest one. If (1) were the case, then because of the inherent
> flaw in the process, then it would have likely been observed up to
> this point that there is a whole class of former students who have
> come to believe some principle that is objectively falsifiable. It
> would be falsifiable perhaps by the construction of a whole class of
> devices whose design is based on that principle and which (because the
> principle is false) obviously don't work in practice. Perhaps you can
> point to some cases like that where devices with designs based on
> relativity or quantum mechanics simply do not work because the
> principles are wrong. Or is it your claim that all such devices happen
> to work by accident, even though the design principles are wrong?

If you're suggesting that it's improbable that a theory could work not
because its premises were correct, but because it simply promoted
correct behaviours, then wonders why religion has fared so well. In
any event, I'm willing to accept Feynman's argument, basically that QM
amounts to a workable mathematical model, and makes no claim to any
truth more fundamental than that.

> > > The point is, your argument boils down to "the only people I see
> > > convinced of alternate dimensions are the people who believe in
> > > alternate dimensions," but that's a circular argument.
>
> > It's not circular. It's a simple statement that there is, to a certain
> > degree, a self-selection process, wherein the people who have a
> > susceptibility to these sorts of arguments are precisely the ones who
> > adopt and build on them.
>
> Or, to couch this in terms of the second option listed above, this
> selection process happens to find those who are susceptible to
> learning something new and which is in conflict with their incoming
> presuppositions?

I really don't think everyone has particularly strong preconceptions
(i.e. they'll believe anything), and nor do I think everyone has a
taste for challenging authority. As I say, my argument is that the pre-
existing interests, aptitudes, and psychology of students probably
determines to a large extent what they're willing to accept as
credible and coherent.

To identify a relatively small minority of people (that is,
physicists), who have necessarily been weeded from a very large
population, and then appeal to a further subset of those in order to
somehow prove that additional dimensions are credible is just silly.
It is just as reasonable to say that the common views of these
"experts" is as much a product of the weeding process.

> > > The only way
> > > for that to hold water would be if the people who believe in them had
> > > always believed in them. Nobody is born knowing these things. We all
> > > had to learn and change our opinions at some point.
>
> > It doesn't require that a person always believed something in
> > particular. It can be as simple as, say, having a preference for
> > mathematics and working with numbers in a very abstract sense.
>
> And by this do you mean "detached from reality"?

Not really, and not in a cynical sense. I mean it simply in the way I
said it, which is that a person may simply enjoy maths in itself, and
they will find a way to see everything through that rubric. So when
you mention "time", it evokes the image of the "t-axis" for such
people, whereas for me I'm more likely to think of a pendulum or
basically some sort of clock. And then, when one mentions "time
slowing down", people who imagined the "t-axis" may be inclined to
develop the view that time has "fundamentally" slowed down (because
the mechanical details of how time is measured is not actually within
the realm of their primary interests), whereas I'm more likely to say
"well, what is to stop the clock slowing down without time itself
slowing down?", or even "what if it just *appears to the eye* that the
clock has slowed down?".

> What do you think the
> role of experimental testing of the quantitative predictions of
> abstract models plays, then?

It has been argued that the role of experimental testing is to find
observations that can be interpreted to fit the pre-existing models.

> > Whereas I have a preference for what might be called "practical
> > mechanics" (and actually I think I'm going to adopt this phrase from
> > now on to describe what I mean by a "physical explanation"), where
> > there are mechanical relationships, moving parts, cause and effect,
> > etc. And that's not to say I don't understand abstract mathematics or
> > can't work with it, but in some sense I don't consider it synonymous
> > with reality, so a mathematical explanation of physical phenomena,
> > however obviously true, still doesn't suffice as a complete picture
> > for me until I've distilled it out into some sort of consistent
> > "practical mechanical" form. And I know Paul will laugh about this
> > being all about "cogs and levers", but really the approach is a lot
> > more flexible than that.
>
> Herein is the presumption that for every abstract and mathematically-
> rich model that makes testable predictions that can be checked with
> experiment, you have faith that there is an equally viable alternative
> model that is not so abstract and is full of cogs-and-levers
> concreteness that is just as successful in making the same
> quantitative testable predictions in the same class of experiments.

That's actually not what I said Paul. I quite clearly said that I do
not see a practical mechanical model as being an "alternative" to the
maths but rather I find it complementary.

> What's amusing about this claim is that if pressed on demonstrating
> the same success in making quantitative testable predictions, I've
> gotten the following responses:
> * "Oh, the math is fine. It's just the underlying concept that needs
> to be swapped out." (Never mind that the math is *derived from* the
> underlying concept.)
> * "But I don't have the mathematical skill to demonstrate that the
> cogs-and-lever model does in fact have the same quantitative testable
> predictions. Some techno-drone should be asked to do that grunt
> work." (This is the Of-course-it-will-work-just-let-worker-bees-show-
> it defense.)
> * "Why do I have to demonstrate that it makes accurate and testable
> predictions of experimentally measurable phenomena at all? That's a
> requirement of the self-serving scientific community. For my purposes,
> it's sufficient to have a qualitative picture, and because that
> qualitative picture involves cogs-and-levers and not abstract
> concepts, then it's automatically better, at least in my eyes." (This
> is the take-your-scientific-method-and-shove-it argument.)

You may mock at will.

From: Ste on 19 Feb 2010 23:28

On 19 Feb, 01:53, mpalenik <markpale...(a)gmail.com> wrote:
> On Feb 18, 4:12 pm, Ste <ste_ro...(a)hotmail.com> wrote:
>
>
>
>
>
> > On 18 Feb, 16:35, mpalenik <markpale...(a)gmail.com> wrote:
>
> > > On Feb 18, 9:43 am, Ste <ste_ro...(a)hotmail.com> wrote:
>
> > > > I'm confused Mark.
>
> > > > My position is that someone must hold a priori that alternate
> > > > dimensions are a real possibility, in order to hold that any theory
> > > > that employs alternate dimensions is credible. Some here do hold that
> > > > alternate dimensions are a real possibility, so of course they hold
> > > > theories that employ them as credible.
>
> > > > I don't hold that alternate dimensions are a real possibility, so of
> > > > course I don't accept that theories that employ them are credible.
>
> > > The problem is, you act like everybody in this group went into physics
> > > classes knowing and believing everything that was taught in the
> > > physics classes.
>
> > No, I'm basically saying that the only people who came *out* of those
> > classes, and went into theoretical or experimental physics, are the
> > people who by the end believed any of that nonsense.
>
> So, you don't think educated people could possibly understand
> something you don't. Interesting.

That's not what I said.

From: Peter Webb on 20 Feb 2010 00:11

"mpc755" <mpc755(a)gmail.com> wrote in message
news:0c0c70e7-f3f0-4698-a3d7-4799b8db5ce7(a)o5g2000vbb.googlegroups.com...
On Feb 19, 6:52 am, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > > > ________________________________
> > > > > So in all inertial reference frames the speed of light in a vacuum
> > > > > is
> > > > > c,
> > > > > according to you?
>
> > > > As determined by Observers in the inertial reference frame, yes.
>
> > > > ____________________________________
> > > > Terrific. So you agree that the speed of light is constant in all
> > > > inertial
> > > > reference frames, and disagree with the subject line of this post.
> > > > You
> > > > should be telling the OP why he is wrong.
>
> > > But what I do not think the OP understands is the reason why.
>
> > > ________________________________
> > > You can invent any explanation you like, as long as it is consistent
> > > with
> > > the observed fact the speed of light in a vacuum is a constant. I
> > > assume
> > > you also agree with all the other predictions that SR makes? If not,
> > > are
> > > there any you disagree with?
>
> > My fundamental differences with SR are two. One is, SR implies the
> > light travels at 'c' from A and B to M and from A' and B' to M' in
> > nature. This is incorrect. Light travels at 'c' with respect to the
> > aether.
>
> > ________________________________
> > You said in your immediately previous post light always travels at c
> > with
> > respect to the observer.
>
> > Which means it cannot possibly travel at c with respect to the ether,
> > unless
> > all observers are also stationary with respect to the ether, according
> > to
> > what you claimed in your previous post.
>
> > How can light be travelling at c with respect to the observer if it is
> > travelling at c with respect to the ether, unless the observer is at
> > rest
> > compared to the ether?
>
> I said the Observers in each inertial frame of reference will
> determine the light to travel at 'c'. I did not say the light is
> actually traveling at 'c' in nature.
>
> ___________________________
> That's fine. I have no idea what "in nature" is supposed to meand, but
> what
> SR predicts is that each person measuring the speed of light in a vacuum
> will get the same answer of c, irrespective of their local reference
> frame.
> You seem to agree.
>
> Three Observers get together at M' on the train and synchronize their
> clocks. The Observers will determine the light to travel at 'c'
> because the clock being moved to B' on the train 'ticks' slower while
> being moved because it is being moved against the 'flow' of aether.
> The clock being moved to A' 'ticks' faster than both the clocks at M'
> and B' while being moved because it 'ticks' faster because it is being
> moved with the 'flow' of the aether and is more at rest with respect
> to the aether while being moved than both the clocks at M' and B'.
> When the clocks stop being moved they are no longer synchronized but
> the Observers are unable to know this. When the clocks are stopped
> being moved they all exist under the same amount of aether pressure
> and all 'tick' at the same rate.
>
> The non-synchronized clocks on the train allow the Observers on the
> train to conclude the light travels at 'c' with respect to the train.
>
> _________________________________________
> Sorry, not interested in the whole train thing.
>

Then you will not understand how light propagates in nature. You will
not understand what occurs physically in nature in terms of the
propagation of light.

_______________________________
Actually, as I understand Maxwell's eqns quite well, I know exactly how
light propogates. Thanks anyway.

> Light propagates at 'c' with respect to the aether.
>
> _______________________________________
> But you agree with the SR in that all observers measure the speed of light
> as c, completely irrespective of any motion they may have relative to the
> ether? Because that is exactly what SR predicts, and I believe to be true.
>

> > And you haven't answered my other question. Is there any other
> > prediction
> > of
> > SR that you disagree with, or do you think that the equations of SR
> > correctly explain what happens in inertial frames of reference? If you
> > disagree with any of the equations, which one(s)?
>
> It is not so much a prediction but an understanding of nature. SR
> assumes time changes the faster something is moving. That is
> incorrect. Clocks 'tick' slower the faster they are moving with
> respect to the aether

________________________________________________
No, the eqns of SR says that it depends upon the speed relative to the
observer, not to the ether.

In fact, the ether doesn't appear at all in SR.

So you are making a claim that the time dilation formula in SR is wrong, and
you *don't* agree with SR.

Which is the opposite of what you claim above.

> because the faster the clock is moving with
> respect to the aether the more aether pressure exerted on the clock
> causing it to 'tick' slower.
>
> __________________________________
> Putting aside your mumbo-jumbo explanation, I just want to confirm that
> you
> agree that what SR predicts is exactly what happens. If not, and you have
> any experiment, test, measurement or observation where you think that the
> results would not be different from what SR predicts, what are these
> experiments, tests, measurements or observations?

My explanation explains what occurs physically in nature which allows
the Observers on the train to be moving with respect to the aether at
the same time conclude light propagates at 'c' with respect to the
train.

___________________________________
You keep changing your story.

First you said that light always travels at c with respect to the observer.
Then you said that light always travels at c with respect to the ether.

First you said that you agreed with the equations of SR.
Then you said the equation for time dilation in SR is wrong.

Again:

Q1. You believe light always travels at c with respect to:
a) The observer, or
b) The ether
c) neither of the above

Q2. You believe the equations of SR are:
a) Correct
b) Correct except for the time dilation one
c) Neither of the above.

From: Peter Webb on 20 Feb 2010 00:19

> You said light moves with speed c relative to
> the observer,

Again, I have not said light moves at 'c' with respect to the
Observers on the train. I have said, repeatedly, the Observers on the
train will conclude/determine the light speed to be 'c'.

________________________________
If observers on the train measure the speed of light, whta do they get?

I never said
it was actually propagating at 'c' with respect to the train. I have
said light propagates at 'c' with respect to the aether.
_____________________________
So if we are moving at velocity v relative to the ether, and measure the
speed of light, what will we get as an answer?

> but you have also said light moves with speed c relative to
> the ether. The only way both of these can be true is if the observer is
> always at rest relative to the ether. Unless you have some other
> explanation.
>
> > And you haven't answered my other question. Is there any other
> > prediction
> > of
> > SR that you disagree with, or do you think that the equations of SR
> > correctly explain what happens in inertial frames of reference? If you
> > disagree with any of the equations, which one(s)?
>
> ______________________________________
> You didn't answer that question, either. You are very shy. Are you scared
> we
> will laugh at you?

How does your unwillingness to read the response I reflect anything
about anyone besides yourself?

_______________________________________
I have now asked you this question about 10 times, and you still refuse to
answer it. You keep saying that if I read a long piece about trains,
embankments, and lightening, I should be able to work out what you think the
answer should be. I can't. Here it is again:

The earth is moving relative to the ether at speed v. We measure the speed
of light in the direction in which we are travelling through the ether. The
measured speed of light will be what, exactly?

c+v? c-v; c? sqrt(1-(v/c)^2)*c ? Something else?

Why won't you tell us?

From: Peter Webb on 20 Feb 2010 00:22

"mpc755" <mpc755(a)gmail.com> wrote in message
news:76046417-462a-4e57-8c52-dcbbba501e66(a)h12g2000vbd.googlegroups.com...
On Feb 19, 7:31 am, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> "mpc755" <mpc...(a)gmail.com> wrote in message
>
> news:caf06774-b01d-4536-90fa-7086e39b3df5(a)i39g2000yqm.googlegroups.com...
> On Feb 19, 1:12 am, "Peter Webb"
>
>
>
> <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > "mpc755" <mpc...(a)gmail.com> wrote in message
>
> >news:27f905eb-2174-433f-b24d-03c80bd81617(a)i39g2000yqm.googlegroups.com...
> > On Feb 18, 11:59 pm, "Peter Webb"
>
> > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > "mpc755" <mpc...(a)gmail.com> wrote in message
>
> > >news:6576dabb-16ea-43d9-8741-c2d1af70b789(a)g11g2000yqe.googlegroups.com...
> > > On Feb 18, 11:22 pm, "Peter Webb"
>
> > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > > "mpc755" <mpc...(a)gmail.com> wrote in message
>
> > > >news:0f10e987-c21e-44cc-beec-03d48b731317(a)j27g2000yqn.googlegroups.com...
> > > > On Feb 18, 10:59 pm, "Peter Webb"
>
> > > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > > > > > ________________________________
> > > > > > > So claim that the measured speed of light in a laboratory on
> > > > > > > earth
> > > > > > > travelling at speed relative to the ether of v is still c? Is
> > > > > > > this
> > > > > > > your
> > > > > > > claim?
>
> > > > > > For the laboratory on the Earth the aether is at rest with
> > > > > > respect
> > > > > > to
> > > > > > the Earth so discussing this in terms of the Earth moving at 'v'
> > > > > > with
> > > > > > respect to the aether is meaningless and shows you did not read
> > > > > > my
> > > > > > responses because the laboratory is analogous to the embankment.
>
> > > > > > __________________________________
> > > > > > So completely independent of the speed at which the earth moves
> > > > > > with
> > > > > > respect
> > > > > > to the ether, the measured speed of light in a vacuum on earth
> > > > > > is
> > > > > > always
> > > > > > c
> > > > > > ?
>
> > > > > The speed of light is always determined to be 'c'.
>
> > > > > ________________________________
> > > > > So in all inertial reference frames the speed of light in a vacuum
> > > > > is
> > > > > c,
> > > > > according to you?
>
> > > > As determined by Observers in the inertial reference frame, yes.
>
> > > > ____________________________________
> > > > Terrific. So you agree that the speed of light is constant in all
> > > > inertial
> > > > reference frames, and disagree with the subject line of this post.
> > > > You
> > > > should be telling the OP why he is wrong.
>
> > > But what I do not think the OP understands is the reason why.
>
> > > ________________________________
> > > You can invent any explanation you like, as long as it is consistent
> > > with
> > > the observed fact the speed of light in a vacuum is a constant. I
> > > assume
> > > you also agree with all the other predictions that SR makes? If not,
> > > are
> > > there any you disagree with?
>
> > My fundamental differences with SR are two. One is, SR implies the
> > light travels at 'c' from A and B to M and from A' and B' to M' in
> > nature. This is incorrect. Light travels at 'c' with respect to the
> > aether.
>
> > ________________________________
> > You said in your immediately previous post light always travels at c
> > with
> > respect to the observer.
>
> > Which means it cannot possibly travel at c with respect to the ether,
> > unless
> > all observers are also stationary with respect to the ether, according
> > to
> > what you claimed in your previous post.
>
> > How can light be travelling at c with respect to the observer if it is
> > travelling at c with respect to the ether, unless the observer is at
> > rest
> > compared to the ether?
>
> You would already know the answers to the questions if you read the
> posts you refuse to read.
> ________________________________
> Well, for whatever reason I don't know. But you seem very shy about
> explaining what you believe.

How does you unwillingness to read the response which answers your
questions reflect on anyone but yourself? I have asked you dozens of
times to read the explanation as to what occurs in nature in order for
the Observers on the train to conclude light travels at 'c' with
respect to the train at the same time light is traveling at 'c' with
respect to the aether.

> You said light moves with speed c relative to
> the observer,

Again, I have not said light moves at 'c' with respect to the
Observers on the train. I have said, repeatedly, the Observers on the
train will conclude/determine the light speed to be 'c'. I never said
it was actually propagating at 'c' with respect to the train. I have
said light propagates at 'c' with respect to the aether.

> but you have also said light moves with speed c relative to
> the ether. The only way both of these can be true is if the observer is
> always at rest relative to the ether. Unless you have some other
> explanation.
>
> > And you haven't answered my other question. Is there any other
> > prediction
> > of
> > SR that you disagree with, or do you think that the equations of SR
> > correctly explain what happens in inertial frames of reference? If you
> > disagree with any of the equations, which one(s)?
>
> ______________________________________
> You didn't answer that question, either. You are very shy. Are you scared
> we
> will laugh at you?

How does your unwillingness to read a response which actually answers
your questions reflect on anyone but yourself?

Atomic clocks are separted on a train moving relative to the
aether. The clock moving towards the front of the train is under
greater aether pressure then the clock being moved to the back of the
train. The clock being moved to the front of the train is under more
aether pressure because that clock is being walked against the 'flow'
of the aether. The clock being walked to the back of the train is
under less aether pressure because that clock is being walked with the
'flow' of the aether. While the clock is being walked to the front it
'ticks' slower than the clock being walked to the back of the train
because of the additional aether pressure the clock being walked to
the front of the train is under.

Let's assume after the clocks are walked to A' and B' the clocks at
A', M', and B' read 12:00:02, 12:00:01, and 12:00:00 respectively if
you could see all three clocks at the same time. The clock at A'
'ticked' faster than the clock at M' while it was being walked to A'
because it was being walked with the 'flow' of the aether and was more
'at rest' with respect to the aether than the clock at M' was and was
therefore under less aether pressure than the clock at M' was while it
was being walked to A'.

Once all of the clocks are at A', M', and B', they are all at rest
with respect to the train and they are all under the same amount of
aether pressure and will 'tick' at the same rate.

So, even though the Observers synchronized their clocks, once the
clocks are walked to their destination, the clocks are out of sync, in
nature.

Now, a flash of light occurs at M' at 12:00:01. The light propagates
with the flow of the aether to A' and takes two seconds to arrive
there. The light propagates against the flow to B' and takes four
seconds to get there. When the light arrives at A' and B' both clocks
read 12:00:04. As far as the Observers at A', B', and C' are concerned
the lightning strikes were simultaneous.

Now, the light is reflected by mirrors at A' and B'. Since the light
traveled with the 'flow' of the aether and was reflected after two
seconds by the mirror at A' and will take four seconds to travel back
to M' and since the light traveled against the 'flow' of the aether
and was reflected after four seconds by the mirror at B' and will take
two seconds to travel back to M' the light from the flash at M'
arrives simultaneously back at M' and the clock at M' reads 12:00:07.

When the Observers get back together and calculate how far the light
traveled and the time of the arrival of the light based upon the time
on their atomic clocks, the Observers on the train conclude the light
waves propagated at 'c' with respect to the train.

The light waves actually propagated at 'c' with respect to the aether
but the Observers are unaware they are moving relative to the aether.
If the Observers were aware they were moving relative to the aether
they would then be able to calculate where the light traveled from
with respect to the aether and determine the light waves propagated at
'c' with respect to the aether.

______________________________________
Here's a much simpler question, which has no mirrors, trains, embankments,
lightning etc.

Lets say the earth is moving relative to the ether at speed v. We measure
the speed of light in a vacuum on earth in the direction in which the earth
is moving through the ether. What do we measure the speed of light to be in
that laboratory on earth? c? c+v? c-v? Something else?