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

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From: Ste on 11 Mar 2010 07:43

On 11 Mar, 01:51, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> No, perhaps you didn't understand. As I say, this is *not* the twins
> paradox, because in the twins paradox only *one* twin leaves Earth.
>
> ________________________
> Its functionally the same. It is exactly the twins paradox, but with two
> twins apparently doing exactly the same thing.
>
> Even if you cannot see that, the explanation on the Wikipedia page of the
> Twins Paradox is trivially adapted for two twins.
>
> I assume that you do not understand the Wikipedia twins paradox page, or
> else you would know the answers to your questions already. Which parts don't
> you understand?

Let's just go through it step by step Peter, as we have been doing.
It's pointless spending 10 more postings arguing about how the
Wikipedia page does or does not answer the question, or how it is or
is not relevant. As I've just said in a post to Inertial, the only
analogy between my scenario and the twins paradox is that, in my
scenario, both twins leave Earth, and both return the same age as each
other - hence no paradox, and hence bearing no resemblance at all to
the twins paradox.

From: mpc755 on 11 Mar 2010 07:44

On Mar 10, 11:37 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
> On Mar 10, 10:01 pm, mpc755 <mpc...(a)gmail.com> wrote:
>
>
>
> > On Mar 10, 8:52 pm, Bruce Richmond <bsr3...(a)my-deja.com> wrote:
>
> > > On Mar 10, 8:13 pm, "Peter Webb"
>
> > > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > > According to both SR and LET there is no experiment that can reveal
> > > > which frame is at rest WRT the ether, so there is no way to know which
> > > > frame is more at rest WRT the ether.
>
> > > > ______________________
> > > > Wrong. Only LET has this problem. There is no ether in SR, so the question
> > > > of its velocity doesn't even arise.
>
> > > Einstein did not rule out the possibility of an ether, he said that it
> > > made no difference if there was one, that it was superfluous. If you
> > > claim my statement is wrong you are claiming there is an experiment
> > > that can reveal the ether frame.
>
> > Another complete misquote of Einstein.
>
> >http://en.citizendium.org/wiki/Ether_%28physics%29
>
> > 'In his 1905 paper Einstein refers to the ether only once:
>
> > The introduction of a "luminiferous aether" will prove to be
> > superfluous inasmuch as the view here to be developed will not require
> > an "absolutely stationary space" provided with special properties, nor
> > assign a velocity vector to a point of the empty space in which
> > electromagnetic processes take place.'
>
> > What part of 'inasmuch as the view here to be developed will not
> > require "an absolutely stationary space"' do you not understand?
>
> > Just as you do not understand Einstein's definition of motion you do
> > not understand what Einstein meant by a superfluous aether.
>
> > Einstein's definition of motion requires there to be particles which
> > can be separately tracked through time.
>
> > Einstein's definition of a superfluous aether is one in which it is an
> > absolutely stationary space.
>
> > The aether is displaced by matter. The aether is not at rest when
> > displaced. The aether 'displaces back'. The pressure associated with
> > the aether displaced by massive objects is gravity. A moving particle
> > has an associated aether wave.
>
> Fine, go back to Neverland.
>

Fine, remain ignorant about what Einstein meant by a superfluous
aether. How does this following quote fit with your misunderstanding
of Einstein saying the aether makes no difference?

"According to the general theory of relativity space without ether is
unthinkable" - Albert Einstein

From: mpc755 on 11 Mar 2010 07:46

On Mar 11, 12:21 am, "Peter Webb"
<webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>
> news:ca6a0dbf-23e8-42ff-b741-ae709e93dc66(a)z4g2000yqa.googlegroups.com...
> On Mar 10, 10:39 pm, "Peter Webb"
>
>
>
> <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > "Bruce Richmond" <bsr3...(a)my-deja.com> wrote in message
>
> >news:1f04b278-4b2e-4602-9ce8-716f62cff45e(a)f8g2000yqn.googlegroups.com...
> > On Mar 10, 8:13 pm, "Peter Webb"
>
> > <webbfam...(a)DIESPAMDIEoptusnet.com.au> wrote:
> > > According to both SR and LET there is no experiment that can reveal
> > > which frame is at rest WRT the ether, so there is no way to know which
> > > frame is more at rest WRT the ether.
>
> > > ______________________
> > > Wrong. Only LET has this problem. There is no ether in SR, so the
> > > question
> > > of its velocity doesn't even arise.
>
> > Einstein did not rule out the possibility of an ether, he said that it
> > made no difference if there was one, that it was superfluous.
>
> > ___________________________
> > And indeed there is no ether in SR, so there is no problem with
> > calculating
> > its speed. A bit like saying that zoology has a problem because it doesn't
> > say how fast Unicorns can run; it doesn't have a problem, as according to
> > zoology Unicorn's don't even exist so they can't run.
>
> > If you
> > claim my statement is wrong you are claiming there is an experiment
> > that can reveal the ether frame.
>
> > __________________________
> > What part of "SR does not even include an ether" don't you understand?
>
> What part of "If there isn't one you can't measure it" do *you* not
> understand?
>
> _____________________
> Do you think that zoology has a problem because it knows nothing about
> Unicorns?
>
> The difference between LET and SR is that the ether exists in LET, but its
> speed cannot be determined. SR doesn't even have an ether; they are
> different situations. LET assumes that "Unicorns" exist but says some
> properties cannot be determined; SR says they don't exist at all.

And the aether exists in GR:

"According to the general theory of relativity space without ether is
unthinkable" - Albert Einstein

And the aether exists in Einstein's 'first paper':

http://www.worldscibooks.com/phy_etextbook/4454/4454_chap1.pdf

So, yes there is an aether in SR.

From: Ste on 11 Mar 2010 07:48

On 11 Mar, 01:58, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
wrote:
> "Ste" <ste_ro...(a)hotmail.com> wrote in message
>
> > except for the fairly
> > obvious explanation that it is the reference clock which is undergoing
> > a "real" slowdown.
>
> Or, that you have no idea of what SR predicts, and have completely and
> falsely assumed that observers see clocks jump ahead when turnaround occurs.

I'm merely going off what "experts" here say happens. I didn't say
there is a "leap ahead". Paul Draper (if I remember correctly) said
there is a "leap ahead". Now perhaps I misunderstood, but that is what
was said.

From: Peter Webb on 11 Mar 2010 08:31

"Ste" <ste_rose0(a)hotmail.com> wrote in message
news:2a6d123a-6595-465f-bc22-842952845362(a)g11g2000yqe.googlegroups.com...
> On 11 Mar, 01:51, "Peter Webb" <webbfam...(a)DIESPAMDIEoptusnet.com.au>
> wrote:
>> No, perhaps you didn't understand. As I say, this is *not* the twins
>> paradox, because in the twins paradox only *one* twin leaves Earth.
>>
>> ________________________
>> Its functionally the same. It is exactly the twins paradox, but with two
>> twins apparently doing exactly the same thing.
>>
>> Even if you cannot see that, the explanation on the Wikipedia page of the
>> Twins Paradox is trivially adapted for two twins.
>>
>> I assume that you do not understand the Wikipedia twins paradox page, or
>> else you would know the answers to your questions already. Which parts
>> don't
>> you understand?
>
> Let's just go through it step by step Peter, as we have been doing.
> It's pointless spending 10 more postings arguing about how the
> Wikipedia page does or does not answer the question, or how it is or
> is not relevant. As I've just said in a post to Inertial, the only
> analogy between my scenario and the twins paradox is that, in my
> scenario, both twins leave Earth, and both return the same age as each
> other - hence no paradox, and hence bearing no resemblance at all to
> the twins paradox.

Well, I never thought there was a paradox, and as you agree, I have to
wonder what you are going on about.

If you do still have a problem, then the easiest way is by drawing a diagram
like the ones on http://en.wikipedia.org/wiki/Twin_paradox . That is hard to
do on usenet.

The only other way of answering these questions is to use the equations of
SR, eg

If one twin travels at 0.9c for one year then his elapsed time in his frame
of reference is sqrt(1-0.9^2) maybe 0.4 years, and that will show on his
clock, and that is the time that other people see his clock as showing.

I don't know if that will answer your question; if you really want to answer
it you will need to understand the diagrams on the web page.