Eric Baird wrote in message
...
| On Wed, 07 May 2008 12:52:09 +0200, "Paul B. Andersen"
| wrote:
|
| Albertito wrote:
| On May 6, 8:11 pm, "Paul B. Andersen"
| wrote:
| Albertito skrev:
|
| Hi all,
| In recent threads I was trying to show velocities
| do not add as Einstein's addition formula states,
| but strictly as euclidean vectors,
| w = u + v,
| Have you done the one thing that can prove
| Einstein's formula wrong?
|
| If you have, why don't you tell us about
| the experiment that falsified Einstein's formula?
|
| [..]
|
| --
| Paul
|
| http://home.c2i.net/pb_andersen/
|
| Someone has already pointed out to you that the
| Pioneer anomaly may be very well a experiment that
| can falsify Einstein's formula.
|
| Not really.
| There are too may open questions to do that.
|
| But you said you have tried to show that velocities
| do not add as Einstein's addition formula states,
| but strictly as euclidean vectors w = u + v
|
| Don't you know of any experiments testing how
| velocities transform?
| How did Einstein's velocity transform and
| the Galilean velocity transform do in those tests?
| Were any of them falsified?
|
| I think that one of the problems with discussing velocity addition
| under SR vs "older models", and then talking about experimental
| verification, is that people tend to forget that lots of the older
| models could also generate their own velocity-addition formulae.
|
| Any model that assumes that the velocity of light is somehow mangled
| by the motion of objects tends to generate these sorts of formulae.
| The //status// of velocity-addition under SR is unusual, but the
| associated phenomenology isn't especially new. The significance of the
| match between Fizeau's experiment and SR sometimes gets exaggerated, I
| don't think the match was supposed to be any better than the match
| between Fizeau and Fresnel's old aether-dragging model (which Fizeau's
| experiment was seemingly meant to test).
|
| If we're sticking to strictly optical effects, we find that quite a
| few theories have "non-Galiean" relationships when composite shifts
| are involved.
| For instance, with ancient emission theory, the Doppler shift law for
| a recedign object was f'/f = (c-v)/c , so if you watched an object
| receding at half the speed of light, it's frequency would be halved.
|
| If there was then a second object beyond it, also receding, at half
| lightspeed wrt /it/, then you'd normally tend to say that that second
| object was receding from you at exactly the speed of light ... but it
| wouldn' t be receding at the speed of //its own// light.

You'd still have zero frequency - if you could observe it.
|
| For a signal passed from the more distant object, to the intermediate
| object, to you, the frequency of the light (according to old emission
| theory) would be freqOriginal×0.5×0.5 ,

It would be (and still is) f'/f = (c-v-u)/c = 0.


| so you'd expect to see the
| furthest object's signals, relayed vie the intermediate object, to
| have one quarter of their original frequency, as we'd expect under
| emission theory if we'd observed it directly while it was only
| receding at 0.75c, rather than c.

No I would not. I'd expect (and get) zero. Nor does the second
emitter have to be "more distant", it can quite easily be catching up to
and passing the first emitter. The light it emits is INDEPENDENT of
the first emitter.


| The "effective" recession velocity calcualtion for the
| indirectly-observed object under emission theory would then be
| 0.5c+0.5c = 0.75c

Wrong. 0.5c +0.5c = 1.0c.
You are playing games with Xeno's paradox.

| Similar "non-Galilean" patterns show up under other models where
| lightspeed is variable, and can be justified by pointing out that a
| relative "velocity", defined as a fraction of the speed of light, can
| end up being assigned a different nominal value when the speed of the
| light-signal that's being used as a reference changes.
|
|
| Obviously, a lot of the old models were pretty stinky in places, but
| we have to remember that the main advantage of the Galiean transforms
| isn't perhaps so much their historical relavance, as their narrative
| value in explaining the thought-processes that take us from (a)
| assuming that the speed of light is globally fixed in the laboratory
| frame (fixed stationary absolute aether), to (b) arriving at a
| "relativised" version of that global-c description, provided by
| special relativity.

Einstein said:
the speed of light from A to B is c-v,
the speed of light from B to A is c+v,
the "time" each way is the same.

That's the garbage relativity is built on.


|
| If we're going to try to make a fair comparison,

Fair comparison?
There is NO comparison between sense and nonsense, Eric.