Re: A little challenge for relativists.


"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:slrndp1ep0.r7g.dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Harry:
> >"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> >news:slrndp055j.64k.dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >> Harry:
> >> >
> >> >"Bilge" <dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> >>
> >> >> Yes, it is. Absolute simultaneity defines a symmetry. That
symmetry
> >> >> defines the galilean group.
> >> >
> >> >Bilge, aeons ago I asked you to provide a real world example - which
> >should
> >> >be easy, if you talk experimental physics. Just specify a
measurement
> >that
> >> >according to you can be done with SRT but can't be done if an
absolute
> >frame
> >> >exists, say moving at 0.6c "absolute" towards Orion, and then what.
Or,
> >if
> >>
> >> Define the frame.
> >
> >Why don't you define it? OK I'll go ahead and do it: let's take a
physical
> >frame S, moving at 0.6c "absolute" towards Orion. At rest in this frame
is
> >an observer, let's call him Bilge. According to the theory he can't
directly
> >measure his speed, but he can measure other, related effects that are
> >consequences of the theory.
>
> That doesn't define the frame. To define a frame, and initialize the
> data, you must specify the positions of the other objects in that
> frame on a the line defined as t = 0 (Or some other definition which is
> self consistent). The line t = 0, has no intrinsic meaning, so _you_
> have to specify what it means. I'm not going to do it for you. Before
> you take another stab at it, you might look up the commutation relations
> for the poincare algebra.

Bilge, no experimentalist needs to "look up the commutation relations for
the poincare algebra" or things like that. Anyway, you now showed in your
comment about Newton's theory:
Message-ID: <slrndp1g0d.r7g.dubious@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>
that your real issue is not with GRT/SRT, but already with classical
mechanics - which is much more basic.
Then it's a waste of time to try to show you that Newton's absolute space
concept is also compatible with SRT.

Harald

> >He can also observe what is happening in another physical frame S' that
is
> >moving in such a peculiar way (if I understood you correctly) that Bilge
> >can't measure the relative speed between the two systems, in local
units.
>
> You not only didn't understand me, you aren't even on the same page.
> The poincare group has ten killing vectors which define ten observables.
> You cannot specify all ten when initializing your data. The choice
> is up to you, but once you specify a complete set which commutes,
> you cannot insist the rest be observables.
>
> >> That means initialize the energy, momenta and
> >> positions of everything relevent at the time t = 0 (i.e., now).
> >> Since no observer can do that, you'll have to figure out what
> >> you can define.
> >
> >What would be relevant for your example? You failed to explain where you
> >think is a problem. But you give me the impression that according to
you, if
>
> It's _your_ example, not mine. I could care less if you manage to ever
> specify an experiment that is self-consistent, so you'll have to go study
> on your own. Here's a hint, though. The poincare group has ten killing
> vectors which correspond to, (1) time and space translations, (2) 3
lorentz
> boosts, (3) 3 spatial rotations. You also have the mass^2 as a casimir
> operator. You'll need to pick the set that best suits the coordinates
> in which you define t = 0.
>
>
> >Bilge doesn't *know* his speed, that therefore he can't *have* a speed.
If
> >that's what you mean, then that's a logical error. But surely you can't
mean
> >that... right?
>
> You're right. I can't mean that. In fact, I can't mean anything
> close to that.
>
>


.

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