sci.physics.relativity

On Mar 5, 5:18=A0am, Albertito wrote:
> On 5 mar, 04:11, Tom Roberts wrote:
>
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> > Albertito wrote:
> > > In 1893 Ernst Mach stated the so-called Mach Principle:
> > > =A0 "For me only relative motion exists. When a body rotates
> > > =A0 =A0relative to the fixed stars centrifugal forces are produced.
> > > =A0 =A0When it rotates relatively to some differ=ADent body but not
> > > =A0 =A0relative to the fixed stars, no centrifugal forces are produced=
.
> > > =A0 =A0I have no objection to calling the first "rota=ADtion" as long =
as it
> > > =A0 =A0be remembered that nothing is meant except relative rotation
> > > =A0 =A0with respect to the fixed stars."
>
> > That is merely one of many statements like this made by Mach over
> > several decades. There is no definitive version of "Mach's Principle",
> > but there are numerous rather similar statements that differ in details.=

>
> > > SR does not incorporate Mach Principle, and that's a serious flaw!
>
> > Yes, SR does not include Mach's principle. But this is not a flaw -- SR
> > was never intended to include such things. SR is a model of an EMPTY
> > universe, or a model of the LOCAL behavior of any other universe.
>
> I see, SR is a model of an EMPTY universe, that's the reason why SR
> is so EMPTY of sense, it can describe an EMPTY universe.

Exactly!

If the masses of the universe are the source of inertia,
then a theory that models inertia without those masses,
isn't modeling inertia.

Sue...

>
> > GR also does not include Mach's Principle, in part because it's not
> > clear what that "principle" is, and in part because all statements of it=

> > appear to be wrong, or at least inconsistent with the other foundations
> > of GR (which have strong experimental support). In GR, rotation can be
> > defined locally without reference to any "fixed stars"; indeed there are=

> > many interesting manifolds of GR with no such "fixed stars" at all. Yet
> > "centrifugal forces" are "produced" by rotations relative to the
> > locally-inertial frames.
>
> The soft spot of SR and GR are rotations. Serious flaws and anomalies
> occur in both theories when rotations are considered.
>
> > And this has NOTHING to do with the subject of this thread -- Mach's
> > principle does not imply a "preferred frame" (just read the first
> > sentence of his statement above). Yes, the fixed stars define a
> > particular frame, but it is not "preferred" in any way (it's just the
> > frame they happen to be at rest in [on average]).
>
> It is preferred because of all centrifugal forces generate through
> it,
> and that defines what is inertia.- Hide quoted text -
>
> - Show quoted text -