Re: The CMBR falsifies SR

Ilja Schmelzer wrote:
"tomgee" <tyropress@xxxxxxxxx> schrieb
Ilja Schmelzer wrote:
<cmaj10@xxxxxxxxx> schrieb
In GR, Einstein said that we don't know that there truly exists any
inertial frame. But if there were any absolute frame, we would for
sure
know that there are some inertial frames.

Sorry, but this is nonsense. Inertial frames are not defined in GR.

Hold up a minute here. Just because they are not defined in
GR does not mean his point is invalid. All he's saying is that
we cannot find an inertial frame wrt the universe from where
we can measue the motion of a single object.

GR lives without a notion of an "inertial frame" and is doing fine.
To search for an inertial frame you have first to define its meaning.

I have already done that for you. If you disagree with it,
which apparently you do, then argue that and not that I
have yet to define it. I have said that I-frames are not
real objects, but a figment of our imaginations, so we do
not "search" for I-frames, we create them.

A system of coordinates where every worldline defined by
x^i = const is geodetic?

Even if that is so, I did not invent the concept - I am only
explaining it.

In this case, Robertson-Walker-coordinates are an "I-frame".
Nonetheless, such "I-frames" will not be helpful if you consider
something inhomogeneous.

I don't see where that relates to the definitions of I-frames
vs non-inertial FoR.

I-frames are
not real wrt the universe, we can only make them up. An I-
frame is simply a point of reference in our minds. They are
not real "frames" in space, they are suppositions from where
observers are said to be observing.

If we define them as special systems of coordinates, they
define solutions of the Einstein equations. These solutions
are global, not associated with any partial observer living
on some single worldline.

They are associated to the observer(s) we specify,
whose POV is what determines whether a FoR is
inertial or non-inertial.

An I-frame is one in which we are stationary within it.

An I-frame as defined above does not know about some "we".

I did not say it does. You just made the assumption that I
said such a thing or that such a thing must occur for my
statement to hold. Both assumptions are wrong.

A notion of an "I-frame of observer x" is not known in GR
and I see no reasonable way to define it (the definition I
suggested defines only a global property of being an
"I-frame", without dependence of observers.

If you will note the subject of this topic, you will see it
does not refer to GR. And my definition does not
translate into your definition that it is an "I-frame of
observer x", but rather mine is that I-frames are
defined by the points of view of any observer we
designate. Newton's law 1, e.g., does not designate
a specific observer, therefore the observer can only
be any reader of the law. Ten persons positioned
differently across the universe and reading it at the
same time do not (or should not) understand it
differently from each other no matter where they are
located within the universe (i.e., assuming they all
understood it correctly to begin with).

A novel written in the third person is the 3rd person's
POV and no one else's POV. However, in a case
where issues are in contention, more than one
person can hold the same POV and thus there can be
agreement among those who do. If everyone is in
agreement with Newton's 1st law, then all who read it
are doing so from the same POV, i.e., as observers
of a FoR which is stationary wrt us, and therefore it is
an inertial FoR for us, but in which an object is in
motion relatively to the frame, and thus relatively to us.

Without clear definitions of your notions I cannot follow
your argumentation. I do not even understand what you
want to show.

I hope this post makes it clearer to you.

.

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