Re: Physical interpretation in physics.


"Jeckyl" <noone@xxxxxxxxxxx> wrote in message
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Yes indeed - rotation relative to what?

Any inertial frame in which the centre of rotation is at rest

Nice try. :-)

Pretty much perfect

Relative to what do you think that "inertial frames" are not
rotating?

Every other inertial frame

I can give you a similar answer: they are not rotating relative to
Newtonian frames!

Rotation is absolute .. independent of the iFoR in which it is
measured
Acceleration is absolute .. independent of the iFoR in which it is
measured
Velocity is not.

Only iFoR really count, because they are the FoR where the laws of
physics apply uniformly and consistently.
Consistency ain't the issue.
If the 'laws' dont appl consistently, they aren't laws.
Indeed. It ain't an issue.

Yes .. consistency is. If the results and predictions are not
consistent, then there is no more physics.

Here's another consistent one: God exists because it's written in the
bible and the bible must be true because in it God says that the
bible is inspired by him. ;-)
Nonsense
Exactly - consistent but that's not the issue. :-)

Consistent is not sufficient .. I didn't say it was .. but it is
necessary. Do you know the difference between necessary and sufficient
conditions?

I already tried to explain that to you. Nonsense can be perfectly
consistent. That's not the problem.

Again .. you just don't get it ..

It looks like a speach confusion. ;-)

Laws of physics have to be consistent. that nonsense can also be
consistent does not mena the laws of physis is nonsense, or that
consitency is not required for laws of physcis.

Agreed. And as I repeatedly stressed, that's not the issue for the physical
interpretation of physics.

Perhaps logic isn't your forte

It looks more like it ain't yours ;-)

iFoR can be virtual in which case they can have no physical effect.
What do you mean 'can be' .. they aren't physical to begin with.
The most classical (nearly) inertial frame by Galileo is a ship that
sails a steady course at sea. That's very physical.
No .. he ship is physical .. the frame of reference is a concept
A ship can serve as a frame of reference

No .. the ship is just a ship. We can associate the concept of a frame of
reference with it :)

A frame is commonly a thing - check the dictionary :-)

but what we commonly mean with it is a construct of the mind - and we
agree on that, it's not constructive to pretend to disagree on what you
already made clear to agree with.

I'm not .. you're the one insisting that frames of reference are physical.
They aren't .. they can simply be associated with, and described by,
something physical

Instead you misread what I wrote and next argued against your own straw man.
Let it be. :-)

There is no framework out there .. there doesn't need to be any actual
object that htey are associated with. They are a concept.
Exactly. Concepts of the mind can't physically affect you - except
perhaps if you believe in telekinesis. :-)
Who said they did? That's really the point.. if you are at rest wrt
some frame of reference and I am at rest wrt some different frame of
reference, then there is no physical effect on us from that. The same
laws of physics apply.

The point that Newton made was that you can also choose a frame of
reference that is rotating relative to it; and other laws of physics
apply.

So you get different physics in a non-inertial frame of refernece.. No one
is disagreeing with that.

No one suggested that anyone is disagreeing with that. :-)

The concepts of the mind can model what is physical .. and they do very
nicely.
Sure.

Why is it you have a problem with intertial frames of reference .. did
you miss the lecture on that?
In fact you didn't understand my lecture to you on that - which was a
retake of those of Newton, Mach and Einstein. :-)

You gave a lecture .. where?

Here above. ;-)

The question was about the physical cause that makes them look
special or "preferred".
There is none .. there doesn't need to be one .. because they aren't
physical.
Then let's get back to your explanation, and substitute the appropriate
words according to your own clarification:
Summarizing the conversation:
Maxwell:
"Newton's bucket demonstrates the absolute nature
of relative rotation (bucket relative to the local 'fixed stars')"
Harald:
Yes indeed - rotation relative to what?
Jeckyl:
Any inertial frame in which the centre of rotation is at rest.
They aren't physical.
But the location of the centre of the rotation is a physical location.
And the motion is relative to that.

There is no motion relative to a co-rotating frame.

What co-rotating frame?

The one in which the object is in rest.

If you like, pick another object that is at rest relative to the center
of rotation. Then you can get the roation relatie to the line joining
those points.
See above - the centre of rotation wasn't the issue that Newton and Mach
discussed.

I wasn't discussing Newton and Mach

Then you are in the wrong thread! You responded to my reaction to:
"Newton, which viewed space as purely passive & not contributing to the
process"

The choice seems to be between Newton/Lorentz and Mach, or as
Einstein attempted, a bit of both - he fancied combining apparently
incompatible ideas. According to Einstein's original GRT,
acceleration and rotation are RELATIVE - but that didn't really work.
Probably because they aren't.

Thus, for the explanation of the physical cause of inertia and its
manifestations such as the "absolute" speed of rotation, the choice
appears to be between:
- Physical Space (local, Newton)
- Physical effects from The Stars (action-at-a-distance by means of X,
Mach);
or, as you seem to assert here above,
- Unphysical influence by the human mind.

I did not claim any such thing. I said nothing about the physical cause
of inertia (which is really metaphysics anyway)

This IS about metaphysics. Newton and Mach admitted to the need of a
metaphysical postulate on which to base mechanics on; Mach's disagreement
concerned the particular model, not the requirement for one. Einstein
didn't use such a model as postulate; nevertheless he could not escape
their logical arguments about physical interpretation of the laws of
physics.

Fine .. nothing wrong with metaphysics, or physics .. as long as one knows
what one is referring to.

Right.

It appears all this has drifted so far off topic, I don't know what was
being talked about .. oh that's right .. whether rotation was absolute ..

In fact, it was about the claim that "Newton viewed space as purely passive
& not contributing to the process".
And we were agreeing that rotation is absolute.

as we have the concept of an inertial frame of reference (and whatever
physical things it may correspond to),

The "whatever" was Newton's argument. :-)

and because rotation is acceleration (non-inertial), it is absolute wrt
the inertial frames of reference in which our laws of physics are framed.
At least in terms of SR. Things are less clear when we bring GR into play
:)

That depends on one's version of GRT. :-)
I'm out of here. Enjoy your weekend!

Harald


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