Misunderstandings of Einstein's "happiest thought"

On Jul 12, 2014, at 5:07 PM, Paul Zielinski <This email address is being protected from spambots. You need JavaScript enabled to view it.> wrote:

I was talking about two different things: (1) Einstein's theory of free float; and (2) my theory of free float -- all based on GR.

Both models involve two fields that mutually cancel in LIFs.

=> Einstein's model for free float ("happiest thought") involves two real physical fields that mutually cancel.

=> My model for free float involves (1) a real gravity field and (2) a fictitious kinematical field, that only appear to cancel in LIFs.

This has been my position all along. I think you got confused about which was my understanding of Einstein's position and which was own
position on free float.

Einstein was sloppy in the pop explanation. Or it was perhaps a bad translation from the original German. Also the meaning of “inertial frame” is different in Newton’s theory from Einstein’s GR

In Newtonian gravity, F = -GMmr/r^3 is considered a “real force” with the surface of Earth as an “inertial frame”.

From the mature GR POV real gravity is the distortion of the flat Minkowski geodesics caused by Tuv mass-energy sources.

In artificial gravity there is no such actual geodesic distortion.

In mature GR the term F^i = -GMmx^i/r^3 ~ m{Levi-Civita Connection}^i00, i = 1,2,3

The geodesic equation is

DV^u/ds = 0

i.e.

d^2x^u/ds^2 - {Levi-Civita Connection}^uvwdx^v/dsdx^w/ds = 0

This is Newton’s first law of particle mechanics in an arbitrary local frame.

The surface of Earth is no longer an inertial frame as it is in Newton’s theory.

In GR each point on the surface of Earth is a LNIF with a radially outward proper tensor acceleration g = -GMr/r^3 at fixed r in curved space-time.

r = 0 is the Center of Mass (COM) of Earth

For the geodesic test particle d^2x^u/ds^2 is the relative kinematical acceleration measured by light signals connecting the test object to the detector at the origin r0 of the LNIF.

Note that if the detector is located at r0 on surface of Earth, then r = &r + r0 …

The geodesic equation’s domain of validity here is only when &r/r0 << 1.

The proper acceleration DV^u/ds is a first rank GCT & Lorentz Group tensor. It is a local observable measured by NEAR EM fields of an accelerometer in the rest frame of the object being measured.

In contrast, the kinematical relative acceleration dV^u/ds of the test particle is not a tensor, it is measured by RETARDED FAR EM fields connecting the test particle to the detector on the past light cone of the detector = future light cone of the test particle.

The physical meaning of Newton’s second law is:

Proper acceleration of test particle (NEAR EM FIELD MEASUREMENT) =

Kinematical acceleration of test particle (FAR EM FIELD MEASUREMENT) - Proper acceleration of detector (A DIFFERENT NEAR EM FIELD MEASUREMENT).

FICTITIOUS FORCE ON THE TEST PARTICLE ~ REAL FORCE ON THE DETECTOR

The “cancellation” of gravity, simply means switching off the real force on the detector taking it from an LNIF to a LIF.

There is no actual cancellation of two independently existing real dynamical force fields.

I agree with Jim as to what Einstein's view of GR actually was, at least up to 1920. But I don't personally agree with Einstein's pre-1920
position.

This is too vague. One must show the actual relevant Einstein texts, and one must NOT WEIGH TOO HEAVILY the English translations of his popular informal language explanations to the lay pubic in contrast to his technical remarks. Einstein was not a native English speaker. Things get lost in translation.

As far as I can see the entire Machian interpretation of GR is based on Einstein's identification of purely kinematical frame acceleration
fields with real physical gravity fields. I don't make that identification.

You are inconsistent because your claim of a non-zero real third rank tensor inside the plain Levi - Civita connection (no torsion, no non-metricity) is such a real gravity field needing cancellation by another real gravity field in the LIF. You have contradicted yourself.

I think it is technically wrong to argue from general covariance of the GR field equations that transforming a solution for non-rotating T_uv
to a rotating kinematical frame gives you another solution in the untransformed CS for the same T_uv. It only gives you a possible solution
for some other T_uv.

In other words, to get actual Lense-Thirring rotational dragging you need physically rotating T_uv, not just non-rotating T_uv viewed from
a rotating kinematical frame. That's why I don't buy Sciama's argument from general covariance in his first paper. The "Machian" argument
is circular.

Yes. Sciama was himself muddled on this point.

On 7/12/2014 4:33 PM, JACK SARFATTI wrote:

When did you change your mind?

Jim seems to believe that although his language is so obscure it's hard to know what he's really trying to say there.

The physical reason for weightlessness on the geodesic is very simple the real force is turned off. Enough said

Sent from my iPad

On Jul 12, 2014, at 3:19 PM, Paul Zielinski <This email address is being protected from spambots. You need JavaScript enabled to view it.> wrote:

I DO NOT BELIEVE THAT THERE ARE TWO REAL PHYSICAL FIELDS THAT CANCEL INSIDE AN LIF.

Misunderstandings of Einstein's "happiest thought" - the equivalence principle