On Nov 11, 2010, at 11:06 AM, Paul Zielinski wrote in quotes:
"But we are talking about two distinct things here: gravity, and inertia."
As I said, gravity as curvature is independent of inertia of test particles.
All slower-than-light test particles follow the same timelike geodesic paths - their inertia = rest mass cancels out of the problem.
The curvature is geodesic deviation - key word is geodesic.
Inertia only is important in off-geodesic motions from non-gravity forces.
The origin of inertia is given in the standard model.
"Einstein naively tried to identify the two, ..."
How, precisely in terms of the formalism?
There is no theory of "m" in GR. It is a primitive and it is irrelevant except for the source Tuv tensor for a gas of particles.
"but since de Sitter we know that things are not quite that simple, even according to Einstein's own theory of gravity."
There are two problems in classical GR.
Generation of curvature via
Guv + 8piG/c^4Tuv = 0
Geodesic motion of neutral test particles (including null geodesics geometrical optics limit of light rays).
D^2x^u/ds^2 = 0
note there is no "m" in the geodesic equation - nor in the curvature geodesic deviation equation.
D denotes covariant tensor producing derivative relative to the torsionless Levi-Civita connection - in the 1916 version of GR.
"Notwithstanding the various attempts to make "Mach's principle" work within the framework
of the GTR as a causal explanatory hypothesis, once all gravitating matter is removed from
spacetime, according to the GTR objects in unforced motion still follow inertial trajectories,
and one must still apply non-gravitational forces to move them off those trajectories. In which
case it is hard to see how such a situation can be explained by long range physical interactions
with distant matter which is not even present."
You mean if Tuv = 0 globally so that
Ruv = 0
one can still have geon solutions - but they are not very physical.
Yes, globally flat Minkowski spacetime is an unstable solution of GR and same rules of inertia for off geodesics apply.
Inertia is the response of the test particle to applied non-gravity forces - even when Tuv = 0 - only test particles.
As you say -- if it ain't broke, why try to fix it with redundant hypotheses of the Machian type?
My retrocausal hologram conjecture is a new form of post-selected Mach's Principle in Aharonov's sense.
A retarded photon leaving us now will infinitely redshift in a finite time at our future horizon along our idealized world line because dark energy virtual bosons accelerate the rate of expansion of space. In contrast an advanced photon will infinitely blue shift from the horizon back to us. In Cramer's transaction, these two infinite shifts exactly cancel - the confirmation wave comes back at exactly the frequency the offer wave was emitted with.
In this sense our future horizon is the Wheeler-Feynman perfect absorber allowing the net retardation and the correct Arrow of Time.
Note that virtual quanta at the horizon are converted to real quanta at the Planck temperature.
We are at r = 0, the virtual quanta act like static LNIF detectors - this is the reason for Kip Thorne's electrical membrane model of the horizon.
Our future de Sitter metric is g00 = 1 - /\r^2 ---> 0 at the future horizon r = /\^-1/2.
The effective Unruh temperature of the converted virtual ---> blackbody quanta is
T = (hc/\^1/2/kB)(1 - /\r^2)^-1/2
remember we are at r = 0 in this static LNIF representation.
Of course that is not to say that we can't look for deeper explanations that could account for
the success of the 1916 theory, and its Riemannian spacetime model, at the phenomenological
gravity is a field that is the very fabric of space-time
if it ain't broke don't try to fix it
it ain't broke
indeed Einstein's theory is the Jewel in The Crown of God.
In any case Roy needs to understand the hard reality that physicist's minds are closed on this and rightly so
We have a beautiful theory that works.
On Nov 11, 2010, at 8:28 AM, Jonathan Post wrote:
> Einstein was influenced by Mach, who held that gravity was NOT a
> property of individual bodies.
> Mach's Principle states that: "mass there influences inertia here."
> Isaac Newton had, of course, suggested that space was an absolute
> backdrop. Newton’s vision of space contained an engraved set of
> coordinates and he mapped all motions as movements with respect to
> those coordinates. Ernst Mach disagreed with this foundationally,
> believing rather that motion was only meaningful if measured with
> respect to another object, not to Newton’s coordinates. Mach believed
> that motion ultimately depended on the distribution of matter, or its
> mass, not on the properties of space itself.
> Mach did not put this, so far as I know, in terms of flow. Nor is
> this, in my humble opinion, best addressed through poetic metaphor,
> even though I am an award-winning Science Poet whose poems have
> appeared in venues such as "Science", Caltech's alumni magazine
> "Engineering & Science", and as the invited frontispiece of a NASA
> proceedings of a conference on New Physics and Spacecraft Propulsion.
> I am often outrageous in papers outside the consensus paradigm, even in
> widely read venues such as Scientific American an the arXiv. But it
> helps to understand the protocols of academic publication.
> To have refereed publication in mainstream Physics journals or
> proceedings, one must prove to the referees and editor that one is
> facile with the existing literature, and especially the Mathematical
> Physics as such, equation by equation, as Jack Sarfatti keeps
> patiently summarizing and citing.
> -- Prof. Jonathan Vos Post
>> Gravity as a flowing field is not well understood, if it was you could generate a kind of "hydroelectric" kind of power. It is impossible to get antigravity or electricity from any point in space as long as "people in the field" hold fast to gravity as a property of individual bodies. It is not true that gravity is well understood and signed should not be satisfied with what they think is well understood. My 70 page thesis on the unified field with a new beginning has all the answers you're looking for -- just read it.
>> Inside the box thinkers in the field who have no interest in alternative ideas will not advance one iota thinking gravity is a property of individual bodies. I would challenge any physicist to an open debate on this subject.
>> Hi Roy
>> What you have is a poetic metaphor, but that is not the way real theoretical physics is done.
>> It's poetry but not physics the way professional university academics do it.
>> One needs equations with interpretations and predictions that can be tested.
>> Einstein's theory of gravity is precise, it is beautiful to the people who use it and it passes every test with amazing accuracy and precision.
>> People in the field have no interest in alternative ideas about what is already well understood.
>> Thank you for opening your web site to me, we are very much in agreement. What if space is not actually space but rather it is gravity flowing and curving around particles spinning from it like eddies in a stream? In that case, universal gravity transforms into the pressures of local gravitation that is inseparable from space-time curvature. In other words, gravitation curvature as a force could even be the driving power of photons and other particles.
>> I reject the idea of gravity as being force free. Gravity flows from a singularity infinitely long, smooth and uniform creating a three-dimensional shadow realm like the winding of a ball of string -- a three-dimensional universe before matter and time began. Where there is no mass there can be no time. The vast distances between celestial objects is really the dimensions of gravity that we call space.
>> Sarfatti Lectures on Physics 2012
>> Einstein’s theory of gravity (General Relativity)
>> Einstein eliminated Newton’s gravity force and replaced it by force-free motion in curved space-time. This is the meaning of the Einstein equivalence principle and it explains why physicists are confused and stumped when they naively try to unify gravity with electromagnetism and the weak-strong forces.
>> The theory of symmetry called group theory in mathematics shows that gravity is universal. It is the compensating local gauge field of the symmetries of spacetime. In contrast, electromagnetism and the weak-strong forces are the compensating local gauge fields of the symmetries of the extra dimensions of string-brane theory.
>> The Meaning of Einstein’s 1905 Special Theory of Relativity (SR)
>> The basic idea of relativity is to compute local invariant observable numbers that are the same for different measurements of the actual same events.
>> SR only works for the above measurements of the same actual events by detectors in unaccelerated motions in a globally flat 4D spacetime. Each detector will not feel g-forces. Of course, the test particles measured may be accelerating.
>> The Meaning of Einstein’s 1916 General Theory of Relativity (GR)
>> GR works now for all detectors that are now allowed to accelerate feeling g-forces. However, the local invariant observable numbers are limited to locally coincident detectors. “Coincident” here means that the spacetime separations of a pair of detectors measuring the same actual events must be small compared to the scale of radii of curvature.
>> The tetrad fields describe the relationships between an unaccelerated “local inertial frame” (LIF) and a coincident accelerating “local non-inertial frame” (LNIF).
>> Einstein’s “general coordinate transformations” called “diffeomorphisms” by the mathematicians are the relationships between two coincident accelerating LNIFs.
>>  “Relativity DeMystified” David McMahon (McGraw Hill) - basic reference for background
>>  The mathematician's idea here has excess formal baggage not needed by experimental physicists.