Loop Quantum Gravity? Failed?

On Jun 12, 2005, at 4:52 AM, iksnileiz@earthlink.net wrote:

Jack Sarfatti wrote:


On Jun 11, 2005, at 4:58 PM, iksnileiz@earthlink.net wrote:


Jack Sarfatti wrote:



Paul

Rovelli calls the "tetrad field" the "gravity field" in his new book on "Quantum Gravity".




OK, that makes sense to me.

I agree with you that the non-trivial part B of the tetrad field may be the key to separating observer-dependent and objective aspects of the Einstein field, and arriving at a satisfactory understanding of gravitational energy.



Rovelli starts from there, but he has no idea that ALSO the dimensionless

Bu^a ~ BuLp(argVacuumODLRO)^,a for the 4D Diff(4) macro-quantum supersolid world crystal

analogous to

v = (h/m)GradargGroundstateODLRO for the 3D macro-quantum superfluid

g(curved metric)uv ~(flat)uv + B(uIv) + B(uBv) for "spin 2"

Note that elastic linear B term and the plastic nonlinear B^2 term.

Also, B while not a spin2 Diff(4) first rank tensor field all by itself, is a Minkowski spacetime spin 1 Yang-Mills vector field.


No surprise, since he is working with a different model.

Personally, I think you are way ahead of him.

Lubos is probably correct about the lack of contact of loop quantum gravity with observation and that it cannot even reproduce GR. Baez admitted that at GR 17. Of course string theory has its weaknesses too but may be closer to observation? We also have to look at Wilczek's objections to some of Penrose's statements.


Maybe Alex can explain to you why he and I propose to draw a fundamental distinction between raw mathematical spacetime CSs, on the one hand, and physical spacetime CSs ("moving CSs") that in GR represent observer reference frames, on the other.


Yes, he did, but I am not convinced that his idea is any better than mine, which is that a local frame (inertial or non-inertial) is an equivalence class of local coordinate charts at P that do not change the motion of the detector.


I think that's a different issue.

Maybe.

Also, as I've mentioned, spacetime coordinate transformations, as *mathematically* defined, do not change any observer's world line.

That's what I call a kind of gauge freedom. That is, all GCTs that do not change the state of motion of a detector are physically equivalent. An example of a physical GCT is starting in the rest LIF of a detector in space and then firing a rocket engine attached to the detector. The transformation, in that case, tetrad eu^a(P), that describes the relation between the momentarily coincident LIF with indices a & LNIF with indices u at same P. But you see here a complete local equivalence of the inertial force to the gravity since the physical difference is Bu^a in

eu^a(P) = Iu^a + Bu^a(P)

i.e. Bu^a(P) encodes the information of switching on the rocket engine!

You cannot locally distinguish inertial force from gravity force!


Similarly, I mean a local event as a coincidence of at least two processes, like Rovelli's "collision" of two point particles, that is clearly an active Diff(4) invariant "object".


Spacetime "events" are addressed by coordinates,

This is wrong. Rovelli is correct on that part. Events are coincidences like the collision of two point particles (toy model).

but are not defined by them. So it should be obvious
that such "events", just like manifold points, are absolutes with respect to such transformations.

You have the wrong idea here. I mean you have garbled things above. Physical events are invariants to be sure, but "manifold points" are not.



See Rovelli's explanation of Einstein's solution of the "hole problem".

For example, any transition overlap function between 2 local charts for same "coincident" P that leaves c^2(LC)00^i, i = 1,2,3 invariant is not physical. Note that points A & B in Rovelli's are same P = {~| A,B,C ...} That is A ~ B if B = active Diff(4) on A etc.


In my POV, *none* of the mathematically defined coordinate transformations on the spacetime manifold has any physical meaning at all until such a meaning is attached to them, or to some subset of them.

Chasing your own tail. Circular. Meaningless until you show an independent procedure.

In my model, you define a *parallel set of GCTs* to which physical meaning is attached. This parallel set of GCTs is a *copy* of a subset of the mathematical GCTs (Einstein's "moving coordinates") which is given a physical interpretation in terms of a set of observer frames.

I do not understand your remark here. It's too vague. Define "copy", define "observer frame". Relate your key terms to the mathematical symbols of GR. Provide operational gedankenexperiments. I have no idea what you are talking about.


That is, think of EM and weak and strong fields Au ... as animals living on Leviathan the Great White Whale Moby Dick which is the geometrodynamic tetrad field e = I + B.



The Ashtekar idea is a much more fancy way of doing what I have done more simply, i.e. the basic field is the tetrad = flat + curved,

Yes, but you have to be careful about how the coordinate-basis tetrad is physically interpreted. There is more than one possible interpretation.


Rovelli et-al show a completely coordinate-free Cartan form tetrad e. In fact the tetrad e is a 1-form independent of coordinates. Torsion and curvature are 2-forms. No problem!


Of course -- in the abstract, the tetrad is mathematically defined in a a coordinate-free manner as a set of basis vectors spanning a vector space that is constructed at each point on the manifold.

Note also Rovelli's remark that you cannot do spinors without using tetrads. See Kiehn's latest on MACRO spinor solutions of EM field solitons (if I got that right?).

But then this tetrad field can be further *interpreted* in terms of the set of tangent manifolds (tangent bundle). This is not automatic.

Too vague. I don't know what you mean. "interpreted"? How? Give an example. Your head is too much in the clouds.

You can also choose a coordinate basis. That is not automatic either.


e = eu^a&adx^u

e is a dimensionless Cartan 1-form

&a is a 1-co-form vector field basis in the tangent fiber with dimension 1/length

dx^u is a 1-form basis in base space with dimension length


Yes, fine.

I can see you've been studying this stuff.

Beginning to. There are some ambiguities in getting everything dimensionally consistent with factors of Lp. Mathematicans doing physics ignore all that setting everything = 1 and I think they make mistakes as a result e.g. mixed dimensions of the same components of the (LC) connection field for example. Some ~ r others ~ 1/r for SSS solution in some books. First rule in Physics 101 is that any equation should be consistent in units and physical dimensions.


You can make them anholonomic (non-coordinate) sticking in Lie brackets - all well-known techniques.

e.g.

[dx^a,dx^b] = Wab^cdx^c

Wab^c = Jim Corum's object of anholonomy with dimension length



As I'm sure you know, the tetrad starts out simply as a coordinate- independent basis for a any 4D vector space defined at each point on the spacetime manifold.


Yes, and what it represents physically is the state of linear elastic warping B(uIv) and nonlinear plastic cracking B(uBv) of the perfect Minkowski Planck lattice that is the pre-inflationary massless conformal false vacuum without any gravity and inertia at all!


If you construct such a tetrad field, yes it can be interpreted that way.

It's very important - that's Hagen Kleinert's key idea. Tensors were invented for elasticity theory in 19th Century.

e.g. the state of warping and cracking of the 4D active Diff(4) invariant supersolid Higgs vacuum at P is given by the base space reciprocal lattice vector field

eu(P) = eu^a&a = (Iu^a + Bu^a)&a

where &a = nab&^b and [eu(P)] is a length^-1 i.e. eu - &u = Bu = crystal distortion reciprocal lattice "phonon" wave vector away from equilibrium along the u axis (u = 0,1,2,3), e^u - dx^u = B^u is the lattice distortion with dimension of length.

nab = flat Minkowski metric of pre-inflation unstable false conformal massless twistor vacuum without gravity and inertia because vacuum ODLRO = 0

In the long-wave approximation this looks to me like a theory of continuous media in 4D.

That's Kleinert's idea. I have simply plugged into that with

Bu^a = Bu&^aargVacuumODLRO

Bu^a is a pure number. Therefore Bu is a length in that convention since &^a is 1/length

Bu = Bu^adxa

dxa = (Mink)abdx^b

Bu = Bu&^aargVacuumODLROdxa

&^aargVacuumODLROdxa = 1


but Ashtekar & Co do not use local gauge invariance & vacuum ODLRO directly the way I do.


OK.


They do not seem to even be conscious of vacuum ODLRO - but maybe I have underestimated them there.



Maybe not.


We will see as I read Rovelli's book.


OK.


What they are doing in loop gravity is overly-complicated (complexification of the tetrad, taking self-dual "instanton" part etc.) Where all the Pundits go wrong is not realizing that there even is a macro-quantum theory whose rules are different from micro- quantum theory. I get diff(4) invariance + background independence non-perturbatively trivially!

Hawking made this error at GR 17. Susskind makes it also. So does Lubos. Of course, I could be wrong, but we shall see.


I'm inclined to agree.


Micro-QM is linear, nonlocal, unitary with signal locality. Macro- QM is nonlinear, local, non-unitary with signal nonlocality. Gravity + dark energy is a "More is different" macro-quantum phenomenon.

Vacuum ODLRO makes quantum theory (QT) and general relativity (GR) completely consistent with each other.



I think it's an interesting and very promising approach.


BTW John Baez in Ch 5 last part also waffles on gravity energy problem, p. 452 Notes to Part III



YES.

So does Penrose in "Road to Reality".


I think I gave the real answer as to why this is really a pseudo- problem:

BTW from my "Rovelli Notes"
The non-trivial warp part B of the Einstein-Cartan tetrad components e = I + B comes into being and becoming from the simultaneous local gauging and spontaneous vacuum symmetry breaking of the spacetime translation group T4, therefore there is no reason at all, from Noether’s theorem, to imagine that either total energy or total linear momentum of the pure gravity field as the spacelike integral of a local density should be conserved as the lapse function "time" pushes forward from one spacelike slice to another in the ADM 3+1 foliation. Indeed, the Hamiltonian of the pure gravity field is strictly zero because of the constraint structure of Einstein’s field equation.

The error you make Paul is to over-extend flat spacetime ideas to where they do not work. Conservation of total energy is simply a piece of T4 symmetry, i.e. time displacement invariance. It is certainly FALSE for the gravity vacuum. The whole attempt is wrong and that includes what Alex has proposed IMHO. Local conservation? Yes! Global conservation in general? No!


Then in Einstein's theory, where physically does the energy carried away by gravitational waves go?

When there is the flat background in weak field there is no problem. Since "total energy" is meaningless in a curved spacetime, it need not go anywhere! "Total energy" conservation is an artifact of T4 symmetry. Gravity is the breaking of T4 symmetry. Without the symmetry there is no conservation law, e.g. Noether's theorem. Read Wigner.

Locally there is no problem of course. The stress-energy current density is shared between the gravity and matter fields in

Tuv(Matter)^,v + tuv(Matter-gravity)^,v = 0

in 1916 GR.

You can get a global conservation approximately only with asymptotic flat space-times.

How does it get there?

I agree that inside Einstein GR, strictly speaking, there is no such thing as gravitational vacuum stress-energy.


For example, the Wheeler-DeWitt equation in the superspace whose points are 3D geometries 3gij is

H(pure gravity)(BIT Wave Function of Multiverse) = 0

leading to the “problem of time” in idealistic non-Bohmian attempts at quantum gravity that are only thoughtlike BIT with no rocklike hidden variable IT. In the Bohmian interpretation, the super- geodesic equation of motion for the IT hidden variable is separate from the above Wheeler-DeWitt equation for the pilot BIT wave functional that need not depend on any time parameter.


I would have to think about this.

Shelly Goldstein has shown this in detail.


All you can say is

Sum of all Tuv = 0 locally, i.e. matter + gravity + exotic zpf vacua





Or, more generally, you can introduce *some* kind of source field for vacuum G_uv.
This provides an objective localizable physical "container" for the energy lost through gravitational radiation -- which is not the situation in orthodox GR.


No, you are confusing apples (zero point dark energy) and oranges (classical gravity waves).


No, not at all. I'm just saying that adding a *gravitational* vacuum source field for G_uv is *one* way out of this, because then you have somewhere for the gravitationally radiated energy to go that can be defined objectively,
i.e., in an observer-coordinate-free (frame-independent) manner.

This is not even wrong. You have no math to justify this confused idea.

Of course, a gravitating ZPF might also be a kind of "vacuum source field", but not a *gravitational* vacuum source field , which latter is still present even in the absence of all matter, including EM fields.

Meaningless if you cannot show a math model illustration.


Residual zero point energy "exotic vacua" of both dark energy (Pioneer 10 & 11 anomaly a_g = -cH) and dark matter (Galatic Halos flat stellar rotation curves) & stability of extended electron Bohm hidden variable and Ken Shoulders mesoscopic "charge clusters" does give a local tuv(zpf) but that has nothing at all to do with classical gravity waves in weak field approximation on a flat background.


Right.

You seem to contradict yourself. In any case what you wrote above is so vague I do not know what you were trying to say.


With

TOTAL Tuv^;v = 0

Therefore, any total energy-momentum = 0

Universe is a "free lunch".

In my view the search for quantum gravity is a serious error. Gravity is emergent in the inflationary vacuum phase from micro-quantum theory to macro-quantum theory. God plays dice in the unstable pre-inflationary micro-quantum vacuum that has no gravity and no inertia in it. The rules change completely in the Big Bang. God loads the dice significantly in order for gravity and dark energy to emerge into Being and Becoming. Our post-inflationary expanding accelerating universe in the multiverse of parallel worlds next door is a vibrating “super-solid” or “world crystal”.


It's certainly a promising alternative to the usual perturbative approach. The macro-quantum ghost of the departed Maxwellian aether.

It's not "departed", we are fish swimming in it, or rather the "fish" are themselves phase ripples in it - solitons i.e. vacuum geons like Chapline & Laughlin's "dark energy stars" on micro-scale of "mass without mass" (Wheeler) in which the zero point energy false vacuum cores give effective strong short range gravity G* ~ 10^40G on the fermi scale of 10^-13 cm ~ e^2/mc^2.


But we are not fish swimming in Maxwell's *classical mechanical* ether.

Hence "departed".

This is where Rovelli's philofawzy is good. More on that later.



The only flag I would raise here is about the stability of the vacuum LRO. According to your BEC model, why is the gravitational vacuum observed to be so stable? What exactly would it take to disrupt and destabilize this LRO?



This means you still do not understand the key idea. Ask why is the superconductor ground state stable? It's the same problem!


OK. If it's really not a problem, then it's not a problem.

If you read PW Anderson you will see why. Actually I have explained it many times. It's the released binding energy when the ionized virtual e+-e- plasma of the false vacuum FUSES in the inflation to the vacuum ODLRO condensate of bound virtual positronium! The released energy heats up the real quark-gluon plasma post-inflation.


The Goldstone phase of Vacuum ODLRO is "rigid" that's part of "More is different". That's why space-time is stiff. If you do not do your homework and read the key "superfluid" papers in PW Anderson's "A Career in Theoretical Physics" you will never really understand the idea here. Soft condensed matter physicists are very familiar with this idea.


Yes, I know there is a lot of literature on this. I'll try and get hold of Anderson's "Career".



And what about light propagation? How does light propagate through the vacuum BEC? Could the characteristics of the vacuum BEC be responsible for the permeability and dielectric constant of the vacuum?



That's Puthoff's dead end. I will not go there.


Just a question.

Wouldn't it be reasonable to expect that the properties of your all-pervading positronium BEC would determine at least some optical characteristics of the vacuum?

Indeed it does. It makes guv!


I get guv that's enough. Light is ds^2 = 0. I follow Einstein there.


But you can't deny that if your vacuum BEC exists, then light has to travel through it to get from A to B.

Yes, but QED shows direct effects are MINISCULE!


Hal has wasted 20 years or more on that and has gotten nowhere important. I think Ibison is finally persuading him to look in my direction?


Hal's theory is a toy model that was designed to be used as a heuristic tool for "engineering".

It has not done anything important there at all. Where are the engineering plans for saucers that fly? They don't exist - I mean not based on PV.

It's not an exact quantum theory of the physical vacuum, and it doesn't claim to be.

The truth is that PV has failed to deliver on any of its promises in 20 years! Time is up for Hal. The Devil will have his due! :-)