Gravitational Time Dilation

[Write4U]

In the theory of general relativity the local spacetime curvature is made up with components of stress and energy, in all forms, and for the Einstein Field Equations it's the stress-energy tensor.
http://en.m.wikipedia.org/wiki/Stress–energy_tensor

I must apologize for my sloppy editing before posting. I did find one other answer which seems to address the issue with a subtle difference.

Expert answer by Hilmar Zonneveld (Confidence votes 53.3K)
"No, but there is energy related to gravity (gravitational potential energy)".

If Zonneveld is also correct, the question then becomes if "gravitaional potential energy" is the same as "stress energy tensor" in this context. Why would he consider those conditions as not energetic in themselves, even as they are formed by stress and energy?

Indulge my curiosity one more time.
Can the example of the curved road be used at all? The curvature was formed by application of energy and may be considered a tensor in the road, but is it energetic in and of itself?

 

[paddoboy]

That's an interesting paper on a specific analogue theory of gravity using GR as the basis. The part on the kerr metric gets a reference [267] in the Visser et al paper on analogue gravity models and what they're being derived to analyze.
http://arxiv.org/abs/gr-qc/0505065
Personally. I don't agree with the authors claim that it helps lay people understand GR. But it sounds good and could be generally true? Anybody can learn how to use the metric and figure out for themselves how GR works as a theoretical model. All I've come across are arguments over it without any discussion what an analogue theory is used for. Especially before I read any text on Relativity theory.

Very interesting brucep.
As I have said numerous times, there are many useful analogies, and the river/waterfall mathematically supported analogy is one. But yes, each to there own.
The over riding problem here is as usual, the usual anti GR cranks, still trying to poke a hole in GR.
The half a dozen or so threads by one nut, all cynically and cunningly leading to his BNS, also stands out like dog ball's, and the fact that it has been totally invalidated and rebuked, has made no difference at all to this clown.
And yet I have lily livered posts questioning me on what is and what isn't a theory as distinct from reality and at the same time giving up on this said clown. Quite pathetic.

 

[brucep]

I must apologize for my sloppy editing before posting. I did find one other answer which seems to address the issue with a subtle difference.


If Zonneveld is also correct, the question then becomes if "gravitaional potential energy" is the same as "stress energy tensor" in this context. Why would he consider those conditions as not energetic in themselves, even as they are formed by stress and energy?

Indulge my curiosity one more time.
Can the example of the curved road be used at all? The curvature was formed by application of energy and may be considered a tensor in the road, but is it energetic in and of itself?

The tensor describes the sources which create spacetime curvature [gravity] Like John Wheeeler said mass tells spacetime how to curve and spacetime tells matter how to move. In this case mass is synonymous with the components of the tensor.
Gravitational potential energy is not the same as the stress-energy tensor. It's not a potential. Thesr's no potential gravitational energy in GR. I don't know who Zonneveld is so I can't comment on what you said he/she believes. Maybe this will be a better explanation. The components of the stress-energy tensor are delivered to the local spacetime by gravitational radiation. Waves that moves through the tidal field. Since there is no meaningful analogue for gravitional waves in Newton's theory they're are no meaningful analogue for gravitational potential in GR. I think. LOL for sure GR predicts the components of the tensor are present locally.

 

[Write4U]

The tensor describes the sources which create spacetime curvature [gravity] Like John Wheeeler said mass tells spacetime how to curve and spacetime tells matter how to move. In this case mass is synonymous with the components of the tensor.
Gravitational potential energy is not the same as the stress-energy tensor. It's not a potential. Thesr's no potential gravitational energy in GR. I don't know who Zonneveld is so I can't comment on what you said he/she believes. Maybe this will be a better explanation. The components of the stress-energy tensor are delivered to the local spacetime by gravitational radiation. Waves that moves through the tidal field. Since there is no meaningful analogue for gravitional waves in Newton's theory they're are no meaningful analogue for gravitational potential in GR. I think. LOL for sure GR predicts the components of the tensor are present locally.

Thanks for your patience. I'll chew on that for awhile. "Gravitational Radiation" certainly sounds energetic to me.

 

[Daecon]

Intuitively I would have said no. I view energy as a dynamically active force, where IMO, gravity is a static (though causal) field of warped space which an objects must follow, but is not energetic in and of itself.

Is a bend in the road a form of energy, because it forces a car to change direction?

Perhaps I am just making a semantic argument. I tried looking it up and found multiple conflicting answers. But the only answer I have found that addresses the specific question:


Of course science does consider gravity as a one of the four fundamental forces.
http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html

Thanks for responding, I was starting to think my question had gotten lost in the flow of the thread.

 

[RajeshTrivedi]

The mockery of physics is your own childish banter in comparing Earth to a BH where complete gravitational collapse has been undertaken according to the GR edict.
Again, a BH will hold its shape simply because firstly the gravity is a fossil field from the star from whence it collapsed and secondly the property of nonlinearity of gravity/spacetime.
This can be seen with the following definition of an "Eternal BH"
http://scienceworld.wolfram.com/physics/EternalBlackHole.html
A massless black hole which is a stable topological structure held together by the nonlinearity of its gravitational field.
And the following covers it fairly well also........
http://www.einstein-online.info/spotlights/gravity_of_gravity
One reason why the physics of general relativity is much more difficult than that of Newton's theory of gravity or the theory of electrodynamicsis a property called non-linearity. In short, gravity can beget further gravity - where gravitational systems are concerned, the whole is not the sum of its parts.

Now once again, tell us why anyone should take the word of an Electrician who cannot even grasp the fact that once the Schwarzchild radius is reached, further collapse is compulsory, and invokes instead a BNS. Hans Christian Andersen could not have done better!
And also in reality, perhaps you need to forget about any pretentious mathematical calcs etc when you attempt to answer any question or make one of your profoundly stupid claims, as Professor Bennett Link, showed yours maths as actually nothing more than a dog's breakfast.

You are almost every where, and most likely you have lost track of yourself, in fact I would say that small delusion of grandeur which you are pushing in another thread has crept into you, may be due to some good words by Profs.

I will attempt to make you see the Physics behind your latest latch of this non linearity.

Wiki definition of non linear system...which is fairly ok

.........In physics and other sciences, a nonlinear system, in contrast to a linear system, is a system which does not satisfy the superposition principle – meaning that the output of a nonlinear system is not directly proportional to the input........

(See the example which I gave you with respect to m1/E1 and M2/E2 in couple of above posts.), in fact this is the issue with GR equations (those tensor equations), they are non linear, and since they represent spacetime/Gravity so we can loosely say that Gravity is non linear. It is purely mathematical outcome of those GR equations. It is nothing like some Physical / Chemical or even structural property, but those big profs who use this word they know what it means, but you are interpretation is thoroughly gobbled up.


Now coming to the Black Hole shape which again you are spreading as if that is 2 + 2 = 4. As per present theory classically and your 100% complianced worship once inside EH, things have to collapse to r= 0, which is a point singularity. And of course nothing physical can be assigned to a point singularity, mass cannot be assigned, spin cannot be assigned and even charge cannot be assigned (your no hair parameters); So how to resolve this crisis as they have to be accounted for ? So first resolution is that BH is actually a spacetime, infinitely or heavily curved...the angular momentum is retained by ErgoSphere (field)....and what about Gravity, thats where your theory of Fossil Field and Gravity Gravitates comes, because source mass is practically vanished at r = 0. So as OnlyMe says these are complex theoretical issues, which even graduate scholars will find difficult to grasp and argue, so do not be so adamant and do not take these science commercial journals as gospel truth. I am shocked, that preacher of yours, calls every one dummy, idiot wind but spares you, he need not call you by names but he can always nudge you even by private messages.


PS :

1. Read it carefully without bias, you will understand.
2. See the link, http://en.wikipedia.org/wiki/Nonlinear_system, GR is also listed as example of non linear system nearly at the bottom of page. It will help understand the point.

 

[paddoboy]

I will attempt to make you see the Physics behind your latest latch of this non linearity.

I have a reasonable knowledge of the physics behind nonlinearity and gravity and have given professional links supporting that stance.
On the other hand your problem is that you dismiss mainstream cosmology out of hand, simply for an excuse to wangle in your own nonsensical fairy tales like BNSs.
Your total dishonest nature in refusing to discuss your alternative rubbish in the proper section, has been re-enforced by your threads being moved to the appropriate section.
Let me tell you once again. Once a Schwarzchild radius is reached, total collapse is inevitable. Most cosmologists of reasonable experience [certainly not electricians with inflated egos] believe the the classical point Singularity is not reached and some logical grounds for this exist. GR breaks down at the quantum/Planck level, so most seem to agree that the mass lies between this level and the classical point singularity.
What you need to accept is that a Singularity need not be infinite, but "may " lead to infinite quantities.
Either way we are certain due to the predictions of GR [which you deny] that no BNS or anything else exists between the EH and the center where the mass resides, except of course critically curved spacetime.

1. Read it carefully without bias, you will understand.

Since I'm not the one preaching an alternative hypothesis and holding onto it for dear life, the bias obviously and totally rests in your lap.

 

[RajeshTrivedi]

What you need to accept is that a Singularity need not be infinite, but "may " lead to infinite quantities.

But still can you elaborate the beauty above ?? You try to elaborate and you will see what a hopeless nonsense you write.

 

[paddoboy]

But still can you elaborate the beauty above ?? You try to elaborate and you will see what a hopeless nonsense you write.

No'again you are just railing against common sense and logic, since I have been instrumental in rebuking your BNS and having your other nonsense moved to the fringes.
All you need do is show one link, one expert opinion that supports what you have to say. You keep avoiding that. I keep reminding you.
Just one...that's all, because no one with any respect could take the word of a lay person such as yourself.
C'mon rajesh...just one link!

 

[paddoboy]

But still can you elaborate the beauty above ?? You try to elaborate and you will see what a hopeless nonsense you write.

You know the answer rajesh. You just lack the common sense and decency to admit it.
GR fails at the quantum/Planck level, so it can be said that the Singularity starts there.

 

[RajeshTrivedi]

GR fails at the quantum/Planck level, so it can be said that the Singularity starts there.

Still there only ??

No, GR does not fail at Q/P level....classically and mathematically it fails just at r = 0. Period. This is you bloodiest goofy latch...., continued continuing and will continue......

 

[paddoboy]

Many questions you have still not answered rajesh.
[1] If you do not accept BH's what do you have to explain the effects we see on spacetime and matter/energy? [BNS not accepted as they have been logically invalidated.
[2] Since according to GR it is impossible for any signal to travel from the center of a BH back out to the EH, how does a BH hold its shape, in light of the fact that you reject fossil fields and the nonlinearity of gravity/spacetime?
[3]Since you still seem to be insisting of the existence of your nonsense BNS, why don't you show some honesty, some intestinal fortitude and forget about your ego problem and post in the correct section?
[4] If the strong nuclear force is never surpassed as you say, how do you explain the complete disassembling of matter, sometimes even before crossing the EH.
[5]Have you ever heard of tidal gravitational effects?
[6] How do you explain the GR edict that tells us that when the Schwarzchild radius is reached, further collapse is compulsory.
[7]Why should anyone on this forum accept the "beliefs" and anti mainstream answers of a non professional person on the subject of BH cosmology, without you obtaining some reputable link to support your claims, such as I have done.

 

[paddoboy]

Still there only ??

No, GR does not fail at Q/P level....classically and mathematically it fails just at r = 0. Period. This is you bloodiest goofy latch...., continued continuing and will continue......

Wrong again!!GR certainly does fail at the quantum/Planck level. both in BHs and at the BB scenario...Duh! That's why we research for a QGT!
But maybe you can supply a link, just one, to support that?

 

[RajeshTrivedi]

Wrong again!!GR certainly does fail at the quantum/Planck level. both in BHs and at the BB scenario...Duh! That's why we research for a QGT!
But maybe you can supply a link, just one, to support that?

Even the Big Grin is amused at you, must be scratching its bald head !!

 

[paddoboy]

http://en.wikipedia.org/wiki/Planck_scale

In particle physics and physical cosmology, the Planck scale (named after Max Planck) is an energy scale around 1.22 × 1019 GeV (which corresponds to the mass–energy equivalence of the Planck mass2.17645 × 10−8 kg) at which quantum effects of gravity become strong. At this scale, present descriptions and theories of sub-atomic particle interactions in terms of quantum field theory break down and become inadequate, due to the impact of the apparent non-renormalizability of gravity within current theories.

At the Planck scale, the strength of gravity is expected to become comparable with the other forces, and it is theorized that all the fundamental forces are unified at that scale, but the exact mechanism of this unification remains unknown. The Planck scale is therefore the point where the effects of quantum gravity can no longer be ignored in other fundamental interactions, and where current calculations and approaches begin to break down, and a means to take account of its impact is required.

Even the Big Grin is amused at you, must be scratching its bald head !!

All you need is a link rajesh, instead of acting the clown
While they may have laughed at Galileo, they also laughed at Bozo the clown.

 

[RajeshTrivedi]

http://en.wikipedia.org/wiki/Planck_scale

In particle physics and physical cosmology, the Planck scale (named after Max Planck) is an energy scale around 1.22 × 1019 GeV (which corresponds to the mass–energy equivalence of the Planck mass2.17645 × 10−8 kg) at which quantum effects of gravity become strong. At this scale, present descriptions and theories of sub-atomic particle interactions in terms of quantum field theory break down and become inadequate, due to the impact of the apparent non-renormalizability of gravity within current theories.

At the Planck scale, the strength of gravity is expected to become comparable with the other forces, and it is theorized that all the fundamental forces are unified at that scale, but the exact mechanism of this unification remains unknown. The Planck scale is therefore the point where the effects of quantum gravity can no longer be ignored in other fundamental interactions, and where current calculations and approaches begin to break down, and a means to take account of its impact is required.

All you need is a link rajesh, instead of acting the clown
While they may have laughed at Galileo, they also laughed at Bozo the clown.

Oh !! I understood your problem now !! What you are trying to say is that GR cannot be quantized (Gravity in GR cannot be formulated as Quantum Field Theory)...... so GR fails at quantum level.

Am I right !!
(all along you have been mixing this withthat singularity lies at Quantum / Planck's level, which is incorrect, classical point singularity lies at r = 0 only)

 

[paddoboy]

Oh !! I understood your problem now !! What you are trying to say is that GR cannot be quantized (Gravity in GR cannot be formulated as Quantum Field Theory)...... so GR fails at quantum level.

Am I right !!
(all along you have been mixing this withthat singularity lies at Quantum / Planck's level, which is incorrect, classical point singularity lies at r = 0 only)

You view it whatever way you like with your obvious bias.
The mass and the singularity will reside somewhere between the quantum/Planck level and the classical point singularity which most believe will not be reached.
A QGT should reveal that.
You still fail to answer the questions I have posed, which totally detracts from what little credibility you have.

 

[brucep]

The tensor describes the sources which create spacetime curvature [gravity] Like John Wheeeler said mass tells spacetime how to curve and spacetime tells matter how to move. In this case mass is synonymous with the components of the tensor.
Gravitational potential energy is not the same as the stress-energy tensor. It's not a potential. Thesr's no potential gravitational energy in GR. I don't know who Zonneveld is so I can't comment on what you said he/she believes. Maybe this will be a better explanation. The components of the stress-energy tensor are delivered to the local spacetime by gravitational radiation. Waves that moves through the tidal field. Since there is no meaningful analogue for gravitional waves in Newton's theory they're are no meaningful analogue for gravitational potential in GR. I think. LOL for sure GR predicts the components of the tensor are present locally.

I misstated. In GR the gravitational potential is replaced by the metric tensor.
http://en.m.wikipedia.org/wiki/Gravitational_potential#General_relativity

 

[tashja]

Maybe tashja might like to contact Prof. Hamilton and get an opinion on this.

Apologies for the tardy response, Q. I sent Prof. Hamilton a link to the thread, and asked him to help us with the ''waterfall'' analogy argument. Here's his reply:

The waterfall model of black holes captures the essence of a mathematical
description of black holes in general relativity. Einstein's GR
emerged from the notion that there is no absolute spacetime. In GR,
one cannot assert that a point of spacetime is moving in a certain way.
Nevertheless, GR does pick out preferred coordinate systems in at least
some kinds of spacetime. In cosmology for example, there is a gauge
(choice of coordinates and tetrad frame), commonly called conformal
Newtonian gauge, in which the only perturbations retained are physical
perturbations. The coordinates and frame picked out by conformal
Newtonian gauge essentialy coincides with the frame of reference of the
Cosmic Microwave Background.

The question of whether space "really" falls into a black hole,
or whether space "really" expands with the Universe, are deeper
questions that remain a subject of debate among theoretical physicists.
I have my own opinion on these matters, but cannot assert that my
opinion is correct, because there is still no understanding
of the nature of spacetime itself at the most fundamental level.

Most physicists would probably express the view that spacetime
must somehow become "quantized" at some tiny (Planck) scale.
But how this happens is unsettled. Perhaps the leading theory
of quantum gravity is (super)string theory. But string theory predicts
10 spacetime dimensions, not 4. Do the other 6 dimensions curl up,
perhaps into a Calabi-Yau manifold, as has been speculate?

An interesting thought experiment is to imagine what spacetime would
look like of spacetime were genuinely empty, a vacuum. In reality,
our Universe is not empty, but rather gorged with cosmic microwave
backgrond photons, one per cubic millimeter. Does the presence of
these photons constantly "observing" spacetime help docohere and
sharpen spacetime? For example, do cmb photons (and other particles)
falling into a black hole help sharpen its horizon? I rather suspect
yes. since something sets boundary conditions at horizons, and I
think that something is Nature and not mathematicians.

OnlyMe writes

Theoreticians don't even agree exactly what happens at the event horizon, let alone inside...

which is sadly true. Sensible discussion has been replaced by
a cacophany of nonsense on firewalls.

Hope this helps,
Andrew

 

[tashja]

And a response from Prof. Carlip as well:

There are two sources here. The "waterfall" analogy is due to
Unruh, and was used to describe "analog black holes" -- fluid
flows that have a sonic event horizon. The reference is
W.G. Unruh, Phys. Rev. Lett. 46 (1981) 1351. The fluid flow
is described by an effective metric that, close to the sonic
horizon, look very much like the Schwarzschild metric. In
particular, it leads to a prediction of Hawking radiation of
phonons almost exactly analogous to black hole Hawking radiation.

The "river model" is to Hamilton and Lisle, Am. J. Phys. 76
(2008) 519, http://arxiv.org/abs/gr-qc/0411060. This is
an interpretation of the ordinary Schwarzschild metric in
Painleve-Gullstrand coordinates. It is, of course, an analogy
-- any plain language description of GR is necessarily going
to be an analogy -- but Hamilton and Lisle demonstrate that
it is a pretty good one. In particular, the coordinates are
tied to infalling observers, a sensible choice in GR, and it's
not such a bad analogy to say that relative to those observers,
space "flows." Hamilton and Lisle work out the details, for
both the Schwarzschild and the more complicated Kerr case.

Steve Carlip