# Paper: A causal mechanism for gravity

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On 5/18/2020 at 7:41 PM, Mordred said:

The statement of the photon gravitating to a higher refractive index in the above will not work for gravitational lensing.

Different frequencies of light respond differently in a medium.

If we consider the gravitational field as a medium for the propagation of electromagnetic waves, the refractive index of this medium can be described by a very simple formula

N=sqrt (Phi)/c

this formula shows that the refractive index N depends only on the gravitational potential of Phi and does not depend on the frequency of photons, that is, there will be no dispersion in this medium.

Photons propagate in a physical vacuum, and even if there are 0 protons per cubic kilometer in it, still from the point of view of modern physics, a vacuum is not a torricellian void, that is, a vacuum can be considered as a material medium.

On 5/19/2020 at 3:38 PM, Strange said:

Well, one can use Newtonian gravity in most cases for simplicity. The OP's model cannot even reproduce Newtonian gravity so its simplicity is irrelevant.

Yes, OP's mode cannot be considered a full-fledged theory of gravity, but it can be considered a theory of the interaction of gravity and electromagnetism.

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15 hours ago, MigL said:

If it can't be true, you must be able to explain X ray diffraction with those same photon 'tennis balls'.
Or maybe you can explain the photoelectric effect with EM waves ?

Whether light displays its wave nature, or its particle nature, depends on the observation you are attempting to make.
Some models are better suited for describing specific aspects of reality than others.

I think you're objecting to the tennis ball analogy because you're thinking that the photon analysis suffers a problem here while the wave does not, and that isn't true either. Like you said:

On 5/18/2020 at 10:53 PM, MigL said:

The peaks and troughs of a wave are in effect signal pulses, and frequency of a particular EM emission is, in effect a clock.

The signal pulses that A emits and the signal pulses that B detects must be equal in number. If A emits 10 signal pulses and then turns off his watch, B must detect 10 signal pulses. Your analysis would require B to detect 20 signal pulses (at 1/2 wavelength) in order for c to remain globally constant. There is no need to go in to other scenarios because this is an insurmountable problem...unless we declare that c varies remotely. It's an extremely common misconception that Relativity claims c is constant, but it obviously is not. C is constant locally...but that's it. This should be obvious because c is a velocity vector (it has a direction) and no one denies that the path of light can be bent.

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Posted (edited)
40 minutes ago, SergUpstart said:

If we consider the gravitational field as a medium for the propagation of electromagnetic waves, the refractive index of this medium can be described by a very simple formula

N=sqrt (Phi)/c

this formula shows that the refractive index N depends only on the gravitational potential of Phi and does not depend on the frequency of photons, that is, there will be no dispersion in this medium.

Photons propagate in a physical vacuum, and even if there are 0 protons per cubic kilometer in it, still from the point of view of modern physics, a vacuum is not a torricellian void, that is, a vacuum can be considered as a material medium.

I suggest you look at velocity dispersion in astrophysical measurements.

Quite frankly dispersion occurs in galaxy clusters etc.

If you have a medium light no longer propogates at c.

Edited by Mordred

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2 minutes ago, Mordred said:

If you have a medium light no longer propogates at c.

Unless you have a medium that has no detectable properties at all (i.e. disappears when approached with Occam's Razor) and is only there because it makes someone feel more comfortable (see also: Lorentz Ether Theory).

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Einstein was not against the ether in principle. See his article "Ether and the theory of relativity" 1920.

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Posted (edited)

40 minutes ago, rjbeery said:

The signal pulses that A emits and the signal pulses that B detects must be equal in number. If A emits 10 signal pulses and then turns off his watch, B must detect 10 signal pulses. Your analysis would require B to detect 20 signal pulses (at 1/2 wavelength) in order for c to remain globally constant. There is no need to go in to other scenarios because this is an insurmountable problem...

No, you are confused.
The 'insurmountable problem' is your invalid assumption of simultaneity between frames.

Edited by MigL

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3 minutes ago, MigL said:

No, you are confused.
The 'insurmountable problem' is your invalid assumption of simultaneity between frames.

MigL, please consider what I'm writing before dismissing it, because this isn't a simultaneity problem. If A emits 10 signal pulses and then turns off his watch...how many signal pulses will B detect, ever? This has nothing to do with simultaneity whatsoever.

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On 5/18/2020 at 11:12 PM, studiot said:
On 5/18/2020 at 9:22 PM, rjbeery said:

Dispersion and scattering effects are not solely a function of the refractive index, right? The material matters. Dispersive effects can range wildly in a variety of materials.

The point is that in any physically substantial environment whatsoever ( I daren't say medium though that is the usual phrase)  the transmission of light leads to two beams or rays.

The main beam passes through, diminishing according to the Beer Lambert or similar law. Spectrophotometers mainly use this beam.

The scattered ray, off at some angle, is the basis of Raman spectroscopy, which is also used in chemical analysis.

On 5/19/2020 at 12:02 AM, rjbeery said:
On 5/18/2020 at 11:12 PM, studiot said:

The point is that in any physically substantial environment whatsoever ( I daren't say medium though that is the usual phrase)  the transmission of light leads to two beams or rays.

Scattering is definitely something to think about, but it occurs when there's an abrupt change in media with an associated change in refractive index. We're considering a smooth, continuous gradation so I'm not sure how optics would normally handle that. Also, the Einstein Lens apparently doesn't differentiate by wavelength so perhaps spacetime neither disperses nor scatters as a "medium". I do appreciate the input, so thank-you.

There is no  change in media, abrupt or otherwise, in a chemical sample in a spectrophotometer.

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30 minutes ago, studiot said:

The point is that in any physically substantial environment whatsoever ( I daren't say medium though that is the usual phrase)  the transmission of light leads to two beams or rays.

Free space has permittivity, permeability and energy. It's definitely an "environment", so whether we call it a medium or not is semantics. I think we can all agree that free space does not disperse or reflect light, and there is nothing restricting us from proclaiming that this is simply a property of free space. If a person wants to demand that all media must disperse light, I think that would require some theoretical support.

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Posted (edited)
19 hours ago, rjbeery said:

Is it only useful relative to two points in spacetime?

Time dilation is a relationship between distant clocks (not a property of them), wherein ‘distant’ just means that the clocks are separated in space and/or in time.

19 hours ago, rjbeery said:

Is time dilation represented in the field equations?

Time dilation arises from the metric, which is a particular solution to the field equations for given initial and boundary conditions.

19 hours ago, rjbeery said:

Can we derive even derive a complete, universally valid time dilation field in GR?

No - again, because it is a relationship between clocks, not a fixed value that can be assigned to a given event.

Edited by Markus Hanke

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Posted (edited)
45 minutes ago, rjbeery said:

Free space has permittivity, permeability and energy. It's definitely an "environment", so whether we call it a medium or not is semantics. I think we can all agree that free space does not disperse or reflect light.

Energy doesn't exist on its own. It simply the ability to perform work.

Space devoid of all particles is simply a volume. Light can transverse that volume without the need of a medium or eather.

Space or spacetime isn't a medium to have permeability. It isn't some mysterious fabric which you often hear described in pop media or poorly written literature.

It is far more than semantics with regards to the actual physics and the relevant applicable formulas.

A term that no physicist would argue is to use the term field. This is a mathematical descriptive that entails any set of values or mathematical objects such as vectors, tensors, spinors etc under a coordinate treatment. In essence a field is an abstract mathematical object.

Edited by Mordred

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47 minutes ago, rjbeery said:

Free space has permittivity, permeability and energy. It's definitely an "environment", so whether we call it a medium or not is semantics. I think we can all agree that free space does not disperse or reflect light, and there is nothing restricting us from proclaiming that this is simply a property of free space. If a person wants to demand that all media must disperse light, I think that would require some theoretical support.

Especially as I have collected the bits together for you.

You are clearly not following the (simple) point I am making.

You have not one referred to the Raman effect, have you not come across it?

Meanwhile others are pushing for mathematics.
Here is some mathematics connecting refractive index, permittivity and permeability, including for the vacuum.

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1 hour ago, rjbeery said:

Free space has permittivity, permeability and energy.

According to Hawking, the energy of space is negative. Excerpt from Stephen Hawking's final book

"To help you understand this strange but important idea, let me draw a simple analogy. Imagine a person who wants to make a hill on an even place. The hill is the universe. To implement his plan, our man needs to dig a hole in the ground and use the soil to fill the hill. In other words, it creates not only a hill, but also a pit, which is essentially a negative version of the hill. The substance that was in the pit is now in the hill, so everything is perfectly balanced. The same principle underlies the creation of the Universe.

When the Big Bang produced a huge amount of positive energy, it simultaneously produced the same amount of negative energy. Thus, negative and positive energy add up to zero-as usual. Another law of nature.

Where is all this negative energy now? In the third ingredient of our cosmic cooking recipe — in space. It may seem strange, but according to the laws of nature related to gravity and dynamics — one of the oldest scientific laws — space is a huge store of negative energy. Enough to balance everything and reduce it to zero."

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3 hours ago, rjbeery said:

If A emits 10 signal pulses and then turns off his watch...how many signal pulses will B detect, ever?

And B will detect 10 pulses, but with different spacing, because the frequency of the pulses also changes.
( maybe you should consider what I'm writing before dismissing it )

38 minutes ago, SergUpstart said:

Where is all this negative energy now?

This is a reference to gravitational potential becoming more and more negative as the universe expands.
IOW, work has to be done to move mass to apart, since gravity does positive work as the mass approaches.
I remember coming across this same idea in Principles of Modern Cosmology by P J E Peebles.
And I've always considered it an 'accounting' convention.

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1 hour ago, Mordred said:

Space or spacetime isn't a medium to have permeability. It isn't some mysterious fabric which you often hear described in pop media or poorly written literature.

That's a strange comment, only because vacuum space does have permeability. What, exactly, is curving when we say that spacetime curves? You can't say it is "simply a volume" and then begin assigning attributes to it.

1 hour ago, studiot said:

Here is some mathematics connecting refractive index, permittivity and permeability, including for the vacuum.

To both of you, I would say that the issue has been resolved to my satisfaction. The function of refractive index as it relates to frequency varies by medium, and sometimes quite wildly. We can postulate that this function is independent of frequency for free space. Period. There is nothing preventing this, and the Einstein Lens already gives us evidence that it is true. I see no value in continuing this line of discussion.

7 minutes ago, MigL said:

And B will detect 10 pulses, but with different spacing, because the frequency of the pulses also changes.

If c weren't moving more slowly for B from A's perspective, how does A explain B's light clock ticking half as fast? That involves photons which are not changing depth in the gravity well at all. To be honest, MigL, I'm here looking for objections to the analogy in the OP. If your objection is that c is literally a global constant (and not a local one) then I'm comfortable with handling that objection and don't see much value in trying to "convert" you.

1 hour ago, Markus Hanke said:

Time dilation arises from the metric, which is a particular solution to the field equations for given initial and boundary conditions.

If it "arises from the metric" for specified circumstances then why can't we calculate a global time dilation field for that same solution and given conditions?

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27 minutes ago, rjbeery said:

I see no value in continuing this line of discussion.

Well in that case I will bow out and not bother further.

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26 minutes ago, rjbeery said:

What, exactly, is curving when we say that spacetime curves?

Geometry. There is no "thing" that curves. It is purely about what we measure.

27 minutes ago, rjbeery said:

You can't say it is "simply a volume" and then begin assigning attributes to it.

You are the only one assigning attributes to it.

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28 minutes ago, Strange said:

Geometry. There is no "thing" that curves. It is purely about what we measure.

OK then, whatever description, mechanism, semantic juggling or interpretation that allows us to consider spacetime to be curved will also allow us to consider spacetime to have a particular refractive index. Call it an illusion; call it geometry; call it "purely about what we measure." Please see my comment above, I don't believe further discussion on this is constructive. Thanks Strange.

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Just now, rjbeery said:

OK then, whatever description, mechanism, semantic juggling or interpretation that allows us to consider spacetime to be curved will also allow us to consider spacetime to have a particular refractive index. Call it an illusion; call it geometry; call it "purely about what we measure."

How about calling it what it is: an analogy.

The trouble is that analogies can be very powerful to illustrate a specific concept. But they break down when applied more widely or when you try and base new ideas on them. An obvious example is the "rubber sheet" analogy for GR. Some people just accept it for what it is. Others ask (very perceptively) "but if the dents in the sheet cause gravity then what is pulling the objects down to make the dents." See, the analogy has broken down.

So, yes, you can draw an analogy between the Newtonian equation for gravity and Coulomb's law. But if you try and got beyond that simple analogy, you run into problems (gravity only attracts, while similar charges repel, and so on).

Similarly, you can draw an analogy between refraction and gravitational lensing. But they are not the same thing.

7 minutes ago, rjbeery said:

I don't believe further discussion on this is constructive.

If you are unable to understand the difference between an analogy and science, then maybe you are right. You will never learn. How many years have you been flogging this particular horse,  while everyone tells you it is already dead?

How much real science could you have learned in that time? How much excitement of gaining knowledge have you missed out on?

It is sad that you have let yourself become obsessed by one mistaken idea that stops you learning anything new.

I shall suggest that this thread is closed.

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Curvature, or geodesics, can be related to geometry; That is what GR does.
Go ahead and relate refractive index to geometry.
And use math, not analogies or hand-waving.

As you have already told 3 people you don't want to discuss your idea anymore, I suggest you are in the wrong Forum.
And there is no point keeping this thread open if we aren't welcome to discuss its merits.

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1 hour ago, rjbeery said:

If it "arises from the metric" for specified circumstances then why can't we calculate a global time dilation field for that same solution and given conditions?

Because the only way that you can have the same conditions globally is with an empty universe that has uniform curvature (which must be either flat or positive). Which isn't relevant to what you are trying to model.

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18 minutes ago, rjbeery said:

OK then, whatever description, mechanism, semantic juggling or interpretation that allows us to consider spacetime to be curved will also allow us to consider spacetime to have a particular refractive index. Call it an illusion; call it geometry; call it "purely about what we measure." Please see my comment above, I don't believe further discussion on this is constructive. Thanks Strange.

"Matter tells spacetime how to curve, spacetime tells matter how to move"

So let's look closer at the first part.

First remove all matter (the full standard model of particles).

End result curvature equals zero zip Nada.

Now when you add other fields such as the Higgs field, weak field EM field,  Strong field.

Now you can get curvature bit only if the distribution of those fields is Non uniform. (Anistropic)

I mentioned the path of least action previously in this thread. It is this principle that determines the path taken

The descriptive spacetime is curved is actually a sloppy descriptive. What really is curved isn't the volume.

What curves is the Geodesic paths for massless particles this is the null geodesic. The fields of the standard model and how they interact or couple to the particle in motion is what determines the amount of curvature of the geodesic path.

Space is just volume. Spacetime is a metric that describes space with time as a dimension under a geometry basis. However spacetime without particles is simply a volume.

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18 minutes ago, Strange said:

I shall suggest that this thread is closed.

18 minutes ago, MigL said:

And there is no point keeping this thread open if we aren't welcome to discuss its merits.

I'm not opposed to discussing merits. What I'm saying is that, once both sides understand each other and acknowledge an impasse, further discussion is a waste of time. Joigus believes that cavity interaction explains remote dilation. I explained why I disagree. MigL believes that time dilation can be explained by adjusting both frequency and wavelength such that c remains constant, globally. I explained why I disagree. Strange demands things and then is unusually dismissive when they are provided. I explained why that discourages me from doing it again. There is literally no benefit to me to attempt to change minds here; I'm here for criticisms. Mordred demands that spacetime would disperse light if it had a refractive index, for example. That's a valid point, and I dealt with it to my satisfaction.

To be honest, someone from another forum asked if I knew Markus Hanke from here. I did not know him, but he is why I started a couple of threads here, and his responses so far have been the most interesting to me.

Anyway, there is still an active discussion going on so I think closing the thread is premature.

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3 minutes ago, Mordred said:

Space is just volume. Spacetime is a metric that describes space with time as a dimension under a geometry basis. However spacetime without particles is simply a volume.

Exactly. The concept of spacetime in GR is just a mathematical model. Just like the electromagnetic field.

Questions asking if spacetime "really" curves or if the electric field "exists" are irrelevant. These are useful tools (useful because they work).

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Posted (edited)

Correct now gravity is described under the Stress energy momentum tensor. This under GR is the portion that in essence curves the metric. So here is a simplified sample showing the Dust solution.

Dust is matter only equation of state p=0.

Dust solution no force acting upon particle. (No acceleration)

$T^{\mu\nu}=\rho_0\mu^\mu\nu^\mu$

$T^{\mu\nu}x=\rho_0(x)\mu^\mu(x)\mu^\nu(x)$

Rho is proper matter density

Four velocity

$\mu^\mu=\frac{1}{c}\frac{dx^\mu}{d\tau}$

$ds^2=-c^2d\tau^2=-c^2dt^2+dx^2+dy^2+dz^2=-c^2dt^2(1-\frac{v^2}{c^2})^\frac{1}{2}=\frac{1}{\gamma}$

$T^{00}=\rho_0(\frac{dt}{d\tau})^2=\gamma^2\rho_0=\rho$ $\rho$ is mass density in moving frame.

$T^{0i}=\rho_0\mu^o\mu^i=\rho^o\frac{1}{c^2}\frac{dx^o}{d\tau}\frac{dx^2}{d\tau}=\gamma^2\rho_0\frac{\nu^i}{c}=\rho\frac{\nu^i}{c}$

$\nu^i=\frac{dx^i}{dt}$

$T^{ik}=\rho_0\frac{1}{c^2}\frac{dx^i}{d\tau}\frac{dx^k}{d\tau}=\gamma^2\rho\frac{\nu^i\nu^k}{c^2}=\rho\frac{\nu^i\nu^k}{c^2}$

Thus

$T^{\mu\nu}=\begin{pmatrix}1 & \frac{\nu_x}{c}&\frac{\nu_y}{c} &\frac{\nu_z}{c} \\\frac{\nu_x}{c}& \frac{\nu_x^2}{c} & \frac{\nu_x\nu_y}{c^2}& \frac{\nu_x\nu_z}{c^2}\\ \frac{\nu_y}{c}& \frac{\nu_y\nu_z}{c^2} & \frac{\nu_y^2}{c^2}& \frac{\nu_y\nu_z}{c^2}\\ \frac{\nu_z}{c} &\frac{\nu_z\nu_x}{c^2}&\frac{\nu_z\nu_y}{c^2}&\frac{\nu_z}{c^2}\end{pmatrix}$

Edited by Mordred

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