# Paper: A causal mechanism for gravity

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4 minutes ago, Mordred said:

No I am a Professional Cosmologist with degrees in particle physics. I can prove any refractive index treatment of spacetime wrong.

I can do the same with any treatment of spacetime as a medium wrong. Lol all I have to do is point out previous research papers.

I have even been hired to research refractive indexes by a survey camera manufacturer. That grant paid my income for a year.

I don't doubt your credentials (and at some point I would love to ask you some questions on black holes!) but I'm having a problem understanding your objection to the refractive index. Do you have an objection to GR time dilation? Assuming not, generating a refractive index field via mapping from the GR time dilation field is trivial.

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A refractive index requires scatterrings. Those scatterrings and the degree of change in angles will involve the wavelength.

If I look at an Einstein Ring I will get distrortions that do not depend on wavelength. I have been involved in doing those tests studying the CMB as my speciality is early universe dynamics. In order to get a telescope even the Hubble telescope on must often use a gravitational lens to extend the distance to get deep field imaging.

A simple analogy for time dilation would be signal propogation delay.

Take a digital signal in electronics you can delay that signal through electrical cross talk.

Now extend that analogy to the 18 coupling constants of the standard model of particle physics.

Edited by Mordred
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9 minutes ago, Mordred said:

A refractive index requires scatterrings. Those scatterrings and the degree of change in angles will involve the wavelength.

If I look at an Einstein Ring I will get distrortions that do not depend on wavelength. I have been involved in doing those tests studying the CMB as my speciality is early universe dynamics. In order to get a telescope even the Hubble telescope on must often use a gravitational lens to extend the distance to get deep field imaging.

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. If the spacetime "material" had dispersive qualities, such that refraction depended on wavelength, then I believe gravitational mass would not equal inertial mass in all gravity fields. To me, this necessitates that the spacetime "material" displays zero dispersion, and I'd actually use the fact that the Einstein Ring distortions do not depend on wavelength as a supporting argument to the idea.

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1 hour ago, rjbeery said:

And most people wouldn't consider 96% "wildly inaccurate".

It is much less accurate than our current theory of gravity.

1 hour ago, rjbeery said:

There are no fudge factors in this spreadsheet to get that result -- I described what I was going to analyze, and then I did so.

No. But it gives the wrong results and then you start inventing ways of trying to correct for that. Unlike GR where the correct result (to a very high degree of accuracy) falls out of the the theory.

1 hour ago, rjbeery said:

If I did this right, you can view and copy the spreadsheet above, after which you're free to adjust it all you want.

Why? It obviously doesn't work. And we have a theory that does.

5 minutes ago, rjbeery said:

If the spacetime "material" had dispersive qualities

What "material" do you think 1 kilometre is made of, or one second?

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Maybe you should look more closely at what causes a refractive index. Ie permittivity of a material for starters then step into how dispersions occur.

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1 minute ago, Strange said:

No. But it gives the wrong results and then you start inventing ways of trying to correct for that. Unlike GR where the correct result (to a very high degree of accuracy) falls out of the the theory.

Wait, what? I thought it was obvious why the analysis was an approximation but I'll be explicit -- I modeled a photon moving in an octogon. We have no idea what the photon's actual path in in this theoretical EM mass particle, but we can bet it isn't an octogon. I also approximated various things, such as the mass of the Earth, and the value of G. Frankly, you seem curiously dismissive, which is perfectly fine but please don't ask for things insincerely.

2 minutes ago, Mordred said:

Maybe you should look more closely at what causes a refractive index. Ie permittivity of a material for starters then step into how dispersions occur.

With respect, Mordred, I think you're applying your real-world experiences too heavily to this model. I don't know "how" spacetime could have a refractive index any more than I know "how" spacetime could curve due to an energy-momentum tensor. To the extent that GR works because the math works, and to the extent that this analogy works, asking "how" is another chapter.

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3 minutes ago, rjbeery said:

Wait, what? I thought it was obvious why the analysis was an approximation but I'll be explicit -- I modeled a photon moving in an octogon. We have no idea what the photon's actual path in in this theoretical EM mass particle, but we can bet it isn't an octogon. I also approximated various things, such as the mass of the Earth, and the value of G. Frankly, you seem curiously dismissive, which is perfectly fine but please don't ask for things insincerely.

That is why it would be much better if you did some math and derived, for example, $F = G\frac{m_1 m_2}{r^2}$ from your model.

Or, even better: $R_{\mu \nu} - \tfrac{1}{2}R \, g_{\mu \nu} + \Lambda g_{\mu \nu} = \frac{8 \pi G }{c^4} T_{\mu \nu}$

Then we would know you had an accurate and useful model.

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12 minutes ago, rjbeery said:

With respect, Mordred, I think you're applying your real-world experiences too heavily to this model. I don't know "how" spacetime could have a refractive index any more than I know "how" spacetime could curve due to an energy-momentum tensor. To the extent that GR works because the math works, and to the extent that this analogy works, asking "how" is another chapter.

And yet I have zero problem understanding time dilation. The problem is explaining it to laymen. (Though it took understanding mean lifetimes and it's connection to the Langrangian)

Refactive index is the wrong approach.

Try gravitational redshift under refractive index.

Edited by Mordred
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1 hour ago, 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.

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1 hour ago, Mordred said:

Try gravitational redshift under refractive index.

I think what you're questioning here is whether or not redshift would occur using a graded refractive index in the same way that it occurs in a gravitational field. Indices of refraction keep the frequency of light constant, but vary the wavelength. It should be obvious that media with a lower refraction index would exhibit a longer wavelength.

39 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.

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.

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20 minutes ago, rjbeery said:

I think what you're questioning here is whether or not redshift would occur using a graded refractive index in the same way that it occurs in a gravitational field. Indices of refraction keep the frequency of light constant

Why would I ask to keep the frequency of light cobstant  ?

How would you get gamma rays, microwaves, x rays UV rays or even a color spectrum?

I am asking you to learn how dispersion is frequency dependent. Then you would recognize a gravitational lens nor spacetime  involves refraction.

You have an emitter frequency (or more exact a range of frequencies from a distant star. ) Gravitational  redshift affects that wide range of frequencies equally.

Where a refractive index would not. Due to dispersion.

Edited by Mordred
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7 hours ago, Mordred said:

The mass term cannot be described under refractive index. Or radiation pressure (pressure has directional components).

Because I was the one to mention radiation pressure, and just to clarify, I never intended to argue that radiation pressure is a plausible point of departure to build the components of either the energy-momentum tensor, or the Einstein tensor, or anything else in GR. It was intended as a simple illustration that the slowing down of clocks (a frame-dependent effect, as I've repeated here to the OP till I got blue in the face) has nothing to do with the slowing down of photons. And it was in response to this rather bizarre statement by the OP:

On 5/15/2020 at 1:38 AM, rjbeery said:

Photons do not slow down locally, I agree, but remote photons must slow down. If you're wearing a watch which uses photons as a timing mechanism, and I'm wearing the same watch but sitting far above you in a powerful gravity well, how else could I explain that your watch is ticking more slowly?

(my emphasis)

And as photons do not slow down in any sense that I know of in a gravitational field, and please correct me if I'm wrong, I surmised that if a clock made of photons (and necessarily other things non-photonic) does slow down in a gravitational field, what other reason could it be attributed to but the fact that it's not made just out of photons, but also massive / charged matter interacting with them? IOW, the photons that are going back and forth inside the clock cannot be accountable for the slowing down of the clock, but the presence of the cavity, with which they interact. What the detailed analysis of this interaction would be is another matter, which I won't even try to analyze here or elsewhere. But there, that's how else you could explain it: because it's not 'just' photons falling!

On the other hand, I totally agree with what the experts have said as far as I've been able to read and understand. And specifically concur totally with the point that considering space-time as a "medium" is completely the wrong way to try to approach it.

My last point, and sorry for the lengthy argument. I'm not saying that GR is necessarily to stay with us forever, or that I'm 100 % sure of its total infallibility. But for anybody who claims to have come up with something new and/or better to supersede it or rival it, as Strange has been the most insistent to say on on this forum (from which the only thing of interest is the opinion of the learned people who have responded to the tsunami of nonsense) the minimum required is to reproduce its many impressive results.

And sorry for the diacritics. They're just to emphasize what I consider the important points I want to make.

Edited by joigus
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2 hours ago, Mordred said:

You have an emitter frequency (or more exact a range of frequencies from a distant star. ) Gravitational  redshift affects that wide range of frequencies equally.

Mordred, you are giving the same objection in another form, which I have already addressed. Dispersion is not tied to refractive index, but is specific to the medium itself. Some media have wide dispersion, others have very little. The fact that gravity affects all frequencies equally, and the fact that an Einstein Lens does as well, implies that spacetime does not produce dispersion effects at all if we are modeling it as a refractive medium through which light is traveling.

56 minutes ago, joigus said:

And as photons do not slow down in any sense that I know of in a gravitational field, and please correct me if I'm wrong, I surmised that if a clock made of photons (and necessarily other things non-photonic) does slow down in a gravitational field, what other reason could it be attributed to but the fact that it's not made just out of photons, but also massive / charged matter interacting with them? IOW, the photons that are going back and forth inside the clock cannot be accountable for the slowing down of the clock, but the presence of the cavity, with which they interact.

I've repeated it a few times now -- this idea leads to a logical contradiction. A literal contradiction. Watch A is high in the sky, while watch B is low in a gravity well. Observer A, holding watch A, claims that watch B is ticking once for every two ticks of his local watch. Observer B, holding watch B, agrees with him (2 ticks up there = 1 tick down here). The watches are large -- 1 light-nanosecond wide, which is about a foot, I believe. Two ticks on A means that the photon has traveled across the watch 4 times (= 4 feet), whereas watch B's photon has only traveled 2 feet because the "cavity interaction" has, we are supposing, delayed its transmission by a full nanosecond.

Now we get silly and make interstellar photon clocks, 100 light-years wide, but put them in the same arrangement. Observer A and B both agree that for every two ticks on clock A, we have only one tick on clock B. They also continue to agree that for every two ticks on watch A, we have one tick on watch B. However, now the "cavity interaction" for the interstellar clocks must delay the photon emissions in clock B by 100 years. That's the contradiction. The photons in the clocks and watches "have no clue" how wide the watch or clock is that they are in, and neither do the absorbing/emitting atoms that make up the machinery.

We simply cannot attribute gravitational time dilation to cavity interaction or radiation pressure.

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1 hour ago, rjbeery said:

Mordred, you are giving the same objection in another form, which I have already addressed. Dispersion is not tied to refractive index, but is specific to the medium itself.

Wrong the index of refraction depends upon the wavelength of light.

You should really try learning a topic before making wrongful statements.

Quote

For real materials, the situation is more complicated. Ob- viously, the phase velocity of light waves is slower in a material than in vacuum, because n ≥ 1 (except for a few very special cases, such as refraction of x-rays in some materials). But waves with different λ travel at different velocities in media; long waves travel faster than short waves, except over very narrow ranges centered about very specific wavelengths (the resonances), which are beyond the scope of this laboratory. Therefore, n is smaller for longer waves than for shorter

Here is a brief article covering Snells law and dispersion

As previously stated any attempt to employ refractive index to spacetime will fail.

Let's try the following thought experiment.

The LIGO detector uses lasers in its 4 km arms. The location is fixed yet they calibrate the detector by placing a test weight near each detector.

So the only thing that changes is the amount of mass near the detector. Yet the laser paths will experience a time delay. The elevation does not change nor does the local fields except for the addition of mass nearby.

It is the mass term that causes the above delay the spacetime path becomes curved.

Secondly a rocket ship travelling at near c will also experience time dilation So how does your model account for two rocket ships travelling at different speeds in space away from any gravitational bodies

By the Principle of equivalence inertial mass and gravitational mass are indistinguishable from one another.

$m_i =m_g$ nothing I have seen in your model accounts for this.

I won't even get into your explanation of electron and photon behavior.

You don't even require an EM field to have spacetime curvature or time dilation.

All matter and force fields contribute to the mass term. Including mass less particles such as the Higgs boson.

There is two main types of mass in GR. Invariant mass or rest mass and variant mass (relativistic or inertial mass}.

Your theory doesn't have a chance of succeeding. For several of the reasons myself and others have mentioned.

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I suggest doing your analysis of the two observers in a gravity well, with EM waves instead of photons.
The peaks and troughs of a wave are in effect signal pulses, and frequency of a particular EM emission is, in effect a clock.

Now consider a specific emission deep in a gravity well, as observed by an observer much higher in the gravity well.
Using your same logic ( as you previously applied to the photons ) the higher up observer will see the peaks and troughs of that specific emission arriving slower, and more separated. IOW, lower frequency and longer wavelength ( otherwise known as red-shift ), and if you multiply the two together, you still get c .

Alternatively, an observer lower in the gravity well will see waves from that same specific emission ( but now higher up in the well ) arriving with peaks and troughs at a faster rate, or more closely spaced. IOW, higher frequency and shorter wavelength ( also known as blue-shift ).

In both cases, the frequency/wavelength shifts are not observed at the same depth in the gravity well, but only at differing depths.
That is a 'comparison' and what is meant by relative, certainly not 'absolute'. And in neither case is c measured to be different from the speed of light by any observer.

Its amazing how much confusion you can avoid, by using the right model for the circumstances.

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19 hours ago, Strange said:

As GR is so useful as the starting point of your model, for checking the result of your model and then coming up with a way of fixing the results of your model ... why not just use GR?

And here the question should be put so, which model is simpler from the point of view of mathematics, i.e. more convenient for calculations.

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4 minutes ago, SergUpstart said:

And here the question should be put so, which model is simpler from the point of view of mathematics, i.e. more convenient for calculations.

As well as providing the same degree of accuracy and flexibility.

The Einstein field equations can literally be used for any field theory. Which makes it incredibly useful as you can describe how all fields evolve with the energy momentum relations. At least until quantization becomes important.

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32 minutes ago, SergUpstart said:

And here the question should be put so, which model is simpler from the point of view of mathematics, i.e. more convenient for calculations.

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.

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6 hours ago, rjbeery said:

I've repeated it a few times now -- this idea leads to a logical contradiction.

And I've I told you:

On 5/15/2020 at 6:58 PM, joigus said:

For any object moving, you set clocks and systems of laser beams going back and forth to measure positions and time intervals (the latter calculated taking into account how much the signals delay in reaching the observer, it's not 'subjective' time we're talking about; it's not 'when I see the object.')

MigL also told you:

On 5/15/2020 at 6:08 PM, MigL said:

IOW, one 'signal' has to climb/descend to the height/depth of the other for the comparison to be made.
You cannot circumvent that ( no mixed frames ).

And, along the same lines, I said:

On 5/15/2020 at 6:58 PM, joigus said:

For what observer? For all inertial observers! Now, that's what I would call invariant (I'd never say 'absolute'.) And in order to do that, you need a system of signals, as they're trying to tell you. You need a way to bring it all together, so to speak.

IOW, it's not t2-t1 for the arrival times of the signals that mark up the ticking of the clock --the perceived time, which is the thing you seem to be thinking about, although nobody can be sure-- what determines the clock's ticking, it's the mean average of tout and tin. tout and tin being the delays in the forward and backward trip of your signals. The process repeated for 2 fiducial ticks of the remote clock, and then the calculation.

The source of all your inconsistencies about "remote clocks" starts, I'm sure, from the very simple fact that you don't understand what it means to measure time in SR, let alone in GR, which is affected by second order derivatives. There are as many as 20 independent ones, that's known since the 19th Century. We could talk Einstein, we could talk Weyl if you want, but let's drop the tensors for a while, if you please. Please, tell me that you recognize something like what follows in terms of outgoing and ingoing signals in order to define coordinate time:

$t=\frac{1}{2}\left(t_{\textrm{out}}+t_{\textrm{in}}\right)$

where tout is the coordinate time of signal sending in your system, and tin is the coordinate time of signal receiving in your system. The coordinate time of distant events must be defined in terms of the times signals delay. k-calculus was developed by H. Bondi and is a very simple tool to understand this, and if you take my advise and read carefully chapter 1 of D'Inverno, which I recommended you, you will understand.

IOW, you can keep your own close observations as your clock, so to speak, but for remote objects, you must send signals and, upon receiving them back, guess the coordinate time for the distant object. It's always like that in any relativity, S or G. Please, oh please, try to understand that and maybe we can talk about something meaningful and go on to tensors. Otherwise nothing we discuss is going to be meaningful. I think that's a preliminary requisite.

I don't have much time, sorry if I mistyped or made another similar mistake.

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On 5/18/2020 at 3:03 PM, SergUpstart said:

Three coordinates of the gravitational acceleration vector + three coordinates for the torsion field vector?

GR uses the Levi-Civita connection, so there is no torsion.
Also, if there were any vector fields involved, then those would be 4-vectors, not 3-vectors; and two separate vector fields still do not capture the necessary degrees of freedom.

On 5/18/2020 at 4:45 PM, rjbeery said:

Couldn't we start with a mapping of gamma relative to some arbitrary observer (i.e. infinitely distant and inertial)?

The field equations - like all physical quantities in GR - need to be covariant, so no, you can’t make any kind of explicit reference to an observer.

On 5/18/2020 at 4:15 PM, Mordred said:

The reason you need a rank two tensor describe gravity is that you a gradient to describe gravity.

One could also think of it in terms of gravitational radiation fields. These fields extend to infinity, and wave fronts in free space propagate at the speed of light; furthermore you have two distinct polarisation modes. In terms of field quanta, this automatically implies massless spin-2 bosons - which, mathematically speaking, can only “couple” to rank-2 tensors. So this is the lowest rank object that is needed to fully capture all relevant degrees of freedom of gravity.

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1 hour ago, Markus Hanke said:

One could also think of it in terms of gravitational radiation fields. These fields extend to infinity, and wave fronts in free space propagate at the speed of light; furthermore you have two distinct polarisation modes. In terms of field quanta, this automatically implies massless spin-2 bosons - which, mathematically speaking, can only “couple” to rank-2 tensors. So this is the lowest rank object that is needed to fully capture all relevant degrees of freedom of gravity.

Good point particularly when it comes to GW waves. +1

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19 hours ago, Mordred said:

Wrong the index of refraction depends upon the wavelength of light.

You should really try learning a topic before making wrongful statements.

This graph is the refractive index for water. The function of refraction index is not as simply dependent on wavelength as you are suggesting. The shape of the curve depends on the medium material, among other things. I hadn't considered dispersion before this conversation, and I appreciate your input, but I've already said that the function of refractive index by wavelength through spacetime could simply be a constant (i.e. not dependent on wavelength at all). The Einstein Lens could be proof of this. If you aren't satisfied with this response that's OK, but I'm not sure any further commentary on this topic is constructive.

18 hours ago, MigL said:

Alternatively, an observer lower in the gravity well will see waves from that same specific emission ( but now higher up in the well ) arriving with peaks and troughs at a faster rate, or more closely spaced. IOW, higher frequency and shorter wavelength ( also known as blue-shift ).

This can't be true. Instead of peaks and troughs, imagine tennis balls. Observer A hits a ball down towards B every second, and numbers them. If observer B is receiving these tennis balls at a higher frequency than 1 per second (from A's perspective) then he would be receiving tennis balls not even served yet. We rectify this by allowing A to claim that the frequency is the same but the wavelength (i.e. distance between tennis balls) is shorter for B -- and it would literally look like that to A because hitting tennis balls into a field of dilated time is like hitting them into a puddle of syrup. The frequency remains constant, but the wavelength shortens. (Wavelength) * (frequency) = (c) locally, and (wavelength at B from A's perspective) * (frequency at B from A's perspective) = (c at B from A's perspective) which means that light is moving more slowly at B from A's perspective.

8 hours ago, joigus said:

Please, oh please, try to understand that and maybe we can talk about something meaningful and go on to tensors. Otherwise nothing we discuss is going to be meaningful. I think that's a preliminary requisite.

I did my best to explain my perspective on cavity interactions. If you think we still harbor a difference of opinion then I would agree that further discussion isn't going to be meaningful. Thanks though, Joigus.

5 hours ago, Markus Hanke said:

The field equations - like all physical quantities in GR - need to be covariant, so no, you can’t make any kind of explicit reference to an observer.

With these objections, it makes me question the function of gamma and GR time dilation in general. Is it only useful relative to two points in spacetime? Is time dilation represented in the field equations? Can we derive even derive a complete, universally valid time dilation field in GR?

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46 minutes ago, rjbeery said:

This can't be true. Instead of peaks and troughs, imagine tennis balls.

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.

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That is an example for water which does show how refractive index  does change for different wavelengths. Particularly with a material depending upon the materials properties.

It is a good example of the dispersion effect So I will grant +1 for that graph and your effort in taking the effort based on our feedback.

Now in gravitational lensing or gravitational redshift we do not have the frequency dependency.

If I look with a spectrograph at a gravitational lens I do not see or measure a different ratio of change with a frequency dependancy

Edited by Mordred
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1 hour ago, rjbeery said:

I did my best to explain my perspective on cavity interactions. If you think we still harbor a difference of opinion then I would agree that further discussion isn't going to be meaningful. Thanks though, Joigus.

You're most welcome. It's such a pleasure to break the spell. Good luck to everybody else.

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