Simple geometric proof GR's GW's are impossible

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Q-reeus, Jul 7, 2016.

1. Q-reeusValued Senior Member

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So now you actually acknowledge that Feynman's beads will not and logically cannot experience GW induced transverse motions as he originally claimed?
Once you give a clear yes or no to that, the rest is irrelevant. Or you can propose some rational case for the need to at all consider arbitrarily small bead internal stresses?
[But let's cut out any nonsense that bead stress is possibly relevant, far less important, with a simple observation. Energy dissipation owing to internal stresses, minute as it could be at best compared to Feynman's notion of sliding along the stick, IS OBVIOUSLY MATERIAL DEPENDENT. For the same bead mass, one made of plasticine would generate vastly greater internal losses than one made of diamond. In fact the latter would fapp be absolutely zero. You wish to argue then that material dependent parameters can play a fundamental role in figuring out if a GR GW makes sense?! Be my guest.]

Last edited: Jul 16, 2016

3. PhysBangValued Senior Member

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No. Not in the slightest. You haven't addressed the original thought experiment at all. Nor have you completed your own thought experiment. You have claimed that there can be no motion. Even if we accept that, you have not shown that there are not other forms of energy transfer that occur in your toy scenario.

Until you actually work through your thought experiment, there is nothing to even evaluate.
We need to consider any transfer of energy, since that is what the original thought experiment is about. Remember way back when I said that you had a reading comprehension problem because of your bias? Here is is again: you missed the point of the thought experiment so you ignore the relevant features when designing your own.

Some physical interactions will always be dependent on the materials used. For example, dropping a ball made of dough will result in a different number of bounces than dropping a ball made of hardened rubber.

5. Q-reeusValued Senior Member

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Profound. Profoundly irrelevant. On that note, let's end this charade now. Another fine record of how serious attempts at garnering useful, intelligent feedback, on anything slightly away from mainstream kosher approved, are doomed from the start here at SF. Sigh.

7. PhysBangValued Senior Member

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You clearly are not serious, since you avoid even discussing the idea that your thought experiment is leaving out important details. You either will not consider completing your argument or you have given it a try and you can't do it.

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9. Q-reeusValued Senior Member

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See my response to PhysBang next post. The glove fits for you to. Have a nice day.

10. Q-reeusValued Senior Member

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Who is not serious did you say? I asked you way back this thread - did Feynman for instance ever suggest 'bead internal stresses' were relevant to sticky bead argument? No response. It's not hard to do a rough order of magnitude comparison between material independent bead-motion-along-stick vs internal-stresses-in-beads. Although latter not only depends on bead material, but bead dimensions. Again, something the original beads-along-stick case is insensitive to. A double plus for that, yet still fatally flawed as per #1. To me it's so obvious the internal stress BS is just that, utterly irrelevant, intentionally vexatious BS. Which if you dared to seriously propose such to a GW specialist or even general physicist, would deservedly receive from such a mix of scorn and laughter. Yet such is the generally superficial environment here at SF, it probably seems perfectly reasonable argument to most of the yawning bystanders here.

The only perplexing question in my mind, is what is your's and one or two others real motivation for such disingenuous crap. Answers that will never be divulged and really, why should I care?
The one good thing to be taken from this episode is - never ever try presenting anything similar at SF again. Life's too short to waste on dealing with fools and knaves.

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11. PhysBangValued Senior Member

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Of course it's not relevant for his thought experiment, he just requires that some energy be transferred to the bead system. In your case, you are claiming that certain motions aren't allowed. If this is in fact the case, then we might expect to see some sort of stress or deformation of the beads themselves. The default assumption is that energy is transferred to the system and you haven't done anything to make anyone doubt this because your argument lacks details.

You keep dancing around this issue. It's not surprising.

Heck, you could win a Nobel prize if you just completed the details of your argument.

12. expletives deletedRegistered Senior Member

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Double post blanked. Sorry.

Last edited: Jul 16, 2016

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14. expletives deletedRegistered Senior Member

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PhysBang:

Q-reeus:

A request for clarifcation, if you please, sirs.

@PhysBang in particular:

1) Bearing in mind the underlying aLIGO experimental premise, ie, that passing GWs change the spatial distance between the test masses (rather than the test masses themselves being 'stressed' or deformed etc in situ) and allegedly cause the LASER beam's photons to "travel" less/more distance" BETWEEN the test masses, may I ask how your 'internal stresses' question re any test masses (ie, the counterparts to 'beads' in Q-reeus's OP scenario) relates to the overall spatial-only effects of GR GWs as hypothesized for the aLIGO scenario?

2) Having regard to your assertion that energy is transferred to the beads (ie test masses), can you please explain:

a) the mechanism via which energy can be transferred to the beads/test masses, and;

b) how that would not defeat the whole premise underlying the aLIGO experimental expectations regarding spatial-only effects of passing GWs without any significant effects (if at all) on the test masses (ie, beads in this thread's OP)?

I ask the above only to clarify this discussion for myself; and it is not to be taken as my commenting either way regarding the OP itself at this time. Thanks.

Last edited: Jul 16, 2016
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15. expletives deletedRegistered Senior Member

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Schmelzer:

Q-reeus:

Another request for clarification, if you please, sirs:

@ Schmelzer in particular:

Can you please clarify how, why and where the physical OP scenario changed to philosophical scenario(s) as implied in your responses and counter arguments to Q-reeus and his physical OP? Thanks.

Last edited: Jul 16, 2016
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16. SchmelzerValued Senior Member

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I have consistently argued that claims of "logical contradictions" in established theories are a strong hint that the claim is crank science. The OP contains such a claim: "GR's and similar tensor gravity theories brand of pure tensor GW's are logical absurdities". So far the background. I have never claimed that such an argument is more than a weak plausibility argument - but as a heuristic, it works nicely.

Later I have argued that if you have a solution, that means, functions $g_{mn}(x,t)$, and they fulfill the Einstein equations of GR, they are valid solutions and not "logically inconsistent".

Q-reeus has objected that this reasoning is incorrect, and used solutions with closed causal loops as an example where my reasoning would go wrong. He rejects them based on the grandfather paradox. But they are otherwise valid solutions of the GR equation.

Here I defended myself, arguing that even if I reject them because of the grandfather paradox, I would not name this "logically inconsistent" or so.

I think this part was a normal exchange of arguments, and see no problem at all with such a sidestep into philosophy. Anyway, there is no sharp boundary. Physical theories are full of metaphysical principles and concepts, and there is nothing wrong with this.

17. Q-reeusValued Senior Member

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False assertions don't change the facts. The base conceptual bottleneck is yours. It's you that refuses to acknowledge or at best honestly can't even see the real issue.
Just one more time. GR GW's are allowed only purely transverse pure shear spatial metric perturbations. Normally only ever applied to a local patch where incident wave has essentially plane wave form. The ubiquitous 'deforming ellipse' picture (small ellipses in ilustration of #1 and #60). With purported local strain orientations as per illustration and specified in #1. But has axially symmetric character globally. Apply that to a circular array of beads lying in the equatorial plane of a linear quadrupole oscillator. The circle radius large enough to correspond to far-field condition. No need to even consider the beads at all. Just realize that azimuthal component h_φφ of purported shear strain, supposedly finite on local basis, cannot be non-zero while still maintaining the purely transverse strain stipulation. The circular array, to undergo circumferential strain must simultaneously radially expand (or contract in other half cycle). Which immediately violates claimed pure transverse character. Over in the original precedent PhysicsForums in 2012 thread I put it thus: try blowing up a balloon without increasing it's diameter. Absurd contradiction.
Same thing here. The immediate implication, directly imposed by circular symmetry, is there can be no such shear strains existing at all.
In #1 it was stated without proof, that nevertheless allowing radial expansion - contrary to GR GW's character - would have to have an radial displacement amplitude constant for all r, in order that transverse relative motions matched the necessary 1/r decline in transverse displacement between beads i.e circumferential expansion/contraction of metric. That is transverse metric strain h_φφ x r = K/r x r = K, a constant. An unphysical situation for any free-space wave. So desperate out - 'radial breathing' option is not an option.

Has it not dawned on you this implies, within GR paradigm, a null perturbation everywhere. In #1 I went into the case of meridian lines. Which at any given instant have opposite sign of shear strain h_θθ to that of h_φφ equatorial or generally latitudinal lines. Well beads on intersections of latitudinal and meridian lines can't both move out and inward simultaneously. Beads 'choosing sides' as to move in or out is crazy thinking. Everything is conflicting thus self-contradictory. Hence the sole resolution within GR is no shear or radial strains can exist. HENCE NONE OF YOUR BEAD INTERNAL STRAINS EXIST TO WORRY ABOUT. Moot. Nothing at all.
If from that you cannot figure it means tossing out an illogical GR solution, and finding something that does make coherent sense, I won't try again. In EM there is simply no comparable issue. Vector fiedls of dipole or quadrupole or any higher order multipole have entirely self-consistent configurations. There are no comparable symmetry constraints bedeviling GR's TT GW's. In Carver Mead's G4v, lowest multipole order is like in GR, quadrupole, but spatial component character of GW fields are completely analogous to equivalent EM ones. It works. Only tidal components of such will register with free floating mirrors of aLIGO, but initial calculations confirm the same overall registered response, but different angular details. Nothing observationally resolved viz-a-viz GR vs G4v yet - as explained previous posts.

Do not keep bringing up spurious issued - 'beads stresses'. Above should have been evident in #1. Take it or leave it - final effort to get through. Being charitable it really has been a genuine conceptual issue.

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18. expletives deletedRegistered Senior Member

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Schmelzer:

Thankyou for your response to my request for clarification of the philosophy versus physical confusion.

The question arises whether a non-physical "solution" to the equations is ever "logical" except in, or even in, the mathematical construct itself?

As far as I can read of your exchange with Q-reeus, the contention is that the physical OP challenges the physical validity of philosophical "logic" of "pure mathematical constructs".

That seems to be the starting stance from the OP. Whereas you introduce the purely "axiomatic self-consistency" aspect of the maths construct which the OP already challenges as to its validity.

Hence the OP assertion that such purely axiomatically derived mathematical GW "solutions" are not physically possible in the real world?

It seems to me that the different stances are as argued even before this discussion arose between you two; so I haven't learned anything different than what I already understood to be the difference between the physical and the purely philosophical and/or mathematical perspectives.

It also seems to me that it is that very difference in perspectives which is treated by the OP scenario and challenge; which effectively questions whether your stance, even though it may be "logical solutions" in purely mathematical axiomatic terms, is actually valid or not in physical reality terms?

Can you two arrive at a common understanding which distinguishes between the two aspects:

1) "axiomatically logical solutions", and;

2) "physical validity" of said "axiomatically logical solutions"

...with a view to agreeing that while 1) may be philosophically/mathematically "self consistent", it however may not be logically consistent with the physically real phenomena as per 2)?

That agreement and distinction is already there between you, I feel, but is buried amongst the semantical jousting and misunderstandings. That is all I have to observe for the moment on that issue between you. I will watch the further discussion with interest. Thankyou.

Last edited: Jul 16, 2016
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19. SchmelzerValued Senior Member

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My problem is that as formulated in #1 as in your variant it makes no sense to me. Logic is essentially mathematical logic. I accept Jaynes that probability theory is the logic of plausible reasoning, so, add probability theory. With this understanding of what means logic, a mathematical solution which violates logic is nonsense.

One can, of course, challenge the physical validity of GR, and prefer some alternative theory of gravity. What I'm doing too. But this does not mean that there is some logical problem with GR solutions.

The phrase "logically consistent with the physically real phenomena" makes IMHO no sense. And, by the way, I have a theory what he thinks, and would be ready to present some good counterarguments (ok, may be yet not for all imaginable answers, but for some). And he knows this and blocks this, by not answering my questions.

You know, nobody would answer "see above" as if the answer would be above, and then refuse to answer, if he would not feel that it may be dangerous to answer.

20. expletives deletedRegistered Senior Member

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Schmelzer:

It has long been my understanding that mathematical reasoning is a subset of logical reasoning per se. An axiom may be put to start a mathematical chain of reasoning which must be logically consistent with that starting axiom. That is the only "logical" aspect to mathematical reasoning from an axiom. In philosophy a postulated premise may be used as the starting point for a logically consistent philosophical chain of reasoning. But neither of these two chains of reasoning (ie, mathematical starting from axiom; philosophical starting from premise) has to be "logical" in the physically real sense having regard to the "logical chain of reasoning" derived directly from the starting Observationally Testable starting postulate for Testing the "physically real logicality" of any consequential reasoning chain and conclusions (purporting to be 'physically real solutions') which are valid within the evolving theory of that Natural Phenomena.

Your contentions with Q-reeus seems to conflate and confuse all three types of "chains of reasonings" under the same "logics" umbrella, but the "logics trains" are essentially differently based and must be carefully kept separate if a particular scenario is to be examined under the applicable type of logic train. As just explained, there is a 'purely axiomatic train' in mathematics; and a 'purely premises train' in philosophy; and 'physically real postulates train' in reasonings addressing the physically real phenomena.

What I see Q-reeus doing is questioning the physical validity of the first two 'logic trains' and its consequential conclusions in the thinking and logic of a physically real context.

That is what my observations, for my own understandings purposes, have teased out of your discussion with Q-reeus. Thankyou both for your interesting discussion to date on this OP.

Last edited: Jul 16, 2016
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21. PhysBangValued Senior Member

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The stresses to which I refer only bear on the very specific scenario that Q-reesus has designed. They seem to be saying that no energy is transferred to the system he describes and I'd like a fuller account of that claim.
By changing the relative location of objects in regions through which they pass, the gravitational waves impart a velocity on free test particles that can be resisted by friction. That is, the gravitational waves change the momentum of the systems they pass through.

I don't know what this question means. Interferometers don't measure the energy passes to a system (at least not directly). Q-reesus claims that gravity waves do not transfer energy to his bead system, but has offered no argument that this is the case.

22. expletives deletedRegistered Senior Member

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PhysBang:

Can you clarify for me please; when you say, "the system", are you referring to the space itself encompassed/occupied by the setup, or referring to the separated test masses (ie, 'beads') themselves?

You assume apriori that gravitational waves do what you say; but the whole OP is challenging that very assumption as unphysical, and offered arguments in support of the OP. And you have not explained the mechanism for energy being transferred into the 'beads' (ie, "free test particles"). Can you do that please so I can then follow your argument on that clarified basis?

I am unclear as to what aspects you are arguing/addressing. For example, the aLIGO setup is designed to detect any fluctuation in the distance in the 'legs' of space vacuum along which the laser beam travels between test masses (that is what produces any off-phase 'interference' signals). As far as I am aware, no actual GR GWs energy or effect is actually expected to be imparted on the test masses themselves. It is the laser travel distance fluctuations which are supposed to be detectable as set up. The test masses (having reflective surfaces) merely are there to maintain the to-and-fro 'lock' of phase of the laser beams, which any alleged GR GWs would 'de-lock' and so 'detected' because the reflections would move out of phase if the the vacuum/space itself which was traversed by the laser beam was distorted. Are we at cross purposes regarding the question whether GR GWs transfer energy to space itself or to beads/test mass motion?

Last edited: Jul 16, 2016
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23. PhysBangValued Senior Member

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The system in question is his loop of beads.
I'm just following the original Feynman argument as well as the published papers based on it. They can be found through the wikipedia link that Q-reesus provided in his OP. There exist these derivations and there are systems observed that lose energy exactly equal to the predictions of GR, so I have some confidence in these derivations.

I believe that the energy transferred to the LIGO system is very minute and thus of no import to the detection method. Q-reesus is attempting to claim that the gravity waves of GR cannot possibly transfer energy, not that gravity waves do not exist.