Q-reeus

4 hours ago, Mordred said:

 ...I had already made the connection from reading the original paper of this thread that the vector gravity model would have spin 1 statistics. As opposed to the spin 2 of GR. As mentioned earlier in this thread vectors are rank 1 tensors which corresponds, also according to how the opening paper is presented the Graviton would need to follow the spin 1/2 rules being in his paper of the fermion family this would correspond to the SU(2) group under the Pauli matrixes. Fermions anticommute (antisymmetric) while bosons commute.(Symmetric) as per the Pauli exclusion principle. This will correspond the  position and momentum operators of QM (QFT has different creation and annihilator operators) with which one being the field itself...

While it's true VTG hypothesizes fundamental (but evidently quite different) Fermionic components for both the photon and graviton, in each case these 'primitive' and massless Fermions are in VTG always coupled in Fermion-antiFermion pairs to give net spin-1 composite entities (photon and graviton) each obeying spin-1 Bose-Einstein statistics:
See point 4 under 2 - Postulates of the vector theory of gravity, and 11.3 - Photon as composite particle.

I suppose one rough analogy is Cooper pairing of electrons in superconductors.

Also in VTG it's only transverse GW's that are quantized as Fermion-antiFermion pair gravitons. The static/quasi-static 'longitudinal' gravitational field is unquantized i.e. purely classical. Seems odd maybe but Svidzinsky makes the case.

But yes any final settlement may be (unfortunately) much further out than what might be reasonably hoped.

4 hours ago, Mordred said:

 

28 minutes ago, michel123456 said:

Disgression about the reputation points. FYI as an external observer and simple user I noticed that the OP has minus 80 points. That is not good because it shows incivility or worse. Then you jumped in, with neg points also (for some to me unknown reason). After following your posts I came to the conclusion that you are simply unfamiliar with the Forum. For that reason I gave you some rep points so that you appear as neutral.IMHO there is good stuff in your posts. Interesting at least.

Thanks for a bit of thumbs up michel123456. My neg points were iirc initially earned in another thread. Whether justly so not worth arguing now that water has flowed under the bridge. Anyone can check back over my posting history if really interested. I don't covet points but find it perplexing as to any presumed criteria and voting rights.

Will just use this occasion to emphasize one thing. Regardless of any opinion of VTG, it's viability vs GR will all be decided decisively on just one issue - probably later in 2019. Namely, whether further multi-messenger NS-NS merger events continue to support, or contradict, Svidzinsky & Hillborn's critique as per
https://arxiv.org/abs/1804.03520
https://arxiv.org/abs/1812.02604
Until someone of significance, probably from LIGO_Virgo collaboration, provides a detailed direct response, might as well just sit back and wait.

27 minutes ago, Mordred said:

I for one care little about the reputation system. I do thank you for sharing the article but give me the pleasure of examining it my own way. I have learned over 35 years of studying physics that one never understands a theory until he understands the mathematics of such. I don't ever follow the hype often accompanying a theory. Its far too distracting, when the real fun is actually studying it yourself in detail. How else can one truly understand the mind of the author who wrote it.

OK understood. Best with your further studying there.

I'm about ready to just walk away from this place. There is just so little positive feedback, no 'thank you's' for providing useful inputs and links. And a VERY strange pattern of scoring that makes me wonder what the rules are.

2 hours ago, Mordred said:

...He doesn't have event horizons as he keeps the photon particle energy constant at the EH in so far as his redshift doesn't suggest the particle loses energy due to redshift but preserves its energy....

There is no event horizon because the exponential metric of VTG has no logical room for one! Redshift is not being 'suppressed' at all in VTG. It's naturally there and only in the entirely unphysical limit as r -> 0 would redshift approach infinite value, unlike the pathological GR Schwarzschild solution where it happens at r = 2M. According to Matt Visser et. al., an exponential metric has an inbuilt fail-safe feature that amounts to it being a 'traversible wormhole' with maximum curvature at r = M. I gave the link in Q3 back in my first post here:
https://www.scienceforums.net/topic/117068-vector-theory-of-gravity/?do=findComment&comment=1081799
If one really wants a straightforward, first-principles rigorous derivation of why exponential redshift is THE correct form, take a look at Appendix A here:
https://arxiv.org/abs/1606.01417

46 minutes ago, beecee said:

Well about as much usefulness of your fabricated interpretated criticisms of Koberlein's evaluation. I'll accept my "No peer review" error,  but we all nkow q-reeus that literally thousands of papers every year, most peer reviewed, are never heard of again, to be lost in cyber space.

I'm always puzzled though why you have never commented on the fact that his paper is being researched by many scientists in many quarters, without any fear or favour, and as erroneously denied by the author of the OP.

And of course your recognition of the scientific method in that his paper, like any paper, needs to "run the gauntlet" is also unknown.

These are facts. It does not nor has not invalidated GR in Koberlein's evaluation, and whether the aLIGO and VIRGO research around the world find likewise is not as yet known. So again, why can't you accept these facts, rather then making excuses?

Highlighted are the only words that matter in that rambling and disjointly worded piece. Since Svidzinsky's theory is in your mind so below par, why the continued aggressive posting?
Show your disdain by ignoring VTG. Give this thread a rest.

14 minutes ago, beecee said:

Anyway, I suggest you stay tuned, as I have more replies forthcoming, from impartial professionals, to evaluate this still hypothetical, yet to be peer reviewed paper....

Nothing useful will come from my tearing your distortions apart one by one. But above red highlighted is a hint of just how wrong you are in general. Kindly inform yourself of the easily verified fact that Svidzinsky's paper necessarily underwent very extensive peer review before being published!

On 1/9/2019 at 1:44 PM, beecee said:

Thanks for that.

Just received a reply via E-Mail on the Svidzinsky paper thus.....

 

From: Brian Koberlein <brian.koberlein@gmail.com>
Date: 1/9/2019 1:09:45 PM 
Subject: Re: General Relativity and Vector gravity 

Barry, 

If your forum member thinks this paper means GR is dead, they are either lying or don’t understand the paper. The paper presents an alternative gravity model known as a “background independent” model. These kinds of models have been studied for decades, usually in the hopes that they might provide some way to quantum theory. Nothing particularly new here. 

The author of the paper states explicitly that the gravity wave results are consistent with the predictions of GR, and points out that his model is also consistent with the data. He does this because background independent models have been known to disagree with GR in ways we can now prove experimentally. So basically, this is a “this alternative model isn’t dead yet!” He goes on to talk about dark energy as a way to argue that maybe we should look at the model further. 

Again, this is pretty standard for a speculative theoretical physics paper. It’s what we do. Come up with ideas to see if they work, because someday hopefully one of them will. There are literally thousands of papers like this out there, and none of them have disproved GR so far. 

In short, the paper doesn’t say GR is wrong. It actually says its right, and this model could also be right. It also doesn’t say black holes don’t exist, but instead claims that black holes wouldn’t have an event horizon. They would have an apparent horizon, which is basically an event horizon (except for really technical differences I won’t go into). The paper in no way makes GR dead, nor does it make the gravitational wave results invalid. 

Brian 

::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

On the reply, the claim re BH's that Brian detailed are exactly what I had in mind. I remember the sensationalist headlines a few years ago, re Hawking supposedly claiming BH's did not exist, based on similar quantum detail re the EH.

 

from the previous reply E-Mail....."The paper presents an alternative gravity model known as a “background independent” model. These kinds of models have been studied for decades, usually in the hopes that they might provide some way to quantum theory. Nothing particularly new here". 

https://en.wikipedia.org/wiki/Background_independence

Well if some mathematically challenged GR devotee-enthusiast can't personally poke an actual hole in VTG, why not do some shotgun emailing with the hope of netting at least one presumably GR expert figure, who actually replies and encouragingly suggests a hole or two are sort of there for real? Of course if said GR expert has been given a distorted picture (VERY likely!) of what unnamed 'anti-GR protagonist' (me) is actually claiming about VTG vs GR, there is a double issue at stake. But let's initially assume said GW expert's response is based on an accurately pitched query. Itemizing:

1: "If your forum member thinks this paper means GR is dead, they are either lying or don’t understand the paper."

That the respondent was accurately informed of my true position is right there severely in doubt.

2: "The paper presents an alternative gravity model known as a “background independent” model. These kinds of models have been studied for decades, usually in the hopes that they might provide some way to quantum theory. Nothing particularly new here."

What?! GR itself is THE quintessential example of a background independent theory! VTG is actually best characterized as a fixed prior geometry metric theory. And which has an effective background independence.

3: "The author of the paper states explicitly that the gravity wave results are consistent with the predictions of GR, and points out that his model is also consistent with the data."

Half true. Consistent with GR wrt e.g. the gross energy-loss and perihelion advance of an in-spiraling binary e.g. the famous Hulse-Taylor results. And with all but perhaps the final moments of detected merger event waveforms. Dramatically different wrt GW character, polarizations, and angular distribution patterns for amplitude/intensity.

4: "In short, the paper doesn’t say GR is wrong. It actually says its right, and this model could also be right."

Again, half true at best. Certain gross features of cosmological structure are equivalent e.g. FLRW metric, but in certain other respects there are fundamental differences. For instance how to naturally account for initial inflationary phase, and presently observed accelerated expansion are novel features of VTG.

5: "It also doesn’t say black holes don’t exist, but instead claims that black holes wouldn’t have an event horizon. They would have an apparent horizon, which is basically an event horizon (except for really technical differences I won’t go into)."

Huh? An event horizon is THE distinguishing characteristic of a BH! VTG's exponential metric contrasts sharply with GR's Schwarzschild metric. But only 'close up'. No horizons of any kind exist in VTG. Which is perfectly consistent with a VTG quiescent 'BH imitator' looking very black.

6: "The paper in no way makes GR dead, nor does it make the gravitational wave results invalid."

This comes full circle - back to point 1 above! I can only hope the respondent's mistakes were owing to a hurried skimming of Svidzinsky's paper. Email campaigns can be risky.

15 hours ago, studiot said:

 

1)

But you continue to complain about a 'negative response'; I looked back and confirmed that not only did I welcome warmly your first post, but you received several upvotes for it.

2 & 3)

I am an applied mathematician, not a cosmologist so I am more interested in the maths behind it than the cosmology itself.

I would have thought that someone who is 'new to this' would have asked what was meant when someone who has been studying and applying maths for more than 60 years made the comments I did.
Certain (mathematical) events stand out in that time. Several times I have had to unlearn what I was taught as 'gospel' in order to progress to more advanced Mathematics.
Vector theory was one of those times.
Physicists are prone to deploy a very simple version of mathematical vector theory, and neglect to say that their theories mostly need to be extended to affine spaces to be of any real use.
Integrals are vectors, continuous functions are vectors, and yes tensors are vectors.
Which is why the tensor - vector- scalar heirarchy is an unfortunate classification.

A vector is a member of one the two sets that are needed to make up a minimal vector space.
Useful vector spaces also often contain extra structure, by way of adding extra sets along with perhaps a few extra axioms.
It is this extra structure that distinguished one vector space from another.
Relationships between the members of the two or more sets in the vector space conform to a basic set of between 8 and 10 vector space axioms.

4)

I am sorry if you found the quoted question vague, I thought it simple and direct.

 

 

Point taken that vectors can have a much more general nature than that relevant to the physical description of Svidzinsky's VTG. You want expert input then why not do as I suggested and contact Svidzinky directly? His university webpage with contact details shown there:
http://iqse.tamu.edu/faculty.php?uname=asvidzinsky

6 hours ago, Mordred said:

Well regardless of your opinion I see little value in his article. I formed my own opinion of it via my own reading and study of his article. I am already familiar with the GW plotter site. As far as sensitivity goes I can literally get you papers that also state that LISA would be more sensitive. One of  those papers contains the original formula I provided. The paper itself is specific to a lecture  on GW waves and contained that rough 1010 back of the envelope calculation.

Here is NASA'a quick rundown on its precision.

"These signals are extremely small and require a very sensitive instrument to detect. For example, LISA aims to measure relative shifts in position that are less than the diameter of a helium nucleus over a distance of a million miles, or in technical terms: a strain of 1 part in 10²⁰ at frequencies of about a millihertz. "

https://lisa.nasa.gov/

In essence it follows precisely what I am stating. The detector will be able to detect a change many orders more fine that LIGO will. This isn't a mistake. Simple logic should tell you that if the signal strength is many orders weaker it will take a more sensitive detector to pick up that signal.

 A simple analogy is that if you have two digital multimeters and look at the specifications. The multimeter that that measure a microvolt will be more sensitive than one that can only pick up the Millivolts range. But hey if you wish to buy that low grade DMM feel free lol.

Its also a simple logic that a signal with a stronger radiated power will be easier to detect....the second formula directly correlates to that radiated energy. Obviously you will not grasp the relation between frequency and the energy of the signal.

 

 

LISA more sensitive - in it's own bandwidth of operation? Well obviously. Apples and oranges again. If on the other hand you are again insisting on applying that arcane third criteria for sensitivity while excluding the other two, that's your choice. The remainder of your post there is unfortunately too confused to be worth further replying to. In essence I sense an unwillingness to concede when proven wrong earlier on several quite mistaken and/or totally irrelevant claims.

5 hours ago, studiot said:

I haven't distorted anything.
In fact I have repeated offered you discussion about fundamental assumption or 'axioms' proposed by Svidzinsky
Discussion which you have steadfastly avoided.

Added to attitude like that displayed in the above quote you are likely to receive negative responses anywhere.

Further I observe that many of my earlier posts in this thread welcomed both the OP (who has now let us) and the subject here for adult debate, not playgrund catcalls.

First, please note I didn't carte blanche tar everyone with the same brush. Second, your own words here seem to be encouraging further negative scoring! Go check the continued hostility from one poster here in particular, who keeps up a barrage of negative commentary yet without incurring any negative scoring on his part. Interesting - no?

Now, wrt your 'axioms' issues, on checking back to your first post here, I note you stated the following:
"I was particularly interested in his distinction between 'vector' and 'tensor' (midway down the abstract) so my first task is to find out what he means by this, as tensors are technically vectors but only some vectors are tensors and GR relies on this."

That has it backwards - vectors are a rank 1 subset of tensors.
I note on p2 here you complained: "So no response to my vector field question then, and we still have to go offsite to read any replies?"

But I found no earlier specific question just a vague appeal for discussion on it. If the well structured manuscript itself is not sufficiently clear for your needs, consider emailing the author directly for further expert clarification. I'm a layman btw not claiming expert understanding of it's content.

On 1/7/2019 at 9:32 PM, Mordred said:

 Your still wrong on sensitivity. I even gave you a relevent formula....

I knew your understanding back there was quite wrong, but had to search around to find simple formulae clearly proving it. Check out the expression for energy transport rate (i.e. power density) for a plane monochromatic GW under 'Energy transport' here:
http://www.tapir.caltech.edu/%7Eteviet/Waves/gwave_details.html

Clearly no dependency on frequency, just ~ h^2. In complete analogy to the dependence on square of E field for power density of a plane monochromatic EM wave owing to an electric quadrupole oscillator. For instance compare eqn (76) to (77) p22 here:
www.phys.lsu.edu/~jarrell/COURSES/ELECTRODYNAMICS/Chap9/chap9.pdf
No unphysical f^2 factor tacked on there either. (That power always goes as E^2 or H^2 for an EM wave is independent of source multipole moment)
So what GW 'power density' is it that varies as f^2h^2? I don't particularly care since it has zilch to do with what actually matters re detection - strain amplitude. However because it is for whatever arcane reason actually sometimes used as a 3rd 'measure of detector sensitivity', one can guess it refers to a hypothetical 'accessible power density'. Based on some peculiar criteria evidently of some academic interest. Here is a nice site with a calculator to compare the two actually useful, non-misleading sensitivity criteria:
http://gwplotter.com/

On 1/7/2019 at 9:32 PM, Mordred said:

 Tell me why you would think that a detector incapable of picking up lower frequencies can possible be more sensitive than a detector that can only pick up higher frequencies when the frequency itself is directly related to the energy of that frequency ?

Last part is wrong - see above. And what is the point in trying to compare sensitivity of one detector way outside its design bandwidth with another one in the middle of its bandwidth?

On 1/7/2019 at 9:32 PM, Mordred said:

here is a simple formula E=hV the energy is directly proportional to the frequency... this is a very basic formula and is well established under physics...

What does the Planck relation between energy and frequency for a single photon have to do with power density in classical unquantized GW's? Nothing. They are unrelated quantities. Random stabs are not making you look good.

On 1/7/2019 at 9:32 PM, Mordred said:

 In order for a detector to pick up weaker signals that detector MUST have sufficient sensitivity to do so. LIGO does not have the required sensitivity to pick up signals in the microhertz range that are specified in the LISA proposal link I provided earlier.

See above. Irrelevant comparisons are just that - irrelevant.

On 1/7/2019 at 9:32 PM, Mordred said:

 Let me ask you another question seeing as your so strongly opposed to any refutation of the Vector gravity paper...

Don't distort my position! Which has consistently been here and elsewhere that Svidzinsky's VTG lists a range of potential advantages compared to GR or similar alternatives, but that the crucial decider will be nature. The still unresolved issue of actual GW mode type. I jumped in here to a thread now vacated by the OP, to provide useful links to articles not previously covered. A waste of time in hindsight given the continued almost universal negativity in response. So I learn about how it is to be even slightly non-mainstream at ScienceForums.net the hard way.

On 1/7/2019 at 9:32 PM, Mordred said:

 If two blackholes merge would that not be significantly different that if two neutron stars collide? The reason I ask this is that the paper under discussion specifies that BH's do not exist in vector gravity. Yet one of the first GW waves detected by LIGO was a BH merger which followed all the predictions including the production of GW waves of GR. It even had the correct ringdown and final mass of the merger event.

I'm not comfortable with everything Svidzinsky advocates - his rather peculiar NS EOS that supposedly allows much larger than usual masses being one.
Anyway, try searching for 'evidence of ring down echoes in black hole merger events' or similar. There are papers out there claiming GR is already in trouble because the detailed merger waveforms hint against pure BH-BH mergers.

On 1/7/2019 at 9:32 PM, Mordred said:

 On a side note linking an article where the author is defending himself in rebuttals merrily enhanced my lack of faith in his model

Given your own slew of mistaken and/or misdirected notions here, I have little faith in your lack of faith.

On 1/7/2019 at 9:32 PM, Mordred said:

 

18 minutes ago, beecee said:

...just as I know your position with your alternative/s hypotheticals.

Actually I don't think you do. Or certainly don't care to present it accurately if you do know it.

18 minutes ago, beecee said:

I know for a fact that V4G and/or any other model are still also rans, though to the credit of aLIGO, VIRGO, research is still being done to  test all, according to current known pricisions with available equipement. Although the greater precision of LISA may be needed to further validate GR or one of the other.

Forget what you were told earlier. LISA will be less sensitive not more, and will likely add little more than a stamp collecting catalog of 'SMBH' merger events. The crucial confirmation of either tensor or vector GW's will almost certainly have been long settled by the time it gets up and running.

18 minutes ago, beecee said:

...Need I point out that Svidzinky's has been murdered in some quarters in the opinions of some reputable experts, as per the article,...

There is NO reference, direct or indirect, to Svidzinsky's VTG in the article proper. so what are you talking about? Never mind, there is just a single reference, in the comments:
https://www.quantamagazine.org/troubled-times-for-alternatives-to-einsteins-theory-of-gravity-20180430/#comment-3905481088

1 hour ago, beecee said:

U'm actually referring to both...

Without till now ever stating that. So now revealed as a personal made up term of a quasi-generic nature.

1 hour ago, beecee said:

...as simply alternatives that have not surpassed GR and serious doubt s that they ever will.

Learn to distinguish between an assertion - as made above - and a proven established statement.

1 hour ago, beecee said:

There obviously has been plenty of spirited responses, ...

NONE in respect of what I wrote last post. But feel free to dredge up an exception (in the technical literature) I'm not aware of.

1 hour ago, beecee said:

In the meantime....

https://www.quantamagazine.org/troubled-times-for-alternatives-to-einsteins-theory-of-gravity-20180430/

Troubled Times for Alternatives to Einstein’s Theory of Gravity

New observations of extreme astrophysical systems have “brutally and pitilessly murdered” attempts to replace Einstein’s general theory of relativity.

extract:

There are also stand-alone theories, like that of physicist Erik Verlinde. According to his theory, the laws of gravity arise naturally from the laws of thermodynamics just like “the way waves emerge from the molecules of water in the ocean,” Zumalacárregui said. Verlinde wrote in an email that his ideas are not an “alternative theory” of gravity, but “the next theory of gravity that contains and transcends Einstein’s general relativity.” But he is still developing his ideas. “My impression is that the theory is still not sufficiently worked out to permit the kind of precision tests we carry out,” Archibald said. It’s built on “fancy words,” Zumalacárregui said, “but no mathematical framework to compute predictions and do solid tests.”

The predictions made by other theories differ in some way from those of general relativity. Yet these differences can be subtle, which makes them incredibly difficult to find.

Consider the neutron-star merger. At the same time that the Laser Interferometer Gravitational-Wave Observatory (LIGO) spotted the gravitational waves emanating from the event, the space-based Fermi satellite spotted a gamma ray burst from the same location. The two signals had traveled across the universe for 130 million years before arriving at Earth just 1.7 seconds apart.

These nearly simultaneous observations “brutally and pitilessly murdered” TeVeS theories, said Paulo Freire, an astrophysicist at the Max Planck Institute for Radio Astronomy in Bonn, Germany. “Gravity and gravitational waves propagate at the speed of light, with extremely high precision — which is not at all what was predicted by those [alternative] theories.”

Need I point out nothing in that article has 'brutally and pitilessly murdered' Svidzinsky's Vector Theory of Gravity? Evidently so.

22 minutes ago, Mordred said:

I don't find it extraordinary at all there is literally 100's of alternative theories competing against GR. Is it LIGO's job to counter them or is it the physics community in general ?

The staff at LIGO's duty is to collect the data....

This situation is different for one reason in particular. Svidzinsky and Hilborn have questioned the very basis of how to properly analyze GW detections:
https://arxiv.org/abs/1812.02604
Such a serious challenge surely demands a spirited response. Not silence.

19 minutes ago, beecee said:

 

Well put Mordred, and as supported by the papers.....

Speaking for the authors of a couple of papers supporting VG4 gravity, I suppose just as any Mother believes her child to be the most beautiful, would be a good explanation. I repeat though, contrary to some pushing the VG4, and their baseless claims re incalcitrance in mainstream circles, that has been absolutely shown to be total whining and baseless excuses.

 

You refer often to a 'GV4'. Maybe confusion with Carver Mead's G4v: https://arxiv.org/abs/1503.04866
Which shares features with and may be styled a rudimentary contemporary of Svidzinsky's Vector Theory of Gravity. But a web search reveals no such animal as 'GV4' gravity.

14 minutes ago, Mordred said:

Well for one thing LIGO has identified the sources of the GW waves it has detected. The paper clearly mentions that there is a distinct difference in the polarization angles for the h+ and the hx components between the 45 degree detection and the perpendicular to the detectors. Yet gravity waves have been detected by several detectors and those results can be compared to find the polarization angles with the current datasets available to distinquish between the two.

The theory also requires both photons and gravitons to be fermion/antifermion pairs yet the photon has spin characteristics of spin 1 which is different that the spin 2 characteristics detected by LIGO. The very design of the detector is specific to detecting a spin 2 quadrupole rather than a spin 1 dipolar wave. Gravitons and GR in general regardless of whether or not the graviton actually exists has successfully follow all the spin 2 characteristics

The paper claims to agree with the LIGO results but one has to ask how is this possible with such a distinctive difference in detectable polarization angles....

edit side note the paper also reminds me too much of vector electrogravity that I read back in the 90's

also the polarization angles detected by LIGO were used to identify the GW wave sources

 

Every objection there has been comprehensively dealt with in either the main published article, or subsequently in the updated arXiv article challenging validity of LIGO_Virgo analysis of NS-NS merger event GW170817. I find it telling that afaik no spokesperson(s) for LIGO_Virgo team have to date publicly responded to that challenge. Which imo is extraordinary.

7 minutes ago, Mordred said:

Good article Beecee... I seriously doubt that GR will be overturned by the VR gravity... The more I read the article the less confidence I have in it

Would you care to provide detailed, technically relevant reasons for that assessment?

2 hours ago, Mordred said:

strain isn't a measure of the detectors sensitivity. LISA will be able to detect much lower frequencies than LIGO. One related formula is the gravitational wave energy flux F∼f2h2 as LISA will be able to detect roughly 105 lower frequency this will correspond to roughly 1010 greater sensitivity.

higher frequencies are easier to detect the energy flux is greater

I could strongly dispute the correctness and/or relevance of every single statement made there, but am content to let it stand as a record against your name - assuming special editing permissions are not exercised later on. Best imo to now end this sidetrack off of main topic. Hopefully the disputed GR vs Vector Gravity GW results referred to earlier will be unambiguously resolved sooner rather than later - to both parties mutual agreement.

16 minutes ago, Mordred said:

did you miss this part when I already stated your correct on other factors being involved ? However your incorrect on LIGO being better than LISA. One other factor I didn't yet mention is seismic interference which wouldn't occur in space this is a serious limitation for LIGO

Er sorry yes I did miss that, maybe because the content in relevant email notification was what I responded to, and that had not included a later edit.

But I'm puzzled why you now evidently claim LIGO (currently - aLIGO) is overall less sensitive than what LISA is projected to be. You dispute accuracy of that chart in Wikipedia article I linked to earlier? All contributions to final detection sensitivity are implicitly contained in those curves. No?!

[PS - re seismic interference. I know they should have, but wonder how well LISA crowd have allowed for e.g. micro-meteorite bombardment, or random solar flares.]

11 minutes ago, Mordred said:

Why do you think I mentioned photon shot noise ?

I'd have to guess. Both aLIGO and LISA will try their best to deal with it. Is this your way of a backdoor admission that my reference to 'factors other than arm length' re greater peak strain sensitivity of aLIGO vs LISA is obviously true? So how well shot noise is handled will be one key factor in overall sensitivity. And without my wasting a lot of time pouring over technical data, it's a fair bet aLIGO can do it a lot better than LISA can. For whatever technical reasons. There are other charts available that illustrate the various contributions to overall sensitivity for the different GW detectors, but I'm not interested in chasing one down right now.

16 minutes ago, Mordred said:

The amplitude of the of the GW frequency and how closely the antenna resonates at  given frequency will give rise to the amount of strain. Greater strain is easier to detect than a smaller strain. The strain is the amount of change in arm lengths this will always depend on the frequency of the signal as well as the sensitivity the antenna is to that particular frequency.

h=ΔLL this is the basic strain formula that applies however your correct that other factors are involved. Such factors are the direction of the signal to the arm in terms of polarizations h+,hx the cross section. Photon shot noise also plays a factor in laser interferometers

There is no disputing the obvious fact measured strain is defined as fractional length change, or that, all other things being equal, it's directly proportional to incident GW amplitude (not power density i.e. intensity). However laser interferometers are not built on a resonance principle like the earlier generation resonant bar and similar detectors.

1 hour ago, Mordred said:

LISA would allow us to detect a spectrum of GW wavelengths that we would not be able to detect on Earth. In order for LIGO or LISA to work the arm lengths are critical to capture the required frequencies. In order to detect a wave the arm length must match a quarter of the wavelength the longer the arms the longer the wavelengths that can be detected. In essence LISA would be far more accurate in so far as it will be able to measure an extremely smaller amount of strain. It should also capture a greater number of events than LIGO.

As can be easily seen from the chart shown here: https://en.wikipedia.org/wiki/Gravitational-wave_astronomy
current aLIGO actually has a peak GW strain detection sensitivity around an order of magnitude greater than that projected for the vastly larger and still future LISA array.
So factors other than arm length evidently play a crucial role in actual instrument capabilities.

26 minutes ago, beecee said:

I see it as entirely relevant that mass/energy warps spacetime and that light follows geodesics in that spacetime. The magnetic field itself does not directly affect it as has been said. My apologies if you find that confusing, but I believe it is simply put and was understood by the author of the OP.

You know perfectly well what my point was, and that I obviously have had no confusion whatsoever over the fact of a magnetic field contributing to gravitation thus to light deflection.
And btw your method of reproduction of maths in that Quora article has introduced various artifacts that make it look somewhat nonsensical. Best to have just provided the link.

16 minutes ago, beecee said:

More correctly and as is made clear, the magnetic field just like any other form of mass/energy warps the spacetime in its vicinity, and light follows geodesics in that curved spacetime. 

Here's another verification quote from an expert.....

https://www.quora.com/Can-a-magnet-bend-light

Q: Can a magnet bend light?

Kris Walker, BSc Adv. Physics & Astrophysics, Monash University (2021)

Answered Sep 27, 2017

 

A; Yes, a magnetic field "has the capacity to bend spacetime and thus light". The Einstein field equations state that

Gμν=8πTμνGμν=8πTμν

If the energy-momentum tensor TμνTμν describes that of an electromagnetic field in free space then its value can be described by the Einstein-Maxwell equation for the electromagnetic stress-energy tensor

TEMμν=14π(F λμFνλ−14FσλFσλgμν)TμνEM=14π(Fμ λFνλ−14FσλFσλgμν)

This value contributes to the final value TμνTμν. The curvature will be negligible for small magnetic fields but for very strong ones the contribution is significant. Like always, the light will appear to curve when travelling a respective geodesic in this warped spacetime.

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I don't see the relevance of that 'more correctly' bit, but certainly the above references agree with my earlier quoted comments. Point I was making was that your originally cited reference was poorly written. First stating a magnetic field has no effect on light. Then after the blah blah blah middle portion, introduced a caveat towards the end that contradicted the first stated position. Far less confusing and potentially misleading, would be to have presented the correct relevant picture at the outset.

20 minutes ago, swansont said:

If the quadrupole mass term is small, then it won’t matter if the magnatic contribution is similar. In order for it to matter, the magnetic term needs to be appreciable, as compared to the mass. Do you have any evidence that it is?

Of course not. I'm not the one here proposing a possible optical test of gravitational deflection by a magnatar magnetic field. Everyone agrees it would be tiny compared to the primary gravitational influence namely magnatar mass. Just how small and how much other competing factors will potentially mask it is - to keep repeating - subject to many specifics, all in the realm of specialist astophysicists! I'm not a specialist astrophysicist.

19 minutes ago, swansont said:

But you were talking about the correction, of a higher-order mass distribution term. How big is that correction?

I'm not that specialist astrophysicist that would have a good handle on the answer. Just the quadrupole moment itself would depend on such specifics as spin rate and mass and detailed EOS for starters. All I pointed out was perturbing influences other than an ab initio assumed dipolar form magnetic field will be present and need to be considered. Any disagreement there?

6 hours ago, swansont said:

Even if this were the case, why would it matter? 

Because a quantitative evaluation of one influence has to be somehow extracted from that of existent competing ones. Even the very spatial form of a given magnatar magnetic field might evolve drastically over time and be very different at a given time to the naive expectation of a simple dipolar distribution.