Doubts about GR (split from Exclusive: Grave doubts over LIGO’s discovery of gravitational waves)

[swansont]

7 hours ago, Q-reeus said:

I also see you or someone has seen fit to simply vanish a post (maybe others - only noticed this one by chance) of mine formally in p2 here:
https://www.scienceforums.net/topic/117103-no-energy-conservation-in-photon-by-ehf-f↓-in-space-of-expansion/
Now have an idea of the kind of editorial freedom wielded here. And a fair idea who successfully pressed for that particular case of 'post -> poof'.

!

Moderator Note

It was moved to the trash can, for being completely off-topic. As I have communicated, such posts are inappropriate.

 

19 hours ago, Q-reeus said:

Could someone in the know tell me who exactly had a hand in having this forked thread booted to Speculations?

!

Moderator Note

That would be me. 

 

7 hours ago, Q-reeus said:

Regarding the snide remarks and outside issues dragged in, please go back and check who initiated, on several occasions, snide remarks and bringing in of extraneous issues from elsewhere. All before I decided to respond. I'm betting though no official warning notice appears against that member's offending posts. I can live with that kind of thing.

!

Moderator Note

You have received no official warnings, either. Just moderator notes, and if you had read them, you would note an admonishment to everyone engaging in such behavior.

But if you keep up with the off-topic commentary, that will change

 

[beecee]

http://science.sciencemag.org/content/360/6395/1342

A precise extragalactic test of General Relativity:

Testing General Relativity on galaxy scales

Einstein's theory of gravity, General Relativity (GR), has been tested precisely within the Solar System. However, it has been difficult to test GR on the scale of an individual galaxy. Collett et al. exploited a nearby gravitational lens system, in which light from a distant galaxy (the source) is bent by a foreground galaxy (the lens). Mass distribution in the lens was compared with the curvature of space-time around the lens, independently determined from the distorted image of the source. The result supports GR and eliminates some alternative theories of gravity.

Science, this issue p. 1342

Abstract:

Einstein’s theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens ESO 325-G004 provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, γ. By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that γ = 0.97 ± 0.09 at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

https://www.forbes.com/sites/startswithabang/2018/06/21/einstein-wins-again-general-relativity-passes-its-first-extragalactic-test/#f92ef682f577

Einstein Wins Again! General Relativity Passes Its First Extragalactic Test:

extract:

For the first time, we've been able to perform a direct test of General Relativity outside of our Solar System and get solid, informative results. The ratio of the Newtonian potential to the curvature potential, which relativity demands be equal to one but where alternatives differ, confirms what General Relativity predicts. Large deviations from Einstein's gravity, therefore, cannot happen on scales smaller than a few thousand light years, or for masses the scale of an individual galaxy. If you want to explain the accelerated expansion of the Universe, you can't simply say you don't like dark energy and throw Einstein's gravity away. For the first time, if we want to modify Einstein's gravity on galactic-or-larger scales, we have an important constraint to reckon with.

 

I am a Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges. I have won numerous awards for science writing since 2008 for my blog, Starts With A Bang, inclu...

 MORE

Astrophysicist and author Ethan Siegel is the founder and primary writer of Starts With A Bang! His books, Treknology and Beyond The Galaxy, are available wherever books are sold.

<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

In reality, and if we are all  honest with ourselves, there can never really be any theory that one could call complete. But again, at this time GR is the best we have and has performed magnificently being head and shoulders above anything else.

Edited December 1, 2018 by beecee

[Q-reeus]

10 hours ago, beecee said:

http://science.sciencemag.org/content/360/6395/1342

A precise extragalactic test of General Relativity:

Testing General Relativity on galaxy scales

Einstein's theory of gravity, General Relativity (GR), has been tested precisely within the Solar System. However, it has been difficult to test GR on the scale of an individual galaxy. Collett et al. exploited a nearby gravitational lens system, in which light from a distant galaxy (the source) is bent by a foreground galaxy (the lens). Mass distribution in the lens was compared with the curvature of space-time around the lens, independently determined from the distorted image of the source. The result supports GR and eliminates some alternative theories of gravity.

Science, this issue p. 1342

Abstract:

Einstein’s theory of gravity, General Relativity, has been precisely tested on Solar System scales, but the long-range nature of gravity is still poorly constrained. The nearby strong gravitational lens ESO 325-G004 provides a laboratory to probe the weak-field regime of gravity and measure the spatial curvature generated per unit mass, γ. By reconstructing the observed light profile of the lensed arcs and the observed spatially resolved stellar kinematics with a single self-consistent model, we conclude that γ = 0.97 ± 0.09 at 68% confidence. Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

https://www.forbes.com/sites/startswithabang/2018/06/21/einstein-wins-again-general-relativity-passes-its-first-extragalactic-test/#f92ef682f577

Einstein Wins Again! General Relativity Passes Its First Extragalactic Test:

extract:

For the first time, we've been able to perform a direct test of General Relativity outside of our Solar System and get solid, informative results. The ratio of the Newtonian potential to the curvature potential, which relativity demands be equal to one but where alternatives differ, confirms what General Relativity predicts. Large deviations from Einstein's gravity, therefore, cannot happen on scales smaller than a few thousand light years, or for masses the scale of an individual galaxy. If you want to explain the accelerated expansion of the Universe, you can't simply say you don't like dark energy and throw Einstein's gravity away. For the first time, if we want to modify Einstein's gravity on galactic-or-larger scales, we have an important constraint to reckon with.

 

I am a Ph.D. astrophysicist, author, and science communicator, who professes physics and astronomy at various colleges. I have won numerous awards for science writing since 2008 for my blog, Starts With A Bang, inclu...

 MORE

Astrophysicist and author Ethan Siegel is the founder and primary writer of Starts With A Bang! His books, Treknology and Beyond The Galaxy, are available wherever books are sold.

<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

In reality, and if we are all  honest with ourselves, there can never really be any theory that one could call complete. But again, at this time GR is the best we have and has performed magnificently being head and shoulders above anything else.

When mining with the evident hope of finding a 'dagger' article(s) to 'kill' my arguments here, it pays to actually understand what said article(s) really covers.
Important clue in your own reproduced Abstract re ScienceMag article (non-paywall version: https://arxiv.org/abs/1806.08300):

Quote

Our result is consistent with the prediction of 1 from General Relativity and provides a strong extragalactic constraint on the weak-field metric of gravity.

WEAK FIELD. Immediately, the finding cannot be a threat to either of the two rival to GR theories mentioned earlier this thread. Both of which are known to reproduce all the weak-field 'confirmations' of GR. So what 'other theories' have been ruled out here? Well the Forbes article makes it pretty clear - MOND type theories meant to do away with dark matter. The authors, as typically done, forget to mention that leaves quite a few rival theories to GR intact, which all likewise pass this galactic lensing study findings.
Sorry - your dagger appears to be pointing inwards. Since you failed to pick up on the weak field implications. Had you done so, it would have been pointless posting the links and cut and paste selections. Back to mining the internet for more ammo.

[beecee]

5 hours ago, Q-reeus said:

When mining with the evident hope of finding a 'dagger' article(s) to 'kill' my arguments here, it pays to actually understand what said article(s) really covers.
Important clue in your own reproduced Abstract re ScienceMag article (non-paywall version: https://arxiv.org/abs/1806.08300):

Actually you have everything arse up.....Firstly I don't carry any dagger,  secondly you do not have an argument, you have a skewered version of a weird overall interpretation of GR. GR at this time still stands as unchallenged as our theory of gravity....dem de there are der facts!  And the reason it still stands as unchallenged is because it has not yet been falsified, and no other hypothetical can predict anymore, though this appears to be where you are caught in your own personal interpretation loop.

Quote

WEAK FIELD. Immediately, the finding cannot be a threat to either of the two rival to GR theories mentioned earlier this thread. Both of which are known to reproduce all the weak-field 'confirmations' of GR. So what 'other theories' have been ruled out here?  Back to mining the internet for more ammo.

Your apparent paranoia re daggers is well just that.....paranoia. And of course I do no more mining of the Internet then you or anyone else.

Whether rival hypotheticals can be ruled out is neither here nor there...This recent experimental result supports further GR, along with GW's as predicted. GR remains our chief working model of gravity.

Again as you constantly are ignoring the fact, any of your pet hypotheticals are always being looked at, tested and researched, the same as GR is being constantly tested at the same time...all by professional experts, not rank amateurs like you or me. And of course they have absolutely no reason to fudge, ignore, fabricate, or in any other way attempt any of the paranoid recalcitrance that many anti mainstream actors like to accuse them of, for many varied personal agendas. In other words, there is no conspiracy in mainstream science, just as there is no conspiracy with other well known accepted notable world events like 9/11 and the Moon landings.

Edited December 1, 2018 by beecee

[beecee]

17 hours ago, beecee said:

In reality, and if we are all  honest with ourselves, there can never really be any theory that one could call complete. But again, at this time GR is the best we have and has performed magnificently being head and shoulders above anything else.

Hiya again q-reeus...It's quite notable,  how you never commented on the final paragraph in my post. It is as you know deep down, 100% factual, and if you are not here to be contrary just for the sake of contrariness, then you should acknowledge that fact, as I have constantly inferred throughout this and other threads.

Anyway once again, I thought I would continue with revealing the error of your ways and found another interesting late 2016 paper.......https://arxiv.org/pdf/1609.09781.pdf

Abstract:

For the last 100 years, General Relativity (GR) has taken over the gravitational theory mantle held by Newtonian Gravity for the previous 200 years. This article reviews the status of GR in terms of its self-consistency, completeness, and the evidence provided by observations, which have allowed GR to remain the champion of gravitational theories against several other classes of competing theories. We pay particular attention to the role of GR and gravity in cosmology, one of the areas in which one gravity dominates and new phenomena and effects challenge the orthodoxy. We also review other areas where there are likely conflicts pointing to the need to replace or revise GR to represent correctly observations and consistent theoretical framework. Observations have long been key both to the theoretical liveliness and viability of GR. We conclude with a discussion of the likely developments over the next 100 years.

extract:

"General Relativity is also unique among theories of fundamental interactions in the Standard Model. Like electromagnetism, but unlike the strong and weak interactions, its domain of validity covers the entire range of length scales from zero to infinity. However, unlike the other forces, gravity as described by General Relativity acts on all particles. This implies that the theory does not fail below the Planck scale. All gravitational phenomena, from infinitesimal scales to distances beyond the observable universe, may be modelled by General Relativity. We may therefore formulate a mathematically rigorous description of General Relativity: it is the most complete theory of gravity ever developed."

. Conclusions:

GR may well survive for another 100 years. After all, Newtonian gravity was around for 200 years. GR has just reached its peak, when data and computing power have caught up with the theory. We are at a pivotal moment in the history of GR. We are on the point of confirming beyond reasonable doubt all its predictions throughout its entire domain of validity. We have seen how modern cosmology is faced with big questions which touch the very foundations of physics. What is this form of matter which interacts only with gravity and apparently with nothing else? Why is the expansion of the universe accelerating? What caused the universe to undergo a period of rapid expansion soon after the Big Bang? These questions, motivated by cosmological observations, lead to questions about fundamental physics. Are there forces and interactions besides the four we know of, that is, gravity, electromagnetism, and the strong and weak nuclear forces? Are there particles beyond the Standard Model? What determines the value of the fundamental constants of nature? What is the real structure of spacetime? Are there extra dimensions? Science needs data, so each of these questions must be addressed through careful experiment. The challenge of modern experimental physics is to probe nature at extreme distances and energies, well outside the capabilities of the instruments that were available to Einstein. It has certainly come a long way, as shown by the detection of gravitational waves in 2015, a feat which was thought to be impossible by many of Einstein’s contemporaries.

General Relativity is not the final theory of gravity, for there is no such thing. As General Relativity turns 100, we would do well to celebrate it with a healthy does of scientific scepticism. Long live General Relativity, and a big welcome to its eventual replacement, whether in our lifetime or not.

Acknowledgments: George F. Smoot acknowledges support through his Chaire d’Excellence Université Sorbonne Paris Cité and the financial support of the UnivEarthS Labex programme at Université Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02). I.D. acknowledges that the research work disclosed in this publication is partially funded by the REACH HIGH Scholars Programme—Post-Doctoral Grants. The grant is part-financed by the European Union, Operational Programme II—Cohesion Policy 2014–2020.

Author Contributions: All the authors conceived the idea and contributed equally.

Conflicts of Interest: The authors declare no conflict of interest.

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You really need to consider in the final paragraph the highlighted, underlined sentence, which is all I have been trying to get you to understand, and may I say what the others on this forum have also tried to get you to understand, not to mention the myriads of reputable links I have given you, pointing to the error in your thinking. Perhaps you should understand that you need to get past any preconceived agenda that you may have?

Hope that helps.

Edited December 1, 2018 by beecee

[Q-reeus]

5 hours ago, beecee said:

...You really need to consider in the final paragraph the highlighted, underlined sentence, which is all I have been trying to get you to understand, and may I say what the others on this forum have also tried to get you to understand, not to mention the myriads of reputable links I have given you, pointing to the error in your thinking. Perhaps you should understand that you need to get past any preconceived agenda that you may have?

Hope that helps.

Only to further demonstrate your confused thinking and erroneous claims. I could hope you would lay off continued serial posting here. But knowing you that is sadly unlikely.

[beecee]

1 hour ago, Q-reeus said:

Only to further demonstrate your confused thinking and erroneous claims. I could hope you would lay off continued serial posting here. But knowing you that is sadly unlikely.

This isnt about me q-reeus...this is about you contradicting the world in general....Serial posting??? It actually appears you just resent critical acclaim of your error ridden, anti GR stance. While GR remains on top of the ladder though, that will continue.

 

•  Again you fail to comment on.... "General Relativity is not the final theory of gravity, for there is no such thing. As General Relativity turns 100, we would do well to celebrate it with a healthy does of scientific scepticism. Long live General Relativity, and a big welcome to its eventual replacement, whether in our lifetime or not". and...."In reality, and if we are all  honest with ourselves, there can never really be any theory that one could call complete. But again, at this time GR is the best we have and has performed magnificently being head and shoulders above anything else".  

1. http://www.staff.science.uu.nl/~hooft101/gravitating_misconceptions.html

 

Edited December 2, 2018 by beecee

[Q-reeus]

1 hour ago, beecee said:

This isnt about me q-reeus...this is about you contradicting the world in general....Serial posting??? It actually appears you just resent critical acclaim of your error ridden, anti GR stance. While GR remains on top of the ladder though, that will continue.

 

•  Again you fail to comment on.... "General Relativity is not the final theory of gravity, for there is no such thing. As General Relativity turns 100, we would do well to celebrate it with a healthy does of scientific scepticism. Long live General Relativity, and a big welcome to its eventual replacement, whether in our lifetime or not". and...."In reality, and if we are all  honest with ourselves, there can never really be any theory that one could call complete. But again, at this time GR is the best we have and has performed magnificently being head and shoulders above anything else".  

1. http://www.staff.science.uu.nl/~hooft101/gravitating_misconceptions.html

 

I could quote you from elsewhere as having stated on numerous occasions that GR is 'as perfect a theory as could ever be' (exact words may vary but that was your position).
Since then you have picked up on articles toning that down somewhat - like your bold text quote above. What exactly you are inferring re my position baffles me. Nothing there to really comment on. It's a safe statement re 'GR is not the last word' - but the hidden subtext to that is 'which will only be modified via a quantum gravity 'final theory'.

As for the 't Hooft article - stop being lazy. Reproduce here any passage(s) specifically bearing on whatever your unstated, notionally relevant point actually is.

[beecee]

2 hours ago, Q-reeus said:

I could quote you from elsewhere as having stated on numerous occasions that GR is 'as perfect a theory as could ever be' (exact words may vary but that was your position).

No you couldn't. The only scientific theory I see as valid to that extent is evolution  of life, which of course you would agree with, and I have never used the word perfect in that regard, and have always said that it is as certain as one could hope for.With GR and the BB reasonably close behind, and my usual statement that all theories grow in certainty over time and as they remain observationaly valid.

Quote

Since then you have picked up on articles toning that down somewhat - like your bold text quote above. What exactly you are inferring re my position baffles me. Nothing there to really comment on. It's a safe statement re 'GR is not the last word' - but the hidden subtext to that is 'which will only be modified via a quantum gravity 'final theory'.

The facts are that contrary to your own position with regards to GR already being in serious doubt, at this time, the evidence says no it is not in any serious doubt, and again no other challenger can do as well withing that zone of applicability. And you questioning that undoubted position is why precisely why this was moved to speculation. Does that clear it up for you?

Quote

As for the 't Hooft article - stop being lazy. Reproduce here any passage(s) specifically bearing on whatever your unstated, notionally relevant point actually is.

I can produce many reputable articles from reputable scientists disputing  the many positions and agendas of the usual anti GR brigade and their fruitless crusades.

Edited December 2, 2018 by beecee

[Q-reeus]

8 hours ago, beecee said:

...The facts are that contrary to your own position with regards to GR already being in serious doubt, at this time, the evidence says no it is not in any serious doubt, and again no other challenger can do as well withing that zone of applicability.

https://www.scienceforums.net/topic/117068-vector-theory-of-gravity/?do=findComment&comment=1081799

You evidently have a conveniently short memory - or just straight-out sheer 'GR = Truth' prejudice.

8 hours ago, beecee said:

And you questioning that undoubted position is why precisely why this was moved to speculation. Does that clear it up for you?

No. There is no objective justification for booting this forked thread to Speculations. That many GR buffs and even famous authority figures, and also higher-ups here, cannot properly handle the straightforward and entirely unambiguous meaning of R_μν = 0 (in vacuo), is no reason to characterize my pointing out it's rigorously logical consequences as 'speculation'. But I well understand why forum 'realpolitik' has processed it here differently. There are conflicting positions on 'gravity does/does not gravitate' among GR authorities. Unfortunate fact.

8 hours ago, beecee said:

I can produce many reputable articles from reputable scientists disputing  the many positions and agendas of the usual anti GR brigade and their fruitless crusades.

As you see it - as one having zero technical expertise to pass objective judgement.

[beecee]

4 hours ago, Q-reeus said:

https://www.scienceforums.net/topic/117068-vector-theory-of-gravity/?do=findComment&comment=1081799

You evidently have a conveniently short memory - or just straight-out sheer 'GR = Truth' prejudice.

I remember it very well. I also remember some of the errors in your thinking and obscure interpretation on the matter as others pointed out. Again, GR at this time is not in any serious doubt. It remains secure and you have yet to show otherwise, in spite of your crusade.

Quote

No. There is no objective justification for booting this forked thread to Speculations. That many GR buffs and even famous authority figures, and also higher-ups here, cannot properly handle the straightforward and entirely unambiguous meaning of R_μν = 0 (in vacuo), is no reason to characterize my pointing out it's rigorously logical consequences as 'speculation'. But I well understand why forum 'realpolitik' has processed it here differently. There are conflicting positions on 'gravity does/does not gravitate' among GR authorities. Unfortunate fact.

Please, don't be so nonsensical. Let me drill it into to you again...this isn't about me...it isn't about this forum or your erroneous claims...It isn't about science academia in general, that again you are making erroneous claims about. This is now all about the silly conspiracy nonsense you are inferring and that  has shown on many occasions to be totally fabricated in the minds of anti relativists. Do you also accept the 9/11 nonsense? Your claims are on the same level.

Quote

As you see it - as one having zero technical expertise to pass objective judgement.

I have never shied away from my zero technical expertise, and have been up front in that regard on this forum. What are your technical expertise? 

ps: Oh you forgot Q-reeus to reply to my answer below following another of your baseless accusations....

12 hours ago, beecee said:

No you couldn't.

So what is it? You can't back up what you claimed and was mistaken? You were telling porky pies? Or just simply frustration on your part in not being able to show that GR is finished. 

Of course the fact that as yet GR is not in any doubt is why this is in speculation.

Edited December 2, 2018 by beecee

[Phi for All]

22 hours ago, beecee said:

Hiya again q-reeus...It's quite notable,  how you never commented on the final paragraph in my post.

17 hours ago, Q-reeus said:

Only to further demonstrate your confused thinking and erroneous claims. I could hope you would lay off continued serial posting here. But knowing you that is sadly unlikely.

16 hours ago, beecee said:

This isnt about me q-reeus...this is about you contradicting the world in general.

15 hours ago, Q-reeus said:

I could quote you from elsewhere as having stated on numerous occasions that GR is 'as perfect a theory as could ever be' (exact words may vary but that was your position).

5 hours ago, Q-reeus said:

https://www.scienceforums.net/topic/117068-vector-theory-of-gravity/?do=findComment&comment=1081799

You evidently have a conveniently short memory - or just straight-out sheer 'GR = Truth' prejudice.

!

Moderator Note

Both of you need to stop the bickering and veiled personal attacks, as well as bringing up arguments from other forums. This isn't allowed here, as it drags perfectly good discussions into the dirt, and requires members to go elsewhere in order to know what you're on about.

If you can't argue the science without making it personal, you don't belong here. The sniping stops NOW.

 

[beecee]

The whole premise of this so called debate is that GR is wrong and has been superseded by an alternative model, and that scientific academia are simply being recalcitrant and stubborn in accepting that as a fact.

Of course it is obvious it is not a fact and just plain stupid to believe that science/cosmology is simply refusing to let go. I have even posted a "sensationalistic headline article re GW's and the possibility that it maybe more attuned to another model other then GR type GW's. As yet there is no definitive evidence that shows that GR type GW's is invalid, and in contradiction to the erroneous claims of recalcitrance  by the many scientists at VIRGO and aLIGO, they are considering it as many other scientists around the world are considering and researching it. The BICEP2 error claiming evidence of "rapid inflation" was due to an enthusiastic driven preemptive announcement.  In double quick time though, fellow scientists were quick to point out the more likeley scenario of "dust contamination" A great example of science correcting science and moving ahead and evident in life everyday of every year as further new observations are made. 

But of course any evidence found perhaps questioning any incumbent scientific model such as GR, which we all know has an outstanding absolutely incredible track record, must be conclusive to have the incumbent automatically superseded as it appears is claimed here. Any new hypotheticals, claiming to be better then some well held incredibly accurate and predictive incumbent model, needs to "run the gauntlet" just as the incumbent model had done. So far that hasn't happen. So far GR still reigns as supreme and the best theory of gravity we have. That position at this time, despite claims by the authors and creators of new models, and their  supporters has not altered.

Here is a article and link discussing the many other models of gravity and the demise of most of them......

Apr 30, 2018

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:

"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.”

"Further limits come from new pulsar systems. In 2013, Archibald and her colleagues found an unusual triple system: a pulsar and a white dwarf that orbit one another, with a second white dwarf orbiting the pair. These three objects exist in a space smaller than Earth’s orbit around the sun. The tight setting, Archibald said, offers ideal conditions for testing a crucial aspect of general relativity called the strong equivalence principle, which states that very dense strong-gravity objects such as neutron stars or black holes “fall” in the same way when placed in a gravitational field. (On Earth, the more familiar weak equivalence principle states that, if we ignore air resistance, a feather and a brick will fall at the same rate.)"

 

"The triple system makes it possible to check whether the pulsar and the inner white dwarf fall exactly the same way in the gravity of the outer white dwarf. Alternative-gravity theories assume that the scalar field generated in the pulsar should bend space-time in a much more extreme way than the white dwarf does. The two wouldn’t fall in a similar manner, leading to a violation of the strong equivalence principle and, with it, general relativity".

 

"Over the past five years, Archibald and her team have recorded 27,000 measurements of the pulsar’s position as it orbits the other two stars. While the project is still a work in progress, it looks as though the results will be in total agreement with Einstein, Archibald said. “We can say that the degree to which the pulsar behaves abnormally is at most a few parts in a million. For an object with such strong gravity to still follow Einstein’s predictions so well, if there is one of these scalar fields, it has to have a really tiny effect.”

The test, which should be published soon, will put the best constraints yet on a whole group of alternative gravity theories, she added. If a theory only works with some additional scalar field, then the field should change the behavior of the pulsar. “We have such sensitive tests of general relativity that they need to somehow hide the theory’s new behavior in the solar system and in pulsar systems like ours,” Archibald said.

The data from another pulsar system dubbed the double pulsar, meanwhile, was originally supposed to eliminate the TeVeS theories. Detected in 2003, the double pulsar was until recently the only binary neutron-star system where both neutron stars were pulsars. Freire and his colleagues have already confirmed that the double pulsar’s behavior is perfectly in line with general relativity. Right before LIGO’s October announcement of a neutron-star merger, the researchers were going to publish a paper that would kill off TeVeS. But LIGO did the job for them, Freire said. “We need not go through that anymore.”

"A few theories have survived the LIGO blow — and will probably survive the upcoming pulsar data, Zumalacárregui said. There are some Horndeski and beyond-Horndeski theories that do not change the speed of gravitational waves. Then there are so-called massive gravity theories. Ordinarily, physicists assume that the particle associated with the force of gravity — the graviton — has no mass. In these theories, the graviton has a very small but nonzero mass. The neutron-star merger puts tough limits on these theories, Zumalacárregui said, since a massive graviton would travel more slowly than light. But in some theories the mass is assumed to be extremely small, at least 20 orders of magnitude lower than the neutrino’s, which means that the graviton would still move at nearly the speed of light"

 

"There are a few other less well-known survivors, some of which are important to keep exploring, Archibald said, as long as dark matter and dark energy remain elusive. “Dark energy might be our only observational clue pointing to a new and better theory of gravity — or it might be a mysterious fluid with strange properties, and nothing to do with gravity at all,” she said.

Still, killing off theories is simply how science is supposed to work, argue researchers who have been exploring alternative gravity theories. “This is what we do all the time, put forward a working hypothesis and test it,” said Enrico Barausse of the Astrophysics Institute of Paris, who has worked on MOND-like theories. “99.9 percent of the time you rule out the hypothesis; the remaining 0.1 percent of the time you win the Nobel Prize.”

"Schmidt thinks it’s necessary to measure the laws of gravity on large scales as directly as possible, using ongoing and future large galaxy surveys. “For example, we can compare the effect of gravity on light bending as well as galaxy velocities, typically predicted to be different in modified-gravity theories,” he said. Researchers also hope that future telescopes such as the Square Kilometer Array will discover more pulsar systems and provide better accuracy in pulsar timing to further improve gravity tests. And a space-based replacement for LIGO called LISA will study gravitational waves with exquisite accuracy — if indeed it launches as planned in the mid-2030s. “If that does not see any deviations from general relativity, I don’t know what will,” said Barausse."

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While we can say that GR along with all scientific theories are being put to the test everyday of every year by many professional scientists in professional ways, no one that claims to be "impartial"  can at this time claim that GR is in any serious doubt. It still stands as our superior model of gravity.

Will the SKA  as per the article and as I have previously mentioned throw any more tests for GR? Will the space based LISA that will further add accuracy to GW's detection, enable us to use further more precise  tests of gravity? Will they re-enforce GR, or show limitations on it and enhance the viability of any other alternative?  We don't know as yet but my money is still on GR. 

[beecee]

Here's a couple of nice aLIGO video [around 15 minutes long] on GW's, there discoveries, and the potential consequences.........

https://www.youtube.com/watch?v=XQMKODLyeS4

https://www.youtube.com/watch?v=O_puOPsuR4Q