Andre> fatal flaws in the paper were reported: 

Heh-heh... ROFL!!!

That critique is just plain stupid! The guy does not even know how to read! One expects more --- even from people in an economics department.

 That nature post is from 2015

According to the linked article,

http://iopscience.iop.org/article/10.1088/1742-6596/405/1/012019

and other you can google, f(R) predicts massive and massless propagating modes. The observed waves could be the massless modes; hence I don't think f(R) is ruled out by this observation.

The presence of 2 polarizations is by no means restricted to GTR

There are other theories  that suggest this result without the paradoxes of GTR

Moreover, Einstein was not able to predict the existence of dark matter, which other theories do automatically.

Unfortunately the maths of GTR implies infinite curvature and zero time passage at the black hole event horizon  and the black hole becomes a singularity- and yet the black hole has a radius,

In other theories the prediction is that  the force of gravity is exactly 6.25 times that of ordinary gravity at any horizon, including both the event horizon of black holes and the Cosmological event horizon

The solution is to alter the maths of GR.

Additionally GR falls down in a number of areas, so any new maths should also resolve these problems

Yes GR works in the weak fields of the the solar system, and Intermediate

fields of neutron stars. 

1). It produces infinite density singularities in the very strong fields

such as in black holes.

2).It does not necessarily explain dark matter in galaxy cores where we

know super-massive black holes exist and the galactic dark matter

therein,

3). It does not explain dark mater present in galactic halo's,and galactic

clusters such as the bullet cluster,

4).It does not explain the presence of cosmological dark matter as a whole.

5). It has not yet been fully corroborated by the studies of neutron stars

and in black holes.

6). It does not easily explain the presence of dark energy and cannot be

translated in quantum gravity.

7). It predicts that time stops at the event horizon

Here I enclose a number of publications which explain all of these

phenomena, whilst agreeing with the results of GR where it has been

thoroughly tested.

1).First to obviate the infinite density singularities.

1a)

https://www.researchgate.net/publication/32897680_An_advanced_dynamic_adaptation_of_Newtonian_equations_of_gravity?ev=prf_pub

1b)

https://www.researchgate.net/publication/269689554_The_formulation_of_Dynamic_Newtonian_advanced_gravity_DNAg?ev=prf_pub

2).Secondly we explain the presence of dark matter at the centre of the

galaxy.

2a)

https://www.researchgate.net/publication/228858219_Advances_in_Black_Hole_Gravitational_Physics_and_Cold_Dark_Matter_Modelling._The_Gravity_of_Dark_Matter

3) Thirdly it is possible to explain the presence of dark matter in the

galactic halo.

3a)

https://www.researchgate.net/publication/269689929_Advances_in_Black_Hole_Physics_and_Dark_Matter_Modelling_of_the_Galactic_Halo?ev=prf_pub

4). It is able to explain the presence of cosmological dark matter

https://www.researchgate.net/publication/32897680_An_advanced_dynamic_adaptation_of_Newtonian_equations_of_gravity

5). It is corroborated in neutron stars (including Data from radiation

damping ) and is corroborated by black hole studies.

5a)

https://www.researchgate.net/publication/32888463_An_advanced_modification_of_dynamicgravitation

5b).

https://www.researchgate.net/publication/269667939_Corroboration_of_Dynamic_Black_Hole_Gravitational_Physics_from_Observations_of_Cygnus_X-1

6) it explains dark energy and translates into quantum gravity

https://www.researchgate.net/publication/32899306_String_quintessence_and_the_formulation_of_advanced_quantum_gravity

7). It does not offer infinite time dilation at the event horizon

https://www.researchgate.net/publication/287213872_Finite_Gravitational_Time_Dilation_In_Black_Holes_Using_Dynamic_Newtonian_Advanced_Gravity_DNAg

Read full-text

Article An advanced dynamic adaptation of Newtonian equations of gravity

Article The formulation of Dynamic Newtonian advanced gravity, DNAg

Article Advances in Black Hole Gravitational Physics and Cold Dark M...

Article Advances in Black Hole Physics and Dark Matter Modelling of ...

Article An advanced modification of dynamic gravitation

Article Corroboration of Dynamic Black Hole Gravitational Physics fr...

Article String quintessence and the formulation of advanced quantum gravity

Article Finite Gravitational Time Dilation In Black Holes Using Dyna...

gravitational waves in viable f(R) theories under a non-zero background curvature. In general, an f(R) theory contains an extra scalar degree of freedom corresponding to a massive scalar mode of gravitational wave. For viable f(R) models, since there always exits a de-Sitter point where the background curvature in vacuum is non-zero, the mass squared of the scalar mode of gravitational wave is about the de-Sitter point curvature. However, in the presence of matter density in galaxy, the scalar mode can be heavy. Explicitly, in the exponential gravity model, the mass becomes almost infinity, implying the disappearance of the scalar mode of gravitational wave, while the Starobinsky model gives the lowest mass around 10−24eV, corresponding to the lowest frequency of 10−9 Hz, which may be detected by the current and future gravitational wave probes, 

http://arxiv.org/abs/1106.5582

GW don't change anything at the moment... they will only provide a better observation of the universe as far as strong, gravitational sources (black holes, neutrons stars etc) are concerned.

Every rotating non uniform (non spherical) mass distribution (quadrupole) indeed generates a gravitational potential which variates in time (making the LIGO's mirrors oscillate) with respect to a detection point. Nothing to do with dark energy and so on. Officially we still have to wait for the mechanisms of quantum gravity and the quantum nature of space. This is only a macroscopic astronomic phenomenon (which arrives to us apparently as a small, very weak phenomenon because of the great distance from the quadrupole). 

Less than 10 days after the anouncement, fatal flaws in the paper were reported:

https://www.researchgate.net/publication/294705090_A_first_critical_review_of_event_GW150914_observed_by_LIGO_detectors_Livingston_and_Hanford#feedback/165157

Data A first critical review of event GW150914 observed by LIGO d...

 Andre> fatal flaws in the paper were reported: 

Heh-heh... ROFL!!!

That critique is just plain stupid! The guy does not even know how to read! One expects more --- even from people in an economics department.

 No; f(R) theories, also, predict gravitational waves. They don't have anything to do with dark matter, since the latter is part of the matter part of the action and contributes through the energy-momentum tensor and not part of the gravitational part; and they don't forbid a cosmological constant term. Their principal focus is parametrizing inflation. 

While models may be constructed, where f(R) terms might contribute to both, first of all they don't forbid the ``usual'' forms, so it's hard to disentangle the contributions. 

Cf. http://arxiv.org/pdf/0805.1726v4.pdf for instance (this might be the paper K. Olaussen linked to; but the link doesn't work, unfortunately).

Stam> might be the paper K. Olaussen linked to; but the link doesn't work, unfortunately).

I should have checked that the link worked. I have fixed it now (repeated below); it is a different paper.

http://iopscience.iop.org/article/10.1088/1742-6596/405/1/012019

Note added: It seems to me that the Link mechanism of ResearchGate automatically does some mangling of inserted links, some time after one has checked that the links actually works...

 Though the new link points to ``request full-text'' on researchgate-this http://iopscience.iop.org/article/10.1088/1742-6596/405/1/012019/pdf

is the link to the article itself. It should be stressed, however, in regard to the statements made in the question, that setting the cosmological constant to zero in this model is done by hand-nothing forbids including it. Nor does the fact that it describes massive modes imply that it can't be coupled to matter, in particular dark matter, whose polarization need not be that of massive gravitons.