What's new inPhysics in ManySheeted SpaceTimeNote: Newest contributions are at the top! 
Year 2016 
Antimatter as dark matter?
It has been found in CERN (see this ) that matter and antimatter atoms have no differences in the energies of their excited states. This is predicted by CPT symmetry. Notice however that CP and T can be separately broken and that this is indeed the case. Kaon is classical example of this in particle physics. Neutral kaon and antikaon behave slightly differently. This finding forces to repeat an old question. Where does the antimatter reside? Or does it exist at all? GUTs predicted that baryon and lepton number are not conserved separately and suggested a solution to the empirical absence of antimatter. GUTs have been however dead for years and there is actually no proposal for the solution of matterantimatter asymmetry in the framework of mainstream theories (actually there are no mainstream theories after the death of superstring theories which also assumed GUTs as low energy limits!). In TGD framework manysheeted spacetime suggests possible solution to the problem. Matter and antimatter are at different spacetime sheets. One possibility is that antimatter corresponds to dark matter in TGD sense that is a phase with h_{eff}=n× h, n=1,2,3,... such that the value of n for antimatter is different from that for visible matter. Matter and antimatter would not have direct interactions and would interact only via classical fields or by emission of say photons by matter (antimatter) suffering a phase transition changing the value of h_{eff} before absorbtion by antimatter (matter). This could be rather rare process. Biophotons could be produced from dark photons by this process and this is assumed in TGD based model of living matter. What the value of n for ordinary visible matter could be? The naive guess is that it is n=1, the smallest possible value. Randell Mills has however claimed the existence of scaled down hydrogen atoms  Mills calls them hydrinos  with ground state binding energy considerably higher than for hydrogen atom. The experimental support for the claim is published in respected journals and the company of Mills is developing a new energy technology based on the energy liberated in the transition to hydrino state. These findings can be understood in TGD framework if one has actually n=6 for visible atoms and n=1, 2, or 3 for hydrinos. Hydrino states would be stabilized in the presence of some catalysts. See this. The model suggests a universal catalyst action. Among other things catalyst action requires that reacting molecule gets energy to overcome the potential barrier making reaction very slow. If an atom  say (dark) hydrogen  in catalyst suffers a phase transition to hydrino (hydrogen with smaller value of h_{eff}/h), it liberates binding energy, and if one of the reactant molecules receives it it can overcome the barrier. After the reaction the energy can be sent back and catalyst hydrino returns to the ordinary hydrogen state. The condition that the dark binding energy is above the thermal energy gives a condition on the value of h_{eff}/h=n as n≤ 32. The size scale of the dark largest allowed dark atom would be about 100 nm, 10 times the thickness of the cell membrane. The notion of phosphate high energy bond is somewhat mysterious concept and manifests as the ability provide energy in ATP to ADP transition. There are claims that there is no such bond. I have spent considerable amount of time to ponder this problem. Could phosphate contain (dark) hydrogen atom able to go to the hydrino state (state with smaller value of h_{eff}/h) and liberate the binding energy? Could the decay ATP to ADP produce the original possibly dark hydrogen? Metabolic energy would be needed to kick it back to ordinary bond in ATP. So: could it be that one has n=6 for stable matter and n is different from this for stable antimatter? Could the small CP breaking cause this? For background see the chapter More about TGD inspired cosmology. 
Minimal surface cosmology
Before the discovery of the twistor lift TGD inspired cosmology has been based on the assumption that vacuum extremals provide a good estimate for the solutions of Einstein's equations at GRT limit of TGD . One can find imbeddings of RobertsonWalker type metrics as vacuum extremals and the general finding is that the cosmological with supercritical and critical mass density have finite duration after which the mass density becomes infinite: this period of course ends before this. The interpretation would be in terms of the emergence of new spacetime sheet at which matter represented by smaller spacetime sheets suffers topological condensation. The only parameter characterizing critical cosmologies is their duration. Critical (overcritical) cosmologies having SO3× E^{3} (SO(4)) as isometry group is the duration and the CP_{2} projection at homologically trivial geodesic sphere S^{2}: the condition that the contribution from S^{2} to g_{rr} component transforms hyperbolic 3metric to that of E^{3} or S^{3} metric fixes these cosmologies almost completely. Subcritical cosmologies have onedimensional CP_{2} projection. Do RobertsonWalker cosmologies have minimal surface representatives? Recall that minimal surface equations read as D_{α}(g^{αβ} ∂_{β}h^{k}g^{1/2})= ∂_{α}[g^{αβ} ∂_{β}h^{k} g^{1/2}] + {_{α}^{k}_{m}} g^{αβ} ∂_{β}h^{m} g^{1/2}=0 , {_{α}^{k}_{m}} ={_{l} ^{k}_{m}} ∂_{α}h^{l} . Subcritical minimal surface cosmologies would correspond to X^{4}⊂ M^{4}× S^{1}. The natural coordinates are RobertsonWalker coordinates, which coincide with lightcone coordinates (a=[(m^{0})^{2}r^{2}_{M}]^{1/2}, r= r_{M}/a,θ, φ) for lightcone M^{4}_{+}. They are related to spherical Minkowski coordinates (m^{0},r_{M},θ,φ) by (m^{0}=a(1+r^{2})^{1/2}, r_{M}= ar). β =r_{M}/m^{0}=r/(1+r^{2})^{1/20},r_{M}). r corresponds to the Lorentz factor r= γ β=β/(1β^{2})^{1/2} The metric of M^{4}_{+} is given by the diagonal form [g_{aa}=1, g_{rr}=a^{2}/(1+r^{2}), g_{θθ}= a^{2}r^{2}, g_{φφ}= a^{2}r^{2}sin^{2}(θ)]. One can use the coordinates of M^{4}_{+} also for X^{4}. The ansatz for the minimal surface reads is Φ= f(a). For f(a)=constant one obtains just the flat M^{4}_{+}. In nontrivial case one has g_{aa}= 1R^{2} (df/da)^{2}. The g^{aa} component of the metric becomes now g^{aa}=1/(1R^{2}(df/da)^{2}). Metric determinant is scaled by g_{aa}^{1/2} =1 → (1R^{2}(df/da)^{2}^{1/2}. Otherwise the field equations are same as for M^{4}_{+}. Little calculation shows that they are not satisfied unless one as g_{aa}=1. Also the minimal surface imbeddings of critical and overcritical cosmologies are impossible. The reason is that the criticality alone fixes these cosmologies almost uniquely and this is too much for allowing minimal surface property. Thus one can have only the trivial cosmology M^{4}_{+} carrying dark energy density as a minimal surface solution! This obviously raises several questions.
See the new chapter Can one apply Occam's razor as a general purpose debunking argument to TGD? or article with the same title. 
LIGO blackhole anomaly and minimal surface model for star
The TGD inspired model of star as a minimal surface with stationary spherically symmetric metric suggests strongly that the analog of blackhole metric as two horizons. The outer horizon is analogous to Scwartschild horizon in the sense that the roles of time coordinate and radial coordinate change. Radial metric component vanishes at Scwartschild horizon rather than divergence. Below the inner horizon the metric has Eucldian signature. Is there any empirical evidence for the existence of two horizons? There is evidence that the formation of the recently found LIGO blackhole (discussed from TGD view point in is not fully consistent with the GRT based model (see this). There are some indications that LIGO blackhole has a boundary layer such that the gravitational radiation is reflected forth and back between the inner and outer boundaries of the layer. In the proposed model the upper boundary would not be totally reflecting so that gravitational radiation leaks out and gave rise to echoes at times .1 sec, .2 sec, and .3 sec. It is perhaps worth of noticied that time scale .1 sec corresponds to the secondary padic time scale of electron (characterized by Mersenne prime M_{127}= 2^{127}1). If the minimal surface solution indeed has two horizons and a layer like structure between them, one might at least see the trouble of killing the idea that it could give rise to repeated reflections of gravitational radiation. The proposed model (see this) assumes that the inner horizon is Schwarstchild horizon. TGD would however suggests that the outer horizon is the TGD counterpart of Schwartschild horizon. It could have different radius since it would not be a singularity of g_{rr} (g_{tt}/g_{rr} would be finite at r_{S} which need not be r_{S}=2GM now). At r_{S} the tangent space of the spacetime surface would become effectively 2dimensional: could this be interpreted in terms of strong holography (SH)? One should understand why it takes rather long time T=.1 seconds for radiation to travel forth and back the distance L= r_{S}r_{E} between the horizons. The maximal signal velocity is reduced for the lightlike geodesics of the spacetime surface but the reduction should be rather large for L∼ 20 km (say). The effective lightvelocity is measured by the coordinate time Δ t= Δ m^{0}+ h(r_{S})h(r_{E}) needed to travel the distance from r_{E} to r_{S}. The Minkowski time Δ m^{0}_{+} would be the from null geodesic property and m^{0}= t+ h(r) Δ m^{0}_{+} =Δ t h(r_{S})+h(r_{E}) , Δ t = ∫_{rE}^{rS}(g_{rr}/g_{tt})^{1/2} dr== ∫_{rE}^{rS} dr/c_{#} . The time needed to travel forth and back does not depend on h and would be given by Δ m^{0} =2Δ t =2∫_{rE}^{rS}dr/c_{#} . This time cannot be shorter than the minimal time (r_{S}r_{E})/c along lightlike geodesic of M^{4} since lightlike geodesics at spacetime surface are in general timelike curves in M^{4}. Since .1 sec corresponds to about 3× 10^{4} km, the average value of c_{#} should be for L= 20 km (just a rough guess) of order c_{#}∼ 2^{11}c in the interval [r_{E},r_{S}]. As noticed, T=.1 sec is also the secondary padic time assignable to electron labelled by the Mersenne prime M_{127}. Since g_{rr} vanishes at r_{E} one has c_{#}→ ∞. c_{#} is finite at r_{S}. There is an intriguing connection with the notion of gravitational Planck constant. The formula for gravitational Planck constant given by h_{gr}= GMm/v_{0} characterizing the magnetic bodies topologically for mass m topologically condensed at gravitational magnetic flux tube emanating from large mass M. The interpretation of the velocity parameter v_{0} has remained open. Could v_{0} correspond to the average value of c_{#}? For inner planets one has v_{0}≈ 2^{11} so that the the order of magnitude is same as for the the estimate for c_{#}. See the new chapter Can one apply Occam's razor as a general purpose debunking argument to TGD? or article with the same title. 
Minimal surface counterpart of ReissnerNordstöm solution
Occarm's razor have been used to debunk TGD. The following arguments provide the information needed by the reader to decide himself. Considerations at three levels. The level of "world of classical worlds" (WCW) defined by the space of 3surfaces endowed with Kähler structure and spinor structure and with the identification of WCW space spinor fields as quantum states of the Universe: this is nothing but Einstein's geometrization program applied to quantum theory. Second level is spacetime level. Spacetime surfaces correspond to preferred extremals of Käction in M^{4}× CP_{2}. The number of field like variables is 4 corresponding to 4 dynamically independent imbedding space coordinates. Classical gauge fields and gravitational field emerge from the dynamics of 4surfaces. Strong form of holography reduces this dynamics to the data given at string world sheets and partonic 2surfaces and preferred extremals are minimal surface extremals of Kähler action so that the classical dynamics in spacetime interior does not depend on coupling constants at all which are visible via boundary conditions only. Continuous coupling constant evolution is replaced with a sequence of phase transitions between phases labelled by critical values of coupling constants: loop corrections vanish in given phase. Induced spinor fields are localized at string world sheets to guarantee welldefinedness of em charge. At imbedding space level the modes of imbedding space spinor fields define ground states of supersymplectic representations and appear in QFTGRT limit. GRT involves postNewtonian approximation involving the notion of gravitational force. In TGD framework the Newtonian force correspond to a genuine force at imbedding space level. For background see the chapter Can one apply Occam's razor as a general purpose debunking argument to TGD?. 
How to build TGD spacetime from legos?
TGD predicts shocking simplicity of both quantal and classical dynamics at spacetime level. Could one imagine a construction of more complex geometric objects from basic building bricks  spacetime legos? Let us list the basic ideas.
What could be the simplest surfaces of this kind  legos?
Geodesic minimal surfaces with vanishing induced gauge fields Consider first static objects with 1D CP_{2} projection having thus vanishing induced gauge fields. These objects are of form M^{1}× X^{3}, X^{3}⊂ E^{3}× CP_{2}. M^{1} corresponds to timelike or possible lightlike geodesic (for CP_{2} type extremals). I will consider mostly Minkowskian spacetime regions in the following.
What about minimal surfaces and geodesic submanifolds carrying nonvanishing gauge fields  in particular em field (Kähler form identifiable as U(1) gauge field for weak hypercharge vanishes and thus also its contribution to em field)? Now one must use 2D geodesic spheres of CP_{2} combined with 1D geodesic lines of E^{2}. Actually both homologically nontrivial resp. trivial geodesic spheres S^{2}_{I} resp. S^{2}_{II} can be used so that also nonvanishing Kähler forms are obtained. The basic legos are now D× S^{2}_{i}, i=I,II and they can be combined with the basic legos constructed above. These legos correspond to two kinds of magnetic flux tubes in the ideal infinitely thin limit. There are good reasons to expected that these infinitely thin flux tubes can be thickened by deforming them in E^{3} directions orthogonal to D. These structures could be used as basic building bricks assignable to the edges of the tensor networks in TGD. Static minimal surfaces, which are not geodesic submanifolds One can consider also more complex static basic building bricks by allowing bricks which are not anymore geodesic submanifolds. The simplest static minimal surfaces are form M^{1}× X^{2}× S^{1}, S^{1} ⊂ CP_{2} a geodesic line and X^{2} minimal surface in E^{3}. Could these structures represent higher level of selforganization emerging in living systems? Could the flexible network formed by living cells correspond to a structure involving more general minimal surfaces  also nonstatic ones  as basic building bricks? The Wikipedia article about minimal surfaces in E^{3} suggests the role of minimal surface for instance in biochemistry (see this). The surfaces with constant positive curvature do not allow imbedding as minimal surfaces in E^{3}. Corals provide an example of surface consisting of pieces of 2D hyperbolic space H^{2} immersed in E^{3} (see this). Minimal surfaces have negative curvature as also H^{2} but minimal surface immersions of H^{2} do not exist. Note that pieces of H^{2} have natural imbedding to E^{3} realized as lightone proper time constant surface but this is not a solution to the problem. Does this mean that the proposal fails?
Dynamical minimal surfaces: how spacetime manages to engineer itself? At even higher level of selforganization emerge dynamical minimal surfaces. Here string world sheets as minimal surfaces represent basic example about a building block of type X^{2}× S^{2}_{i}. As a matter fact, S^{2} can be replaced with complex submanifold of CP_{2}. One can also ask about how to perform this building process. Also massless extremals (MEs) representing TGD view about topologically quantized classical radiation fields are minimal surfaces but now the induced Kähler form is nonvanishing. MEs can be also Lagrangian surfaces and seem to play fundamental role in morphogenesis and morphostasis as a generalization of Chladni mechanism. One might say that they represent the tools to assign material and magnetic flux tube structures at the nodal surfaces of MEs. MEs are the tools of spacetime engineering. Here manysheetedness is essential for having the TGD counterparts of standing waves. For background see the chapter Can one apply Occam's razor as a general purpose debunking argument to TGD?. 
Can one apply Occam's razor as a general purpose debunking argument to TGD?Occarm's razor have been used to debunk TGD. The following arguments provide the information needed by the reader to decide himself. Considerations at three levels. The level of "world of classical worlds" (WCW) defined by the space of 3surfaces endowed with Kählerstructure and spinor structure and with the identification of WCW space spinor fields as quantum states of the Universe: this is nothing but Einstein's geometrization program applied to quantum theory. Second level is spacetime level. Spacetime surfaces correspond to preferred extremals of Kähler action in M^{4}× CP_{2}. The number of field like variables is 4 corresponding to 4 dynamically independent imbedding space coordinates. Classical gauge fields and gravitational field emerge from the dynamics of 4surfaces. Strong form of holography reduces this dynamics to the data given at string world sheets and partonic 2surfaces and preferred extremals are minimal surface extremals ofKähler action so that the classical dynamics in spacetime interior does not depend on coupling constants at all which are visible via boundary conditions only. Continuous coupling constant evolution is replaced with a sequence of phase transitions between phases labelled by critical values of coupling constants: loop corrections vanish in given phase. Induced spinor fields are localized at string world sheets to guarantee welldefinedness of em charge. At imbedding space level the modes of imbedding space spinor fields define ground states of supersymplectic representations and appear in QFTGRT limit. GRT involves postNewtonian approximation involving the notion of gravitational force. In TGD framework the Newtonian force correspond to a genuine force at imbedding space level. For background see the chapter Can one apply Occam's razor as a general purpose debunking argument to TGD?. 
Emergent gravity and dark UniverseEric Verlinde has published article with title Emergent Gravity and the Dark Universe > (see this). The article represents his recent view about gravitational force as thermodynamical force described earlier and suggests an explanation for the constant velocity spectrum of distant stars around galaxies and for the recently reported correlation between the real acceleration of distant stars with corresponding acceleration caused by baryonic matter. In the following I discuss Verlinde's argument and compare the physical picture with that provided by TGD. I have already earlier discussed Verlinde's entropic gravity from TGD view point (see this). The basic observation is that Verlinde introduces long range quantum entanglement appearing even in cosmological scales: in TGD framework the hierarchy of Planck constants does this in much more explicit manner and has been part of TGD for more than decade. It is nice to see that the basic ideas of TGD are gradually popping up in literature. Before continuing it is good to recall the basic argument against the identification of gravity as entropic force. As Kobakidzhe notices neutron diffraction experiments suggests that gravitational potential appears in the Schrödinger equation. This cannot be the case if gravitational potential has thermodynamic origin and therefore follows from statistical predictions of quantum theory: to my opinion Verlinde mixes apples with oranges. Verlinden's argument Consider now Verlinde's recent argument.
The physical picture has analogies with my own approach (see this) to the explanation of the correlation between baryonic acceleration with observed acceleration of distant stars. In particular, long range entanglement has the ieentification of dark matter in terms of phases labelled by the hierarchy of Planck constants as TGD counterpart.
Could TGD allow to resolve the basic objection against gravitation as entropic force or generalize this notion?
See the chapter TGD and GRT of "Physics in ManySheeted Spacetime". 
Is inflation theory simply wrong?I listened a very nice lecture about inflation by Steinhardt, who was one of the founders of inflation theory and certainly knows what he talks. Steinhardt concludes that inflation is simply wrong. He discusses three kind of flexibilities of inflationary theory, which destroy its ability to predict and makes it nonfalsifiable and therefore pseudoscience. Basically cosmologists want to understand the extreme simplicity of cosmology. Also particle physics has turned to be extremely simple whereas theories have during last 4 decades become so complex that they cannot predict anything.
Inflation theories The great vision of inflationists is that these features of the universe result during an exponentially fast expansion of cosmos  inflationary period  analogous to supercooling. This expansion would smooth out all inhomogenities and anisotropies of quantum fluctuation and yield almost flat universe with almost constant temperature with relative fluctuations of temperature of order 10^{5}. The key ingredient of recent inflation theories is a scalar field known as inflaton field (actually several of them are needed). There are many variants of inflationary theory (see this). Inflation models are characterized by the potential function V (Φ) of the inflaton field Φ analogous to potential function used in classical mechanics. During the fast expansion V(Φ) would vary very slowly as a function of the vacuum expectation value of Φ . Super cooling would mean that Φ does not decay to particles during the expansion period.
Steinhardt discusses the "There is no viable alternative" defense, which also Mtheorists have used. According to Steinhardt there are viable alternatives and Steinhardt discusses some of them. The often heard excuse is also that superstring theory is completely exceptional theory because of its unforeseen mathematical beauty: for this reason one should give up the falsifiability requirement. Many physicists, including me, however are unable to experience this heavenly beauty of super strings: what I experience is the disgusting ugliness of the stringy landscape and multiverse. The counterpart of inflation in TGD Universe It is interesting to compare inflation theory with the TGD variant of very early cosmology (see this ). TGD has no inflaton fields, which are the source of the three kind of infinite flexibilities and lead to the catastrophe in inflation theory. Let us return to the basic questions and the hints that TGD provides.
I have proposed what could be seen as analog of this picture in ZEO but without bounces (see this). Cosmos would be conscious entity which evolves, dies, and reincarnates and after the reincarnation expands in opposite direction of geometric time .
See the chapter TGD inspired cosmology of "Physics in ManySheeted Spacetime". 
TGD interpretation for the new discovery about galactic dark matterA very interesting new result related to the problem of dark matter has emerged: see the ScienceDaily article In rotating galaxies, distribution of normal matter precisely determines gravitational acceleration. The original articl can be found at arXiv.org. What is found that there is rather precise correlation between the gravitational acceleration produced by visible baryonic dark matter and and the observed acceleration usually though to be determined to a high degree by the presence of dark matter halo. According to the article, this correlation challenges the halo model model and might even kill it. It turns out that the TGD based model in which galactic dark matter is at long cosmic strings having galaxies along it like pearls in necklace allows to interpret the finding and to deduce a formula for the density from the observed correlation.

Does GW150914 force to modify the views about the formation of binary blackhole systems?The considerations below were inspired by a popular article related to the discovery of gravitational radiation in the formation of blackhole from two unexpectedly massive blackholes. LIGO has hitherto detected two events in which the formation of blackhole as fusion of two blackholes has generated a detectable burst of gravitational radiation. The expected masses for the stars of the binary are typically around 10 solar masses. The later event involve a pair with masses of 8 and 14 solar masses marginally consistent with the expectation. The first event GW150914 involves masses of about 30 solar masses. This looks like a problem since blackhole formation is believed to be preceded via a formation of a red super giant and supernova and in this events star loses a large fraction of its mass. The standard story evolution of binary to a pair of blackholes would go as follows.
See the article LIGO and TGD. For background see the chapter TGD and Astrophysics. 
Is Dragonfly a "failed" galaxy?In Phys.Org there was an article telling about the discovery of a dark galaxy  Dragonfly 44  with mass, which is of the same order of magnitude as that of Milky Way from the estimate based on standard model of galactic dark matter, for which the region within halflight radius is deduced to be 98 per cent dark. The dark galaxies found earlier have been much lighter. Dragonfly 44 posesses 94 globular clusters and in this respects remembles ordinary galaxies in this mass range. The abstract of the article telling about the discovery gives a more quantitative summary about the finding. Recently a population of large, very low surface brightness, spheroidal galaxies was identified in the Coma cluster. The apparent survival of these Ultra Diffuse Galaxies (UDGs) in a rich cluster suggests that they have very high masses. Here we present the stellar kinematics of Dragonfly 44, one of the largest Coma UDGs, using a 33.5 hr integration with DEIMOS on the Keck II telescope. We find a velocity dispersion of 47 km/s, which implies a dynamical mass of M_{dyn}=0.7× 10^{10} M_{sun} within its deprojected halflight radius of r_{1/2}=4.6 kpc. The masstolight ratio is M/L=48 M_{sun}/L_{sun}, and the dark matter fraction is 98 percent within the halflight radius. The high mass of Dragonfly 44 is accompanied by a large globular cluster population. From deep Gemini imaging taken in 0.4" seeing we infer that Dragonfly 44 has 94 globular clusters, similar to the counts for other galaxies in this mass range. Our results add to other recent evidence that many UDGs are "failed" galaxies, with the sizes, dark matter content, and globular cluster systems of much more luminous objects. We estimate the total dark halo mass of Dragonfly 44 by comparing the amount of dark matter within r=4.6 kpc to enclosed mass profiles of NFW halos. The enclosed mass suggests a total mass of ∼ 10^{12} M_{sun}, similar to the mass of the Milky Way. The existence of nearlydark objects with this mass is unexpected, as galaxy formation is thought to be maximallyefficient in this regime. To get some order of manitude perspective it is good to start by noticing that r_{1/2}=4.6 kpc is about 15,000 ly  the distance of Sun from galactic center is about 3 kpc. The diameter of Milky Way is 3155 kpc and the radius of the blackhole in the center of Milky Way, which is smaller than 17 light hours. The proposed interpretation is as a failed galaxy. What could this failure mean? Did Dragonfly 44 try become an ordinary galaxy but dark matter remained almost dark inside the region defined by half radius? It is very difficult to imagine what the failure of dark matter to become ordinary matter could mean. In TGD framework this would correspond to phase transition transforming dark identified as h_{eff}=n×h phases to ordinary matter and could be imagined but this is not done in the following. Could the unexpected finding challenge the standard assumption that dark matter forms a halo around galactic center? The mass of Dragonfly 44 is deduce from the velocities of stars. The faster they move, the larger the mass. The model for dark matter assumes dark matter halo and this in turn gives estimate for the total mass of the galaxy. Here a profound difference from TGD picture emerges.
See the article Some astrophysical and cosmological findings from TGD point of view. For background see the chapter TGD and Astrophysics. 
Does GRT really allow gravitational radiation?In Facebook discussion Niklas Grebäck mentioned Weyl tensor and I learned something that I should have noticed long time ago. Wikipedia article lists the basic properties of Weyl tensor as the traceless part of curvature tensor, call it R. Weyl tensor C is vanishing for conformally flat spacetimes. In dimensions D=2,3 Weyl tensor vanishes identically so that they are always conformally flat: this obviously makes the dimension D=3 for space very special. Interestingly, one can have nonflat spacetimes with nonvanishing Weyl tensor but the vanishing Schouten/Ricci/Einstein tensor and thus also with vanishing energy momentum tensor. The rest of curvature tensor R can be expressed in terms of so called KulkarniNomizu product P• g of Schouten tensor P and metric tensor g: R=C+P• g, which can be also transformed to a definition of Weyl tensor using the definition of curvature tensor in terms of Christoffel symbols as the fundamental definition. KulkarniNomizu product • is defined as tensor product of two 2tensors with symmetrization with respect to first and second index pairs plus antisymmetrization with respect to second and fourth indices. Schouten tensor P is expressible as a combination of Ricci tensor Ric defined by the trace of R with respect to the first two indices and metric tensor g multiplied by curvature scalar s (rather than R in order to use index free notation without confusion with the curvature tensor). The expression reads as P= 1/(D2)×[Ric(s/2(D1))×g] . Note that the coefficients of Ric and g differ from those for Einstein tensor. Ricci tensor and Einstein tensor are proportional to energy momentum tensor by Einstein equations relate to the part. Weyl tensor is assigned with gravitational radiation in GRT. What I see as a serious interpretational problem is that by Einstein's equations gravitational radiation would carry no energy and momentum in absence of matter. One could argue that there are no free gravitons in GRT if this interpretation is adopted! This could be seen as a further argument against GRT besides the problems with the notions of energy and momentum: I had not realized this earlier. Interestingly, in TGD framework so called massless extremals (MEs) (see this and this) are foursurfaces, which are extremals of Kähler action, have Weyl tensor equal to curvature tensor and therefore would have interpretation in terms of gravitons. Now these extremals are however nonvacuum extremals.
See the article Does GRT really allow gravitational radiation?. For background see the chapter Basic extremals of the Kähler action. 
Cosmic redshift but no expansion of receding objects: one further piece of evidence for TGD cosmology"Universe is Not Expanding After All, Controversial Study Suggests" was the title of very interesting Science News article telling about study which forces to challenge Big Bang cosmology. The title of course involve the typical popular exaggeration. The idea behind the study was simple. If Universe expands, one expects that also astrophysical objects  such as stars and galaxies  should participate the expansion, and should increase in size. The observation was that this does not happen! One however observes the cosmic redshift so that it is quite too early to start to bury Big Bang cosmology. The finding is however a strong objection against the strongest version of expanding Universe. That objects like stars do not participate the expansion was actually already known when I started to develop TGD inspired cosmology for quarter century ago, and the question is whether GRT based cosmology can model this fact naturally or not. The finding supports TGD cosmology based on manysheeted spacetime. Individual spacetime sheets do not expand continuously. They can however expand in jerkwise manner via quantum phase transitions increasing the padic prime characterizing spacetime sheet of object by say factor two of increasing the value of h_{eff}=n× h for it. This phase transition could change the properties of the object dramatically. If the object and suddenly expanded variant of it are not regarded as states of the same object, one would conclude that astrophysical objects do not expand but only comove. The sudden expansions should be however observable and happen also for Earth. I have proposed a TGD variant of Expanding Earth hypothesis along these lines (see this ). When one approximates the manysheeted spacetime of TGD with GRT spacetime, one compresses the sheets to single region of slightly curved piece of M^{4} and gauge potentials and the deviation of induced metric from M^{4} metric are replaced with their sums over the sheets to get standard model. This operation leads to a loss of information about manysheetedness. Manysheetedness demonstrates its presence only through anomalies such as different value of Hubble constant in scales of order large void and cosmological scales (see this ), arrival of neutrinos and gamma rays from supernova SN1987A as separate bursts (see this ), and the above observation. One can of course argue that cosmic redshift is a strong counter argument against TGD. Conservation of energy and momentum implied by Poincare invariance at the level of imbedding space M^{4}× CP_{2} does not seem to allow cosmic redshift. This is not the case. Photons arrive from the source without losing their energy. The point is that the properties of the imagined observer change as its distance from the source increases! The local gravitational field defined by the induced metric induces Lorentz boost of the M^{4} projection of the tangent space of the spacetime surface so that the tangent spaces at source and receiver are boosted with respect to other: this causes the gravitational redshift as analog of Doppler effect in special relativity. This is also a strong piece of evidence for the identification of spacetime as 4surface in M^{4}× CP_{2}. For details see the chapter More about TGD inspired cosmology or the article Some astrophysical and cosmological findings from TGD point of view. 
The new findings about the structure of Milky from TGD viewpointI learned about two very interesting findings forcing to update the ideas about to the structure of Milky Way and allowing to test the TGD inspired Bohr model of galaxy based on the notion of gravitational Planck constant (see this, this, this, and this) The first popular article tells about a colossal void extending from radius r_{0}=150 ly to a radius of r_{1}= 8,000 ly (ly=light year) around galactic nucleus discovered by a team led by professor Noriyuki Matsunaga. What has been found that there are no young stars known as Cepheids in this region. For Cepheids luminosity and the period of pulsation in brightness correlate and from the period for pulsation one can deduce luminosity and from the luminosity the distance. There are however Cepheids in the central region with radius about 150 ly. Second popular article tells about the research conducted by an international team led by Rensselaer Polytechnic Institute Professor Heidi Jo Newberg. Researchers conclude that Milky Way is at least 50 per cent larger than estimated extending therefore to R_{gal}= 150,000 ly and has ring like structures in galactic plane. The rings are actually ripples in the disk having a higher density of matter. Milky way is said to be corrugated: there are at least 4 ripples in the disk of Milky Way. The first apparent ring of stars about at distance of R_{0}=60,000 ly from the center. Note that R_{0} is considerably larger than r_{1}=8,000 ly: the ratio is R_{0}/r_{1}= 15/2 so that this findings need not have anything to do with the first one. Consider now the TGD based quantum model of galaxy. Nottale proposed that the orbits of planets in solar system are actually Bohr orbits with gravitational Planck constant (different for inner and outer planets and proportional to the product of masses of Sun and planet). In TGD this idea is developed furthe (see this): ordinary matter would condense around dark matter at spherical cells or tubes with Bohr radius. Bohr model is certainly oversimplification but can be taken as a starting point in TGD approach. Could Bohr orbitology apply also to the galactic rings and could it predict ring radii as radii with which dark matter concentrations  perhaps at flux tubes  are associated? One can indeed apply Bohr orbitology by assuming TGD based model for galaxy formation.
This would suggest that visible matter has condensed around dark matter at Bohr quantized orbits or circular flux tubes. This dark matter would contribute to the gravitational potential and imply that the velocity spectrum for distance stars is not quite constant but increases slowly as observed . The really revolutionary aspect of this picture is that gravitation would involve quantum coherence in galactic length scales. The constancy of the CMB temperature supports gravitational quantum coherence in cosmic scales. For details see the chapter TGD and Astrophysics or the article Three astrophysical and cosmological findings from TGD point of view. 
Blackholes do not absorb dark matter so fast as they shouldFew days ago I encountered a link to a highly interesting popular article telling about the claim of astronomers that blackholes do not absorb dark matter as fast as they should. The claim is based on a model for dark matter: if the absorption rate were what one would expect by identifying dark matter as some exotic particle, the rate would be quite too fast and the Universe would look very different. How could this relate to the vision that dark matter is ordinary matter in large Planck constant phase with h_{eff}=n× h= h_{gr}= GMm/v_{0} generated at quantum criticality? Gravitational Planck constant h_{gr} was originally introduced by Nottale. In this formula M is some mass, say that of black hole or astrophysical object, m is much smaller mass, say that of elementary particle, and v_{0} is velocity parameter, which is assumed to be in constant ratio to the spinning velocity of M in the model for quantum biology explaining biophotons as decay products of dark cyclotron photons. Could the large value of Planck constant force dark matter be delocalized in much longer scale than blackhole size and in this manner imply that the absorption of dark matter by blackhole is not a sensible notion unless dark matter is transformed to ordinary matter? Could it be that the transformation does not occur at all or occurs very slowly and is therefore the slow bottle neck step in the process leading to the absorption to the interior of the blackhole? This could be the case! The dark Compton length would be Λ_{gr}= h_{gr}/m= GM/v_{0} = r_{S}/2v_{0}, and for v_{0}/c <<1 this would give dark Compton wavelength considerable larger than the radius r_{S}=2GM of blackhole. Note that dark Compton length would not depend on m in accordance with Equivalence Principle and natural if one accepts gravitational quantum coherence is astrophysical scales. The observation would thus suggest that dark matter around blackhole is stable against phase transition to ordinary matter or the transition takes place very slowly. This in turn would reflect Negentropy Maximization Principle favoring the generation of entanglement negentropy assignable to dark matter. For details see the chapter Quantum Astrophysics or the article Three astrophysical and cosmological findings from TGD point of view. 
The problem of two Hubble constants persistsThe rate of cosmic expansion manifesting itself as cosmic redshift is proportional to the distance r of the object: the expansion velocity satisfies v=Hr. The proportionality coefficients H is known as Hubble constant. Hubble constant has dimensions of 1/s. A more convenient parameter is Hubble length defined as l_{H}= c/H, whose nominal value is 14.4 light years and corresponds to the limit at which the distant object recedes with light velocity from observer.
The explanation of the discrepancy in terms of manysheeted spacetime was one of the first applications of TGD inspired cosmology. The local value of Hubble constant would correspond to spacetime sheets of size at most that of large void. Global value would correspond to spacetime sheets with size scales up to ten billion years assignable to the entire observed cosmos. The smaller value of the Hubble constant for spacetime sheets of cosmic size would reflect the fact that the metric for them corresponds to a smaller average density for them. Mass density would be fractal in accordance with the fractality of TGD Universe implied by manysheetedness. Reader has perhaps noticed that I have been talking about spacetime sheets in plural. The spacetime of TGD is indeed manysheeted 4D surface in 8D M^{4}×CP_{2}. It corresponds approximately to GRT spacetime in the sense that the gauge potentials and gravitational fields (deviation of induced metric from Minkowksi metric) for sheets sum up to the gauge potential and gravitational field for the spacetime of GRT characterized by metric and gauge potentials in standard model. Manysheetedness leads to predictions allowing to distinguish between GRT and TGD. For instance, the propagation velocities of particles along different spacetime sheets can differ since the lightvelocity along spacetime sheets is typically smaller than the maximal signal velocity in empty Minkowski space M^{4}. Evidence for this effect was observed for the first time for supernova 1987A: neutrinos arrived in two bursts and also gamma ray burst arrived at different time than neutrinos: as if the propagation would have taken place along different spacetime sheets (see this). Evidence for this effect has been observed also for neutrinos arrived from galactic blackhole Sagittarius A. Two pulses were detected and the difference for arrival time was few hours (see this). For details see the chapter More about TGD cosmology or the article Three astrophysical and cosmological findings from TGD point of view.

Gravitational Waves from Black Hole Megamergers Are Weaker Than PredictedThere was an interesting article in Scientific American with title "Gravitational Waves from Black Hole Megamergers Are Weaker Than Predicted" (see this. The article told about the failure to find support for the effects of gravitational waves from the fusion of supermassive blackholes. The fusions of supermassive blackholes generate gravitational radiation. These collisions would be scaled up versions of the LIGO event. Supermassive blackholes in galactic centers are by statistical arguments expected to fuse in the collisions of galaxies so often that the generated gravitational radiation produces a detectable hum. This should produce a background hum which should be seen as a jitter for the arrival times of photons of radiation from pulsars. This jitter is same for all pulsars and therefore is expected to be detectable as kind of "hum" defined by gravitational radiation at low frequencies. The frequencies happen to be audible frequencies. For the past decade, scientists with the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration tried to detect this constant "hum" of lowfrequency gravitational waves (see this. The outcome is negative and one should explain why this is the case. I do not know how much evidence there exists for nearby collisions of galaxies in which fusion of galactic supermassive blackholes really take place. What would TGD suggest? For year ago I would have considered an explanation in terms of dark gravitons with lower detection rate but after the revision of the model for the detection of gravitational waves forced by LIGO discovery the following explanation looks more plausible.
For details see the chapter Quatum Astrophysics.

Correlated Triangles and Polygons in Standard Cosmology and in TGDPeter Woit had an interesting This Week's Hype . The inspiration came from a popular article in Quanta Magazine telling about the proposal of Maldacena and Nima ArkaniHamed that the temperature fluctuations of cosmic microwave background (CMB) could exhibit deviation from Gaussianity in the sense that there would be measurable maxima of npoint correlations in CMB spectrum as function of spherical angles. These effects would relate to the large scale structure of CMB. Lubos Motl wrote about the article in different and rather aggressive tone. The article in Quanta Magazine does not go into technical details but the original article of Maldacena and ArkaniHamed contains detailed calculations for various npoint functions of inflaton field and other fields in turn determining the correlation functions for CMB temperature. The article is technically very elegant but the assumptions behind the calculations are questionable. In TGD Universe they would be simply wrong and some habitants of TGD Universe could see the approach as a demonstration for how misleading the refined mathematics can be if the assumptions behind it are wrong. It must be emphasized that already now it is known and stressed also in the articl that the deviations of the CMB from Gaussianity are below recent measurement resolution and the testing of the proposed nonGaussianities requires new experimental technology such as 21 cm tomography mapping the redshift distribution of 21 cm hydrogen line to deduce information about fine details of CMB now npoint correlations. Inflaton vacuum energy is in TGD framework replaced by Kähler magnetic energy and the model of Maldacena and ArkaniHamed does not apply. The elegant work of Maldacena and ArkaniHamed however inspired a TGD based consideration of the situation but with very different motivations. In TGD inflaton fields do not play any role since inflaton vacuum energy is replaced with the energy of magnetic flux tubes. The polygons also appear in totally different manner and are associated with symplectic invariants identified as Kähler fluxes, and might relate closely to quantum physical correlates of arithmetic cognition. These considerations lead to a proposal that integers (3,4,5) define what one might called additive primes for integers n≥ 3 allowing geometric representation as nondegenerate polygons  prime polygons. On should dig the enormous mathematical literature to find whether mathematicians have proposed this notion  probably so. Partitions would correspond to splicings of polygons to smaller polygons. These splicings could be dynamical quantum processes behind arithmetic conscious processes involving addition. I have already earlier considered a possible counterpart for conscious prime factorization in the adelic framework. This will not be discussed in this section since this topic is definitely too far from primordial cosmology. The purpose of this article is only to give an example how a good work in theoretical physics  even when it need not be relevant for physics  can stimulate new ideas in completely different context. For details see the chapter More About TGD Inspired Cosmology or the article Correlated Triangles and Polygons in Standard Cosmology and in TGD . 
Cyclic cosmology from TGD perspectiveThe motivation for this piece of text came from a very inspiring (interview of Neil Turok by Paul Kennedy in CBS radio ). The themes were the extreme complexity of theories in contrast to extreme simplicity of physics, the mysterious homegeny and isotropy of cosmology, and the cyclic model of cosmology developed also by Turok himself. In the following I will consider these issues from TGD viewpoint. 1. Extreme complexity of theories viz. extreme simplicity of physics The theme was the incredible simplicity of physics in short and long scales viz. equally incredible complexity of the fashionable theories not even able to predict anything testable. More precisely, super string theory makes predictions: the prediction is that every imaginable option is possible. Very safe but not very interesting. The outcome is the multiverse paradigm having its roots in inflationary scenario and stating that our local Universe is just one particular randomly selected Universe in a collection of infinite number of Universes. If so then physics has reached its end. This unavoidably brings to my mind the saying of Einstein: "Any intelligent fool can make things bigger, more complex, and more violent. It takes a touch of genius – and a lot of courage – to move in the opposite direction.". Turok is not so pessimistic and thinks that some deep principle has remained undiscovered. Turok's basic objection against multiverse is that there is not a slightest thread of experimental evidence for it. In fact, I think that we can sigh for relief now: multiverse is disappearing to the sands of time, and can be seen as the last desperate attempt to establish super string theory as a respectable physical theory. Emphasis is now in the applications of AdS/CFT correspondence to other branches of physics such as condensed matter physics and quantum computation. The attempt is to reduce the complex strongly interaction dynamics of conformally invariant systems to gravitational interaction in higher dimensional spacetime called bulk. Unfortunately this approach involves the effective field theory thinking, which led to the landscape catastrophe in superstring theory. Einstein's theory is assumed to describe low energy gravitation in AdS so that higher dimensional blackholes emerge and their interiors can be populated with all kinds of weird entities. For TGD view about the situation see (see this) One can of course criticize Turok's view about the simplicity of the Universe. What we know that visible matter becomes simple both at short and long scales: we actually know very little about dark matter. Turok also mentions that in our scales  roughly the geometric mean of shortest and longest scales for the known Universe  resides biology, which is extremely complex. In TGD Universe this would due to the fact that dark matter is the boss for living systems and the complexity of visible matter reflects that of dark matter. It could be that dark matter levels corresponding to increasing values of h_{eff}/h get increasingly complex in long scales and complexity increases. We just do not see it! 2. Why the cosmology is so homogenous and isotropic? Turok sees as one of the deepest problems of cosmology the extreme homogeny and isotropy of cosmic microwave background implying that two regions with no information exchange have been at the same temperature in the remote past. Classically this is extremely implausible and in GRT framework there is no obvious reason for this. Inflationary scenario is one possible mechanism explaining this: the observed Universe would have been very small region, which expanded during inflationary period and all temperature gradients were smoothed out. This paradigm has several shortcomings and there exists no generally accepted variant of this scenario. In TGD framework one can also consider several explanations.
Turok is a proponent of cyclic cosmology combining so called ekpyrotic cosmology and inflationary cosmology. This cosmology offers a further solution candidate for the homogeny/isotropy mystery. Contracting phase would differ from the expanding phase in that contraction would be much slower than expansion and only during the last state there would be a symmetry between the two halfperiods. In concrete realizations inflaton type field is introduced. Also scenarios in which branes near each other collide with each other cyclically and generate in this manner big crunch followed by big bang is considered. I find difficult to see this picture as a solution of the homogeny/isotropy problem. I however realized it is possible to imagine a TGD analog of cyclic cosmology in Zero Energy Ontology (ZEO). There is no need to assume that this picture solves the homogeny/isotropy problem and cyclicity corresponds to kind of biological cyclicity or rather sequence of reincarnations. 3.1 A small dose of TGD inspired theory of consciousness
The question that I am ready to pose is easy to guess by a smart reader. Could this sequence of life cycles of self with opposite directions of time serve as TGD analog for cyclic cosmology?
For details see the chapter TGD Cosmology. 
What could the detection of gamma ray pulse .4 seconds after the LIGO merger mean?This posting begins with a part from earlier posting to which I added more material, which turns out to relate also to the nohair theorem and to Hawking's recent work (discussed from TGD perspective here) in an interesting manner. It might be that the blackhole formed in the merger breaks nonhair theorem by having magnetic moment. The Fermi Gammaray Burst Monitor detected 0.4 seconds after the merger a pulse of gamma rays with red shifted energies about 50 keV (see the posting of Lubos and the article from Fermi Gamma Ray Burst Monitor). At the peak of gravitational pulse the gamma ray power would have been about one millionth of the gravitational radiation. Since the gamma ray bursts do not occur too often, it is rather plausible that the pulse comes from the same source as the gravitational radiation. The simplest model for blackholes does not suggest this but it is not difficult to develop more complex models involving magnetic fields. Could this observation be seen as evidence for the assumption that dark gravitons are associated with magnetic flux tubes?
In the case of Sun the prediction for energy of cyclotron photons would be E=[v_{0}(Sun)/v_{0}] × [M(Sun)/M(BH)] × 50 keV ∼ [v_{0}(Sun)/v_{0}] keV. From v_{0}(Sun)/c≈ 2^{11} one obtains E=(c/v_{0})× .5 eV> .5 eV. Dark photons in living matter are proposed to correspond to h_{gr}=h_{eff} and are proposed to transform to biophotons with energies in visible and UV range (see this). Good dialectic would ask next whether both views about the gamma rays are actually correct. The "visible" cyclotron radiation with standard value of Planck constant at gamma ray energies would be created in the ultra strong magnetic field of blackhole, would be transformed to dark gamma rays with the same energy, and travel to Earth along the flux tubes. In TGD Universe the transformation ordinary photons to dark photons would occur in living matter routinely. One can of course ask whether this transformation takes place only at quantum criticality and whether the quantum critical period corresponds to the merger of blackholes. The time lag was .4 second and the merger event lasted .2 seconds. Manysheeted spacetime provides one possible explanation. If the gamma rays were ordinary photons so that dark gravitons would have travelled along different flux tubes, one can ask whether the propagation velocities differed by Δ c/c∼ 10^{17}. In the case of SN1987A neutrino and gamma ray pulses arrived at different times and neutrinos arrived as two different pulses (see this so that this kind of effect is not excluded. Since the lightlike geodesics of the spacetime surface are in general not lightlike geodesics of the imbedding space signals moving with light velocity along spacetime sheet do not move with maximal signal velocity in imbedding space and the time taken to travel from A to B depends on spacetime sheet. Could the later arrival time reflect slightly different signal velocities for photons and gravitons? Could one imagine a function for the gamma ray pulse possibly explaining also why it came considerably later than gravitons (0.4 seconds after the merger which lasted 2. seconds)? This function might relate to the transfer of surplus angular momentum from the system.
For details see the chapter Quantum Astrophysics of "Physics in ManySheeted Spacetime" or the article LIGO and TGD. 
LIGO and TGDThe recent detection of gravitational radiation by LIGO (see the posting of Lubos at and the article) can be seen as birth of gravitoastronomy. The existence of gravitational waves is however an old theoretical idea: already Poincare proposed their existence at the time when Einstein was starting the decade lasting work to develop GRT (see this). Gravitational radiation has not been observed hitherto. This could be also seen as indicating that gravitational radiation is not quite what it is believed to be and its detection fails for this reason. This has been my motivation for considering the TGD inspired possibility that part or even all of gravitational radiation could consist of dark gravitons (see this). Their detection would be different from that for ordinary gravitons and this might explain why they have not been detected although they are present (HulseTaylor binary). In this respect the LIGO experiment provided extremely valuable information: the classical detection of gravitational waves  as opposed to quantum detection of gravitons  does not seem to differ from that predicted by GRT. On the other hand, TGD suggests that the gravitational radiation between massive objects is mediated along flux tubes characterized by dark gravitational Planck constant h_{gr} =GMm/v_{0} identifiable as h_{eff}=n× h (see this). This allows to develop in more detail TGD view about the classical detection of dark gravitons. A further finding was that there was an emission of gamma rays .4 seconds after the merger (see the posting of Lubos and the article from Fermi Gamma Ray Burst Monitor). The proposal that dark gravitons arrive along dark magnetic flux tubes inspires the question whether these gamma rays were actually dark cyclotron radiation in extremely weak magnetic field associated with these flux tubes. There was also something anomalous involved. The mass scale of the merging blackholes deduced from the time evolution for so called chirp mass was 30 solar masses and roughly twice too large as compared to the upper bound from GRT based models (see this). Development of theory of gravitational radiation A brief summary about the development of theory of gravitational radiation is useful.
Evolution of the experimental side
LIGO detected an event that lasted for about .2 seconds. The interpretation was as gravitational radiation and numerical simulations are consistent with this interpretation. During the event the frequency of gravitational radiation increased from 35 Hz to 250 Hz. Maximum intensity was reached at 150 Hz and correspond to the moment when the blackholes fuse together. The data about the evolution of frequency allows to deduce information about the source if postNewtonian approximation is accepted and the final state is identified as Kerr blackhole.
The general findings about masses of blackholes and their correlations with the frequency and about the net intensity of radiation are also predictions of TGD. The possibility of dark gravitons as large h_{eff} quanta however brings in possible new effects and might affect the detection. The consistency of the experimental findings with GRT based theory of detection process raises critical question: are dark gravitons there? About the relationship between GRT and TGD The proposal is that GRT plus standard model defines the QFT limit of TGD replacing manysheeted spacetime with slightly curved region of Minkowski space carrying gauge potentials defined as sums of the components of the induced spinor connection and the deviation of metric from flat metric as sum of similar deviations for spacetime sheets (see this). This picture follows from the assumption that the test particle touching the spacetime sheets experience the sum of the classical fields associated with the sheets. The open problems of GRT limit of TGD have been the origin of Newton's constant  CP_{2} size is almost four orders of magnitude longer than Planck length.Amusingly, a dramatic progress occurred in this respect just during the week when LIGO results were published. The belief has been that Planck length is genuine quantal scale not present in classical TGD. The progress in twistorial approach to classical TGD however demonstrated that this belief was wrong. The idea is to lift the dynamics of 6D spacetime surface to the dynamics of their 6D twistor spaces obeying the analog of the variational principle defined by Kähler action. I had thought that this would be a passive reformulation but I was completely wrong (see this).
Can one understand the detection of gravitational waves if gravitons are dark? The problem of quantum gravity is that if the parameter GMm/h=Mm/m_{P}^{2} associated with two masses characterizes the interaction strength and is larger than unity, perturbation theory fails to converge. If one can assume that there is no quantum coherence, the interactions can be reduced to those between elementary particles for which this parameter is below unity so that the problem would disappear. In TGD framework however fermionic strings mediate connecting partonic 2surface mediate the interaction even between astrophysical objects and quantum coherence in astrophysical scales is unavoidable. The proposal is that Nature has been theoretician friendly and arranged so that a phase transition transforming gravitons to dark gravitons takes place so that Planck constant is replaced with h_{gr}=GMm/v_{0}. This implies that v_{0}/c<1 becomes the expansion parameter and perturbation theory converges. Note that the notion of h_{gr} makes sense only of one has Mm/m_{P}^{2}>1. The notion generalizes also to other interactions and their perturbative description when the interaction strength is large. Plasmas are excellent candidates in this respect.
The Fermi Gammaray Burst Monitor detected 0.4 seconds after the merger a pulse of gamma rays with red shifted energies about 50 keV (see the posting of Lubos and the article from Fermi Gamma Ray Burst Monitor). At the peak of gravitational pulse the gamma ray power would have been about one millionth of the gravitational radiation. Since the gamma ray bursts do not occur too often, it is rather plausible that the pulse comes from the same source as the gravitational radiation. The simplest model for blackholes does not suggest this but it is not difficult to develop more complex models involving magnetic fields. Could this observation be seen as evidence for the assumption that dark gravitons are associated with magnetic flux tubes?
In the case of Sun the prediction for energy of cyclotron photons would be E=[v_{0}(Sun)/v_{0}] × [M(Sun)/M(BH)] × 50 keV ∼ [v_{0}(Sun)/v_{0}] keV. From v_{0}(Sun)/c≈ 2^{11} one obtains E=(c/v_{0})× .5 eV> .5 eV. Dark photons in living matter are proposed to correspond to h_{gr}=h_{eff} and are proposed to transform to biophotons with energies in visible and UV range (see this). Good dialectic would ask next whether both views about the gamma rays are actually correct. The "visible" cyclotron radiation with standard value of Planck constant at gamma ray energies would be created in the ultra strong magnetic field of blackhole, would be transformed to dark gamma rays with the same energy, and travel to Earth along the flux tubes. In TGD Universe the transformation ordinary photons to dark photons would occur in living matter routinely. One can of course ask whether this transformation takes place only at quantum criticality and whether the quantum critical period corresponds to the merger of blackholes. The time lag was .4 second and the merger event lasted .2 seconds. If the gamma rays were ordinary photons so that dark gravitons would have travelled along different flux tubes, one can ask whether the propagation velocities differed by &Delta: c/c∼ 10^{17}. Since the geodesics of the spacetime surface are in general not geodesics of the imbedding space signals moving with light velocity along spacetime sheet do not move with maximal signal velocity in imbedding space and the time taken to travel from A to B depends on spacetime sheet. Could the later arrival time reflect slightly different signal velocities for photons and gravitons? For details see the chapter Quantum Astrophysics or the article LIGO and TGD. 