What's new inTGD: Physics as InfiniteDimensional GeometryNote: Newest contributions are at the top! 
Year 2016 
Generalization of Riemann zeta to Dedekind zeta and adelic physics?A further insight to adelic physics comes from the possible physical interpretation of the Lfunctions appearing also in Langlands program (see this. The most important Lfunction would be generalization of Riemann zeta to extension of rationals. I have proposed several roles for ζ, which would be the simplest Lfunction assignable to rational primes, and for its zeros.

Are Preferred Extremals QuaternionAnalytic in Some Sense?A generalization of 2D conformal invariance to its 4D variant is strongly suggestive in TGD framework, and leads to the idea that for preferred extremals of action spacetime regions have (co)associative/(co)quaternionic tangent space or normal space. The notion of M^{8}H correspondence allows to formulate this idea more precisely. The beauty of this notion is that it does not depend on the signature of Minkowski space M^{4} representable as subspace of of complexified quaternions M^{4}_{c}, which in turn can be seen as subspace of complexified octonions M^{8}_{c}. The 4D generalization of conformal invariance suggests strongly that the notion of analytic function generalizes somehow. This notion is however not so straightforward even in Euclidian signature, and the generalization to Minkowskian signature brings in further problems. The CauchyRiemannFuerter conditions make however sense also in Minkowskian quaternionic situation and the problem is whether they allow the physically expected solutions. One should also show that the possible generalization is consistent with (co)associativity. In this article these problems are considered. Also a comparison with Igor Frenkel's ideas about hierarchy of Lie algebras, loop, algebras and double look algebras and their quantum variants is made: it seems that TGD as a generalization of string models replacing string world sheets with spacetime surfaces gives rise to the analogs of double loop algebras and they quantum variants and Yangians. The straightforward generalization of double loop algebras seems to make sense only at the lightlike boundaries of causal diamonds and at lightlike orbits of partonic 2surfaces but that in the interior of spacetime surface the simple form of the conformal generators is not preserved. The twistor lift of TGD in turn corresponds nicely to the heuristic proposal of Frenkel for the realization of double loop algebras. See the article Are Preferred Extremals QuaternionAnalytic in Some Sense? or the chapter Unified Number Theoretical Vision. 
Why would primes near powers of two (or small primes) be important?The earlier What's New was an abstract of an article about how complexity theory based thinking might help in attempts to understand the emergence of complexity in TGD. The key idea is that evolution corresponds to an increasing complexity for Galois group for the extension of rationals inducing also the extension used at spacetime and Hilbert space level. This leads to rather concrete vision about what happens and the basic notions of complexity theory helps to articulate this vision more concretely. Also new insights about how preferred padic primes identified as ramified primes of extension emerge. The picture suggests strong resemblance with the evolution of genetic code with conserved genes having ramified primes as their analogs. Category theoretic thinking in turn suggests that the positions of fermions at partonic 2surfaces correspond to singularities of the Galois covering so that the number of sheets of covering is not maximal and that the singularities has as their analogs what happens for ramified primes. pAdic length scale hypothesis states that physically preferred padic primes come as primes near prime powers of two and possibly also other small primes. Does this have some analog to complexity theory, period doubling, and with the superstability associated with period doublings? Also ramified primes characterize the extension of rationals and would define naturally preferred primes for a given extension.
For details see the chapter Unified Number Theoretic Vision or the article What could be the role of complexity theory in TGD?. 
h_{eff}/h=n hypothesis and Galois groupThe previous What's New was an abstract of an article about how complexity theory based thinking might help in attempts to understand the emergence of complexity in TGD. The key idea is that evolution corresponds to an increasing complexity for Galois group for the extension of rationals inducing also the extension used at spacetime and Hilbert space level. This leads to rather concrete vision about what happens and the basic notions of complexity theory helps to articulate this vision more concretely. I ended up to rather interesting information theoretic interpretation about the understanding of effective Planck constant assigned to flux tubes mediating as gravitational/electromagnetic/etc... interactions. The real surprise was that this leads to a proposal how monocellulars and multicellulars differ! The emergence of multicellulars would have meant emergence of systems with mass larger than critical mass making possible gravitational quantum coherence. Penrose's vision about the role of gravitation would be correct although OrchOR as such has little to do with reality! The natural hypothesis is that h_{eff}/h=n equals to the order of Galois group in the case that it gives the number of sheets of the covering assignable to the spacetime surfaces. The stronger hypothesis is that h_{eff}/h=n is associated with flux tubes and is proportional to the quantum numbers associated with the ends.
These arguments support the view that quantum information theory indeed closely relates not only to gravitation but also other interactions. Speculations revolving around blackhole, entropy, and holography, and emergence of space would be replaced with the number theoretic vision about cognition providing information theoretic interpretation of basic interactions in terms of entangled tensor networks (see this). Negentropic entanglement would have magnetic flux tubes (and fermionic strings at them) as topological correlates. The increase of the complexity of quantum states could occur by the "fusion" of Galois groups associated with various nodes of this network as macroscopic quantum states are formed. Galois groups and their representations would define the basic information theoretic concepts. The emergence of gravitational quantum coherence identified as the emergence of multicellulars would mean a major step in biological evolution. For details see the chapter Unified Number Theoretic Vision or the article What could be the role of complexity theory in TGD?. For a summary of earlier postings see Latest progress in TGD. 
What could be the role of complexity theory in TGD?Chaotic (or actually extremely complex and only apparently chaotic) systems seem to be the diametrical opposite of completely integrable systems about which TGD is a possible example. There is however also something common: in completely integrable classical systems all orbits are cyclic and in chaotic systems they form a dense set in the space of orbits. Furthermore, in chaotic systems the approach to chaos occurs via steps as a control parameter is changed. Same would take place in adelic TGD fusing the descriptions of matter and cognition. In TGD Universe the hierarchy of extensions of rationals inducing finitedimensional extension of padic number fields defines a hierarchy of adelic physics and provides a natural correlate for evolution. Galois groups and ramified primes appear as characterizers of the extensions. The sequences of Galois groups could characterize an evolution by phase transitions increasing the dimension of the extension associated with the coordinates of "world of classical worlds" (WCW) in turn inducing the extension used at spacetime and Hilbert space level. WCW decomposes to sectors characterized by Galois groups G_{3} of extensions associated with the 3surfaces at the ends of spacetime surface at boundaries of causal diamond (CD) and G_{4} characterizing the spacetime surface itself. G_{3} (G_{4}) acts on the discretization and induces a covering structure of the 3surface (spacetime surface). If the state function reduction to the opposite boundary of CD involves localization into a sector with fixed G_{3}, evolution is indeed mapped to a sequence of G_{3}s. Also the cognitive representation defined by the intersection of real and padic surfaces with coordinates of points in an extension of rationals evolve. The number of points in this representation becomes increasingly complex during evolution. Fermions at partonic 2surfaces connected by fermionic strings define a tensor network, which also evolves since the number of fermions can change. The points of spacetime surface invariant under nontrivial subgroup of Galois group define singularities of the covering, and the positions of fermions at partonic surfaces could correspond to these singularities  maybe even the maximal ones, in which case the singular points would be rational. There is a temptation to interpret the padic prime characterizing elementary particle as a ramified prime of extension having a decomposition similar to that of singularity so that category theoretic view suggests itself. One also ends up to ask how the number theoretic evolution could select preferred padic primes satisfying the padic length scale hypothesis as a survivors in number theoretic evolution, and ends up to a vision bringing strongly in mind the notion of conserved genes as analogy for conservation of ramified primes in extensions of extension. h_{eff}/h=n has natural interpretation as the order of Galois group of extension. The generalization of hbar_{gr}= GMm/v_{0}=hbar_{eff} hypothesis to other interactions is discussed in terms of number theoretic evolution as increase of G_{3}, and one ends up to surprisingly concrete vision for what might happen in the transition from prokaryotes to eukaryotes. For details see the chapter Unified Number Theoretic Vision or the article What could be the role of complexity theory in TGD? of the article What could be the role of complexity theory in TGD?. 
Progress in adelic physicsThe preparation of an article about number theoretic aspects of TGD forced to go through various related ideas and led to a considerable integration of the ideas. In this note ideas related directly to adelic TGD are discussed.
Simple arguments lead to the identification of h_{eff}/h=n as a factor of the order of Galois group of extension of rationals.
The intuitive feeling is that the notion of preferred prime is something extremely deep and to me the deepest thing I know is number theory. Does one end up with preferred primes in number theory? This question brought to my mind the notion of ramification of primes (more precisely, of prime ideals of number field in its extension), which happens only for special primes in a given extension of number field, say rationals. Ramification is completely analogous to the degeneracy of some roots of polynomial and corresponds to criticality if the polynomial corresponds to criticality (catastrophe theory of Thom is one application). Could this be the mechanism assigning preferred prime(s) to a given elementary system, such as elementary particle? I have not considered their role earlier also their hierarchy is highly relevant in the number theoretical vision about TGD.
In TGD framework the extensions of rationals (see this) and padic number fields (see this) are unavoidable and interpreted as an evolutionary hierarchy physically and cosmological evolution would gradually proceed to more and more complex extensions. One can say that string world sheets and partonic 2surfaces with parameters of defining functions in increasingly complex extensions of prime emerge during evolution. Therefore ramifications and the preferred primes defined by them are unavoidable. For padic number fields the number of extensions is much smaller for instance for p>2 there are only 3 quadratic extensions. How could ramification relate to padic and adelic physics and could it explain preferred primes?
Number theoretical vision relies on NTU. In fermionic sector NTU is necessary: one cannot speak about real and padic fermions as separate entities and fermionic anticommutation relations are indeed number theoretically universal. What about NTU in case of functional integral? There are two opposite views.
See the chapter Unified Number Theoretic Vision or the article pAdicization and adelic physics. 
About some unclear issues of TGDTGD has been in the middle of palace revolution during last two years and it is almost impossible to keep the chapters of the books updated. Adelic vision and twistor lift of TGD are the newest developments and there are still many details to be understood and errors to be corrected. The description of fermions in TGD framework has contained some unclear issues. Hence the motivation for the following brief comments. Adelic vision and symmetries In the adelic TGD SH is weakened: also the points of the spacetime surface having imbedding space coordinates in an extension of rationals (cognitive representation) are needed so that data are not precisely 2D. I have believed hitherto that one must use preferred coordinates for the imbedding space H  a subset of these coordinates would define spacetime coordinates. These coordinates are determined apart from isometries. Does the number theoretic discretization imply loss of general coordinate invariance and also other symmetries? The reduction of symmetry groups to their subgroups (not only algebraic since powers of e define finitedimensional extension of padic numbers since e^{p} is ordinary padic number) is genuine loss of symmetry and reflects finite cognitive resolution. The physics itself has the symmetries of real physics. The assumption about preferred imbedding space coordinates is actually not necessary. Different choices of Hcoordinates means only different and nonequivalent cognitive representations. Spherical and linear coordinates in finite accuracy do not provide equivalent representations. Quantumclassical correspondence for fermions Quantumclassical correspondence (QCC) for fermions is rather wellunderstood but deserves to be mentioned also here. QCC for fermions means that the spacetime surface as preferred extremal should depend on fermionic quantum numbers. This is indeed the case if one requires QCC in the sense that the fermionic representations of Noether charges in the Cartan algebras of symmetry algebras are equal to those to the classical Noether charges for preferred extremals. Second aspect of QCC becomes visible in the representation of fermionic states as point like particles moving along the lightlike curves at the lightlike orbits of the partonic 2surfaces (curve at the orbit can be locally only lightlike or spacelike). The number of fermions and antifermions dictates the number of string world sheets carrying the data needed to fix the preferred extremal by SH. The complexity of the spacetime surface increases as the number of fermions increases. Strong form of holography for fermions It seems that scattering amplitudes can be formulated by assigning fermions with the boundaries of strings defining the lines of twistor diagrams. This information theoretic dimensional reduction from D=4 to D=2 for the scattering amplitudes can be partially understood in terms of strong form of holography (SH): one can construct the theory by using the data at string worlds sheets and/or partonic 2surfaces at the ends of the spacetime surface at the opposite boundaries of causal diamond (CD). 4D modified Dirac action would appear at fundamental level as supersymmetry demands but would be reduced for preferred extremals to its 2D stringy variant serving as effective action. Also the value of the 4D action determining the spacetime dynamics would reduce to effective stringy action containing area term, 2D Kähler action, and topological Kähler magnetic flux term. This reduction would be due to the huge gauge symmetries of preferred extremals. Subalgebra of supersymplectic algebra with conformal weigths coming as nmultiples of those for the entire algebra and the commutators of this algebra with the entire algebra would annihilate the physical states, and thecorresponding classical Noether charges would vanish. One still has the question why not the data at the entire string world sheets is not needed to construct scattering amplitudes. Scattering amplitudes of course need not code for the entire physics. QCC is indeed motivated by the fact that quantum experiments are always interpreted in terms of classical physics, which in TGD framework reduces to that for spacetime surface. The relationship between spinors in spacetime interior and at boundaries between Euclidian and Minkoskian regions Spacetime surface decomposes to interiors of Minkowskian and Euclidian regions. At lightlike 3surfaces at which the fourmetric changes, the 4metric is degenerate. These metrically singular 3surfaces  partonic orbits carry the boundaries of string world sheets identified as carriers of fermionic quantum numbers. The boundaries define fermion lines in the twistor lift of TGD. The relationship between fermions at the partonic orbits and interior of the spacetime surface has however remained somewhat enigmatic. So: What is the precise relationship between induced spinors Ψ_{B} at lightlike partonic 3surfaces and Ψ_{I} in the interior of Minkowskian and Euclidian regions? Same question can be made for the spinors Ψ_{B} at the boundaries of string world sheets and Ψ_{I} in interior of the string world sheets. There are two options to consider:
I have considered Option II already years ago but have not been able to decide.
About second quantization of the induced spinor fields The anticommutation relations for the induced spinors have been a longstanding issue and during years I have considered several options. The solution of the problem looks however stupifuingly simple. The conserved fermion currents are accompanied by supercurrents obtained by replacing Ψ with a mode of the induced spinor field to get u_{n}Γ^{α}Ψ or ΨΓ^{α}u_{n} with the conjugate of the mode. One obtains infinite number of conserved super currents. One can also replace both Ψ and Ψ in this manner to get purely bosonic conserved currents Ψ_{m}Γ^{α}u_{n} to which one can assign a conserved bosonic charges Q_{mn}. I noticed this years ago but did not realize that these bosonic charges define naturally anticommutators of fermionic creation and annihilation operators! The ordinary anticommutators of quantum field theory follow as a special case! By a suitable unitary transformation of the spinor basis one can diagonalize the hermitian matrix defined by Q_{mn} and by performing suitable scalings one can transform anticommutation relations to the standard form. An interesting question is whether the diagonalization is needed, and whether the deviation of the diagonal elements from unity could have some meaning and possibly relate to the hierarchy h_{eff}=n× h of Planck constants  probably not. Is statistical entanglement "real" entanglement? The question about the "reality" of statistical entanglement has bothered me for years. This entanglement is maximal and it cannot be reduced by measurement so that one can argue that it is not "real". Quite recently I learned that there has been a longstanding debate about the statistical entanglement and that the issue still remains unresolved. The idea that all electrons of the Universe are maximally entangled looks crazy. TGD provides several variants for solutions of this problem. It could be that only the fermionic oscillator operators at partonic 2surfaces associated with the spacetime surface (or its connected component) inside given CD anticommute and the fermions are thus indistinguishable. The extremist option is that the fermionic oscillator operators belonging to a network of partonic 2surfaces connected by string world sheets anticommute: only the oscillator operators assignable to the same scattering diagram would anticommute. What about QCC in the case of entanglement. EREPR correspondence introduced by Maldacena and Susskind for 4 years ago proposes that blackholes (maybe even elementary particles) are connected by wormholes. In TGD the analogous statement emerged for more than decade ago  magnetic flux tubes take the role of wormholes in TGD. Magnetic flux tubes were assumed to be accompanied by string world sheets. I did not consider the question whether string world sheets are always accompanied by flux tubes. What could be the criterion for entanglement to be "real"? "Reality" of entanglement demands some spacetime correlate. Could the presence of the flux tubes make the entanglement "real"? If statistical entanglement is accompanied by string connections without magnetic flux tubes, it would not be "real": only the presence of flux tubes would make it "real". Or is the presence of strings enough to make the statistical entanglement "real". In both cases the fermions associated with disjoint spacetime surfaces or with disjoint CDs would not be indistinguishable. This looks rather sensible. The spacetime correlate for the reduction of entanglement would be the splitting of a flux tube and fermionic strings inside it. The fermionic strings associated with flux tubes carrying monopole flux are closed and the return flux comes back along parallel spacetime sheet. Also fermionic string has similar structure. Reconnection of this flux tube with shape of very long flattened square splitting it to two pieces would be the correlate for the state function reduction reducing the entanglement with other fermions and would indeed decouple the fermion from the network. See the chapter Recent View about Kähler Geometry and Spin Structure of "World of Classical Worlds".
