What Gravitons Are & Could One Detect Them in TGD Universe?

Abstract

What gravitons are in the TGD framework? This question has teased me for decades. It is easy to understand gravitation at the classical level in the TGD framework but the identification of gravitons has been far from obvious. Second question is whether the new physics provided by TGD could make the detection of gravitons possible? The generalized Kahler structure for M⁴ ⊆ H= M⁴ x CP² leads together with holography=generalized holomorphy hypothesis to the question whether the spinor connection of M⁴ could have interpretation as gauge potentials with spin taking the role of the gauge charge. However, the induced M⁴ spinor connection has a vanishing vielbein curvature. The M⁴ Kahler gauge potential remains a candidate for giving rise to graviton-like state: the additional spin would come from the rotation of the monopole flux tube. Also the second fundamental form H^K has M⁴ part M^K behaves like a spin 1 object. One can assign the fundamental vertices with the splitting of closed string-like flux tubes representing elementary particles. The vertices would correspond to the defects of ordinary 4-D smooth structure making possible a theory allowing a creation of fermion pairs. The Kahler part of the M⁴ spinor connection could contribute to electroweak $U(1)$ gauge potential or define a new gauge force. It could also give rise to graviton-like states as monopole flux tubes containing fermion pairs with rotational angular momentum L=1. There are however several objections against this idea. H^K, generalizing the Higgs field, contains M⁴ part M^K and CP² part S^K behaves like Higgs field and the M⁴ part looks like a plausible candidate for graviton. H^K is concentrated at the singularities of space-time as a minimal surface and vanishes elsewhere and is identifiable as a generalized acceleration. The bosonic field equations imply that the vertex generalizes Newton's "F=ma" and gives rise to the TGD counterpart of Einstein's equations. The interpretation of graviton in terms of a generalized acceleration would conform with the Equivalence Principle. The second question considered in this article is whether gravitons can be detected in the TGD Universe. It turns out dark protons at the monopole flux tube condensates give rise to a mild optimism in this respect.