Cosmology & Gravity: Part 2 from Administrator's blog

Abstract: Many physical constants related to quantized gravity, e.g., the Planck length, mass, curvature, stressenergy, etc., are nonanalytic in G at G = 0, and thus have expansions in powers of G whose terms are progressively more divergent with increasing order. Since the gravity field’s classical action is inversely proportional to G, the path integral for gravity-field quantum transition amplitudes shows that these depend on G only through the product ħG, and are nonanalytic in G at G = 0 for the same reason that all quantum transition amplitudes are nonanalytic in ħ at ħ = 0, namely their standard oscillatory essential singularity at the classical ‘limit’. Thus perturbation expansions in powers of G of gravity-field transition amplitudes are also progressively more divergent with increasing order, and hence unrenormalizable. While their perturbative treatment is impossible, the exceedingly small value of ħ G makes the semiclassical treatment of these amplitudes extraordinarily accurate, indeed to such an extent that purely classical treatment of the gravity field ought to always be entirely adequate. It should therefore be fruitful to couple classical gravity to other fields which actually need to be quantized: those fields’ ubiquitous, annoying ultraviolet divergences would thereupon undergo drastic self-gravitational red shift, and thus be cut off. http://prespacetime.com/index.php/pst/article/view/95

Ever-present Lambda and the Quantum Potential of Spacetime (by Willard Mittelman): Abstract: An approach to dark energy is presented that combines ideas of causal set theory with a Machian perspective and a treatment of spacetime as a condensate, yielding a “quantum potential of spacetime” Q whose density ρQ acts as an effective Λ that satisfies the uncertainty relation ∆V∆Λ ~ 1 of unimodular relativity. In contrast to the ever-present Λ of causal set theory, ρQ’s value is always non-negative, and the nonlocality of Q ensures that ρQ is spatially homogeneous, in accordance with observation. http://prespacetime.com/index.php/pst/article/view/96

Is the Universe Rotating? (by B. G. Sidharth): Abstract: Numerous observations and studies suggest that the universe has some sort of overall rotation. We consider this matter and provide a new angle. http://prespacetime.com/index.php/pst/article/view/97

Commentary on Cosmology (Jonathan J. Dickau): Abstract: Cosmology is one area where there is no possibility to reproduce all of what we observe in experiments in laboratories on Earth. But what is real is there for all to see, in the depths of space. So what we do observe must be explained! To that end, scientists have woven an elaborate story about how the universe came to be, and why it is the way we observe it today. But our brave authors have not been afraid to ask “what if the story is not exactly as we were told?” http://prespacetime.com/index.php/pst/article/view/100