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Register a new userDo we live in an anthropic universe?
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Authors
Domingos Soares
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I cast doubt upon the desired consistency between the anthropic principle and modern cosmology.
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We propose that the constants of Nature we observe (which appear as parameters in the classical action) are quantum observables in a kinematical Hilbert space. When all of these observables commute, our proposal differs little from the treatment given to classical parameters in quantum information theory, at least if we were to inhabit a constants eigenstate. Non-commutativity introduces novelties, due to its associated uncertainty and complementarity principles, and it may even preclude hamiltonian evolution. The system typically evolves as a quantum superposition of hamiltonian evolutions resulting from a diagonalization process, and these are usually quite distinct from the original one (defined in terms of the non-commuting constants). We present several examples targeting $G$, $c$ and $Lambda $, and the dynamics of homogeneous and isotropic Universes. If we base our construction on the Heisenberg algebra and the quantum harmonic oscillator, the alternative dynamics tends to silence matter (effectively setting $G$ to zero), and make curvature and the cosmological constant act as if their signs are reversed. Thus, the early Universe expands as a quantum superposition of different Milne or de Sitter expansions for all material equations of state, even though matter nominally dominates the density, $rho $, because of the negligible influence of $Grho $ on the dynamics. A superposition of Einstein static universes can also be obtained. We also investigate the results of basing our construction on the algebra of $SU(2)$, into which we insert information about the sign of a constant of Nature, or whether its action is switched on or off. In this case we find examples displaying quantum superpositions of bounces at the initial state for the Universe.
In the context of string theory we argue that higher dimensional Dp-branes unwind and evaporate so that we are left with D3-branes embedded in a (9+1)-dimensional bulk. One of these D3-branes plays the role of our Universe. Within this picture, the evaporation of the higher dimensional Dp-branes provides the entropy of our Universe.
This book is concerned with the various aspects of hierarchical collective behaviour which is manifested by most complex systems in nature. From the many of the possible topics, we plan to present a selection of those that we think are useful from the point of shedding light from very different directions onto our quite general subject. Our intention is to both present the essential contributions by the existing approaches as well as go significantly beyond the results obtained by traditional methods by applying a more quantitative approach then the common ones (there are many books on qualitative interpretations). In addition to considering hierarchy in systems made of similar kinds of units, we shall concentrate on problems involving either dominance relations or the process of collective decision-making from various viewpoints.
This years Physics Nobel prize for the discovery of neutrino oscillations which resolved the problem of the missing solar neutrinos and the atmospheric muon neutrinos implies that at least one of the three neutrino species has a tiny mass. The neutrino oscillations measure the mass difference squared, and the individual neutrino masses have yet to be accurately ascertained. Particle theory has so far not given a predictive picture for neutrino masses. Here we propose that the anthropic principle may be relevant, as it is frequently invoked to understand other aspects of the universe, including the precise values of fine structure constant or nuclear coupling constant or even the proton-electron mass ratio.
In the late 1990s, observations of 93 Type Ia supernovae were analysed in the framework of the FLRW cosmology assuming these to be `standard(isable) candles. It was thus inferred that the Hubble expansion rate is accelerating as if driven by a positive Cosmological Constant $Lambda$. This is still the only direct evidence for the `dark energy that is the dominant component of the standard $Lambda$CDM cosmological model. Other data such as BAO, CMB anisotropies, stellar ages, the rate of structure growth, etc are all `concordant with this model but do not provide independent evidence for accelerated expansion. Analysis of a larger sample of 740 SNe Ia shows that these are not quite standard candles, and highlights the corrections applied to analyse the data in the FLRW framework. The latter holds in the reference frame in which the CMB is isotropic, whereas observations are made in our heliocentric frame in which the CMB has a large dipole anisotropy. This is assumed to be of kinematic origin i.e. due to our non-Hubble motion driven by local inhomogeneity in the matter distribution. The $Lambda$CDM model predicts how this peculiar velocity should fall off as the averaging scale is raised and the universe becomes sensibly homogeneous. However observations of the local `bulk flow are inconsistent with this expectation and convergence to the CMB frame is not seen. Moreover the kinematic interpretation implies a corresponding dipole in the sky distribution of high redshift quasars, which is rejected by observations at 4.9$sigma$. The acceleration of the Hubble expansion rate is also anisotropic at 3.9$sigma$ and aligned with the bulk flow. Thus dark energy may be an artefact of analysing data assuming that we are idealised observers in an FLRW universe, when in fact the real universe is inhomogeneous and anisotropic out to distances large enough to impact on cosmological analyses.
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