Quantum singularities in FRW universe revisited

The components of the Riemann tensor in the tetrad basis are quantized and, through the Einstein equation, we find the local expectation value in the ontological interpretation of quantum mechanics of the energy density and pressure of a perfect fluid with equation of state $p=\frac{1}{3}\rho$ in the flat Friedmann-Robertson-Walker quantum cosmological model. The quantum behavior of the equation of state and energy conditions are then studied and it is shown that the later is violated since the singularity is removed with the introduction of quantum cosmology, but in the classical limit both the equation of state and the energy conditions behave as in the classical model. We also calculate the expectation value of the scale factor for several wave packets in the many-worlds interpretation in order to show the independence of the non singular character of the quantum cosmological model with respect to the wave packet representing the wave function of the Universe. It is also shown that, with the introduction of non-normalizable wave packets, solutions of the Wheeler-DeWitt equation, the singular character of the scale factor, can be recovered in the ontological interpretation.Comment: 15 pages, revtex, accepted for publication in PR

Synergistic warm inflation

We consider an alternative warm inflationary scenario in which $n$ scalar fields coupled to a dissipative matter fluid cooperate to produce power--law inflation. The scalar fields are driven by an exponential potential and the bulk dissipative pressure coefficient is linear in the expansion rate. We find that the entropy of the fluid attains its asymptotic value in a characteristic time proportional to the square of the number of fields. This scenario remains nearly isothermal along the inflationary stage. The perturbations in energy density and entropy are studied in the long--wavelength regime and seen to grow roughly as the square of the scale factor. They are shown to be compatible with COBE measurements of the fluctuations in temperature of the CMB.Comment: 13 pages, Revtex 3 To be published in Physical Review

Deliberation, Unjust Exclusion, and the Rhetorical Turn

Theories of deliberative democracy have faced the charge of leading to the unjust exclusion of voices from public deliberation. The recent rhetorical turn in deliberative theory aims to respond to this charge. I distinguish between two variants of this response: the supplementing approach and the systemic approach. On the supplementing approach, rhetorical modes of political speech may legitimately supplement the deliberative process, for the sake of those excluded from the latter. On the systemic approach, rhetorical modes of political speech are legitimate within public deliberation, just so long as they result in net benefits to the deliberative system. I argue that neither of these two approaches adequately meets the unjust exclusion charge. Whereas the supplementing approach does not go far enough to incorporate rhetorical speech into public deliberation, the systemic approach goes too far by legitimizing forms of rhetoric that risk only exacerbating the problem of unjust exclusion. More constructively, I draw on Aristotle’s conception of rhetoric, as an art (technē) that is a counterpart to dialectic, to argue for a constitutive approach to rhetoric. I show how this approach provides a more expansive notion of deliberation that remains normatively orientated