Abstract:In this paper, we discuss the properties of one-parameter sequences that
arise when solving the Hamiltonian constraint in Bianchi I loop quantum
cosmology using a separation of variables method. In particular, we focus on
finding an expression for the sequence for all real values of the parameter,
and discuss the pre-classicality of this function. We find that the behavior of
these preclassical sequences imply time asymmetry on either side of the
classical singularity in Bianchi I cosmology.Comment: 5 pages, 3… Show more
“…Many studies have already been devoted to Bianchi-I LQC [97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117]. In particular, it was shown that the bounce prediction is robust.…”
Abstract. Quantum gravity is sometimes considered as a kind of metaphysical speculation. In this review, we show that, although still extremely difficult to reach, observational signatures can in fact be expected. The early universe is an invaluable laboratory to probe "Planck scale physics". Focusing on Loop Quantum Gravity as one of the best candidate for a non-perturbative and background-independant quantization of gravity, we detail some expected features.Invited topical review for Classical and Quantum Gravity.
“…Many studies have already been devoted to Bianchi-I LQC [97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117]. In particular, it was shown that the bounce prediction is robust.…”
Abstract. Quantum gravity is sometimes considered as a kind of metaphysical speculation. In this review, we show that, although still extremely difficult to reach, observational signatures can in fact be expected. The early universe is an invaluable laboratory to probe "Planck scale physics". Focusing on Loop Quantum Gravity as one of the best candidate for a non-perturbative and background-independant quantization of gravity, we detail some expected features.Invited topical review for Classical and Quantum Gravity.
“…We can expand the function B(y) = β 0 + yF (y) in a Taylor series, to read off the values of the sequence β n for any real n, as done in previous work [14]. However, in this case the function is not easily written in a compact form.…”
Section: B βN Sequencementioning
confidence: 99%
“…Similar reasoning lets us ignore the difference between the full recursion relation and the "bulk" relation, where m ≥ 2 allows us to simplify the absolute value signs for m. 2 Notice that we are focussing solely on integer values of the parameter k, despite the fact that µ and τ (and hence m, n) can take any real value. It has been shown elsewhere [14] that using the sequence solution for integer values can be extended to all real numbers.…”
Using the Hamiltonian constraint derived by Ashtekar and Bojowald, we look for pre-classical wave functions in the Schwarzschild interior. In particular, when solving this difference equation by separation of variables, an inequality is obtained relating the Immirzi parameter γ to the quantum ambiguity δ appearing in the model. This bound is violated when we use a natural value for δ based on loop quantum gravity together with a recent proposal for γ. We also present numerical solutions of the constraint.
“…A crucial difference between this conserved quantity and the charge (15) obtained from the APS quantization is what happens to the prefactor of Q at the classical singularity. As stated above, for the APS model (13), at this singularity, C + (0) = 0, so Q can take any real value; this allows the charge for wave functions passing through the classical singularity to be non-zero, and thus provide a relation between semi-classical limits of the wave function far away from the v = 0 point. On the other hand, for the earlier quantization (22), we have the difference in volumes V µ+µ0 − V µ−µ0 at µ = 0 is V µ0 − V −µ0 = 0 so that the charge Q = 0 for any wave function passing through the µ = 0 classical singularity.…”
Section: Non-self-adjoint Constraint Equations In Lqcmentioning
We develop an action principle for those models arising from isotropic loop quantum cosmology, and show that there is a natural conserved quantity Q for the discrete difference equation arising from the Hamiltonian constraint. This quantity Q relates the semi-classical limit of the wavefunction at large values of the spatial volume, but opposite triad orientations. Moreover, there is a similar quantity for generic difference equations of one parameter arising from a self-adjoint operator.
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