Quantum Universe Research Articles

The Concept of Quantum Mechanics and A Reading of Thomas Pynchon's Gravity's Rainbow

Jo, Il-Jae & Kim, Sangkoo. “The Concept of Quantum Mechanics and A Reading of Thomas Pynchons Gravitys Rainbow.” The Journal of Modern British & American Language & Literature. 32.1 (2014): 163-186. This article is intended to examine the interactive relationship, and interdisciplinarity between literature and science. It gives a hermeneutic explanation and analytical interpretation of how Thomas Pynchons novel Gravitys Rainbow is connected with quantum mechanics and how it is represented, based on variable in modern science. Thus major character Slothrop and other characters related to him are analyzed for their mysterious, difficult actions in connection with principles and characteristics of quantum mechanics. The hidden variable theory contains field concept, relativity theory, quantum mechanics, and etc. Gravitys Rainbow shows various scientific theories and discourses, and postmodern societys traits and falls to the fiction in the quantum universe. Many characters, images and motifs in this novel are interconnected and they are not separated from the whole, but placed as a individual whole in the world. The parallel between literature and science is provided on the basis of quantum mechanics. (Pusan National University)

Consistent probabilities in perfect fluid quantum universes

Recently it has been claimed that the Wheeler--DeWitt quantization of gravity is unable to avoid cosmological singularities. However, in order to make this assertion, one must specify the underlying interpretation of quantum mechanics which has been adopted. For instance, several nonsingular models were obtained in Wheeler--DeWitt quantum cosmology in the framework of the de Broglie--Bohm quantum theory. Conversely, there are specific situations where the singularity cannot be avoided in the framework of the consistent histories approach to quantum mechanics. In these specific situations, the matter content is described by a scalar field, and the Wheeler--DeWitt equation looks like a Klein--Gordon equation. The aim of this work is to study a possible singular behavior of quantum cosmological models in which the matter content is described by a hydrodynamical perfect fluid, where the resulting wave equation is a genuine Schr\"odinger equation. In this case, it is shown that the conclusions of the consistent histories and the de Broglie--Bohm approaches coincide in the quantum cosmological models where the curvature of the spatial sections is not positive definite, namely, that the cosmological singularities are eliminated. In the case of positive spatial curvature, the family of histories is no longer consistent, and no conclusion can be given in this framework.

Third Quantization and Quantum Universes

We study the third quantization of the Friedmann-Robertson-Walker cosmology with N-minimal massless fields. The third quantized Hamiltonian for the Wheeler-DeWitt equation in the minisuperspace consists of infinite number of intrinsic time-dependent, decoupled oscillators. The Hamiltonian has a pair of invariant operators for each universe with conserved momenta of the fields that play a role of the annihilation and the creation operators and that construct various quantum states for the universe. The closed universe exhibits an interesting feature of transitions from stable states to tachyonic states depending on the conserved momenta of the fields. In the classical forbidden unstable regime, the quantum states have googolplex growing position and conjugate momentum dispersions, which defy any measurements of the position of the universe.

Anthropic bounds onΛfrom the no-boundary quantum state

We show that anthropic selection emerges inevitably in the general framework for prediction in quantum cosmology. There the predictions of anthropic reasoning depend on the prior implied by the universe's quantum state. To illustrate this we compute the probabilities specified by the no-boundary wave function for our observations at the present time of the values of Lambda and Q in an inflationary landscape model in which both quantities vary. Within the anthropic range of values the no-boundary state yields an approximately flat distribution on Lambda and strongly favors small values of Q. This restores Weinberg's successful prediction of Lambda.

A new perspective on cosmology in Loop Quantum Gravity

We present a new cosmological model derived from Loop Quantum Gravity. The formulation is based on a projection of the kinematical Hilbert space of the full theory down to a subspace representing the proper arena for an inhomogeneous Bianchi I model. This procedure gives a direct link between the full theory and its cosmological sector, thus it allows to test the complete canonical quantization program and to shed light on the foundation of Loop Quantum Cosmology. Furthermore, the emerging quantum cosmological model represents a concrete implementation of a discrete quantum Universe and it opens new perspectives on the phenomenology of early cosmology.

Neither Physics nor Chemistry: A History of Quantum Chemistry, by Kostas Gavroglu and Ana Simões

Neither Physics nor Chemistry: A History of Quantum Chemistry, by Kostas Gavroglu and Ana Simoes. Transformation: Studies in the History of Science and Technology. Cambridge, Massachusetts, MIT Press, 2012. xiv, 351 pp. $40.00 US (cloth). Kostas Gavroglu and Ana Simoes have presented a tour de force in their work on the history of quantum chemistry. Neither Physics nor Chemistry is not, however, for the casual reader. The authors assume that the reader will be familiar with valence bonds, Planck's constant, orbitals, and why X-ray crystallography can elucidate the internal structure or a molecule. If you are more intrigued than put off by the technical material, the book will reward you with a lucid investigation of the development of modern physical chemistry. Physical chemistry is to general chemistry as theoretical physics is to general physics. Physical chemistry is the study of the underlying principles of chemical behaviour and, like theoretical physics, has become over time more mathematical and esoteric. When the discovery of radioactivity in the nineteenth century opened the door to new areas of physics and led to the idea that energy carne in packets (the quanta), physical chemistry had to adapt to the new quantum universe. Underlying the story of quantum chemistry are two concerns. The first is a simple pragmatic question: How much physics do chemists need to know to do their jobs? The second issue is more transcendental: What is the relationship between forces and the structure of the material world? On the issue of the first question, the physicist Hans Hellmann, who fled Nazi Germany to Russia only to be killed in the purges of 1938, neatly summarized this problem by saying ... organic and inorganic chemistry are engaged in organic and inorganic substances, which substances are the topic of theoretical chemistry? Purely theoretical substances? Does quantum theory have any useful role in chemistry at all? (p. 33). For anyone who has assembled molecules out of sticks and plastic balls in a high school chemistry class, the answer seems to be a resounding no. Certainly in the first half of the twentieth century, the majority of chemists would also have answered that complex mathematics and the ghostly world of quantum physics added nothing to the chemists' toolbox. There was a cultural divide between the practical chemists and the physicist who looked at transcendental questions about the underlying principles of nature. Even amongst those who looked at the material world (such as Neils Bohr's work with Ernest Rutherford on the planetary model of the atom) tended to regard chemistry as at best a secondary topic; a by-product of physics. Physicists were looking at the majestic and eternal forces of nature, while chemistry was concerned with the crude world of dyes, chemical warfare and baby soap. There was a serious argument made by some physicists that the material world was just an illusion and the real world was created by fields of force. …

BOOKS: "The Quantum Universe: (And Why Anything That Can Happen, Does); Topological Insulators and Topological Superconductors; Beyond The Stars — Our Origins and the Search for Life in the Universe" By Brian Cox, Jeff Forshaw, B. Andrei Bernevig, Taylor L. Hughes and Paolo Saraceno

BOOKS: "The Quantum Universe: (And Why Anything That Can Happen, Does); Topological Insulators and Topological Superconductors; Beyond The Stars — Our Origins and the Search for Life in the Universe" By Brian Cox, Jeff Forshaw, B. Andrei Bernevig, Taylor L. Hughes and Paolo Saraceno

Cooperative Relaying at Finite SNR—Role of Quantize-Map-and-Forward

Quantize-Map-and-Forward (QMF) relaying has been shown to achieve the optimal diversity-multiplexing trade-off (DMT) for arbitrary slow fading full-duplex networks as well as for the single-relay half-duplex network. A key reason for this is that quantizing at the noise level suffices to achieve the cut-set bound approximately to within an additive gap, without any requirement of instantaneous channel state information (CSI). However, DMT only captures the high SNR performance and potentially, limited CSI at the relay can improve performance at moderate SNRs. In this work we propose an optimization framework for QMF relaying over slow fading channels. Focusing on vector Gaussian quantizers, we optimize the outage probability for the full-duplex and half-duplex single relay by finding the best quantization level and relay schedule according to the available CSI at the relays. For the N-relay diamond network, we derive an universal quantizer that sharpens the additive approximation gap of QMF from the conventional \Theta(N) bits/s/Hz to \Theta(log(N)) bits/s/Hz using only network topology information. Analytical solutions to channel-aware optimal quantizers for two-relay and symmetric N-relay diamond networks are also derived. In addition, we prove that suitable hybridizations of our optimized QMF schemes with Decode-Forward (DF) or Dynamic DF protocols provide significant finite SNR gains over the individual schemes.

A quantum gravitational inflationary scenario in Bianchi-I spacetime

We investigate the ϕ2 inflationary model in the Bianchi-I spacetime using the effective spacetime description of loop quantum cosmology to understand the issues of the resolution of initial singularity, isotropization, effect of anisotropies on the amount of inflation, and the phase-space attractors in the presence of non-perturbative quantum gravitational modifications. A comparative analysis with the classical theory by including more general initial conditions than the ones previously considered in the latter is also performed. We show that, in general, the classical singularity is replaced by a bounce of the mean scale factor in loop quantum cosmology. Due to the underlying quantum geometric effects, the energy density of the inflaton and the anisotropic shear remain bounded throughout the non-singular evolution. Starting from arbitrary anisotropic initial conditions, a loop quantum universe isotropizes either before or soon after the onset of slow-roll inflation. We find a double attractor behavior in the phase-space dynamics of loop quantum cosmology, similar to the one in classical theory, but with some additional subtle features. Quantum modifications to the dynamical equations are such that, unlike the classical theory, the amount of inflation does not monotonically depend on the initial anisotropy in loop quantum cosmology. Our results suggest that a viable non-singular inflationary model can be constructed from highly anisotropic initial conditions in the Planck regime.

Complementarity of quantum discord and classically accessible information

The sum of the Holevo quantity (that bounds the capacity of quantum channels to transmit classical information about an observable) and the quantum discord (a measure of the quantumness of correlations of that observable) yields an observable-independent total given by the quantum mutual information. This split naturally delineates information about quantum systems accessible to observers – information that is redundantly transmitted by the environment – while showing that it is maximized for the quasi-classical pointer observable. Other observables are accessible only via correlations with the pointer observable. We also prove an anti-symmetry property relating accessible information and discord. It shows that information becomes objective – accessible to many observers – only as quantum information is relegated to correlations with the global environment, and, therefore, locally inaccessible. The resulting complementarity explains why, in a quantum Universe, we perceive objective classical reality while flagrantly quantum superpositions are out of reach.

Quantum cosmological perturbations of generic fluids in quantum universes

In previous works, it was shown that the Lagrangians and Hamiltonians of cosmological linear scalar, vector and tensor perturbations of homogeneous and isotropic space-times with flat spatial sections containing a perfect fluid can be put in a simple form through the implementation of canonical transformations and redefinitions of the lapse function, without ever using the background classical equations of motion. In this paper, we generalize this result to general fluids, which includes entropy perturbations, and to arbitrary spacelike hyper-surfaces through a new method together with the Faddeev-Jackiw procedure for the constraint reduction. A simple second order Hamiltonian involving the Mukhanov-Sasaki variable is obtained, again without ever using the background equations of motion.

The Quantum Dance and the World's ‘Extraordinary Liveliness’: Refiguring Corporeal Ethics in Karen Barad's Agential Realism

In her 2007 monograph Meeting the Universe Halfway, Karen Barad introduces her reader to a world of movement and flux, where bodies ceaselessly participate in their own material configuration, where bodily integrity and identity is entangled in the dynamic materialisation of its social and political significance, and where processes of understanding and meaning making are bound up in ‘an ongoing performance of the world in its differential dance of intelligibility and unintelligibility’ (2007: 149). Through her reading of Niels Bohr's ‘philosophy-physics’, Barad introduces us to a quantum universe that poses some counterintuitive challenges to the modernist worldview which understands matter to be determinate and measurable, or that may quietly preserve something of matter's evidence against culture's symbolic dexterity. In advancing her agential realist account, Baradmoves beyond anthropocentric constraints to conceive of the world in its ‘extraordinary liveliness’ (2007: 91), an enlarged and productive scene of agency engaged in an ongoing performance of its own intelligibility, articulating itself differently. With the suggestion that agency is extended beyond the framework that assigns it to the intentions and accountability of the human subject, Barad offers a powerful rethinking of the politics and ethics of identity in her claim that the ethical call is ‘embodied in the very worlding of the world’ (2007: 160). In this paper I undertake a close reading of Barad's argument to consider its implications for how we might conceive a corporeal ethics that accounts for the production of inequalities and exclusions within the very becoming of the world, and becoming embodied. In the process, I argue that through asomatechnical unfolding of matter, the experimental apparatus, and concept, Barad prompts some challenging considerations for feminist approaches to what ‘the ethical’ constitutes or should achieve.

Quantum widening of a causal dynamical triangulations universe

The physical phase of causal dynamical triangulations (CDT) is known to be described by an effective, one-dimensional action in which three-volumes of the underlying foliation of the full CDT play a role of the sole degrees of freedom. Here we map this effective description onto a statistical-physics model of particles distributed on a 1d lattice, with site occupation numbers corresponding to the three-volumes. We identify the emergence of the quantum de-Sitter universe observed in CDT with the condensation transition known from similar statistical models. Our model correctly reproduces the shape of the quantum universe and allows us to analytically determine quantum corrections to the size of the universe. In the first-order approximation, these corrections lead to the widening of the CDT universe in the temporal direction. We also investigate the phase structure of the model and show that it reproduces all three phases observed in computer simulations of CDT. In addition, we predict that two other phases may exist, depending on the exact form of the discretized effective action and boundary conditions. We calculate various quantities such as the distribution of three-volumes in our model and discuss how they can be compared with CDT.

The Ghostly Quantum Worlds

We present the foundations of a new emerging interpretation of quantum theory bearing wide-range implications. Physical basis of the interpretation is non-questionable yet relatively new−it relies on the different structures (decompositions into parts, subsystems) of the quantum Universe. We compare the mutually irreducible structures of the Universe and recognize them as the different facets of the one and the same quantum Universe. Physical picture is interesting and non-reducible to the existing interpretations. As a particularly interesting topic in this context appears the 'free will' topic of current interest in the interpretation of quantum theory. To this end, we arrive at the following interesting observation. The freely chosen actions (e.g., quantum measurements) performed by a (conscious) agent that are still locally observable in the alternate Worlds could seem physically unexplainable ('non-physical', 'ghostly'). NeuroQuantology | December 2012 | Volume 10 | Issue 4| Page 619-628

The quantum universe: (and why anything that can happen, does)

The quantum universe: (and why anything that can happen, does)

Hybrid quantization of an inflationary universe

We quantize to completion an inflationary universe with small inhomogeneities in the framework of loop quantum cosmology. The homogeneous setting consists of a massive scalar field propagating in a closed, homogeneous scenario. We provide a complete quantum description of the system employing loop quantization techniques. After introducing small inhomogeneities as scalar perturbations, we identify the true physical degrees of freedom by means of a partial gauge fixing, removing all the local degrees of freedom except the matter perturbations. We finally combine a Fock description for the inhomogeneities with the polymeric quantization of the homogeneous background, providing the quantum Hamiltonian constraint of the composed system. Its solutions are then completely characterized, owing to the suitable choice of quantum constraint, and the physical Hilbert space is constructed. Finally, we consider the analog description for an alternate gauge and, moreover, in terms of gauge-invariant quantities. In the deparametrized model, all these descriptions are unitarily equivalent at the quantum level.

2-point functions in quantum cosmology

We discuss the path-integral formulation of quantum cosmology with a massless scalar field as a sum-over-histories, with particular reference to loop quantum cosmology. Exploiting the analogy with the relativistic particle, we give a complete overview of the possible two-point functions, deriving vertex expansions and composition laws they satisfy. We clarify the tie between definitions using a group averaging procedure and those in a deparametrised framework. We draw some conclusions about the physics of a single quantum universe and multiverse field theories where the role of these sectors and the inner product are reinterpreted.

Conformal fields and the quantum state of the universe

The creation of a quantum Universe is described by a density matrix which yields an ensemble of universes with the cosmological constant limited to a bounded range Λmin ≤ Λ ≤ Λmax. The domain Λ < Λmin is ruled out by a cosmological bootstrap requirement (the self-consistent back reaction of hot matter). The upper cutoff results from the quantum effects of vacuum energy and the conformal anomaly mediated by a special ghost-avoidance renormalization. The cutoff Λmax establishes a new quantum scale – the accumulation point of an infinite sequence of garland-type instantons. The cosmological evolution starting with these initial conditions also have some new features: the stage of cosmic acceleration can be followed by a big boost singularity – a rapid growth up to infinity of the scale factor acceleration parameter. A correspondence between the 4-dimensional modified quantum Freidmann equations and the Friedmann equations arising in the context of 5-dimensional classical cosmological models was established.

Quantum Big Bang without fine-tuning in a toy-model

The question of possible physics before Big Bang (or after Big Crunch) is addressed via a schematic non-covariant simulation of the loss of observability of the Universe. Our model is drastically simplified by the reduction of its degrees of freedom to the mere finite number. The Hilbert space of states is then allowed time-dependent and singular at the critical time t = tc. This option circumvents several traditional theoretical difficulties in a way illustrated via solvable examples. In particular, the unitary evolution of our toy-model quantum Universe is shown interruptible, without any fine-tuning, at the instant of its bang or collapse t = tc.

Towards a quantum universe

In this short review we study the state of the art of the great problems in cosmology and their interrelationships. The reconciliation of these problems passes undoubtedly through the idea of a quantum universe.