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The most recent observational constraints coming from Planck, when combined with other cosmological data, provide evidence for a phantom scenario. In this work we consider a quantum cosmic phantom model where both the matter particles and scalar field are associated with quantum potentials which make the effective mass associated with the matter particles to vanish at the time of matter-radiation equality, resulting in a cosmic system where a matter dominance phase followed by an accelerating expansion is allowed. © 2014 The Authors.

In this paper, we study the role of coherent states in the realm of quantum cosmology, both in a second-quantized single universe and in a third-quantized quantum multiverse. In particular, most emphasis will be paid to the quantum description of multiverses made up of accelerated universes. We have shown that the quantum states involved at a quantum mechanical multiverse whose single universes are accelerated are given by squeezed states having no classical analogs.

We consider a connection between the holographic dark energy density and the kinetic k-essence energy density in a flat FRW universe. With the choice c ≥ 1, the holographic dark energy can be described by a kinetic k-essence scalar field in a certain way. In this Letter we show this kinetic k-essential description of the holographic dark energy with c ≥ 1 and reconstruct the kinetic k-essence function F (X). © 2009 Elsevier B.V. All rights reserved.

In this Letter we consider a warp drive spacetime resulting from that suggested by Alcubierre when the spaceship can only travel faster than light. Restricting to the two dimensions that retains most of the physics, we derive the thermodynamic properties of the warp drive and show that the temperature of the spaceship rises up as its apparent velocity increases. We also find that the warp drive spacetime can be exhibited in a manifestly cosmological form. © 2007 Elsevier B.V. All rights reserved.

In this Letter we consider a warp drive spacetime where the spaceship can only travel faster than light. Restricting to the two-dimensional case, we find that if the warp drive is placed in an accelerating universe the warp bubble size increases in a comoving way to the expansion of the universe in which it is immersed. Also shown is the result that the apparent velocity of the ship steadily increases with time as phantom energy is accreted onto it. © 2007 Elsevier B.V. All rights reserved.

The Babichev-Dokuchaev-Eroshenko model for the accretion of dark energy onto black holes has been extended to deal with black holes with non-static metrics. The possibility that for an asymptotic observer a black hole with large mass will rapidly increase and eventually engulf the Universe at a finite time in the future has been studied by using reasonable values for astronomical parameters. It is concluded that such a phenomenon is forbidden for all black holes in quintessential cosmological models. © 2006 Elsevier B.V. All rights reserved.

This paper contains a detailed discussion on new cosmic solutions describing the early and late evolution of a universe that is filled with a kind of dark energy that may or may not satisfy the energy conditions. The main distinctive property of the resulting space-times is that they make to appear twice the single singular events predicted by the corresponding quintessential (phantom) models in a manner which can be made symmetric with respect to the origin of cosmic time. Thus, big bang and big rip singularity are shown to take place twice, one on the positive branch of time and the other on the negative one. We have also considered dark energy and phantom energy accretion onto black holes and wormholes in the context of these new cosmic solutions. It is seen that the space-times of these holes would then undergo swelling processes leading to big trip and big hole events taking place on distinct epochs along the evolution of the universe. In this way, the possibility is considered that the past and future be connected in a non-paradoxical manner in the universes described by means of the new symmetric solutions. © 2006 Elsevier B.V. All rights reserved.

By using a properly generalized accretion formalism it is argued that the accretion of phantom energy onto a wormhole does not make the size of the wormhole throat to comovingly scale with the scale factor of the universe, but instead induces an increase of that size so big that the wormhole can engulf the universe itself before it reaches the big rip singularity, at least relative to an asymptotic observer. © 2005 Elsevier B.V. All rights reserved.

The big trip is a cosmological process thought to occur in the future by which the entire universe would be engulfed inside a gigantic wormhole and might travel through it along space and time. In this Letter we discuss different arguments that have been raised against the viability of that process, reaching the conclusions that the process can actually occur by accretion of phantom energy onto the wormholes and that it is stable and might occur in the global context of a multiverse model. We finally argue that the big trip does not contradict any holographic bounds on entropy and information. © 2006 Elsevier B.V. All rights reserved.

By using an unmodified Einstein gravity theory it is shown that all of the speeding-up effects taking place in the current universe are entirely due to the quantum effects associated with the background radiation or to the combination of such effects with those derived from the presence of a cosmological constant, without invoking any dynamic dark energy component. We obtain that in both cases the universe accelerates at a rate slightly beyond what is predicted by a cosmological constant but does not induce any big rip singularity in the finite future. © 2006 Elsevier B.V. All rights reserved.

In order to reconcile the non conventional character of brane cosmology with standard Friedmann cosmology, we introduce in this paper a slowly-varying quintessence scalar field in the brane and analyse the cosmological solutions corresponding to some equations of state for the scalar field. Different compensation mechanisms between the cosmological constant in the bulk and the constant tension resulting from the combined effect of ordinary matter and the quintessence scalar field are derived or assumed. It has been checked that the Randall-Sundrum approach is not necessarily the best procedure to reconcile brane and standard cosmologies, and that there exists at least another compensating mechanism that reproduces a rather conventional behaviour for an accelerating universe. (C) 2000 Elsevier Science B.V.

A brane universe derived from the Randall-Sundrum models is considered in which an additional Misner-like periodicity is introduced in the extra direction. This model solves the ambiguity in the choice of the brane world by identifying the branes with opposite tensions, in such a way that if one enters the brane with positive tension, one finds oneself emerging from the brane with negative tension, without having experienced any tension. We show that the cosmological evolution resulting from this model matches that of the standard Friedmann scenario, at least in the radiation dominated era, and that there exist closed timelike curves only in the bulk, but not in the branes which are chronologically protected from causality violations by quantum-mechanically stable chronology horizons. (C) 2000 Elsevier Science B.V.

It is shown that the curved spacetime induced in a thin film of superfluid 3He-A by the presence of symmetric vortices with the unbroken symmetry phase, admits the existence of closed timelike curves through which only superfluid clusters formed by anti-3He atoms can travel and violate causality. © 1998 Elsevier Science B.V.

Rabi frequencies for multiphoton absorption by atoms or molecules that can be characterized as two- or three-level systems are obtained in the cases of single and double laser perturbations. If the ambiguity in the origin of absolute energy is conveniently gauged off in the three-level model, there appears an additional non-linear frequency which originates from the separate evolution of a relative frequency component induced in the whole system by the simultaneous action of the two perturbations. © 1998 Elsevier Science B.V. All rights reserved.

We discuss possible states of the quantized gravitational field which have no classical counterpart and reflect in the matter field sector as fundamental phenomena. It is known that wormholes can be pictured as squeezed states of spacetime and that such wormholes are able to induce the kind of decoherence required for a consistent interpretation of the quantum measurement, as well as the spontaneous emergence of bunched and antibunched states in all ordinary matter at low energy.

The quantum state of wormholes has been described by a wave function which is a functional of the metric and matter field configurations on a three-sphere S which divides the space-time four-manifold M into two disconnected parts. We present here the alternate proposal that the quantum state of a single wormhole should be described by a non-factorizable density matrix representing a mixed state, rather than a pure state. Such a density matrix would not contain any isolable part which could be given as a product of separate wave functions and represent a pure quantum state. This proposal seems to lead to a mechanism describing the effects of wormholes by which the probability for the scale of wormholes is overwhelmingly concentrated at very small values. © 1991 - Elsevier Science Publishers B.V.

It is shown that the maximally extended metric corresponding to a large wormhole is the unique possible wormhole metric whose baby universe sector is conformally equivalent to the maximal inextendible Kruskal metric corresponding to the interior region of a Schwarzschild black hole whose gravitational radius is half the wormhole neck radius. The physical implications of this result in the black hole evaporation process are discussed.

Infrared multiphoton dissociation experiments with one or two wavelengths in perfluoropropene and difluorochloromethane have been carried out. It is shown that the additional nonresonant wavelength induces an increase of the yield and selectivity of the dissociation process in the larger molecule and an enhancement of the vibrational intermode coupling in the smaller molecule. A rather surprising structure in the dissociation yield-pressure plot has also been discovered for perfluoropropene at the most effective low pressures. © 1990.

Self-focusing and self-defocusing effects of CO2 laser radiation in ammonia gas for 10 R(14) and 9 R(16) laser lines are reported. Results are in agreement with data provided by classi cal dispersion theory. Effects originating from the addition of hexane as a buffer gas are discussed. © 1990.

Multiphoton dissociation experiments in perfluoropropene and difluorochloromethane have been carried out with one or two wavelengths. It is shown that the increase of selectivity induced by a nonresonant radiation is attributable to an enlagement of the unimolecular reaction regime. The behaviour of large and small molecules when irradiated with two IR laser beams is different. Whereas the distinguishability between unimolecular and collisional regimes is enhanced for sufficiently large molecules, it tends to be smoothed in the case of small molecules. © 1990.

It is shown that the classical solution to a consistent six-dimensional Einstein-Gauss-Bonnet pure gravitational theory has the same spacetime analytical structure as the four-dimensional Tolman-Hawking wormhole for an isotropic Robertson-Walker manifold.

The i.r. spectra of Sr, Pb and Ba hydroxylapatites have been studied and the band assignments are reported. It is found that F- and Cl- form hydrogen bonds in the structure of partially halogenated Sr hydroxylapatite. The Sr carbonate-apatite has also been studied. © 1978.

The i.r. spectra of some solid amine hydrochlorides are studied. The bands originating from strong hydrogen bonds between the physically adsorbed molecules and either the bromide of the polycrystalline KBr, the chloride, or other hydrochloride molecules are tentatively assigned and discussed. © 1981.

The rotation potential functions of the OH group and the water molecule in apatites have been determined by the CNDO/2 method, and the corresponding librational frequencies have been calculated. They are consistent with experimentally determined values. © 1976.

A detailed study of the i.r. spectra of solid 3,4-dichloroaniline and 2,6-dichloroaniline was carried out. The torsional barriers of the amine groups were calculated using a rigorous procedure and the CNDO/2 method. © 1986.

The i.r. spectra of some phosphate-arsenate strontium apatites and phosphate-vanadate strontium apatites have been studied and the assignments of their bands realized. It is shown that the symmetry of the distinct anions depends on the apatitic composition and it is suggested the existence of a mechanism of continuous anion migration throughout the apatite lattice. © 1982.

The i.r. spectra of the calcium-strontium arsenate apatites have been studied, and the OH, AsO4, CO3 and cation-oxygen fundamental frequencies assigned on the basis of group theoretical arguments. It is seen that CO3 ions are included in the lattice. It is demonstrated that Ca and Sr undergo continuous ordered migrations throughout the crystal. © 1980.

© 1980 Published by Elsevier Inc.

Infrared experimental evidence is presented in favor of a mechanism of continuous and reversible hydrogen motion from HPO4 2- ··· OH- to PO4 3- ··· H2O in nonstoichiometric hydroxyapatite. It is also shown how such a mechanism is responsible for the presence of a librational OH band at 670 cm-1 in the infrared spectrum of fluoroapatite. © 1978.

The crystalline structure of Ca10-xSrx(AsO4)6(OH)2 has been studied, and the lattice parameters determined. It has been found that the unit cell expands with x. Geometric parameters of the unit cell, which are defined in relation to the hindered rotation of the OH group around the c axis, have been also obtained. From the ir data, the torsional potential function has been calculated in first and second approximations. A method for computing that function in any order approximation is given. A semiempirical curve is found, relating the stretching and torsional motions for both the OH and OD groups. © 1981.

Some halogenated derivatives of arsenate and vanadate-strontium apatites are studied by i.r. spectroscopy. The results seem to support the ionic migration mechanism suggested elsewhere. © 1982.

The torsional OH and OD modes in the two conformations of 3-chlorophenol have been assigned by infrared and Raman spectroscopy. Assuming C1xC2 rotational symmetry, we have computed the coefficients V1 and V2 for that symmetry by using three different procedures. As in the case of other chlorosubstituted phenols, the geometry of the group undergoing rotation is seen to depend on the isotopic exchanging. © 1986.

We have described the energy levels and the wave functions of the quasicontinuum by means of certain linear combinations of the anharmonic energy levels and wave functions of the normal modes, in order to consider mode interaction, and the Hamiltonian of the interaction heat bath-laser field has been formulated considering the laser field classically. In this way the transition amplitudes among heat bath levels can be calculated. © 1986.

The stretching infrared bands of the amine groups associated by intermolecular hydrogen bonding in solid polyethylene solution have been identified at 140 cm-1 in 3,4 dichloaniline and at 176 and 215 cm-1 in 2,6 dichloroaniline. That assignment has been carried out using medium- and far-infrared spectroscopy and some theoretical considerations. © 1986.

After theoretical and experimental studies, an assignment is made at 409 cm-1 for the OH torsional vibration in solid pentachlorophenol. An optimization method is applied to calculate the V2 torsional barrier, which provides larger values than those obtained from the conventional methods used by other authors. © 1981.

Using the minimum coupling Hamiltonian for deascribing the system active mode-laser fields, we have calculated the shifts of the energy levels of the active mode, produced by thr intense laser fields, by means of a methods upon a space-translation transformation. The laser field has been considered classically. © 1986.

The Raman spectra of benzocaine and procaine hydrochlorides in solid phase are reported. From the assigned inversion and torsion modes we have also estimated the corresponding barriers by using the harmonic approximation. © 1986.

The IR spectra of some halogenated symmetric derivatives of phenol in solid state are reported. The CNDO/2 method has been applied to calculate the V2 torsional barrier; this method gives larger values than those obtained from other conventional methods. The origin of the tilt angle in phenols is discussed. © 1985.

Anti-Stokes luminescence is theoretically described from the quantum statistical point of view. It is shown that this phenomenon depends on the statistical properties of the input fields. The cases of cooperative and sequential sensitization mechanisms are separately considered and the anti-Stokes generation rate terms are studied and discussed for both cases. © 1978.

The process of unimolecular multiphoton dissociation (U.M.D.) in an intense classical laser field is analyzed by means of a recently proposed vibrational model. The time evolution of the molecular vibrational states is determined using second-order, time-dependent perturbation theory. Finally, the probability amplitudes for the vibrational transitions are evaluated for the referred model. © 1986.

By using the Laplace transform method we obtain exact analytical solutions for the time development of the photon density matrix in anti-Stokes luminescence. The cases of cooperative and sequential mechanism are separately considered. © 1982.

A discussion of the wave function for an isotropic universe is given. In order to alleviate that wave function from some of the quantum gravity difficulties, a logarithmic factor 1 - ln( R R0) is introduced in the gravitational action integral. The discussion is extended to the primordial Coleman-Weinberg scenario. © 1985.

In a higher-dimensional version of the gravitational action with higher-derivative terms and logarithmic dependence on the curvature scalar, in addition to the four-dimensional gravitational action integral, the non-gravitational Coleman-Weinberg effective potential that governs primordial inflation is obtained. Also, it is obtained that the lenght scale for the internal space decreases monotonously during the inflationary era, at a similar rate as the three spacelike dimensions grow. © 1986.

A new gravitational quantum lagrangian with logarithmic dependence on R is suggested. The resulting propagator seems to have no tachyon or unphysical state poles, nor complex conjugate poles on the physical sheet. © 1985.

A new euclidean solution is obtained for an axion coupled to gravity with a curvature-squared term. This instanton describes the nucleation of a baby universe. It is shown that the effect of the R2-term is to suppress the interactions of baby universes. © 1989.

A new Coleman-Weinberg potential defined for the Planck epoch is suggested. It is shown that such a potential allows the fluctuations of energy density to be of the order 10-5 while preserving the scale-invariance predicted by the conventional SU(5) GUT potential. © 1984.