Introduction

Mersini-Houghton, Laura; Vaas, Rüdiger

doi:10.1007/978-3-642-23259-6_1

Cited by 23 publications

(76 citation statements)

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“…The multiverse hypothesis also comes in multiple flavors (for an overview of the wide variety of forms, see e.g. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]) and one thus needs to be careful to clearly define what one means when discussing issues about the multiverse.…”

Section: Introductionmentioning

confidence: 99%

The interacting multiverse and its effect on the cosmic microwave background

Bouhmadi-López

Kraemer

Morais

et al. 2019

J. Cosmol. Astropart. Phys.

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We study a toy model of a multiverse consisting of canonically quantized universes that interact with each other on a quantum level based on a field-theoretical formulation of the Wheeler-DeWitt equation. This interaction leads to the appearance of a pre-inflationary phase in the evolution of the individual universes. We analyze scalar perturbations within the model and calculate the influence of the pre-inflationary phase onto the power spectrum of these perturbations. The result is that there is a suppression of power on large scales, which can describe well the Planck 2018 data for the cosmic microwave background anisotropies and could thus indicate a possible solution to the observed quadrupole discrepancy.

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Section: Introductionmentioning

confidence: 99%

The interacting multiverse and its effect on the cosmic microwave background

Bouhmadi-López

Kraemer

Morais

et al. 2019

J. Cosmol. Astropart. Phys.

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“…The consequences it might have for black hole formation and the information paradox have been a subject of interest in recent years [9,10,[12][13][14][15][16][17][18][19]. While it has been argued that such effects are too small to prevent the formation of an event horizon [10,19], others contend that such approximations are not reliable and that horizons may not form if pre-Hawking radiation is properly taken into account [13,16]. Indeed, it has been posited that this should be a generic feature of quantum gravity, with the black hole interior and accompanying singularity replaced with a genuine quantum geometry where the notion of event horizon ceases to be useful [20].…”

Section: Introductionmentioning

confidence: 99%

Transition to light-like trajectories in thin shell dynamics

2018

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It was recently shown that a massive thin shell that is sandwiched between a flat interior and an exterior geometry given by the outgoing Vaidya metric becomes null in a finite proper time. We investigate this transition for a general spherically-symmetric metric outside the shell and find that it occurs generically. Once the shell is null its persistence on a null trajectory can be ensured by several mechanisms that we describe. Using the outgoing Vaidya metric as an example we show that if a dust shell acquires surface pressure on its transition to a null trajectory it can evade the Schwarzschild radius through its collapse. Alternatively, the pressureless collapse may continue if the exterior geometry acquires a more general form.

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“…The multiverse, in its wide variety of forms [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26], has become the most general scenario in cosmology. Three of the major frameworks in cosmology, i.e.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main aims of quantum cosmology is to describe the creation of the universe [10,23,[30][31][32][33]. It is a key feature because once the creation of the universe is described, the description of the rest of physical processes in the universe follows from known physical laws.…”

Section: Introductionmentioning

confidence: 99%

Quantum cosmology of a conformal multiverse

Robles-Pérez

2017

Phys. Rev. D

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This paper studies the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of universes, and all of them are periodically distributed along the complex time axis. From a classical point of view, they are then isolated, separated by Euclidean regions that represent quantum mechanical barriers. Quantum mechanically, however, there is a nonzero probability for the state of the universes to tunnel out through a Euclidean instanton and suffer a sudden transition to another state of the spacetime. We compute the probability of transition for this and other nonlocal processes like the creation of universes in entangled pairs and, generally speaking, in multipartite entangled states. We obtain the quantum state of a single universe within the formalism of the Wheeler-DeWitt equation and give the semiclassical state of the universes that describes the quantum mechanics of a scalar field propagating in a de Sitter background spacetime. We show that the superposition principle of the quantum mechanics of matter fields alone is an emergent feature of the semiclassical description of the universe that is not valid, for instance, in the spacetime foam. We use the third quantization formalism to describe the creation of an entangled pair of universes with opposite signs of the momentum conjugated to the scale factor. Each universe of the entangled pair represents an expanding spacetime in terms of the Wentzel-Kramers-Brillouin (WKB) time experienced by internal observers in their particle physics experiments. We compute the effective value of the Friedmann equation of the background spacetime of the two entangled universes, and thus, the effect that the entanglement would have in their expansion rates. We analyze as well the effects of the interuniversal entanglement in the properties of the scalar fields that propagate in each spacetime of the entangled pair. We find that the largest modes of the scalar field are unaware of the entanglement between the universes, but the effects can be significant for the lowest modes, allowing us to compute, in principle, detailed observational imprints of the multiverse in the properties of a single universe like ours.

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Introduction

Cited by 23 publications

References 0 publications

The interacting multiverse and its effect on the cosmic microwave background

The interacting multiverse and its effect on the cosmic microwave background

Transition to light-like trajectories in thin shell dynamics

Quantum cosmology of a conformal multiverse

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