The degree of fine-tuning in our universe — and others

Adams, Fred C.

doi:10.1016/j.physrep.2019.02.001

Cited by 43 publications

(79 citation statements)

References 451 publications

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“…1 For example, inhomogeneous masses can serve as external potentials acting on particle (field) constituents of the model. At the same time, varying couplings can enhance certain processes in one region of space and inhibit them in another region [11].…”

Section: Introductionmentioning

confidence: 99%

IR/UV mixing from local similarity maps of scalar non-Hermitian field theories

Chernodub,

Millington

2021

Preprint

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We propose to gauge the group of similarity transformations that acts on a space of non-Hermitian scalar theories. We introduce the "similarity gauge field", which acts as a gauge connection on the space of non-Hermitian theories characterized by (and equivalent to a Hermitian) real-valued mass spectrum. This extension leads to new effects: if the mass matrix is not the same in distant regions of space, but its eigenvalues coincide pairwisely in both regions, the particle masses stay constant in the whole spacetime, making the model indistinguishable from a standard, low-energy and scalar Hermitian one. However, contrary to the Hermitian case, the high-energy scalar particles become unstable at a particular wavelength determined by the strength of the emergent similarity gauge field. This instability corresponds to momentum-dependent exceptional points, whose locations cannot be identified from an analysis of the eigenvalues of the coordinate-dependent squared mass matrix in isolation, as one might naively have expected. For a doublet of scalar particles with masses of the order 1 MeV and a similarity gauge rotation of order unity at distances of 1 meter, the corrections to the masses are about 10 −7 eV, which makes no experimentally detectable imprint on the low-energy spectrum. However, the instability occurs at 10 18 eV, suggestively in the energy range of detectable ultra-high-energy cosmic rays, thereby making this truly non-Hermitian effect and its generalizations of phenomenological interest for high-energy particle physics.1 Here, we stress the word "spacetime", since we envisage not only space-dependent but also time-dependent phenomena.

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Section: Introductionmentioning

confidence: 99%

IR/UV mixing from local similarity maps of scalar non-Hermitian field theories

Chernodub,

Millington

2021

Preprint

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“…While many anthropic boundaries regarding microscopic physical parameters such as the proton mass, electron mass, fine structure constant, and strength of gravity have been delineated [6][7][8] (for a recent review see [9]), comparatively little attention has been paid to these in the context of the principle of mediocrity. However, these largely determine many of the properties of our mesoscopic world, and so the details of the microphysical parameters will ultimately dictate quite strongly which universes will be capable of supporting observers.…”

Section: Introductionmentioning

confidence: 99%

Multiverse Predictions for Habitability: The Number of Stars and Their Properties

Sandora

2019

Universe

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In a multiverse setting, we expect to be situated in a universe that is exceptionally good at producing life. Though the conditions for what life needs to arise and thrive are currently unknown, many will be tested in the coming decades. Here we investigate several different habitability criteria, and their influence on multiverse expectations: Does complex life need photosynthesis? Is there a minimum timescale necessary for development? Can life arise on tidally locked planets? Are convective stars habitable? Variously adopting different stances on each of these criteria can alter whether our observed values of the fine structure constant, the electron to proton mass ratio, and the strength of gravity are typical to high significance. This serves as a way of generating predictions for the requirements of life that can be tested with future observations, any of which could falsify the multiverse scenario.

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“…(See, for example, [26][27][28] for related reviews.) We can calculate the degree of fine tuning necessary to support certain cosmological structures and the astrophysical and chemical preconditions necessary for life [29]. Rather than making an explicitly anthropic argument [30,31], we can test whether an interaction modeled on horizontal gene transfer can lead to universal and optimal structures as an attractive fixed point.…”

Section: Conclusion and Prospectsmentioning

confidence: 99%

Dynamics of genetic code evolution: The emergence of universality

Argyriadis¹,

He²,

Jejjala³

et al. 2019

Preprint

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We study the dynamics of genetic code evolution. The algorithm of Vetsigian et al.[1] provides a solution that is both optimal and universal. We reproduce and analyze the algorithm as a dynamical system. All the parameters used in the model are varied to assess their impact on achieving universality. We show that by allowing specific parameters to vary with time, the algorithm converges much faster to a universal solution. Finally, we study automorphisms of the genetic code arising due to this model. We use this to examine the scaling of the solutions in order to understand the origin of universality and find that there is a direct link to mutation rate.

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The degree of fine-tuning in our universe — and others

Cited by 43 publications

References 451 publications

IR/UV mixing from local similarity maps of scalar non-Hermitian field theories

IR/UV mixing from local similarity maps of scalar non-Hermitian field theories

Multiverse Predictions for Habitability: The Number of Stars and Their Properties

Dynamics of genetic code evolution: The emergence of universality

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