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[Abridged] Some cosmological theories propose that the observable universe is a small part of a much larger universe in which parameters describing the low-energy laws of physics vary from region to region. How can we reasonably assess a…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-04 Feraz Azhar , Alan H. Guth , Mohammad Hossein Namjoo

The accelerating expansion of the universe presents an exciting, fundamental challenge to the standard models of particle physics and cosmology. I highlight some of the outstanding challenges in both developing theoretical models and…

Astrophysics · Physics 2008-11-26 Eric V. Linder

A complete set of Feynman rules is derived, which permits a perturbative description of the nonequilibrium dynamics of a symmetry-breaking phase transition in $\lambda\phi^4$ theory in an expanding universe. In contrast to a naive expansion…

High Energy Physics - Theory · Physics 2009-10-31 Ian D. Lawrie

We describe the fundamental difference between the nature of problems in traditional physics and that of many problems arising today in systems biology and other complex settings. The difference hinges on the much larger number of a priori…

Quantitative Methods · Quantitative Biology 2011-04-22 A. X. C. N. Valente

This paper considers a new and deeply challenging face of the problem of time in the context of cosmology drawing on the work of Thiemann (2006, 2007). Thiemann argues for a radical response to the cosmic problem of time that requires us to…

General Relativity and Quantum Cosmology · Physics 2025-05-09 Nicola Bamonti , Karim P. Y. Thébault

A glorious achievement of twentieth century Physics is the identification of the building blocks of nature. A related triumph a deep understanding of the forces of interaction. In particular, it has been possible to understand the four…

History and Philosophy of Physics · Physics 2007-05-23 U. A. Yajnik

We identify new, rather serious, physical and axiomatic inconsistencies of the current formulation of string theories due to the lack of invariant units necessary for measurements, lack of preservation in time of Hermiticity-observability,…

General Physics · Physics 2007-05-23 Ruggero Maria Santilli

Symmetry-breaking phase transitions are ubiquitous in condensed matter systems and in quantum field theories. There is also good reason to believe that they feature in the very early history of the Universe. At many such transitions…

Condensed Matter · Physics 2007-05-23 T. W. B. Kibble

The need for revolution in modern physics is a well known and often broached subject, however, the precision and success of current models narrows the possible changes to such a great degree that there appears to be no major change…

History and Philosophy of Physics · Physics 2018-09-07 Shiva Meucci

In contemporary physics space and time are intertwined entities so that kinematical and dynamical quantities are expressed in the four-dimensional space-time. This formulation seems to contradict our every-day experience and perception…

General Physics · Physics 2023-05-23 Orfeu Bertolami

We argue that massive quantum fields source low-frequency long-wavelength metric fluctuations through the quantum fluctuations of their stress-energy, given reasonable assumptions about the analytic structure of its correlators. This can be…

High Energy Physics - Theory · Physics 2017-03-17 Niayesh Afshordi , Hyungjin Kim , Elliot Nelson

The commonly assumed cosmological history of our universe is that at early-times and high-temperatures the universe went through an ElectroWeak Phase Transition (EWPT). Assuming an EWPT, and depending on its strength, there are many…

High Energy Physics - Phenomenology · Physics 2019-02-06 Patrick Meade , Harikrishnan Ramani

Did the universe have a beginning or does it exist forever, i.e. is it eternal at least in relation to the past? This fundamental question was a main topic in ancient philosophy of nature and the Middle Ages. Philosophically it was more or…

General Physics · Physics 2009-10-29 Ruediger Vaas

Cosmological data suggest that we live in an interesting period in the history of the universe when \rho_\Lambda \sim \rho_M \sim \rho_R. The occurence of any epoch with such a "triple coincidence" is puzzling, while the question of why we…

Astrophysics · Physics 2009-09-29 Nima Arkani-Hamed , Lawrence J. Hall , Christopher Kolda , Hitoshi Murayama

The advent of modern technology, permitting the measurement of thousands of characteristics simultaneously, has given rise to floods of data characterized by many large or even huge datasets. This new paradigm presents extraordinary…

Methodology · Statistics 2019-02-14 A. M. Pires , J. A. Branco

The ideas related to the arrow of time are discussed briefly. I then focus on the prevalent physical mechanism in the evolution of the universe and developments in particle physics, spontaneous symmetry breaking, and show that it explicitly…

General Physics · Physics 2019-07-12 Jose A. Magpantay

High-precision measurements of violations of fundamental symmetries in atoms are a very effective means of testing the standard model of elementary particles and searching for new physics beyond it. Such studies complement measurements at…

Atomic Physics · Physics 2009-08-18 J. S. M. Ginges , V. V. Flambaum

The Einstein's equivalence principle and experiments, in which bodies and observers are in different G potentials, have been used to prove that the chain of hypothesis coming from assuming the absolute invariability of the bodies, after a…

Astrophysics · Physics 2007-05-23 Rafael A. Vera

Despite the fact that the fundamental physical laws are symmetric in time, most observed processes do not show this symmetry. Especially the phenomenon of decay seems to involve a kind of irreversibility that makes the definition of a…

Quantum Physics · Physics 2007-05-23 Kim J. Bostroem

This work investigates alternative theories of gravity, the solutions to their field equations and the constraints that can be imposed upon them from observation and experiment. Specifically, we consider the cosmologies and spherically…

General Relativity and Quantum Cosmology · Physics 2007-05-23 T. Clifton
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