搜索结果: 1-15 共查到“universes”相关记录17条 . 查询时间(0.187 秒)
A Brief Introduction to N-universes
n-universes thought experiment time space Occam's razor
2015/7/29
I describe in this paper the basic elements of the n-universes, a methodological tool originally introduced in Franceschi (2001) in the context of the study of Goodman's paradox. As the n-universes ca...
From Feshbach-resonance managed Bose-Einstein condensates to anisotropic universes: Applications of the Ermakov-Pinney equation with time-dependent nonlinearity
Two-dimensional condensate time-varying magnetic confinement scattering wave function ordinary differential equations
2014/12/25
In this work we revisit the topic of two-dimensional Bose–Einstein condensates under the influence of time-dependent magnetic confinement and time-dependent scattering length. A moment approach reduce...
Graph cluster randomization: network exposure to multiple universes
Graph cluster randomization network exposure multiple universes
2013/6/17
A/B testing is a standard approach for evaluating the effect of online experiments; the goal is to estimate the `average treatment effect' of a new feature or condition by exposing a sample of the ove...
Knot Universes in Bianchi Type I Cosmology
Knot Universes Bianchi Type I Cosmology General Physics
2012/4/19
We investigate the trefoil and figure-eight knot universes from Bianchi-type I cosmology. In particular, we construct several concrete models describing the knot universes related to the cyclic univer...
On Shear-Free perturbations of FLRW Universes
On Shear-Free perturbations of FLRW Universes
2011/10/14
A surprising exact result for the Einstein Field Equations is that if pressure-free matter is moving in a shear-free way, then it must be either expansion-free or rotation-free. It has been suggested ...
Light propagation and the average expansion rate in near-FRW universes
Light propagation average expansion rate universes
2011/9/29
We consider universes which are close to Friedmann-Robertson-Walker in the sense that metric perturbations, their time derivatives and first spatial derivatives are small, but second spatial derivativ...
A Note on the Inverse Problem with LTB Universes
Cosmology and Extragalactic Astrophysics (astro-ph.CO) General Relativity and Quantum Cosmology (gr-qc)
2010/12/23
The inverse problem with Lema\^itre-Tolman-Bondi (LTB) universe models is discussed. The LTB solution for the Einstein equations describes the spherically symmetric dust-filled spacetime. The LTB solu...
Redshift Drift in LTB Void Universes
Cosmology and Extragalactic Astrophysics (astro-ph.CO)
2010/12/23
We study the redshift drift, i.e., the time derivative of the cosmological redshift in the Lema\^itre-Tolman-Bondi (LTB) solution in which the observer is assumed to be located at the symmetry center.
Expanding universes in the conformal frame of $f(R) $ gravity
Expanding universes conformal frame $f(R) $ gravity
2010/3/17
The late time evolution of Friedmann-Robertson-Walker (FRW) models with a perfect fluid matter source is studied in the conformal frame of $f(R) $ gravity. We assume that the corresponding scalar fiel...
HOW MANY UNIVERSES ARE NECESSARY FOR AN ICE CREAM TO MELT?
cosmology theory-gravitation-history and philosophy of astronomy
2009/3/13
We investigate a quantitative consequence of the Acausal-Anthropic
approach to solving the long-standing puzzle of the thermodynamical arrow
of time. Notably, the size of the required multiverse is ...
In this letter we construct a new time-periodic solution of the vacuum Einstein's ˉeld equations whose Riemann curvature norm takes the inˉnity at some points. We show that this solution is intrinsica...
The purpose of this paper is to discuss the various types of physical universe which could exist according to modern mathematical physics. The paper begins with an introduction that approaches the que...
The purpose of this paper is to survey the possible topologies of branching space-times, and, in particular, to refute the popular notion in the literature that a branching space-time requires a non-H...
The Standard Model of particle physics in other universes
Particles space-time symmetry structuralism
2008/4/21
The purpose of this paper is to demonstrate how the mathematical objects and structures associated with the particle physics in other universes, can be inferred from the mathematical objects and struc...
Time before Time - Classifications of Universes in contemporary cosmology, and how to avoid the antinomy of the beginning and eternity of the world
cosmology big bang big crunch universe
2008/4/21
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 Midd...