منابع مشابه
Cosmic Topology
General relativity does not allow to specify the topology of space, leaving the possibility that space is multi{ rather than simply{connected. We review the main mathematical properties of multi{connected spaces, and the di erent tools to classify them and to analyse their properties. Following the mathematical classi cation, we describe the di erent possible muticonnected spaces which may be u...
متن کاملCosmological parameters and cosmic topology
Geometry constrains but does not dictate the topology of the three-dimensional space. In a locally spatially homogeneous and isotropic universe, however, the topology of its spatial section dictates its geometry. We show that, besides determining the geometry, the knowledge of the spatial topology through the circles-in-the-sky offers an effective way of setting constraints on the density param...
متن کاملSupernovae observations and cosmic topology
Context. Two fundamental questions regarding our description of the Universe concern the geometry and topology of its 3-dimensional space. While geometry is a local characteristic that gives the intrinsic curvature, topology is a global feature that characterizes the shape and size of the 3-space. The geometry constrains, but does not dictate, the spatial topology. Aims. We show that besides de...
متن کاملThe Cosmic Censor Forbids Naked Topology
For any asymptotically at spacetime with a suitable causal structure obeying (a weak form of) Penrose's cosmic censorship conjecture and satisfying conditions guaranteeing focusing of complete null geodesics, we prove that active topological censorship holds. We do not assume global hyperbolicity, and therefore make no use of Cauchy surfaces and their topology. Instead, we replace this with two...
متن کاملPast and Future of Cosmic Topology
The global topology of the universe, including questions about the shape of space, its volume and its connectedness, is a fundamental issue in cosmology which has been overlooked for many years, except by some pioneering authors (see references in LachièzeRey & Luminet, 1995, hereafter LaLu95). In the first part of the present article, I set out some unexplored historical material about the ear...
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ژورنال
عنوان ژورنال: Scholarpedia
سال: 2015
ISSN: 1941-6016
DOI: 10.4249/scholarpedia.31544