614,757 research outputs found
Foam-like structure of the Universe
On the quantum stage spacetime had the foam-like structure. When the Universe
cools, the foam structure tempers and does not disappear. We show that effects
caused by the foamed structure mimic very well the observed Dark Matter
phenomena. Moreover, we show that in a foamed space photons undergo a chaotic
scattering and together with every discrete source of radiation we should
observe a diffuse halo. We show that the distribution of the diffuse halo of
radiation around a point-like source repeats exactly the distribution of dark
matter around the same source, i.e. the DM halos are sources of the diffuse
radiation
Large Scale Structure of the Universe
Galaxies are not uniformly distributed in space. On large scales the Universe
displays coherent structure, with galaxies residing in groups and clusters on
scales of ~1-3 Mpc/h, which lie at the intersections of long filaments of
galaxies that are >10 Mpc/h in length. Vast regions of relatively empty space,
known as voids, contain very few galaxies and span the volume in between these
structures. This observed large scale structure depends both on cosmological
parameters and on the formation and evolution of galaxies. Using the two-point
correlation function, one can trace the dependence of large scale structure on
galaxy properties such as luminosity, color, stellar mass, and track its
evolution with redshift. Comparison of the observed galaxy clustering
signatures with dark matter simulations allows one to model and understand the
clustering of galaxies and their formation and evolution within their parent
dark matter halos. Clustering measurements can determine the parent dark matter
halo mass of a given galaxy population, connect observed galaxy populations at
different epochs, and constrain cosmological parameters and galaxy evolution
models. This chapter describes the methods used to measure the two-point
correlation function in both redshift and real space, presents the current
results of how the clustering amplitude depends on various galaxy properties,
and discusses quantitative measurements of the structures of voids and
filaments. The interpretation of these results with current theoretical models
is also presented.Comment: Invited contribution to be published in Vol. 8 of book "Planets,
Stars, and Stellar Systems", Springer, series editor T. D. Oswalt, volume
editor W. C. Keel, v2 includes additional references, updated to match
published versio
The Duality of the Universe
It is proposed that the physical universe is an instance of a mathematical
structure which possesses a dual structure, and that this dual structure is the
collection of all possible knowledge of the physical universe. In turn, the
physical universe is then the dual space of the latter
Bubbles created from vacuum fluctuation
We show that the bubbles can be created from vacuum
fluctuation in certain De Sitter universe, so the space-time foam-like
structure might really be constructed from bubbles of in the
very early inflating phase of our universe. But whether such foam-like
structure persisted during the later evolution of the universe is a problem
unsolved now.Comment: 6 page
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