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<< Cosmo.WebHome %TOC% ---- ---+ Cosmology past and ongoing projects in Toruñ - brief summary for main page _include starts here_ %STARTINCLUDE% ---++ Shape of the Universe <a href="/Cosmo/CosmoTopology"><img src="%ATTACHURLPATH%/../CosmoProjects/RBSG08_CCBYSA_GPL_GFDL.jpg" alt="RBSG08 image" width='200' height='200' style="float:left; margin-right: 20px"/></a> <a href="/Cosmo/CosmoCurvature"><img src="%ATTACHURLPATH%/metric_par.jpg" alt="metric parameters image" width='200' height='200' style="float:right; margin-left: 20px"/></a> Scientific models of the Universe are intended to satisfy the Einstein field equations, that roughly speaking, state that curvature = density. The models allow many different sorts of spaces, which have the local property called a *metric* (a sort of rule for locally measuring distances, that determines *curvature*) and have global properties that define them, such as *topology*. Together curvature and topology can be described as *shape*. The metric of our Universe model has many parameters such as the Hubble parameter, the baryon density parameter, the baryonic and non-baryonic dark matter density parameter %$\Omega_m$%, and the dark energy parameter %$\Omega_\Lambda$%. ---+++ Density fluctuations The Universe is not perfectly the same everywhere in space - even when the Universe was just a few hundred thousand years old, some regions were more dense and some were less dense. The more dense regions eventually collapsed under their own weight, via gravity, and formed galaxies, stars, and planets. Can a theory of inflation explain the origin of these *density fluctuations*? There are some observational hints that this might be the case. One of the research strategies for selecting an inflationary theory out of the many available scenarios is to check for non-Gaussian statistical properties of the fluctuations. <!-- %RED%TODO Bartek: Something about results/projects.%ENDCOLOR% --> These fluctuations are not just interesting for galaxy formation, they are also useful for measuring [[CosmoCurvature][the curvature of space]]. ---+++ Collapsed objects Density fluctuations on the smaller scales (up to about 1 Mpc, a few million light-years) collapsed gravitationally, [[GalaxyFormation][forming galaxy clusters and galaxies]] in which stars and planets formed. Comparing observations of galaxies and galaxy clusters to the cosmic microwave background and separating the two effects is a major theme of the observational aspects of the [[http://www.astro.uni.torun.pl/index.php?page=ocra][OCRA]] program using our 32m radio telescope. %STOPINCLUDE% ---- See also CosmoProjectsOld
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14 Jul 2010 - 02:03
BoudRoukema
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Topic revision: r5 - 16 Jul 2013,
BoudRoukema
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