{"id":7824,"date":"2022-06-20T18:30:00","date_gmt":"2022-06-20T16:30:00","guid":{"rendered":"https:\/\/www.lapth.cnrs.fr\/event\/newtonian-regime-in-a-spherical-or-hyperbolic-universe-and-consequences-for-the-role-of-spatial-curvature-in-cosmology\/"},"modified":"2022-06-20T18:30:39","modified_gmt":"2022-06-20T16:30:39","slug":"newtonian-regime-in-a-spherical-or-hyperbolic-universe-and-consequences-for-the-role-of-spatial-curvature-in-cosmology","status":"publish","type":"tribe_events","link":"https:\/\/www.lapth.cnrs.fr\/en\/event\/newtonian-regime-in-a-spherical-or-hyperbolic-universe-and-consequences-for-the-role-of-spatial-curvature-in-cosmology\/","title":{"rendered":"Newtonian regime in a spherical or hyperbolic universe and consequences for the role of spatial curvature in cosmology"},"content":{"rendered":"<div>\n<div>\n<div>\n<div>\n<div>\n<div>\n<div>The standard model of cosmology currently allows for three types of geometries for our Universe (Euclidean, spherical or hyperbolic), each of these types corresponding to a set of different (multiconnected)-topologies. Among these geometries, Newton\u2019s theory of gravity is only defined on the Euclidean one. Still, extending the validity of this theory to the two other cases<span>, with the aim that this should&nbsp;<\/span><span>constitute the limit of a relativistic theory of gravity,<\/span>&nbsp;<span>could provide a strong theoretical tool to probe large scale effects of global topology.&nbsp;<\/span><\/div>\n<div><span>&nbsp; The first part of this presentation will aim at constructing such a theory, using the concept of Galilean structures. We will see that it allows to quantify the effects of topology on the gravitational potential and structure formation.<\/span><\/div>\n<div><span>&nbsp; In the second part, I will show that Einstein&#8217;s equation is necessarily incompatible with&nbsp;<\/span>such an<span>&nbsp;extension of Newton&#8217;s theory<\/span><span>. However, as a physical hypothesis for our Universe, if we require the Newtonian regime to exist regardless of the global geometry and topology, then Einstein&#8217;s equation should be modified. This can be done by adding a &#8220;topological term\u2019\u2019 arising<\/span><span>&nbsp;from the introduction of a second non-dynamical metric in the theory.<\/span><span>&nbsp;The main consequence of this modification is that the expansion law of a homogeneous and isotropic solution&nbsp;<\/span><span>no longer features<\/span><span>&nbsp;the spatial curvature (i.e. $Omega = 1,  forall Omega_k$). I will argue that this result gives a simple solution to the flatness problem, and asks for a reevaluation of the spatial curvature from current cosmological data.<\/span><\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>The standard model of cosmology currently allows for three types of geometries for our Universe (Euclidean, spherical or hyperbolic), each of these types corresponding to a set of different (multiconnected)-topologies. [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"template":"","meta":{"_acf_changed":false,"_tribe_events_status":"","_tribe_events_status_reason":"","footnotes":""},"tags":[],"tribe_events_cat":[18],"class_list":["post-7824","tribe_events","type-tribe_events","status-publish","hentry","tribe_events_cat-weekly-seminars","cat_weekly-seminars"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/tribe_events\/7824","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/tribe_events"}],"about":[{"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/types\/tribe_events"}],"author":[{"embeddable":true,"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":0,"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/tribe_events\/7824\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/media?parent=7824"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/tags?post=7824"},{"taxonomy":"tribe_events_cat","embeddable":true,"href":"https:\/\/www.lapth.cnrs.fr\/en\/wp-json\/wp\/v2\/tribe_events_cat?post=7824"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}