{"id":514,"count":6,"description":"Einstein's equations can do more than just give us models for specific phenomena such as black holes or gravitational waves; they can also be used to describe the universe as a whole. On the basis of general relativity, physicists, mathematicians and astronomers have developed the so-called big bang models. They describe how our universe evolved from an extremely hot and dense early phase to its present state.\r\n\r\nA key property of these models is that the universe has to change over time. Einstein's equation simply do not allow for a stable, eternally unchanging cosmos. According to the big bang models, any universe has to either expand or collapse. Our own universe is expanding, with characteristic consequences for astronomical observation.","link":"https:\/\/www.einstein-online.info\/en\/category\/elementary\/cosmology-elementary\/","name":"Cosmology","slug":"cosmology-elementary","taxonomy":"category","parent":505,"meta":[],"_links":{"self":[{"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/categories\/514","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/categories"}],"about":[{"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/taxonomies\/category"}],"up":[{"embeddable":true,"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/categories\/505"}],"wp:post_type":[{"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/posts?categories=514"},{"href":"https:\/\/www.einstein-online.info\/en\/wp-json\/wp\/v2\/spotlight?categories=514"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}