{"id":285405,"date":"2016-09-27T02:00:00","date_gmt":"2016-09-26T23:00:00","guid":{"rendered":"http:\/\/www.fyysika.ee\/?guid=4f805f546c109de867b334ccd4462832"},"modified":"2016-09-27T02:00:00","modified_gmt":"2016-09-26T23:00:00","slug":"hubble-expansion-is-not-a-velocity","status":"publish","type":"post","link":"https:\/\/www.fyysika.ee\/?p=285405","title":{"rendered":"Hubble expansion is not a velocity"},"content":{"rendered":"<p>In this paper, we clarify the difference between the Hubble expansion and the Doppler shift<br \/>\npedagogically and illustrate both physically and mathematically why the Hubble expansion cannot be<br \/>\nregarded as a velocity. Therefore, we suggest to replace the misleading word \u2018recession velocity\u2019 to<br \/>\nbe \u2018 Hubble recession \u2019 to describe the cosmic expansion. We further derive how the peculiar<br \/>\nvelocity of a galaxy is related to its observed redshift and proper distance, which has practical<br \/>\nuse in the galaxy redshift and distance surveys.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In this paper, we clarify the difference between the Hubble expansion and the Doppler shift<br \/>\npedagogically and illustrate both physically and mathematically why the Hubble expansion cannot be<br \/>\nregarded as a velocity. Therefore, we suggest to replace th&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_genesis_hide_title":false,"_genesis_hide_breadcrumbs":false,"_genesis_hide_singular_image":false,"_genesis_hide_footer_widgets":false,"_genesis_custom_body_class":"","_genesis_custom_post_class":"","_genesis_layout":"","footnotes":""},"categories":[178],"tags":[],"class_list":{"0":"post-285405","1":"post","2":"type-post","3":"status-publish","4":"format-standard","6":"category-rss-fuusikaharidus","7":"entry"},"_links":{"self":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/285405","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=285405"}],"version-history":[{"count":0,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=\/wp\/v2\/posts\/285405\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=285405"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=285405"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fyysika.ee\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=285405"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}