{"id":22497,"date":"2024-04-15T10:30:02","date_gmt":"2024-04-15T05:00:02","guid":{"rendered":"https:\/\/vajiramandravi.com\/current-affairs\/?p=22497"},"modified":"2025-10-11T12:45:04","modified_gmt":"2025-10-11T07:15:04","slug":"hubble-tension","status":"publish","type":"post","link":"https:\/\/vajiramandravi.com\/current-affairs\/hubble-tension\/","title":{"rendered":"What is Hubble Tension?"},"content":{"rendered":"<h2>About Hubble Tension<\/h2>\n<ul>\n<li>The &#8220;Hubble tension&#8221; refers to a <strong>discrepancy between<\/strong> the <strong>measurements of<\/strong> the <strong>rate of expansion of the universe<\/strong>, known as the <strong>Hubble constant<\/strong>.<\/li>\n<li>The Hubble constant, <strong>denoted as H0<\/strong>, describes the <strong>rate at which galaxies are moving away from each other<\/strong> due to the expansion of the universe.<\/li>\n<li>If a researcher wants to estimate the Hubble constant, they have <strong>two main avenues.<\/strong> These are the <strong>cosmic distance ladder<\/strong> and the <strong>cosmic microwave background (CMB).<\/strong><\/li>\n<li><strong>Cosmic Microwave Background (CMB):<\/strong>\n<ul>\n<li>CMB is a <strong>sea of photons<\/strong>, the particles of light, <strong>present throughout<\/strong> the <strong>universe<\/strong>. They are left over from the <a href=\"https:\/\/vajiramandravi.com\/upsc-exam\/big-bang-theory\/\" target=\"_blank\">Big Bang<\/a>, its afterglow.<\/li>\n<li>Scientists have <strong>measured temperature changes in the CMB<\/strong> and studied its large-scale properties using complicated trigonometry.<\/li>\n<li><strong>Based on these studies<\/strong>, cosmologists have <strong>estimated space to be expanding at<\/strong> around 68 kilometres per second per megaparsec ((km\/s)\/Mpc). That is, an object one megaparsec (3.26 million lightyears) away is moving away at <strong>68 km\/s)\/Mpc.<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Cosmic Distance Ladder:<\/strong>\n<ul>\n<li>It is a set of techniques used to <strong>measure the distance to objects<\/strong> that are close, further away, or very far away <strong>from the earth<\/strong>. <strong>One object in particular is<\/strong> the <strong>Cepheid variable star.<\/strong><\/li>\n<li>The <strong>Cepheid variables<\/strong> have a unique feature: their <strong>brightness varies in a predictable way <\/strong>over time.<\/li>\n<li><strong>Based on how bright a Cepheid variable is<\/strong>, scientists can estimate how far away it is. Using this, cosmologists have estimated based on various Cepheid variables (and other such objects) is <strong>73 (km\/s)\/Mpc.<\/strong><\/li>\n<\/ul>\n<\/li>\n<li>Thus, these measurements have yielded slightly <strong>different values for the Hubble constant.<\/strong> This discrepancy is known as the <strong>Hubble tension.<\/strong><\/li>\n<li>The significance of the Hubble tension is that it could poten<strong>tially indicate unknown physics<\/strong> or systematic errors in the measurements.<\/li>\n<\/ul>\n<p>Resolving the tension is crucial for refining our understanding of the universe&#8217;s expansion and its underlying physics.<\/p>\n<hr \/>\n<h3>Q1: What is the Big Bang?<\/h3>\n<p>The big bang is how astronomers explain the way the universe began. It is the idea that the universe began as just a single point, then expanded and stretched to grow as large as it is right now\u2014and it is still stretching.<\/p>\n<p><strong>Source:<\/strong> <a href=\"https:\/\/www.thehindu.com\/sci-tech\/science\/hubble-tension-cosmic-distance-ladder-riess-webb-telescope\/article68064403.ece\" target=\"_blank\" rel=\"nofollow noopener\"><u>How fast is the universe expanding? New data keeps mystery open<\/u><\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>The &#8220;Hubble tension&#8221; refers to a discrepancy between the measurements of the rate of expansion of the universe, known as the Hubble constant.<\/p>\n","protected":false},"author":5,"featured_media":22498,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[],"class_list":{"0":"post-22497","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-upsc-prelims-current-affairs","8":"no-featured-image-padding"},"acf":[],"_links":{"self":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts\/22497","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/comments?post=22497"}],"version-history":[{"count":0,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/posts\/22497\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/media\/22498"}],"wp:attachment":[{"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/media?parent=22497"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/categories?post=22497"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vajiramandravi.com\/current-affairs\/wp-json\/wp\/v2\/tags?post=22497"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}