{"id":520,"date":"2008-07-14T00:40:55","date_gmt":"2008-07-14T05:40:55","guid":{"rendered":"http:\/\/arxivblog.com\/?p=520"},"modified":"2008-07-14T00:41:15","modified_gmt":"2008-07-14T05:41:15","slug":"dark-energy-and-the-bitterest-pill","status":"publish","type":"post","link":"http:\/\/arxivblog.com\/?p=520","title":{"rendered":"Dark energy and the bitterest pill"},"content":{"rendered":"

\u00a0\"Copernican<\/a><\/p>\n

It’s hard to get your head around dark energy, this universe-accelerating stuff that is supposed to fill the cosmos. Dark energy was invented to explain measurements that seem to show that the most distant supernovas all appear to be accelerating away from us. The thinking is that something must be pushing them away and that stuff is dark energy.<\/p>\n

But for many astrophysicists, dark energy is a difficult pill to swallow. It requires the universe to be fine tuned in a previously unexpected, and frankly, unimaginable way.<\/p>\n

So astronomers have begun a systematic investigation of all the assumptions on which the notion of dark energy depends. Nothing is sacrosanct in this hunt–these guys are tearing up the floorboards in the search for an alternative hypothesis. And that means revisiting some of our most fundamental assumptions.<\/p>\n

One of these is the Copernican principle, that the universe is more or less the same wherever you happen to be. Principles don’t come much more fundamental than this but the evidence in its favour, at least on the scale that dark energy seems to behave, is pretty thin.<\/p>\n

In fact, a number of theorists have calculated that the supernova data can be explained without the need for dark energy if our local environment were emptier than the universe as a whole. But to make this idea work, the earth must be sitting in the middle of a void that is roughly the size of the observable universe and that’s not compatible with the Copernican principle, not by a long shot.<\/p>\n

Now Timothy Clifton\u00a0 and pals at the University of Oxford in the UK have worked our how to tell whether such a void exists or not. They say that the next round of highly accurate measurements of nearby supernova should be able to tell us whether we’re in a void or not. So we shouldn’t have long to wait.<\/p>\n

Either way, astronomers will find it hard to settle that troubling sensation in the pit of their stomachs. The truth is that when it comes to swallowing uncomfortable ideas, dark energy may turn out to be a sugar-coated doughnut compared to a rejection of the Copernican principle.<\/p>\n

Ref: arxiv.org\/abs\/0807.1443<\/a>: Living in a Void: Testing the Copernican Principle with Distant Supernovae<\/p>\n","protected":false},"excerpt":{"rendered":"

\u00a0 It’s hard to get your head around dark energy, this universe-accelerating stuff that is supposed to fill the cosmos. Dark energy was invented to explain measurements that seem to show that the most distant supernovas all appear to be accelerating away from us. The thinking is that something must be pushing them away and […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12,6,16],"tags":[],"class_list":["post-520","post","type-post","status-publish","format-standard","hentry","category-changin-the-world","category-hellraisin","category-seein-the-light"],"_links":{"self":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/posts\/520","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=520"}],"version-history":[{"count":0,"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/posts\/520\/revisions"}],"wp:attachment":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=520"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=520"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=520"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}