{"id":251,"date":"2008-01-30T07:08:17","date_gmt":"2008-01-30T12:08:17","guid":{"rendered":"http:\/\/arxivblog.com\/?p=251"},"modified":"2008-01-30T07:08:17","modified_gmt":"2008-01-30T12:08:17","slug":"australians-make-interstellar-hologram","status":"publish","type":"post","link":"http:\/\/arxivblog.com\/?p=251","title":{"rendered":"Australians make interstellar hologram"},"content":{"rendered":"<p><a href=\"http:\/\/arxivblog.com\/wp-content\/uploads\/2008\/01\/interstellar-hologram.jpg\" title=\"Interstellar hologram\"><img decoding=\"async\" src=\"http:\/\/arxivblog.com\/wp-content\/uploads\/2008\/01\/interstellar-hologram.thumbnail.jpg\" alt=\"Interstellar hologram\" \/><\/a><\/p>\n<p>Measure the beam from a pulsar for an hour or so and you&#8217;ll see all kinds of interference fringes in amongst the noise.\u00a0 This intereference is caused by light scattered from the interstellar medium, probably in the form of whisps of\u00a0 gas and dust although nobody knows for sure.<\/p>\n<p>There&#8217;s all kinds of infromation locked in this data. In fact, this interference pattern can be thought of as a kind of\u00a0 hologram of the interstellar medium. But to unlock it, to reconstrcut the image from the interference\u00a0 data, you&#8217;ve gotta know the structure of the light field before it was distorted and this depends on thousands of unknown parameters.<\/p>\n<p>A few astrophysicists have tried to reconstruct these holograms by guessing what these parameters should be but their results have been predictably poor.<\/p>\n<p>Now Mark Walker at the University of Sydney and a few cobbers have made a dramatic improvement by developing an algorithm that can simultaneously optimise the eight thousand coefficients that describe the electric field.<\/p>\n<p>This has allowed them to reconstruct the field and create an image of the interstellar medium. It&#8217;s impressive work.<br \/>\nHaving done that, Walker and co say the information can be used to correct other observations of the\u00a0 such as timing measurements on the pulsar beams. And it might also give an idea what&#8217;s doing all this scattering and how it changes over very short time scales.<br \/>\nCool stuff.<\/p>\n<p>Ref:\u00a0 <a href=\"http:\/\/arxiv.org\/abs\/0801.4183\">arxiv.org\/abs\/0801.4183<\/a>: Interstellar Holography<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Measure the beam from a pulsar for an hour or so and you&#8217;ll see all kinds of interference fringes in amongst the noise.\u00a0 This intereference is caused by light scattered from the interstellar medium, probably in the form of whisps of\u00a0 gas and dust although nobody knows for sure. There&#8217;s all kinds of infromation locked [&hellip;]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,7],"tags":[],"class_list":["post-251","post","type-post","status-publish","format-standard","hentry","category-slimey-stuff","category-stars-in-their-eyes"],"_links":{"self":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/posts\/251","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=251"}],"version-history":[{"count":0,"href":"http:\/\/arxivblog.com\/index.php?rest_route=\/wp\/v2\/posts\/251\/revisions"}],"wp:attachment":[{"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=251"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=251"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/arxivblog.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=251"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}