{"id":629,"date":"2009-03-10T00:49:38","date_gmt":"2009-03-10T00:49:38","guid":{"rendered":"http:\/\/spinor.info\/weblog\/?p=629"},"modified":"2009-03-10T00:49:38","modified_gmt":"2009-03-10T00:49:38","slug":"einstein-and-silberstein","status":"publish","type":"post","link":"https:\/\/spinor.info\/weblog\/?p=629","title":{"rendered":"Einstein and Silberstein"},"content":{"rendered":"<p>I&#8217;m reading about the debate in the 1930s between Einstein and Silberstein about the (non-)existence of a static two-body vacuum solution of the Einstein field equations.<\/p>\n<p>Silberstein claimed to have found just such a solution as a special case of Weyl&#8217;s metric. However, he then concluded that the existence of an unphysical solution implies that Einstein&#8217;s gravitational theory has to be modified.<\/p>\n<p>Meanwhile, Einstein dismissed Silberstein&#8217;s solution on two grounds. First, he claimed that there are additional singularities; second, he claimed that a solution that yields singularities is in any case not a proper solution of a field theory, so it certainly cannot be used to discredit that theory.<\/p>\n<p>I disagree with Silberstein&#8230; just because there exist solutions that are unphysical does not unmake a theory. The equations of ballistics also yield unphysical solutions, such as cannonballs going underground or flying backwards in time&#8230; but it simply means that we chose unphysical initial conditions, not that the theory is wrong.<\/p>\n<p>I also disagree with Einstein&#8217;s second argument though&#8230; field theory or not, some singularities can be quite useful and physically meaningful, be it, say, the &#8220;point mass&#8221; in Newton&#8217;s theory, the &#8220;point source&#8221; in electromagnetism, or, well, singularities in general relativity representing compact (point) masses.<\/p>\n<p>But both these issues are more philosophy than physics. I am more interested in Einstein&#8217;s first argument&#8230; is it really true that Silberstein&#8217;s solution yields more than two singularities?<\/p>\n<p>That is because when I actually calculate with Silberstein&#8217;s metric, I find regular behavior everywhere except at the two singular points. I see no sign whatsoever of the supposed singular line between them. What am I missing?<\/p>\n<fb:like href='https:\/\/spinor.info\/weblog\/?p=629' send='true' layout='standard' show_faces='true' width='450' height='65' action='like' colorscheme='light' font='lucida grande'><\/fb:like>","protected":false},"excerpt":{"rendered":"<p>I&#8217;m reading about the debate in the 1930s between Einstein and Silberstein about the (non-)existence of a static two-body vacuum solution of the Einstein field equations. Silberstein claimed to have found just such a solution as a special case of Weyl&#8217;s metric. However, he then concluded that the existence of an unphysical solution implies that <a href='https:\/\/spinor.info\/weblog\/?p=629' class='excerpt-more'>[&#8230;]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-629","post","type-post","status-publish","format-standard","hentry","category-physics","category-3-id","post-seq-1","post-parity-odd","meta-position-corners","fix"],"_links":{"self":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/629","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=629"}],"version-history":[{"count":2,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/629\/revisions"}],"predecessor-version":[{"id":631,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=\/wp\/v2\/posts\/629\/revisions\/631"}],"wp:attachment":[{"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=629"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=629"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/spinor.info\/weblog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=629"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}