{"version":"1.0","provider_name":"KMI - Nagoya University","provider_url":"https:\/\/www.kmi.nagoya-u.ac.jp\/eng","title":"Causal structures in various modified theories of gravity - KMI - Nagoya University","type":"rich","width":600,"height":338,"html":"<blockquote class=\"wp-embedded-content\" data-secret=\"NnuA0scqZh\"><a href=\"https:\/\/www.kmi.nagoya-u.ac.jp\/eng\/seminar\/924\/\">Causal structures in various modified theories of gravity<\/a><\/blockquote><iframe sandbox=\"allow-scripts\" security=\"restricted\" src=\"https:\/\/www.kmi.nagoya-u.ac.jp\/eng\/seminar\/924\/embed\/#?secret=NnuA0scqZh\" width=\"600\" height=\"338\" title=\"&#8220;Causal structures in various modified theories of gravity&#8221; &#8212; KMI - Nagoya University\" data-secret=\"NnuA0scqZh\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\" class=\"wp-embedded-content\"><\/iframe><script type=\"text\/javascript\">\n\/* <![CDATA[ *\/\n\/*! This file is auto-generated *\/\n!function(d,l){\"use strict\";l.querySelector&&d.addEventListener&&\"undefined\"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!\/[^a-zA-Z0-9]\/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret=\"'+t.secret+'\"]'),o=l.querySelectorAll('blockquote[data-secret=\"'+t.secret+'\"]'),c=new RegExp(\"^https?:$\",\"i\"),i=0;i<o.length;i++)o[i].style.display=\"none\";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute(\"style\"),\"height\"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):\"link\"===t.message&&(r=new URL(s.getAttribute(\"src\")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener(\"message\",d.wp.receiveEmbedMessage,!1),l.addEventListener(\"DOMContentLoaded\",function(){for(var e,t,s=l.querySelectorAll(\"iframe.wp-embedded-content\"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute(\"data-secret\"))||(t=Math.random().toString(36).substring(2,12),e.src+=\"#?secret=\"+t,e.setAttribute(\"data-secret\",t)),e.contentWindow.postMessage({message:\"ready\",secret:t},\"*\")},!1)))}(window,document);\n\/* ]]> *\/\n<\/script>\n","description":"With the aims of solving dark energy\/matter problems and\/or quantizing gravity theory, various modified theories of gravity have been proposed. In most of such theories, however, due to their nonlinearity, superluminal modes generically appear. It makes the causal structure nontrivial and often results in acausality. In this talk, we will discuss about the causal structures in three modified gravity theories, massive gravity, generalized teleparallel gravity and Gauss-Bonnet gravity. The way of analysis is called &#8220;characteristic method&#8221;, which is somehow classical &hellip;"}