<story><title>Gravitational Lensing to Observe Ancient Earth</title><url>http://rein.pk/gravitational-lensing-to-observe-ancient-earth/</url></story><parent_chain></parent_chain><comment><author>ComputerGuru</author><text>Reminds me of one of my favorite books (well, not really. The premise was incredible and the writing was impeccable but it was part one of a trilogy that never materialized): &lt;i&gt;Pastwatch: The Redemption of Christopher Columbus&lt;/i&gt;&lt;p&gt;It was basically a brilliant alternative historical fiction novel based around the premise of being able to rewatch the past.</text></comment>
<story><title>Gravitational Lensing to Observe Ancient Earth</title><url>http://rein.pk/gravitational-lensing-to-observe-ancient-earth/</url></story><parent_chain></parent_chain><comment><author>rcthompson</author><text>So it&amp;#x27;s possible for a beam of light to wrap around a black hole and intersect its own path. This must mean that light doesn&amp;#x27;t follow Kepler orbits[1] in general relativity?&lt;p&gt;[1] i.e. ellipse, parabola, or hyperbola: &lt;a href=&quot;http://en.wikipedia.org/wiki/Kepler_orbit&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Kepler_orbit&lt;/a&gt;</text></comment>