<story><title>Gravitational waves from a binary black hole merger observed by LIGO and Virgo</title><url>https://www.ligo.caltech.edu/news/ligo20170927</url></story><parent_chain><item><author>ChuckMcM</author><text>Pretty awesome, nice to see they confirmation with Virgo.&lt;p&gt;I realize that I&amp;#x27;ve never really considered what it would be like to be &amp;#x27;near&amp;#x27; (say a few 10&amp;#x27;s of thousands of light years away) from an event like this. With all that energy, at what level would it pulverize a planetary body?</text></item></parent_chain><comment><author>jessriedel</author><text>Scott Aaronson estimated the strain if you were 1 AU away from one of the previous BH mergers detected by LIGO and found you would only be stretched by about 50 nm (about a thousandth the width of a human hair).  So you&amp;#x27;d need to be very close indeed to feel something.&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;www.businessinsider.com&amp;#x2F;what-gravitational-wave-feels-like-2016-2&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;www.businessinsider.com&amp;#x2F;what-gravitational-wave-feels...&lt;/a&gt;&lt;p&gt;&lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;www.scottaaronson.com&amp;#x2F;blog&amp;#x2F;?p=2651&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;www.scottaaronson.com&amp;#x2F;blog&amp;#x2F;?p=2651&lt;/a&gt;&lt;p&gt;The alternative take is that LIGO&amp;#x27;s detectors are &lt;i&gt;unfathomably&lt;/i&gt; sensitive, detecting when its ~4km arms stretch by just 10^-19 meters.  That&amp;#x27;s a 10,000th the width of a proton, where the proton is just a 100,000th the width of an atom, and the atom is about a 1,000,000th the width of a hair.</text></comment>
<story><title>Gravitational waves from a binary black hole merger observed by LIGO and Virgo</title><url>https://www.ligo.caltech.edu/news/ligo20170927</url></story><parent_chain><item><author>ChuckMcM</author><text>Pretty awesome, nice to see they confirmation with Virgo.&lt;p&gt;I realize that I&amp;#x27;ve never really considered what it would be like to be &amp;#x27;near&amp;#x27; (say a few 10&amp;#x27;s of thousands of light years away) from an event like this. With all that energy, at what level would it pulverize a planetary body?</text></item></parent_chain><comment><author>contravariant</author><text>This event was 1.8 billion (10^9) light years away. The so called &amp;quot;strain&amp;quot; (i.e. the extent to which the wave stretches &amp;#x2F; compresses things) is around 10^-20 or somewhere around that order of magnitude.&lt;p&gt;To make things dangerous I reckon you&amp;#x27;ll need to have a strain on the order of 1, and since strain is inversely proportional to distance that would give a distance of 10^-11 ly, or around 100 km. Which is not a &amp;#x27;safe&amp;#x27; distance to a black hole in any scenario.</text></comment>