<div dir="ltr">The first paper of a series on the discovery is here:<div><br></div><div><a href="http://www.nature.com/news/ligo-live-inside-the-hunt-for-gravitational-waves-1.19344">http://www.nature.com/news/ligo-live-inside-the-hunt-for-gravitational-waves-1.19344</a><br></div><div><br></div><div><br></div><img src="http://t.sidekickopen35.com/e1t/o/5/f18dQhb0S7ks8dDMPbW2n0x6l2B9gXrN7sKj6v4LR3dW8qSMPY7dKPKPW7fRYjz2zlZNzW5CvrmQ1k1H6H0?si=6537132302139392&pi=79d47e59-bea7-49d7-f4d8-86e560f7c695" style="display:none!important" height="1" width="1"></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Feb 11, 2016 at 12:16 PM, Anders Sandberg <span dir="ltr"><<a href="mailto:anders@aleph.se" target="_blank">anders@aleph.se</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Depends on the number of civs per galaxy, and whether they are
checking for black hole binaries. A rough calculation suggests that
this could wipe out biospheres across a galaxy:<br>
<br>
If we assume the energy release was around 10^50 J over a second,
then the power per square meter at distance d is 10^50/(4 pi r^2)
Watts. So the criticial distance if the danger power is P is
r=sqrt(10^50/4 pi P). If we assume a megawatt/m^2 is enough to cause
biosphere damage, then the distance is 298,000 lightyears. To wipe
out more advanced civilizations I would expect a much higher P; for
a gigawatt the range is 9,400 lightyears - bad in the central part
of a galaxy, but not even covering it.<br>
<br>
So if you are an optimist about civilizations, then you should
expect a fair number to have at least had to flee over long
distances from this. <br>
<br>
I wonder if one can make a gravity wave powered sail? I doubt it,
since most matter is too transparent to the gravity waves to get any
decent coupling. But black holes sometimes get a 1000 km/s kick from
mergers. <br><span class="">
<br>
<br>
<div>On 2016-02-11 16:34, Giulio Prisco
wrote:<br>
</div>
</span><blockquote type="cite"><span class="">
<div>I'm wondering how many zillions of sentient beings died as a
result of the black hole fusion event.</div>
<div><br>
On Feb 11, 2016, at 5:13 PM, John Clark <<a href="mailto:johnkclark@gmail.com" target="_blank"></a><a href="mailto:johnkclark@gmail.com" target="_blank">johnkclark@gmail.com</a>>
wrote:<br>
<br>
</div>
</span><blockquote type="cite">
<div>
<div dir="ltr"><span class=""><font size="4">On Sept. 14
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">
</div>
at 4am the LIGO
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">
detector in </div>
Livingston
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">
Louisiana </div>
detected <font face="arial, helvetica, sans-serif">a burst
</font>
<div class="gmail_default" style="display:inline"><font face="arial, helvetica, sans-serif">
of gravitational waves, 7 milliseconds later the LIGO
detector in Hanford Washington detected the same
thing. The possibility of this being due to chance is </font></div>
vanishingly small
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">
. What they detected was 2 black holes circling each
other at 250 times a second, one was 36 times the mass
of the sun and the other 29 times. The entire signal
only lasted for a fifth of a second. </div>
</font>
<div><font face="arial, helvetica, sans-serif"><br>
</font></div>
<div><font face="arial, helvetica, sans-serif"><a href="http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html" target="_blank"></a><a href="http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html" target="_blank">http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html</a>
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">
</div>
</font></div>
<div><font face="arial, helvetica, sans-serif">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline"><br>
</div>
</font></div>
</span><div><font size="4" face="arial, helvetica, sans-serif">
<div class="gmail_default" style="font-family:arial,helvetica,sans-serif;display:inline">J
ohn K Clark</div>
</font></div>
<div><font face="arial, helvetica, sans-serif"><br>
</font></div>
</div>
</div>
</blockquote><span class="">
<blockquote type="cite">
<div><span>_______________________________________________</span><br>
<span>extropy-chat mailing list</span><br>
<span><a href="mailto:extropy-chat@lists.extropy.org" target="_blank">extropy-chat@lists.extropy.org</a></span><br>
<span><a href="http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat" target="_blank">http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat</a></span><br>
</div>
</blockquote>
<br>
<fieldset></fieldset>
<br>
<pre>_______________________________________________
extropy-chat mailing list
<a href="mailto:extropy-chat@lists.extropy.org" target="_blank">extropy-chat@lists.extropy.org</a>
<a href="http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat" target="_blank">http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat</a>
</pre>
</span></blockquote><span class="HOEnZb"><font color="#888888">
<br>
<pre cols="72">--
Anders Sandberg
Future of Humanity Institute
Oxford Martin School
Oxford University</pre>
</font></span></div>
<br>_______________________________________________<br>
extropy-chat mailing list<br>
<a href="mailto:extropy-chat@lists.extropy.org">extropy-chat@lists.extropy.org</a><br>
<a href="http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat" rel="noreferrer" target="_blank">http://lists.extropy.org/mailman/listinfo.cgi/extropy-chat</a><br>
<br></blockquote></div><br></div>