[ExI] Gravitational Waves Detected By LIGO!

[Giovanni Santostasi]

The first paper of a series on the discovery is here:

http://www.nature.com/news/ligo-live-inside-the-hunt-for-gravitational-waves-1.19344



On Thu, Feb 11, 2016 at 12:16 PM, Anders Sandberg <anders at aleph.se> wrote:

> 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:
>
> 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.
>
> 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.
>
> 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.
>
>
> On 2016-02-11 16:34, Giulio Prisco wrote:
>
> I'm wondering how many zillions of sentient beings died as a result of the
> black hole fusion event.
>
> On Feb 11, 2016, at 5:13 PM, John Clark < <johnkclark at gmail.com>
> johnkclark at gmail.com> wrote:
>
> On Sept. 14
> ​ ​
> at 4am the LIGO
> ​ detector in ​
> Livingston
> ​ Louisiana  ​
> detected a burst ​
> ​ 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
> vanishingly small
> ​ . 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.
>
>
> <http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html>
> http://www.nytimes.com/2016/02/12/science/ligo-gravitational-waves-black-holes-einstein.html
> ​
>
> J ​ohn K Clark
>
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>
> --
> Anders Sandberg
> Future of Humanity Institute
> Oxford Martin School
> Oxford University
>
>
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