[ExI] Gravitational Waves Detected By LIGO!

spike spike66 at att.net
Sat Feb 13 14:03:26 UTC 2016



From: extropy-chat [mailto:extropy-chat-bounces at lists.extropy.org] On Behalf Of Tomaz Kristan
Sent: Saturday, February 13, 2016 3:50 AM
To: ExI chat list <extropy-chat at lists.extropy.org>
Subject: Re: [ExI] Gravitational Waves Detected By LIGO!


Interesting ... Still, what's bothering me is also the super-massive black hole in our Galaxy, five orders of magnitude closer and about five orders of magnitude as massive, orbiting by many massive stars ... but no gravity waves from there.


That was my line of reasoning all along. If we can't gravitationally see this, how we could see something much smaller, so far away?


I am not saying that it is entirely impossible, I am just hard to be convinced in such circumstances.




Tomaz, time to calculate!  The argument that the black hole merger would be indistinguishable from noise is a strong one.  The gravitational noise is caused by that local black hole you mentioned and all the others doing similar things.


As I understand it, a black hole merger would cause a chirp event, where the frequency of the gravitational pulse gets higher (paradoxically) just as the event horizon expands to take in both black holes.  My intuition suggested to me that signal frequency should get lower, since the emitted signal would redshift due to gravity.  But if you think about it, there is a pulse frequency which gets higher as the orbiting object emit energy and drop closer to each other.


On the scales they are talking about, trucks passing by on a nearby freeway might be detectable, but wouldn’t have that increasing frequency signature and wouldn’t show up on both detectors.  


It’s a mind-blower that they were able to extract a signal from all of that ordinary background noise.





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