Why Expect Gravity Waves from Distant Cosmic Events?

[jnorman]

a recent news release indicated that LIGO had a null result on its gravity wave detection work, and that they were concluding that GWs did not exist, at least at a certain level of significance. i am also not surprised. the examples of situations where GWs were to be expected were colliding black holes or supernova explosions.

my question is why we would expect to be able to detect GWs even from either of those types of events. in the event of colliding BHs, we would assume that the BHs in question are rather far removed from the earth, and that, as a "system" (pair of BHs) at any stellar distance from us, the center of gravity would not significantly change as they collide, so why would we expect to detect GWs? same with a supernova - since the center of gravity of the involved material would not change, why would we expect to detect GWs? in order to effectively detect GWs, it seems to me that it would require a fairly extreme change in the center of gravity of a very massive body - something that is not even really possible (is it?)

 

[CFDFEAGURU]

Could you please provide a link to this report?

Thanks
Matt

 

[jnorman]

matt - here is an online news story about it:
http://www.livescience.com/space/090819-gravitational-waves.html

 

[Ich]

a recent news release indicated that LIGO had a null result on its gravity wave detection work, and that they were concluding that GWs did not exist, at least at a certain level of significance.

here is an online news story about it:
http://www.livescience.com/space/090...nal-waves.html

Sorry, those statements contradict each other. Did you actually read the story you're linking to?

 

[CFDFEAGURU]

I think you are misunderstanding what that report is telling you.

From the report;

The fact that this first period of observations did not detect gravitational waves allows researchers to rule out the possibility of waves above a certain amplitude threshold.

This is simply implying that waves of a certain amplitude can be ruled out. Not that gravity waves do not exist.

Thanks
Matt

 

[ZikZak]

Nor was LIGO expecting to detect anything at the current detection limit.