What does a merger rate denote? It is hard to tell if it refers to the implicit strength of the G constant or some feature of gravity waves themselves. Normally I would think it was talking about strength of gravitational attraction.

If we didn’t expect LIGO and VIRGO to have the power to detect gravity waves in anywhere near the range that theory predicted, why did we bother launching those projects? It seems a bit like building a telescope to look at the next valley over in the bottom of your own valley instead of at the top of the hill because it is too much work to climb the hill.

The same result can be imagined easily with water surface model, where transverse waves are serving like the analogy of waves of light and the gravitational waves are behaving like longitudinal sound waves, which are spreading through underwater. Because sound waves are spreading a way faster, then the surface waves, they would manifest like indeterministic noise at the water surface – and no expensive analysis or devices is required for such understanding…

Relativists use a simplified form of Einstein’s field equations to calculate various properties of his gravitational field, including gravitational waves, which are based on the Einstein’s pseudo-tensor. This simplified form is called the linearised field equations. They do this because field equations are highly non-linear (implicit actually) and impossible to solve analytically. So they use the linearised form, simply assuming that they can do so. However Hermann Weyl proved in 1944 already, that linearisation of the field equations implies the existence of a Einstein’s pseudo-tensor that, except for the trivial case of being precisely zero, does not otherwise exist:

http://www.jstor.org/stable/2371768

In another words, the alleged gravitational waves are the consequence of simplification of field equations and they have nothing to do with physical reality. They’re solely an artefact of incomplete formal model used and this fact is known for more than one half of century already.

What gets me though is when I read the Wikipedia article on solutions to the Einstein field equations, it reads like a foreign language; no mention is made of the Schwarzschild solution per se, except a for it as a ‘vacuum solution’, which is a misleading classification to the uninitiated reader if you ask me. What’s written there is fairly inaccessible to me and although it might serve a purpose to experts and savants (does it?), it should not be so confoundedly general or abstract. It, like many other math related articles, start from a high level of abstraction and never seem to descend to the masses of interested readers like myself. I suppose that clicking on ‘Schwarzschild vacuum’ gives you the way to solve the field equation, but linking from hard, abstract, and for pros only pages to simpler and descriptive pages for anyone it is not a good way to link articles.

Anyway, at the time I took the course, I was rather amazed at the prediction of gravity waves, although now I’m not. In retrospect, I should have seen that it is utterly natural and necessary for waves to exist in something analogous to a fabric that can be warped and twisted. So here’s hoping for Advanced LIGO.

But Sean, this search is _not_ for inspiral-only signals: as hinted in the title, this is the first search that used full waveforms created by merging analytical inspiral computations, fits to numerical-relativity mergers, and ringdown waveforms from black-hole perturbation theory. These hybrids are by no means perfect, and they don’t include spin effects, but they do extend how far the search can see, by looking for the extra energy emitted in the merger and ringdown.

@valatan: true that, but even signals computed for nonspinning systems would do pretty well at matching spinning sources. That is to say, this search _would_ have seen moderately spinning sources if they had been close enough.

@Joseph: the mass of the central black hole is actually quite negligible compared to the rest of the galaxy, although locally it can make for nice fireworks. But no big wake as you suggest, unfortunately.

@Arun: LIGO’s “first lock” (the analog of first light for telescope) was at the end of 2000, but it only reached its design sensitivity in 2005. And even after that, it only performed science runs for something like two years of triple coincidence (all three detectors on). So it’s not like it’s been looking for 20 years.

If you keep on banging your heads against walls, you might just break one. Hoorah!