[FRIAM] I could say their's a bit of a gravity to this finding

[Eric Smith]

Hi Gillian,

I totally share your enthusiasm for all this.  I have been following LIGO since it was a garage project up in some basement labs in Caltech in the early 80s, and the requirements seemed so far beyond the technology of the time that it was hard to know whether it would ever succeed.  Also because the frequency of sufficiently big and sufficiently near events was almost totally unknown at the time, so in a way it wasn’t even clear _how hard_ the technical project of reaching an observation would be.  I still find it magnificent and beautiful in a way that seems only describable in the language of art, both that we live in a universe that works this way, and that it has been possible to build a thinkable language faithful to that structure in the real world.  

> Question: Since LIGO is doing a BA job of finding Gravity waves. does that help explain the nature of gravity, and possibly time better?because as I understand it those kind of stars (litterally) bend space so as to cause gravity and time dialations

So far, it isn’t altering anything in the way we understand general relativity, but rather providing more observations that are consistently handled by it.  In a way, it has been considered more-or-less settled for several decades that gravitational radiation exists, and even that GR does a good quantitative job describing it.  Partly this is because the parts of the math of GR that are already well tested are incompatible with _not_ having gravitational waves.  The other reason is that precise timing of the spin-up of certain pulsating binaries has been well matched to models in which they are spinning together by emitting energy in gravitational radiation.  Although the energy lost from those orbital systems is large enough to make an observable impact on their own measurable properties over decade-long timescales, the intensity of the gravitational radiation emitted is many orders of magnitude smaller than the best that we can currently detect.  Thus it was not clear how many big events were available that might be directly observable.

> So if they can detect gravity energy from them then perhaps science  will understand gravity better. I simply don't know what can be done with that knowledge though.

I like the way Kip Thorne emphasizes it when he gives lectures: while the wonder of direct observation of gravitational radiation is a confirmation of a theory but not a change in it, it makes GR a tool to do astronomy, and to answer lots of questions about astrophysical events that we did not otherwise have any way to observe.  It is also worth noting that, whereas light waves are described by a vector, gravitational waves are described by a rank-2 matrix, so they contain _much_ more information about the dynamical properties of the events that create them.  It is true that gravitational waves are sort of smooth and boring compared to spectral signatures in light that tell you about chemical transformations (hence all the heavy element production in the blow-off wave of neutron star collisions), so there are strengths and limitations in each kind of signal.  On the other hand, the exact waveform of the waves from an infall has a whole time-dependent profile, so there is a lot of information in that as well as in the matrix-character of the waves themselves, about the generating process.

Certainly, objects big enough to shape spacetime seem so incomparably bigger than people that they seem beyond the reach of the engineers.  However, we have thought that in the past, and sometimes been wrong.

In shared wonderment,

Eric