Does Gravity Travel at the Speed of Light? (1998)

https://news.ycombinator.com/item?id=6238297

...so then we still get to achieve an effective result of reaching a destination faster than light.

...and since the gravity warps space, and the warp drive exploits warped space, does that mean that the quantum mechanism behind the warp drive is somehow directly related to gravity?

  the ring would contain exotic matter called 
  negative vacuum energy, a consequence of quantum 
  mechanics. The presence of this toroidal ring of 
  negative vacuum energy is what's required from 
  the math and physics to be able to use the warp trick.

http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_rad...

There's a number of competing models which fit existing data.

http://scienceblogs.com/startswithabang/2010/08/25/what-is-t...

See the closing paragraph referencing LISA ~ 2030 A.D.

The real way to measure the speed of gravity is to detect and study gravitational waves. By comparing the arrival of a gravitational-wave signal with that of an electromagnetic signal from an astrophysical source, one could compare the speed of gravity to that of light to parts in 10^(17).

"LIGO, which stands for the Laser Interferometer Gravitational-Wave Observatory, is a large-scale physics experiment aiming to directly detect gravitational waves. [...] At the cost of $365 million (in 2002 USD), it is the largest and most ambitious project ever funded by the NSF.

Observations at LIGO began in 2002 and ended in 2010; no unambiguous detections of gravitational waves have been reported. The original detectors were disassembled and are currently being replaced by improved versions known as "advanced LIGO", scheduled to be operational by 2014.

[...]

Measurable emissions of gravitational waves are expected from binary systems (collisions and coalescences of neutron stars or black holes), supernova of massive stars (which form neutron stars and black holes), accreting neutron stars, rotations of neutron stars with deformed crusts, and the remnants of gravitational radiation created by the birth of the universe."

For more:

http://en.wikipedia.org/wiki/LIGO

http://en.wikipedia.org/wiki/Gravitational-wave_detector

There is a fantastic lecture series by a Yale U. astronomer that touches on this and related topics from a calculus-free perspective:

http://oyc.yale.edu/astronomy/astr-160

Also on youtube and iTunes U.

Special and general relativity (at least, as commonly formulated) also assume that space and time are isotropic and continuous, which means there is no "granule", no "smallest increment" in the field equations. That may or may not be true; we're still trying to figure out if spacetime is quantized or not.