http://einstein.stanford.edu/...
Frame Dragging
The purpose of this activity is to demonstrate how the Earth twists the local spacetime frame, but does not affect a distant spacetime frame. The ball represents the Earth, the honey represents spacetime, and the peppercorns represent other masses (stars, planets, etc.) in the spacetime frame at various distances. The food coloring is used to highlight the honey's motion, and does not represent an astronomical object.
A major limitation of this model is that the Earth spins much faster than you can twist the ball (~1,000 mph), and the spacetime frame spins much, much slower (~10 -9 mph) relative to the Earth's rotation than the honey moves relative to the ball's rotation.
The rotation of the Earth does twist the spacetime frame like the ball twists the honey, although it is not caused by "friction" between the Earth and local spacetime. It is unclear to scientists exactly how this phenomena occurs. The theory of general relativity suggests that spacetime and masses have a mysterious mutual "grip" on each other.
http://www.phys.lsu.edu/...
Gravitomagnetism has a history that is at least as long as that of general relativity itself. The idea that mass currents might generate the gravitational analogue of magnetic fields, and crude experiments to look for such effects predated Einstein. Soon after the publication of general relativity (GR), Lense and Thirring calculated the advance of the pericenter and line of nodes of a particle orbiting a rotating mass.
The gravitomagnetic ``dragging of inertial frames'' by rotating matter has played a part in discussions about the meaning and usefulness of Mach's principle, in astrophysical models of jets near accreting, rotating black holes, and in proposals for testing alternative theories of gravity.
It is no surprise then, that substantial effort during the past 30 or so years has gone into trying to measure gravitomagnetism. A recent preprint by Ignazio Ciufolini and colleagues [1] claims to have succeeded.
There are three main effects of gravitomagnetism in the solar-system:
Precession of a gyroscope: For a gyroscope in a polar Earth orbit at 600 km altitude, the rate is 43 milliarcseconds (mas) per year.
Precession of orbital planes. The orbit of a particle is a ``gyroscope'', whose axis or ``node'' (intersection of the orbit with a reference plane) will also precess.
Precession of the pericenter
Since the early 1960's, measurement of the first effect has been the goal of the Stanford Gyroscope experiment (Gravity Probe B). The goal is to measure the precession of an array of gyroscopes in low Earth orbit to better than one percent. Following years of financial uncertainty, the project was endorsed in 1995 by a panel convened by the National Academy of Sciences [2], and NASA Administrator Daniel Goldin made a firm commitment to the mission. The spacecraft and payload are under construction at Stanford and Lockheed-Martin, and the project is actually slightly ahead of schedule for launch in December 1999 [3].
http://www.universetoday.com/...
http://einstein.stanford.edu/...
http://www.gravityprobeb.com/
http://www.csr.utexas.edu/...
http://www.csr.utexas.edu/...
http://science.nasa.gov/...
http://www.csr.utexas.edu/...
http://www.csr.utexas.edu/...
Time is distance -
divided by velocity