# Frame Dragging and the Properties of Space

• I
e2m2a
I have some questions about space, inertia and frame-dragging that I can’t find anywhere on the internet. The papers that I have found that deal with the subject are often couched in advanced mathematics, so that I can’t get an intuitive grasp of the phenomenon.

I would appreciate if someone could answer on a conceptual level some of the questions I have on the subject.

Question set one: Lense-Thirring rotational frame-dragging. The results of the Gravity probe B experiment suggested very strongly that this effect is real. I kind of get that the spinning earth drags space along with it. But is it the space itself, because it is being dragged, actually has a physical effect on the gyroscopes, causing real torques on the gyroscopes, which causes them to experience precession? Put another way, is space “colliding” with the gyroscopes?

Question set two: I understand the rotational drag effect of space around the earth is incredibly small, such as once in centuries. But in the case of an intense gravitational object, such as a black hole, does this rate of rotation of space equal the rate of the rotating black hole? Another words, is the rate of rotation of space around a rotating body proportional to the mass of the rotating body?

Question set three: Linear frame dragging. On page 106, The Meaning of Relativity, Einstein reflecting on inertia wrote:

But in the second place, the theory of relativity makes it

appear probable that Mach was on the right road in his thought

that inertia depends upon a mutual action of matter. For we

shall show in the following that, according to our equations, inert

masses do act upon each other in the sense of the relativity of

inertia, even if only very feebly. What is to be expected along

the line of Mach's thought?

1. The inertia of a body must increase when ponderable

masses are piled up in its neighbourhood.

2. A body must experience an accelerating force when

neighbouring masses are accelerated, and, in fact, the

force must be in the same direction as the acceleration.

3. A rotating hollow body must generate inside of itself

a \Coriolis _eld," which deects moving bodies in the

sense of the rotation, and a radial centrifugal _eld as

well.

My question pertains to the second point. Was Einstein conjecturing that linear inertial reaction forces arise when there is relative linear acceleration with respect to cosmic mass-energy currents? And was he implying that it is space itself that is being dragged by the accelerating mass-energy currents, and therefore, it is the “accelerating” space that is causing real effects(inertial forces) on test mass objects?

Question set four: My understanding Einstein later rejected Machian explanations as a cause of inertia because it was found that his field equations predict that inertial forces can still exist in a universe empty of mass. But could this rejection been premature? Again, is it possible that space itself has intrinsic properties such that when there is relative acceleration between space and an object, that space itself can “collide” with the object, causing real, physical effects on the object?