In some references, the spin axis is said to remain fixed in the ZAMO frame, while in others, it undergoes Lense-Thirring precession. Is the distinction purely a matter of reference frame, or is there a deeper physical reason?
There are no Black Holes nor there can be Black Holes. The discovery of aether, the electric dipoles, clarify that the gravitational force is the electromagnetic force and it is due to the recessional acceleration of the star systems and it is neither universal force nor due to Black Holes at the centre of galaxies. There is an open challenge to that effect which everyone could see in my profile. This is simply to justify the general theory of relativity. Photos they display are nothing but computer simulations. For the evidence read my publications in peer-reviewed journals which are available in my profile. The very space-time concept has also been shown as baseless this the question of Big Bang having taken place does not arise.
A gyroscope near a Kerr black hole exhibits interesting behavior in the ZAMO (Zero Angular Momentum Observer) frame due to the effects of frame dragging. In the ZAMO frame, which is locally non-rotating but still moving with the black hole’s dragging of spacetime, the gyroscope’s spin axis does not precess relative to the ZAMO itself. This is because the ZAMO is co-moving with the local inertial frame that is being dragged by the black hole’s rotation. Since the gyroscope maintains its spin axis in the local inertial frame, and the ZAMO is designed to follow that frame’s motion, the gyroscope appears fixed relative to the ZAMO.
However, to a distant observer at infinity, the gyroscope does undergo precession due to the Lense-Thirring effect, also known as frame dragging. This effect causes the entire local inertial frame to rotate around the black hole, meaning that although the gyroscope’s spin axis remains unchanged in the ZAMO frame, it is actually moving in the global coordinate system. This is why some references describe the spin axis as fixed in the ZAMO frame, while others refer to the Lense-Thirring precession. The distinction comes from the choice of reference frame rather than a contradiction in physical interpretation.
At a deeper level, the reason for this behavior lies in the nature of general relativity and how it treats freely falling frames. The ZAMO follows a worldline that is not strictly geodesic (because of the acceleration required to maintain zero angular momentum), but it remains locally inertial in the dragged spacetime. Since a gyroscope preserves its spin direction in a locally inertial frame, it does not precess relative to the ZAMO. However, globally, the entire frame is precessing due to the black hole’s angular momentum, leading to the apparent Lense-Thirring precession when viewed from infinity.
Thus, the difference between the two perspectives is rooted in the distinction between local and global frames rather than in any fundamental disagreement about the physics.