In this blog we have studied the inertia of an electric test charge close to a large charge. We observed that the inertia is larger, because if we move the test charge, we have to move some energy in the electric field, too.
The same holds for a test mass close to a large mass. The effect is dramatic near the horizon of a black hole, and adds some 10% to the inertia of a test mass on the surface of a neutron star.
The same holds for a test mass close to a large mass. The effect is dramatic near the horizon of a black hole, and adds some 10% to the inertia of a test mass on the surface of a neutron star.
The speed of light is slower on a neutron star than in faraway space.
Slow speed of light is "frame-dragging"
The slow speed of light can be regarded as a kind of "frame-dragging".
The neutron star restricts the speed at which a test mass can move relative to it. Near the horizon of a black hole, the speed of light is very slow (relative to a faraway observer). The frame-dragging is extreme.
What is usually called frame-dragging is the effect that a rotating mass forces a test mass to orbit along with the surface of the mass.
The rotation effect is a special case of frame-dragging.
The syrup model of a neutron star or a black hole
Syrup is a substance where there are strong interactions between molecules. Frame-dragging is strong in syrup for small test objects, like an ant crawling in the syrup. This is the underlying reason why the syrup model is nice for neutron stars and black holes.
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