Friday, February 1, 2008

History of Gravitomagnetism

It has long been speculated and conjectured that there must be a magnetism like counter part in gravity like in the theory of electricity and magnetism. One of these lines of pursuit was the conventionally known as "gravitomagnetism", which is entirely different from the one presented here as dipole gravity & gravitomagnetism.

The traditional gravitomagnetism starts from the modification of Maxwell's equation to accommodate the known facts in gravity. For example, there is only one known charge(mass) and the force between them is attractive. This resulted in the equation,

where E represents the regular gravity, B the gravitomagnetic field and G the gravitational constant. The entire concept is based on the assumption that the constantly moving charge(mass) creates a gravitomagnetic field around its path like in the case of moving electric charges. However, this formulation didn't result in any new understanding of the gravitational phenomena.

A rotating toroidal ring was its basic model device to create a gravitomagnetic effect. However, a rotating metallic ring did not produce any new physical effect. It did not succeeed in deriving the Lense-Thirring force at the center of the rotating sphere. And it was not useful in solving the emerging mysteries of the universe. In retrospect, one can see that this conventional gravitomagnetism was heavily relied on Maxwell's equation than gravity effect itself. It is basically a Maxwell's equation with the single charges and the attractive force among themselves.

According to the concept of the equivalence principle, an accelerating frame is indistinguishable from the gravitational field itself. However, constantly moving electrons can create magnetic field around their path, which means that the modified Maxwell's equation will predict a gravitomagnetic effect from a constantly moving mass which is in direct disagreement with the equivalence principle.

We can only see it more clearly in the light of dipole gravity, how and why it went wrong. The first and crucial problem was that they tried to find the answer from the outside of general relativity which has been the most successful theory of gravity known today. And also, beyond the fact that the both forces are long range forces, there is little that is common between the two forces.

According to the theory of dipole gravity, accelerating mass in a rotating frame is not the complete condition to create a true gravitomagnetic effect. A rotating cylinder does not create the Lense-Thirring force, which has also been reported by Bass and Pirani. This fact itself already puts a major suspicion on the centrifugal interpretation of the Lense-Thirring force. A rotating sphere creates two opposite gravitomagnets which cancels out pretty good in the far distances.
The only way to create a net long range gravitomagnetic field is by the rotation of a longitudinal axially asymmetric object like a cone, hemisphere and etc.

Only in those cases, the rotational degree of freedom of motion is translated into the finite length element which forms the basis of the gravitational dipole moment.

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