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Single-Particle Electrodynamics - Assassination Science

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particular times depend on the acceleration, etc., of the body as a whole.<br />

Now, the forces on the receiving constituent r, due to the retarded fields<br />

generated by all of the other constituents, are to be summed together to<br />

obtain the net forces on the constituent r; and then, in turn, the forces on<br />

all of the constituents r are to be weighted by the accelerative redshift factor<br />

λ(r), and then summed together to obtain the forces on the body as a whole.<br />

Clearly, in carrying out this procedure, we must have some way of labelling<br />

the generating constituents of the body. We are not talking about<br />

the task of finding the actual retarded time, retarded position, etc.,—this<br />

will be considered in the following sections; rather, we simply need some<br />

way to identify the generating constituents. This may seem trivial, but the<br />

situation is somewhat subtle. To perform the first-mentioned sum above—<br />

namely, that of all of the forces on some particular constituent r due to the<br />

retarded fields of all of the other constituents—we need to perform some sort<br />

of integral over the “sending” sphere. But the various constituents of this<br />

“sending” sphere are all “seen” as they were at different times in the past;<br />

we must effectively integrate the “sending” sphere over a quite complicated<br />

spacetime hypersurface, not over one of its rest-hypersurfaces. And then we<br />

must ensure that we have correctly calculated the relevant transformation<br />

properties of the source densities, over this complicated hypersurface.<br />

The way out of this conceptual nightmare is to label the sending constituents<br />

by the simple three-vector r ′ , which represents the three-position of<br />

the sending constituent in the rest frame of the body:<br />

|r ′ | ≤ ε.<br />

One then computes the particular retarded four-position of this sending constituent<br />

in order that one can compute the generated fields; but one does not<br />

try to use this four-position as the variable for integrating over. Rather, the<br />

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