Annus MirabilisFour papers. One year.
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Read · Special relativity: from clock operations to electrodynamics · Results

§9 · charge and current

Follow the introduction and all ten sections, including field transformations, finite light complexes, moving mirrors, charge-current transformations, and the electron-force conventions.

Newly authored explanatory preview in modern notation, with editorial and physics review pending. Both the kinematic and electrodynamic halves are treated, but this is not a German transcription, an aligned translation, or a complete critical edition. The source paragraphs, footnotes, acknowledgment, and date-lines are not claimed to be fully represented or reviewed here. Headings and argument units are editorial.

Neutrality and current belong to a frame

Charge density and longitudinal current mix under a frame change. Zero charge density with nonzero current is allowed; it cannot be handled by dividing current by charge density to invent one charge velocity.