Note on the law that light-rays are the null geodesics of a gravitational field

@inproceedings{WhittakerNoteOT,
title={Note on the law that light-rays are the null geodesics of a gravitational field},
author={Edmund Taylor Whittaker}
}

In the “special” or “restricted” theory of relativity, for which the line-element ds of the “world” of space-time is given by , the geodesics of the world are straight lines, and the null geodesics (i.e. the geodesics for which ds vanishes) are the tracks of rays of light. When Einstein discovered the “general“ theory of relativity, in which the effects of gravitation are taken into account, he carried over this principle by analogy, and asserted its truth for gravitational fields; it was, in… Expand