On Inertial Reference Frames
Herbert Dingle
It is the universal practice in physics, when describing the motion of a body, to choose a reference frame, i.e. some real or imaginary physical structure which is said to be "at rest", and then the motion of any other body is defined as its motion relatively to that. Of the various possible frames of reference, that known as an inertial system -- formerly, and still sometimes, called a Galilean or Newtonian system. or frame of reference -- appears in the literature of relativity with a frequency unapproached by any other, and motion with respect to it is generally regarded as having a special significance. It is therefore of the first importance, both for theoretical reasons and on account of the possible effects in circumstances in which miscalculations may have dire results, that the meaning of the term, inertial system, shall be clearly understood, and that the term shall be used always in the same sense.
Unfortunately, these conditions are far from. being fulfilled. It is the purpose of this paper, first, to bring to light the widespread confusion that exists on this point; secondly, to show that existing ideas, notwithstanding their variety, are almost unanimously incompatible with the conception of inertial systems held by Einstein and regarded by him as indispensable for the proper understanding of his theories; and finally, to correct an outstanding example of this misunderstanding which might otherwise have unfortunate effects.
