The zero of potential

It is convenient to select a reference point for recording ECG potentials on the torso or EEG potentials on the scalp. The body is a bounded, insulated volume conductor. As such, it is meaningless to seek a point whose potential is at true zero. The choice of a particular reference, and hence the amplitude assigned to a contour, does not change in any way the biophysical information contained in the potential distribution. It does not in any way change the relation between source and potential, except for an additive constant of no physical significance. Standardization of a reference is useful for comparing, more directly, data from different laboratories. An agreed upon reference is necessary when a limited number of leads are used for diagnosis. In the case of the electrocardiogram, the generally agreed upon reference is the WCT. The issue of the zero of potential seems to arouse passions that may sometimes inhibit scientific discourse.