Abstract

A comparison is made of the classical and the relativistic theories of the Doppler effect, with emphasis on the classical and semi-classical sections of Einstein's 1905 paper. One of us (NM) finds that the form and results of special relativity and Doppler equations are sensitive to shifts in assumptions and produce significantly different results -- even reversal of Doppler effects. But, with one set of [2nd principle related] assumptions held constant, a single equation is produced which describes both the special relativity and the Doppler effects in terms of commonly used factors. Other assumptions will likely produce different relationships.

A re-deduction (by FM) of Einstein's Doppler formula from first principles, however, seems to help straighten out contradictions. This requires utmost care in the understanding of relativistic methodology and its diverse ?scenarios" and interpretations (at least three of these are noted). A transient time or initial asymmetric effect, however, persists, which can be demonstrated experimentally, in principle. This favors the classical formula over the relativistic one.