famous world-postulate practically assumes a four-dimensional space in which all phenomena occur, and this say the objectors, on account of the construction of the human mind, can never be intelligible to any one in spite of its mathematical simplicity. They insist that the words space and time, as names for two distinct concepts, are not only convenient, but necessary. Nor can any description of phenomena in terms of a time which is a function of the velocity of the body on which the time is measured ever be satisfactory, simply because the human mind can not now nor can it ever appreciate the existence of such a time. To sum up, then, this model of the universe which the relativists have constructed in order to explain the universe, can never satisfactorily do this, for the reason that it can never be intelligible to everybody. It is a mathematical theory and can not be satisfactory to those lacking the mathematician's sixth sense.
A second serious objection urged against the relativity theory is that it has practically abandoned the hypothesis of an ether, without furnishing a satisfactory substitute for this hypothesis. As has been previously stated, the very experiment which the relativity theory seeks to explain depends on interference phenomena which are only satisfactorily accounted for on the hypothesis of an ether. Then too, there are in electromagnetism certain equations of fundamental importance, known as the Maxwell equations, and it is perhaps just as important that the relativity theory retain these equations, as it is that it explain the Michelson and Morley experiment. But the electro-magnetic equations were deduced on the hypothesis of an ether, and can be explained, or at least have been explained only on the hypothesis that there is some such medium in which the electric and magnetic forces exist. So, say the objectors to the relativity theory, the relativists are in the same illogical (or worse) position that they occupy with reference to the Michelson and Morley experiment, in that they deny the existence of the medium which made possible the Maxwell equations, which equations the relativity theory must retain at any cost. Professor Magie, of Princeton, who states with great clearness the principal objections to the theory, waxes fairly indignant on this point, and compares the relativists to Baron Munchausen, who lengthened a rope which he needed to escape from prison, by cutting off a piece from the upper end and splicing it on the lower. The objectors to the relativity theory point out that there have been advocated only two theories which have explained with any success the propagation of light and other phenomena connected with light, and that of these two, only the ether theory has survived. To abandon it at this time would mean the giving up of a theory which lies at the foundation of all the great advances which have been made in the field of speculative physics.
It remains finally to ask and perhaps also to answer the question,
