Daniel Frost Comstock

“ We are, therefore, forced to the conclusion that, unless we discard one of the two relativity postulates, the simultaneity of two distant events means a different thing to two different observers if they are moving with respect to each other.
The fact that the moving observer disagrees with us as to the reading of his two clocks as well as to the reading of two similar clocks on our "stationary" platform, gives us a complete basis for all other differences due to point of view. ”

“ It has been shown that if material mass be electromagnetic and if lighter elements are formed from heavier ones through violent energy changes, it follows that gravity acts between quantities of confined energy and not between masses in any other sense. ”

“ THE negative result of all experiments to detect the earth's motion through space by its effect on terrestrial phenomena positively requires explanation, and the modern principle of relativity is generally conceded to be the most successful attempt to explain so far made. ”

“ It has been pointed out that the loss of mass, inevitable on this view, which takes place when energy is lost to the system, is large enough to be detected in the case of radioactive changes. If we assume the disintegration theory of the elements, this loss of mass affords a ready explanation of the general, small irregularities to be found in the list of atomic weights, and thus removes a serious difficulty from the path of the disintegration theory. For this loss of mass to take place however, it is not necessary that the whole of the mass be electromagnetic. ”

“ Most people will, I think, agree that one of the very best practical and simple ways would be to send a signal to each point from a point half-way between them. The velocity with which signals travel through space is of course the characteristic "space velocity," the velocity of light. ”

“ In other words, he has just as much fundamental right to consider himself stationary as we have to consider ourselves stationary, and therefore just as much right to apply the midway signal method to set his clocks in unison as we have in the setting of our "stationary clocks." "Stationary" is, therefore, a relative term and anything which we can say about the moving system dependent on its motion, can with absolutely equal right be said by the moving observer about our system. ”

“ If second-order terms in the velocity be neglected, the mass is a simple constant multiplied by the total included electromagnetic energy.
If the mass of ponderable bodies has an electromagnetic origin, then the inertia of matter is to be considered merely as a manifestation of confined energy. From this point of view, matter and energy are thus very closely related and the laws of the conservation of mass and energy become practically identical. ”

“ Two clocks, one at A and the other at B, can therefore be set running in unison by means of a light signal sent to each from a place midway between them.
Now suppose both clock A and clock B are on a kind of sidewalk or platform moving uniformly past us with velocity v. In Fig. 1 (2) is the moving platform and (1) is the fixed one, on which we consider ourselves placed. Since the observer on platform (2) is moving uniformly he can have no reason to consider himself moving at all, and he will use just the method we have indicated to set his two clocks A and B in unison. ”

“ If too, our conclusion respecting the gravitating quality of confined energy be correct, the gravitation constant of the sun has also decreased and the distances of the planets must have increased accordingly. This last increase of planetary distance can be calculated by making the angular momentum of the planet about the sun a constant, and allowing the mass of the planet, together with the gravities of both sun and planet, to grow less with time. ”

“ Suppose the moving observer desires to let us know the distance between his clocks and says he will have an assistant stationed at each clock and each of these, at a given instant, is to make a black line on our platform. ”

“ If, as we have assumed in deriving this expression, the system possesses the same momentum for uniform translation in any direction, this formula for the mass can contain terms of even powers only in the ratio of the velocity of the system to the velocity of light. If we neglect terms of the second and higher orders has the same value as for , which from symmetry of the system must be two-thirds the total energy . ”

“ This is due to the fact that in the moving system forward clocks are behind in time.
In the measurement of time we assume a certain standard motion to be taking place at a constant rate and then take as a measure of time the total displacement which this motion has caused. Time measurement with an ordinary clock is obviously a special case of this general rule.
The moving observer can adopt as his unit of time the time it takes light, moving with the characteristic [2] space velocity V, to travel a certain distance d and return to him. ”

“ If there were perfect conservation of mass this would introduce a certain uniformity in the relations between the atomic weights, a uniformity which apparently does not exist. On the other hand, if we take into consideration the inevitable change of mass when the electromagnetic energy of the system is modified, the atomic weights will involve a correction term depending upon the change in this energy, and hence they will no longer bear simple, exact relations to each other. ”

“ This is seen in the simple case of a moving electron where the crowding of the lines towards the equator with increase of velocity is only partly due to the added energy. It is evident, therefore, that for velocities so great that the second order terms cannot be neglected, the mass depends on complicated terms which vary with the internal structure and motions of the system, and it does not appear as if a general expression for the mass of a system for such high velocities could be found. ”

“ Now it is very important to see that the two clocks are in unison for the observer moving with them (in the only sense in which the word "unison" has any meaning for him) , for if we adopt the first postulate of relativity, there is no way in which he can know that he is moving. ”

“ So also in the case of a single moving electron, the rate of transfer of energy is not given by the integration of the Poynting vector through all space, but differs from this by an amount corresponding to the energyflow along the constraints in the body of the electron. This does not mean that there is any energy associated with the constraints, for of course rigid constraints can neither absorb nor give out energy; there is no storing up, but merely a transfer. ”

“ Whether the inertia of matter has or has not a complete electromagnetic explanation is a question that it will perhaps take many years to answer with any degree of certainty. The experiments of Kaufmann seem to prove that in the case of a single electron the mass is entirely of this origin ”

“ The longest-living author of this work died in 1970, so this work is in the public domain in countries and areas where the copyright term is the author's life plus 52 years or less. This work may be in the public domain in countries and areas with longer native copyright terms that apply the rule of the shorter term to foreign works. ”

“ We might easily imagine a peasant scorning the suggestion that the dimensions of a rigid body changed with the temperature, and declaring, on being pressed that such an idea was clearly against common sense. ”

“ In the above we can, of course, interchange the words "moving" and "stationary."
Next let us turn our attention to the unit of time in each system. It is not hard to show that the unit of time in the moving system will appear to us greater than ours in the ratio √ (1—β2) . ”

“ The energy transfer is not through space in the ordinary sense, but is along the constraint which holds the condenser-plates apart. The plate in the rear picks up, as we may say, the energy of the field, and after it has been transmitted to the forward plate by means of the constraint it is there set down again. On the other hand, when the condenser is moving parallel to the plane of the plates, there is no energy How along the constraint and the Poynting vector adequately represents the transfer of energy. ”

“ At the very outset, it is important to realize that we have no long-standing experience with systems moving with velocities comparable with that of light, and therefore that primitive intuition may not be the very best guide in first introducing us to them. ”

“ Doubtless there is a psychological cause for our reluctance to accept the electromagnetic explanation as complete, constant familiarity with ponderable bodies having blinded us to the possibility of anything being more fundamental ”

“ For a single charged conducting sphere of radius (a) the mass for slow velocities is well-known to be
(e. Potential) .
An interesting verification of equation (16) for the special case of a general, rigid, electrostatic system in translatory motion has been furnished me privately by Mr. G. F. C. Searle. He obtains for such a system (Phil. Mag. Jan. 1907, p. 129) the expression
where is the momentum of the entire system along the direction () of motion, () is the total magnetic energy due to this motion, and () is the common translatory velocity possessed by all parts of the system. ”

“ If we follow the present suggestion, we must search for the components of an element, not by comparing atomic weights, but by comparing the corresponding values of , for the atomic weights deviate because of the lost mass accompanying the dissipation of internal energy. ”

“ So little is known as to the former radiating power of the sun that no even approximate calculation can be made, but it is not difficult to show that the order of magnitude is such as might make the increase in the planetary distances not altogether negligible during great lapses of time. ”

“ Rydberg certainly believes them to represent physical realities, and considering the before-mentioned overwhelming improbability that the approximation of the atomic weights to whole numbers is due to chance, we can hardly doubt that he is right. ”

“ It should be noticed that this theory of loss of mass and its consequences does not require that the whole material mass should be of electromagnetic nature. It only requires that the energy lost in the transformations, explosive or otherwise, should be at the expense of internal electromagnetic energy, i. ”