In his explanation of time dilation, Einstein explains the principal in this way:
(from: The Foundation of the Generalized Theory of Relativity, Albert Einstein, 1916) (parenthetical inserts by the author, cs)
“In order to see this we suppose that two similarly made clocks are arranged one at the center and one at the periphery of the circle, and considered from the stationary system K. According to the well-known results of the special relativity theory it follows — (as viewed from K) — that the clock placed at the periphery will (appear to) go slower than the second one which is at rest. The observer at the common origin of co-ordinates who is able to see the clock at the periphery by means of light (traveling at a finite velocity) will see the clock at the periphery (appear to be) going slower than the clock beside him. Since he cannot allow the velocity of light to depend explicitly upon the time in the way under consideration(why not?) he will interpret his observation by saying that the clock on the periphery “actually” goes slower than the clock at the origin. He cannot therefore do otherwise than define time in such a way that the rate of going of a clock depends on its position,” (relative to himself).
The observer’s conclusions as to the actual rate of the clock’s apparent falling behind is in fact a function of his position relative to the clock’s, not that the peripheral clock is actually measuring the passage of time at a slower rate than the clock at the exact position of the observer. The apparent observed difference lies in the fact that the observation takes place at a significant distance from the observer and his observation is tempered by the finite velocity of light that enables his observation. To say that “time” itself on a distant clock goes slower is a logical fallacy. To an observer at the periphery this observation would not obtain.
In nearly all of Einstein’s assertions, this kind of assumption appears, here, and in his discussion of the simultaneity of two events seen from a moving train etc., all depends on the finite velocity of light or of sound. Relativity is all about observation, as it appears to contradict actuality. If one accepts that the mechanisms of observation are finite in their operation, not as said in the underlined sentence above, then one can accept that the two clocks are simultaneous, not that one is recording time intervals at a slower rate as the other. To describe reality, that is, that the two identical clocks are measuring the passage of time at exactly the same rate, the observer, knowing that his observation of the distant clock is significantly altered by the time passing until the image of that clock reaches him, must make the necessary correction in his calculation (t=d/v).
This has bothered me for a long time, since my interpretation of the role of physics is that its purpose is to describe reality, not to assert that “this is how the world appears to us, not as it actually is.” When he (AE) says that because of the time lapse in observation between that of an observer on a moving train and one in a stationary location proves that two events did not actually “occur” at the same time is also a fallacy. In fact, by measuring the time lapse between the two observations and knowing how far the train has travelled, one can actually determine the velocity of light, or of sound, depending on the nature of the observation.
In the text of Einstein’s On the Electrodynamics of Moving Bodies (1905), the argument is expressed this way.
“If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighborhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an “A time” and a “B time.” We have not defined a common “time” for A and B, for the latter cannot be defined at all unless we establish by definition that the “time” required by light to travel from A to B equals the “time” it requires to travel from B to A.”
If, however, it is desired to have an objective view of this phenomenon, one must postulate the existence of a third observer at C, an equal distance from A and B, whose observations will show that the hands of both clocks have moved an equal distance. The time required for light to travel from A to C is the same as the time required for light to travel from B to C. No discrepancy between the two clocks will be seen. “Time” has not slowed .
The 1905 paper draws a misleading conclusion, which is then cited as confirmation for the same misleading statement in the 1916 paper.
The question to be asked here is whether we are talking about “real” events or about unexamined hypotheticals in which one important factor, the finite velocity of light, has been ignored. The particular falsehood here is the statement that the observer at A has no choice but to conclude that “time” itself has slowed at point B.
This also goes to another important point, that in both papers, the author assumes that what we call “time” is a real, physical entity, capable of distortion by external causes, when it is, in fact, simply a measurement methodology to describe the duration or persistence of objects, events, or phenomena. It also raises important questions about the “truth” that time slows dramatically, approaching zero at lightspeed “c,” as in the famous twin paradox, wherein the twin flying in space at near light velocity supposedly ages at a vastly slower rate than the one remaining stationary on earth.
We look up at the stars and they are not there. We see the memory of when they were, once upon a time.
—Jack Gilbert (1925-2012)
Charles Scurlock – 6/29/2016