[Epistemology vs. ontology: Did Einstein make a fundamental mistake?] - A New Kind of Science: The NKS ForumA New Kind of Science: The NKS Forum
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Epistemology vs. ontology: Did Einstein make a fundamental mistake?
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Posted by: Tam Hunt
For most physicists, the debate over the validity of special and general relativity is long past. However, a new spate of books and articles is appearing that dares to challenge the consensus on this key theory. These developments have been prompted by a failure to find a good theory of quantum gravity (the "theory of everything") and by many observational anomalies, such as the much faster than predicted expansion of the universe. These issues, and in particular Lee Smolin's excellent book, The Trouble With Physics, prompted me to really delve into these issues. So I went back to the source, reading through Einstein's papers and his books, and many other books on SR and GR. I found some potentially disturbing problems, one of which I describe here.
Einstein’s special and general relativity theories hold that time and space are malleable, as a result of the postulate that the speed of light is constant for any observer. However, the conclusion that time and space are malleable arises from Einstein’s definitions of time and simultaneity in relation to the speed of light. He describes, in his 1916 book, a person trying to determine if two lightning flashes are simultaneous, in the following scenario: a length of rail track is chosen and a mirror is placed at each end (points A and B). The physicist sits on the track exactly at the mid-point of the two mirrors (point M). If the lightning flashes, which in this hypothetical situation fall exactly on both mirrors, are reflected by the mirrors to the observer at the mid-point, the lightning flashes are, by definition, simultaneous.
The interesting conclusion in the theory of special relativity arises when we consider the same events occurring from the perspective of an observer on a train traveling on the same length of track. The observer on the train will not perceive the two flashes of lightning simultaneously. This is the case because the observer on the moving train is moving toward one of the lightning flashes, reducing the time it takes for light from the lightning flash to arrive at the observer’s location, and away from the other lightning flash. Due to this definition of simultaneity, simultaneity is, for Einstein, different for different observers.
Einstein writes:
"There is only one demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled. That my definition satisfies this demand is indisputable. That light requires the same time to traverse the path A to M as for the path B to M is in reality neither a supposition nor a hypothesis about the physical nature of light, but a stipulation which I can make of my own free will in order to arrive at a definition of simultaneity."
In other words, to arrive at a way of empirically determining simultaneity, Einstein stipulates (postulates) that the speed of light is constant for any observer and thus arrives at a definition of simultaneity that ultimately leads to an ontological statement about the nature of time, space and motion. This is a stunning passage when we consider that much of the last hundred of years of physics has shoehorned itself into the special and general theories of relativity. If a theory conflicts with relativity theory, it is by default considered invalid by almost all physicists. Yet Einstein’s entire theoretical structure is built on nothing more than an attempt to allow for measurement of simultaneity – in a rather arbitrary manner that contradicts our most closely held intuitions about the nature of space, time and free will.
Epistemological limitations should not, however, be converted into an ontological strait jacket. There is of course more than “one demand to be made of the definition of simultaneity,” as Einstein discusses. Another demand that cannot be ignored is that such a definition not lead to paradox. (Perhaps foreseeing the potential for paradox in his theory, Einstein stated in his 1905 paper: “We assume that this definition of synchronism is free from contradictions …”).
Einstein goes even further, suggesting that time itself – not just simultaneity – depends entirely on the observer’s vantage point: “We are thus led also to a definition of ‘time’ in physics. … [W]e understand by the ‘time’ of an event the reading … of one of these clocks which is in the immediate vicinity (in space) of the [lightning flash]. In this manner a time-value is associated with every event which is essentially capable of observation.” Einstein has in these passages defined time and simultaneity in such a way that allows for an empirical determination of simultaneity. This theoretical structure, however, did not take into account the actual nature of time, the actual speed of light or its constancy (or lack thereof, which is a debated topic now with the various "variable speed of light" theories recently developed), or other consequences flowing from such a conception of time and simultaneity. Nor did Einstein consider fully other alternatives that would equally well allow for an empirical determination of simultaneity.
Einstein concludes: “Now before the advent of the theory of relativity it had always tacitly been assumed in physics that the statement of time had an absolute significance, i.e., that it is independent of the state of motion of the body of reference. But we have just seen that this assumption is incompatible with the most natural definition of simultaneity….” Einstein quickly dismissed alternatives to his hypothetical method for measuring simultaneity (he discussed only one other possibility in his original 1905 paper), so it is not clear what he means by “the most natural definition” of simultaneity and time. The physicist Hans Ohanian supports this view with his statement in 2008 book, Einstein’s Mistakes:
"Einstein failed to consider all possible variants of the use of light signals and clocks for measurements of the speed of light. Einstein was very inventive, but he had a one-track mind, and after he was stuck by his mystical inspiration about clock synchronization by light signals he ceased to think about alternatives. If he had thought about it a bit longer, maybe he would have come up with a dozen alternative methods for measuring the one-way speed of light."
A more natural method for measuring simultaneity would seem to be to synchronize accurate clocks and place such clocks at A and B. The clocks would have to be capable of registering when a flash of lighting occurs. If the clocks show the exact same time (to the desired level of precision) for lightning flashes at A and B, the lightning flashes are, in this alternative formulation, considered simultaneous. Such a method was theoretically possible at the turn of the 20th Century, even if clocks were not particularly accurate at that time. In this alternative method for establishing simultaneity, no postulate about the speed of light, in a vacuum or in our atmosphere, constant or not, is necessary. And an observed simultaneity will hold true for any observer capable of reading the clocks at any point after the events have occurred, remotely or at the actual site, no matter what the observers’ motion is relative to the other.
The empirical evidence in favor of special and general relativity is a matter for another post/forum, but even if we accept the empirical evidence we may still challenge the unreasonable foundations of relativity theory on the way to finding a better theory that explains the evidence just as well.
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