Searching for Tachyons (continued)
Objections to Tachyons
Dr. Tiwari cites the two main objections to tachyons in discussions published in Physics Today magazine in 1969. First, there was the contention that the notion of imaginary mass for tachyons raises questions about how the General Theory of Relativity (GTR) can be applied to them, so as to gain an adequate understanding of the role that inertia and gravitational mass play in tachyonic frames of reference. That is, the assumption was that only detectable changes in energy and momentum would be observable for tachyons, and the notion of the tachyon will therefore remain a mere theoretical curiosity as long as we do not know anything about how tachyons interact with ordinary matter and gravity. Secondly, there was the contention that the mere existence of tachyons would violate the "principle" of causality; assuming, of course, that it is impossible to violate this principle in any way, and therefore that tachyons do not and cannot exist.
However, Tiwari does not provide resolutions to these objections; presenting the issues as unresolved. On the other hand, he does suggest that a better understanding would result from a better understanding of how time is involved; more specifically, the time ordering of events. He states: "Anyone who thinks deeply on the meaning of time-ordering inevitably arrives at the conclusion that dynamical laws, whether classical or quantum, have built-in time symmetry, and do not provide us a direction of time."
Noting also that Newton's absolute time was actually a metaphysical concept, Tiwari writes: "Einstein adopts a measurement convention for the 'relative time' of Newton by employing constancy of the velocity of light as a standard. Past and future ordering of events makes physical sense only if the relativistic time is seen in the context of time-elapse of the absolute time." Also: "Relativistic paradoxes and contrived arguments to save the causality principle result from treating the relative time defined by Einstein's convention as the true time." What exactly, then, is this "true time"?
As an alternative, Tiwari suggests that, instead of assuming that the velocity of light is the fundamental consideration, we should regard time as the fundamental consideration, and, after mentioning the Planck Length and the Planck Time, holds that there must be an "absolute time interval," which could be the Planck Time -- although he unexpectedly asserts that the Planck Length could not be used as the corresponding absolute length. With that, he nevertheless suggests that, using his approach, "a range of speeds, less than or greater than c, is possible", and that the principle of causality "retains its key position" in the resulting framework -- although "the meaning of mass (real or imaginary) for any object has to be understood afresh." This point, despite a first impression it may convey, does not pose a threat to Tiwari's approach, because mass is not measurable anyway. The weight of an object is measurable, for instance, from which we can calculate the mass, but mass itself is not directly measurable (resting or moving).
By the way, although Tiwari does go into "tachyonic effects in gravity and superstrings", he provides only an overview of what is already known, and, other than his suggestion that we pay more attention to time, does not give any original means of resolving the two objections. Rather, he feels that superstring theory will possibly provide answers at some point in the future. And I do not doubt that. But I also believe there are other ways.
The data from superluminal photonic-tunneling experiments, overall, could be viewed as dismissing the second objection outright, while my tachyonics-operator can be used to unify General Relativity and Quantum Mechanics; answering the question as to how any possible tachyons in existence could be interacting with real matter, and with gravity (a special tachyon, in my view, constitutes gravity itself).
[More to come.]
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