Searching for Tachyons (continued)
Tiwari On The Experiments
Under the sub-heading "Experimental Searches", Tiwari starts the topic by mentioning a few seemingly serious attempts to detect tachyons, noting that: "The first experimental investigation by T. Alvager and P. Erman was based on the suggestion that tachyons might be present in beta decay. Presence of a charged tachyon in a strong radioactive beta source was searched during the years 1963-65, but in vain." His citation is a 1969 article in Physics Today magazine, in which Bilaniuk and Sudarshan discuss these series of experiments. [See: Physics Today, 22(5) (1969).]
However, I found more details in an obscure archived paper* by Sudarshan, in which it is stated: "The simplest method of identification of a tachyon is to measure its energy and momentum and verify that the momentum is larger than the energy; equivalently one may measure the velocity directly by a time of flight method. The first method has already been employed by T. Alvager and P. Erman who used a magnetic deflection in a double focussing beta spectrometer to select the momentum of the particles, and a semiconductor counter to measure the energy. They concluded that in Thulium 170 there were less than 10^-4 tachyons per electron, if at all." [Nobel Institute Report, 1966.]
* Paper; The Nature of Faster-Than-Light Particles and Their Interactions, by E.C.G. Sudarshan (of the University of Texas at Austin). Sub-topic; Methods of Experimental Detection of Tachyons. This paper is labeled; ARKIV FOR FYSIK Band 39 nr 40. And I obtained it online by a Google search using the keyword "T. Alvager".
Now, Tiwari next writes: "Another experiment was based on detecting Cherenkov radiation emitted by charged tachyons. In the experiment carried out by Alvager and Kreisler gamma rays from a 5-millicurie cesium-134 radioactive source collide with lead. A strong electric field is applied to this presumed source of tachyons so that emission of Cherenkov radiation is detectable; but the results were negative." [Citation: T. Alvager and M.N. Kreisler, Phys.Rev. #171, year 1968, page 1357.] But Sudarshan, citing the 1962 American Journal of Physics article "Meta-Relativity", by Bilaniuk, Deshpande, and himself, correctly points out that: "Both of these experiments presume that the tachyons are electrically charged; if the tachyons are neutral, both the experiments must give negative answers." [Citation: Am. J. Phys. #30, page 718 (1962).]
In my opinion, while the literature abounds with people touting these results as proving tachyons don't exist, what the experiments actually show, and only show, is that tachyons are either electrically neutral, or, if any of them are charged, they simply do not possess the kind of electric charge that we are used to dealing with, and that even this is true only within the detection ranges established by the limits of the experiments. It is more likely, given what we know about tachyons theoretically, that the assumption that any of them have a detectable form of electric charge is not really a valid inference, and the null results of the experiments just cited tend not to support the contention that tachyons do not exist, but rather that it is not logical to demand this assumption.
Because of the alternate-dimensional nature of tachyons, any form of electric charge that any of them might exhibit would probably be a superluminal analog of what we know as electric charge. Hence, any experiment designed to detect tachyons based on the idea that they posses a standard form of electric charge is doomed to failure from the outset. What we can learn from this experiment, then, is simply not to base the designs of new experiments on the initial assumption that charged tachyons could possess the standard form of electric charge, because of the obvious theoretical implication that tachyonic charge is probably not like the electric charge that we know.
In Sudarshan's 1969 paper, he suggested that "there are four experimental methods of searching for tachyons which do not require them to be charged particles." I quote:
(a) Search for "decays in flight" of a stable particle: If we find that a particle which is stable in its own rest frame (like the proton) appears to decay in flight we can be sure that at least one of the "decays" products is a tachyon.
(b) Large angle scattering: If fast particles scatter through large angles with pronounced resonance in the invariant momentum transfer, a tachyon is being emitted (or absorbed!).
(c) Poles in the scattering amplitudes: If the scattering amplitude between two ordinary particles exhibits a pole in the invariant momentum transfer variable for negative (space-
like) values we can conclude that a tachyon is being exchanged. [Footnote: "For suitable kinematics the pole may appear in the physical region; it is therefore desirable to have a tachyon with width."]
(d) Effective mass plots: The original method of identifying pion-pion resonances can be
adapted to the present case by plotting the effective 4-momentum squared of a collection of pions with some of the pions in the initial state and some in the final state. A peak in such an effective squared mass plot at a negative value would be evidence for a tachyon. One has to eliminate, in such an analysis, the purely kinematic enhancements. [Here, for the said "original method", Sudarshan cites an entry by himself, G. PINSKI, and K.T. MAHANTHAPPA, in Proceedings from the Tenth International Conference on High Energy Physics (Rochester, 1960).]
I predict that one or more of these methods will provide proof for the tachyon's existence, but that entirely new kinds of apparatus must be designed to accomplish the task.
Sudarshan next states that: "All these methods presume that the tachyon, whether it is charged or neutral, participates in strong interactions. A fifth method which may be employed consists of a search for the missing mass squared in a suitably selected set of
processes. In principle, missing mass spectroscopy can be used independent of the strength of the interactions of tachyons." Tiwari, in the chapter on tachyons, does not comment on the four methods Sudarshan listed above, although he does cite Sudarshan in many other places in his book, and, as of the time of publication (2003), asserted that the missing mass method, with all other experiments based on the detection of Cherenkov radiation, as well as searches associated with cosmic rays, had yielded no hard evidence for the existence of tachyons. But I insist that looking for Cherenkov radiation is a waste of time, in searching for tachyons, so more attention should be paid to other experiments.
Researchers have, of course, calculated a negative value for the squared rest-mass of the muon neutrino; implying that this type of neutrino is a tachyon. However, Tiwari pointed out that, while claims that this is evidence for the imaginary mass of neutrinos in general, "such a claim is not supported by researches in neutrino physics." Yet, Tiwari did not actually provide a citation that contradicts the claim. And he admitted too that "the question remains unsettled"; directing the reader to a summary of the then "current status" on the subject. [Reference: V. Barger, D. Marfatia, and K. Whisnant, Physical Review Letters #88, year 2002, page 011302.] Unfortunately, the review he suggests has grown too dated, and the most up-to-date information on this can be had by doing a web-search using the keywords "tachyons" and "muon neutrinos".
My take on all of this is that the searchers have been searching in the wrong places, because of faulty initial assumptions. For instance, all of the cited experiments relied on the assumption that something unusual would be detectable using the same equipment and instruments used to study bradyons and luxons. But trying to detect tachyons based on detectable electric charge, particle decays, scattering angles, scattering amplitudes, missing mass, or Cherenkov radiation presupposes that tachyons will behave in ways that can be discerned from our bradyonic frame of reference. Even the indication that the muon neutrino may have a negative squared rest-mass, and documented superluminal phenomena (such as superluminal photonic tunneling), seem to me to be revealing more about the underlying nature of the universe (that it has superluminal substructure), rather than serving as dependable indicators of the existence of various kinds of tachyons.
Clearly, whether we use Einstein's STR or Lorentzian Relativity, tachyons exist in an alternate-dimensional frame, as viewed from a real bradyonic frame. Consequently, new research directions are needed, with new conceptualizations, new instrumentation, and new interpretations of the data collected in the experiments. I believe, then, that Tiwari is on the right track, in calling for a re-examination of our definitions of space and of time to gain a deeper understanding of nature, though it will require a revision both of Einstein's theories and of Quantum Mechanics.
However, I see that effort as part of an overall sea-change in our way of thinking; perhaps a key part -- but not the whole story. In my estimation, the initial assumption that brings about the next great leap in our intellectual development, though presently only a kind of science-fiction hypothesis, is that gravity is tachyonic. I contend that the search for the tachyon and the search for the quanta of gravity can be viewed as one in the same search; if it turns out that the quanta of gravity are tachyonic. In fact, I hold that this realization, used to define the parameters on which experiments are based, will yield breakthrough results at some point in the future; maybe even in the near future. Tiwari, of course, does not suggest this, and gives only a review of what is presently understood about tachyonic effects in gravitational fields, and tachyons in superstring theories (discussed next).
[More to come.]