OVNIs ‑ Un problème scientifique international

Matters of Definition

It would seem logically necessary to frame, early in any discussion of the UFO problem, a working definition of what shall be understood by an "Unidentified Flying Object." The effort quickly entangles one in semantic difficulties of a more or less obvious nature. Clearly, untrained observers can report as a UFO a wide range of things seen in the sky or moving near the earth's surface, or even resting on the surface in an un-flying manner. Fireballs, which are meteors brighter than -5 magnitude by present astronomical definition, constitute a good example. Many persons are quite unfamiliar with the phenomenology of fireballs and bolides, and will turn in sincere and often rather accurate descriptions of fireballs under the claimed headings of UFOs. Aircraft running lights, aircraft landing lights, aerial reconnaissance strobe lights, re-entering satellite debris, bright planes, and a wide miscellany of other sources of night-luminous objects, all are reported from time to time as "UFOs."

The U.S. Air force, and various persons who scoff at the notion that there exists a scientifically significant UFO problem, are entirely correct in suggesting that many UFO reports fall into this category. Only a little experience in querying observers makes clear that, of all reports that temporarily bear the label "UFO," a substantial fraction are, indeed, misidentified natural phenomena of such types. There is plenty of noise mixed in with whatever real signal may exist; that this is so need not surprise any scientist. Noise-filtering is a standard problem in many areas of research.

The UFO problem which I have come to regard as so extremely important, centers around that portion of all reports of initially unidentified objects which is left as a residue after filtering out the bulk of inadequately reported or obviously misidentified phenomena. A little reflection on the foregoing remarks reveals that it is scarcely a clear-cut definition. Nevertheless, it may afford an initial basis to begin discussion.

A curiously similar definitiona problem arises in dealing with the class of ball lightning reports. In the literature one can find reports of luminous masses, tagged as "ball lightning," that span so broad a range of phenomena that one must be quite careful that he is not subsuming many diverse phenomena under that single heading. The situation with respect to ball lightning turns out to be similar to that for UFOs in the further significant sense that the basi nature of each phenomena is not yet clearly understood, so that clear-cut working definitions are simply not yet possible. Such a situation is really not new in science, centering around such terms as atom, compound, force, species, ether, disease. meteor, etc.

In point of fact, the above definitional problems cause rather less trouble in scientific discouse on the UFO problem that a philosopher might predict. So let's proceed.

Matters of UFO History

Although I would probably be incorrect to assume that all CASI members are thoroughly familiar with the history of the past twenty years of the UFO problem, I do not choose to elaborate that history here in great detail. Much of my own view of that history has been summarized in a form now available elsewhere (reference 1). It appears to me that, following an initial flurry of official USAF concern that American UFO observations of 1947 might be hostile aeronautical devices (reference 2), an era of puzzled investigation ensued in the period 1948-1952. This was the era of USAF Project Sign and Project Grudge, a period generally devoid of solid scientific talent. I have studied many of the 243 cases finally analyzed by and reported by Project Grudge, and I can only say that, even in that earliest phase of official investigation, it is startling to see how little scientific insight was brought to bear on reports of a frequently very intriguing nature.

1952 was the high-water mark of the official American UFO studies, a brief year's energetic investigation that was still not characterized by strong scientific expertise, but which was definitely characterized by vigorous Air Force checking and data-gathering in many striking cases. The year 1952 saw about 100 reports turned into Project Bluebook, and some 300 of these were conceded to be Unidentified. When I visited Bluebook for the first time in 1966, I was quite astonished at the number of feet of files there were on 1952 cases. I was much more astonished to scan the contents of randomly sampled file-folders, revealing case after case of entirely inexplicable nature, many comming from within Air Force channels (reported by piots, controllers, ground crewmen, etc.), telling the story of an astounding year in American UFO history.

The wave of 1952 reports drew strong press attention, above all after Washington, DC became the site of two nights (July 19 and 26) of radar-visual sightings of Unknowns. These were explained away in a big press conference on July 29 as due to anomalous radar propagation and optical refraction anomalies. (More about this below.) By late 1952, intelligence organizations became concerned over the UFO problem, evidently because of overloading of reporting and investigative channels. In January of 1953, the Robertson Panel, assembled by the CIA, met and ruled that there was neither evidence of hostility nor evidence of scientific significance in all those reports. All this I have discussed in enough detail previously (reference 1) that I must gloss over many further points of great historical interest.

I have studied the final report of the Robertson Panel, which was declassi- tief for a brief period prior to the CIA's reclassifying it in the summer of 1966. From repeated re-examination of the details of UFO history and from personal discussions with four of the active members of the Robertson Panel, I form the impression of a brief but futile attempt to look for something of interest in UFOs, followed by CIA's request that the Air Force adopt a policy of "debunking flying saucers" in order to "decrease public interest." After 1953, no further rigorous Bluebook UFO investigation program ever reappeared. The UFO problem went steadily downhill, its priority status at WPAFB declined, and in en 1966, when I visited Bluebook three times, its staff consisted of a major, a sergeant, and a secretary, plus a lieutenant then being broken in in for future investigative duty. The total amount of scientific talent visibly focussed on UFOs via the staff and its consulting pool appeared to me to be grossly out of proportion to the embarrassment being created for the Air Force by a continuing series of absurd and scientifically outrageous "explanations" of individual UFO reports.

The references listed here will provide further insights and facts concerning the past twenty years' history of UFO matters (see references, 3, 4, 5). For information on many cases in the Air Force files prior to 1953, and for what appears to be a generally realible history of Air Force handling of the problem prior to 1953, see reference 6. For the viewpoints of a UFO investigator operating through those years, but outside of official channels, see the several books of Keyhoe (reference 7).

When the full history of the UFO problem is written, Keyhoe's efforts to get the UFO problem out into the light of open scientific investigation will, I believe, be acknowledged as having been of great significance, despite the slowness with which his efforts (and similar efforts of others) have borne fruit. His role as Director of NICAP (National Investigations Committee on Aerial Phenomena) has been seriously misunderstood by USAF personnel. Failing to recognize the utter inadequacies of their own UFO investigations, the USAF mistook Keyhoe's criticisms and his efforts to press for Congressional investigations, as ill-conceived Keyhoe's all-too-well-conceived efforts pressed against massive resistance based on what seem to be generally honest misconceptions on the part of misinformed officials.

I elaborate these viewpoints here because I believe that the misinformation generated within American information channels by the illusion that Project Bluebook was a scientific operation has diffused outside our national boundaries, and has misled officials, scientists, and members of the public throughout the world. International scientific progress on the UFO problem will not begin until that misinformation is clearly recognized.

The alternative historical interpretation which holds that there has existed a conspiracy to conceal the truth about the UFO problem, a conspiracy sometimes painted in on a canvas of international scale, does not square with such facts as I have been able to glean. I am, to be sure, puzzled by the sometimes startling similarity between "explanations" for UFOs emanating from foreign official channels (often foreign air forces) and "explanations" of the type so painfully familiar in USAF press releases following widely-publicized UFO cases. But I ascribe this similarity to factors other than a highly effective international conspiracy to which many countries would have to be party. Stanton (reference 4) has some pithy remarks on the conspiracy theory. Young (reference 5), by contrast, does feel there exists some American cover-up at high levels; I would be prepared to defend my alternative of the grand foul-up hypothesis against every instance he cites in defense of his grand cover-up hypothesis. I do not equate that assurance to categorial rejection of the grand cover-up hypothesis; new facts or interpretations could still change my views on this issue. I reiterate a point I made earlier (reference 1): I suspect that some of those who have so long insisted on the conspiracy theory have not been in a position to recognize clearly how scientifically inadequate the Bluebook work has been since 1953; they may have confused incompetence with inscrutability.

Scientifically, what's sorely needed is a number of entirely fresh starts, free from all pressures of governmental bodies that have taken an established position. This may be better achieved in countries other than the U.S. Because of twenty years of Air Force assurances that there's really nothing to all the talk about UFOs and nothing of any scientific or technological significance, that view is dominant in Washington, in higher scientific circles, and among most of the elder statesmen of science in the U.S. Months of effort on my own part to generate some new scientific UFO research on an adequate national scale, with adequate science-agency support, seem to have created only very slight response. Even if those in Washington admit to marginal doubt about UFOs being a lot of nonsense, they insist on the propriety of waiting for Condon's report from Colorado. My own doubts about waiting for Colorado have recently been expressed (reference 8).

Some Illustrative UFO Reports

There is an essential similarity in the types of unexplained phenomena reported from around the world. Discs and cigar-shaped objects dominate; night-time observations are most common; and highly unconventional performance characteristics are described by observers from varying geographical and cultural areas. To bring out these points, a small number of specific cases will be briefly summarized.

Alternatives to the Extraterrestrial Hypothesis

Since I have previously discussed eight alternative hypotheses (reference 1, 8), I shall not recapitulate them here. But I feel that all of the obviously competing alternative hypotheses seem inadequate; by a process of elimination I have come to the extraterrestrial hypothesis. Although argument by elimination is logically sound, it is not the one that scientists like to see used in a difficult problem. They much prefer positive arguments. The reason for this preference is simple: Success of argument by elimination demands that you have all possible hypotheses in your initial set, and one may not be so clever or unbiased as to start from that point. With respect to UFOs, one would prefer "solid evidence," in the form of a tail fin, a jettisoned motor, a crashed UFO, a lot of good photos, etc. Such positive evidence does not seem to exist, despite stories to the contrary.

Hoaxes, illusions, hallucinations, frauds, and fabrication must continually be considered. Frauds and fabrications are by far the most troublesome from the viewpoint of report-evaluation. Suggestions that UFOs are advanced vehi- cles of a secret terrestrial technology seem absurd when one scrutinizes UFO reports and then examines the nature and state of advancement of global technologies.

The leading alternative to the extraterrestrial hypothesis is that of "misidentified natural phenomena," viewed in terms broad enough to include conventional aircraft, satellites, balloons. The Bluebook position has for years been that UFOs are almost entirely such misidentifieds, and Bluebook has repeatedly asserted that their small percentage of unidentifieds would fall into that category if more adequate data were at hand. After studying hun- dreds of their cases, I do not agree. I say instead that adequate and open-minded crutiny of the roughly 12,000 cases now on file at Air Force Project Bluebook would probably raise the percentage of unidentifieds from the cur- rently acknowledged few per cent to perhaps 30-40 per cent.

An extremely important point to recognize is that intelligence personnel at airbase levels from which the bulk of Bluebook's reports originate simply do not bother to go through the complicated filing process on any UFO report they feel involves someone seeing Venus or a strobe-light. They operate with a degree if airbase-level flexibility on UFO reporting that serves effectively to filter out the obvious misidentifieds, as well as a lot more, I fear. Few persons sense this important point. The system is so loosely organized and depends so much on the interest and zeal of the individual base intelligence personnel that some obvious misidentifieds fo get up to Bluebook, but by no means the large numbers that one might guess. The net result is that the Bluebook files are fascinating, not boring as I suspect many USAF officials with little scientific training think to be the case.

In addition to being fascinating, I found the Bluebook files to be extremely irritating, because after looking at the reported observational material one sees the official "explanation," and from a scientific viewpoint there is usually an unbelievable gap between the report-content and the official categorization. When one tries to query, on scientific grounds, the USAF personnel responsible for those categories of explanations, one finds they cannot engage in anything like a scientific discussion because scientifically skilled personnel are not involved in the Bluebook operation. It is clear that this has been true for the past fifteen years, and earlier cases point unfortunately in the same direction, even back in the 1952 period of temporarily energetic investigatory work.

So when one hears that the USAF position is that the bulk of the UFO reports they get are misidentifieds, it is necessary to probe much further to get at the truth.

Reflections and Mirages -- Menzel's Views

It is not only Bluebook that stresses misidentifieds. For about 15 years, the former director of Harvard College Observatory, Dr. D.H. Menzel, has been saying that UFO reports fall almost entirely in that category. His two books (references 11, 13), other writings, and many television and lecture discussions have invariably emphasized that position. It has been of particular scientific interest to me that a majority of his alternative explanations fall within my own area of expertise, atmospheric physics. Consequently, I have examined his arguments rather carefully and must say that they do not convince me at all. Since I have cited specific instances and discussed specific objects elsewhere (references 1, 8), I shall not give numerous examples here.

But one category of Menzel's explanations that has evidently influenced Bluebook thinking (witnessed by the fact that similar explaining shows up in the official files) deals with "reflection" of light from atmospheric in- versions and "haze layers." Menzel's explanation of the August 20, 1949, Las Cruses, New Mexico sighting by Dr. Clyde Tombaugh is a case in point (reference 11, p. 266). Menzel argues that lights from windows on some house, reflected off an elevated inversion layer, produced the appearance of six yellowish rectangles that Tombaugh and his family members saw shooting across the sky. Tombaugh first spotted the geometric array of six pale-yellow rec- tangles almost directly overhead. menzel suggests that they were reflections of window lights on an inversion layer at which haze had collected (despite Tombaugh's strong emphasis on the unprecedented transparency of the air that night). Since only collimated beams like searchlight beams can yield distinct spots on haze layers, one seems left only with the notion that when Menzel says "reflection," he means just that.

Let us examine the possibility that atmospheric inversion layers could yield perceptible reflectivity at near-normal incidence such as would have to be involved if Menzel's suggestion is to be acceptable. For ideally sharp refractive index discontinuities, the Young-Fresnel equation (see reference 14, p. 420) gives the reflectivity R across a discontinuity between to media of relative refractive index n as

R = [ (n-1) / (n+1) ]²

for normal incidence. Even for off-normal incidence angles out to several tens of degrees, the order of magnitude of R is well-established by that familiar optical relation. Menzel's qualitative discussions about how UFO apparitions stem from reflection off atmospheric discontinuities frequently involve such near-normal incidence. Hence the question becomes that of asking how large n can become. For visible light in air at NTP, the refractive index relative to a vacuum is about 1.0003, and the temperature effects across an inversion boundary (even if idealized as mathematically sharp) make changes only in about the fifth of sixth decimal place of that parameter. Clearly, then, one will make a gross overestimate of R to go the extreme case of "inversion" separating standard air from a perfect vacuum, i.e., by inserting into the Young-Fresnel relation the magnitude n=1.0003. The result is seen to be roughly

R = 10^-7

This negligibly small reflectivity could not conceivably yield window-reflections of the type adduced by Menzel to account for sightings such as Tombaugh's, despite its grossly overestimating the actual "inversion layer" reflectivity that might be encountered in the real atmosphere. Such quantitative considerations are what are not found in Menzel's defense of his discussions of UFO misidentifications, even in areas where his particular pro- fessional background ought to have made him sense the orders of magnitude involved.

In the February issue of Air Force/Space Digest (reference 15) will be found a letter discussing an observation of an odd aerial apparition seen by Lt. Col. R. G. Hill, and treated by AF/SD as an example of UFO reports that are explainable if only one looks far enough. I have spoken with Col. Hill to get a few details and can only wonder if Menzel's "inversion-reflection" ideas and Bluebook's misuse of the same have not misled Hill and the editors of this journal. The four luminous discs which Hill saw on November evening six years ago are tentatively explained in Hill's communication as "possibly the result of some atmospheric phenomenon that cause two interfacing layers of air to reflect the light from a nearby source such as the mercury vapour lamps illuminating the parking lot at the shopping center where these objects appeared. As I have stated to Col. Hill and to AF/SD, this is quantitatively quite out of the question.

Indeed, everyday experience with window-glass, whose refractive index relative to air is about 1.5, ought to have served to prevent the widespread misimpression concerning UFOs caused by "inversion-reflections." Window-glass gives an unimpressive normal-incidence reflectivity of about 4 per cent; yet it is obvious that it must be orders of magnitude more reflective than adjoining air layers could ever be.

This type of UFO explanation is being so seriously misapplied by Bluebook staff and consultants, that I believe it may be well to carry the counter-arguments one step closer to the real atmosphere for deserved emphasis. One never actually deals with mathematically sharp index-discontinuities in the earth's atmosphere, only with layers across which density ,ay vary in some smooth (even if locally steep) manner. For such "transition layers" in the index distribution, one cannot apply the Young-Fresnel equation. The mathematical problem is generally quite difficult, but Rayleigh (reference 16) has found one model that permits useful mathematical analysis of wave-propagation at the kind of inversions that occur in our atmosphere.

To give great benefit of doubt to inversion-reflection, one might imagine an inversion layer of such meteorologically improbable intensity that the air above the layer was 20 degrees Centigrade hotter than below, and in which all of this absurdly large temperature jump was concentrated within a transition layer of the unreasonable small thickness of a mere one centimeter. I emphasize that such intense inversions are not known in the atmosphere, so I shall still be seriously overestimating reflectivities by applying the Rayleigh theory to such a case. The computed reflectivity, again treating normal incidence, is found to be

R = 10^-19

I repeat, even this is an overestimate by a very large margin of what to expect in the real atmosphere.

Mirage phenomena are very real, but involve angles of incidence so far from near-normal that the small, but significant, gradients across real inversions do give refractive anomalies of readily perceptible magnitude. But one's line of sight must strike the inversion layers at almost grazing angle (on the order of tens of minutes departure from the horizontal), whereas Menzel has treated miraging in his UFO discussions as if it could occur with lines of sight that depart by many degrees from the horizontal. This is quantitatively absurd.

I could discuss other aspects of atmospheric physics that are mishandled in Menzel's treatment of UFOs, but wish to turn to another, newer effort to account for UFO reports in terms of another alleged type of atmospheric-physi- cal phenomena: plasma-UFOs, discussed by Philip Klass.

Corona, Ball Lightning, and Plasma-UFOs - Views of Klass

In working from the method of multiple hypotheses, one needs to look in all directions for possible alternatives. Quite early in my examination of the UFO problem, I was confronted by colleagues with challenges on the ground that UFOs could be some unrecognized form of plasmoid. For example, scientists at the Lunar and Planetary Laboratory of the University of Arizona proposed that, since the wake of an entering meteoroid is a plasma and since the meteor-wake boundary could spin off masses of incandescent plasma that descend into the lower atmosphere and are reported as a UFO. I pointed out seemingly insurperable difficulties centering around rapid ion-recombination and buoyancy of hot plasmoids that would have made it most improbable that any such plasmoids could penetrate from entry-levels to the near-surface levels where innumerable UFOs have been reported. But mainly I stressed the more basic point that the type of UFO reports that are provocative are not mere balls of luminosity but structured objects described by seemingly quite credible witnesses as resembling machines of some type.

I reiterate this strong objection when I turn to the recent writings of Aviation Week Senior Avionics Editor Philip J. Klass. My most basic objection to his plasma-UFO theory is that he does not confront the fact that the interesting UFO reports do not involve hazy, glowing, amorphous masses, but reportedly sharp-edged objects often exhibiting discernible structural details, carry discrete lights or port-like apertures, and maneuver for time-periods and in kinematical patterns that are extremely difficult to square with his plasma-UFO hypothesis. It also fails to deal quantitatively with parts of the argument that are, in terms of existing scientific knowledge, amenable to quantitative analysis.

I interject here that this last objection can and should be turned against my own position as to the extraterrestrial hypothesis on the grounds that we do not know something about prospects of interstellar travel and that certain quantitative objections about propulsion difficulties can be raised against such travel. Indeed, many have already cited these difficulties, including Purcell, von Hoerner, and Markowitz. My own lame yet not necessarily invalid defense is that we may not yet know all there is to know about the technology of interstellar travel, and hence our attempts at quantitative assessment of the extraterrestrial surveillance hypothesis may be inconclusive. Beyond that I cannot go (see references 1, 8).

Klass has developed his position in two magazine articles (reference 17) and a just-published book (reference 18). He does not assert that all UFOs are plasma-UFOs; he feels that other misidentifications contribute. But he does argue that most students of the UFO problem (and he cites me as an example) seem to have missed the "plasma fingerprint" which he sees in so much of the UFO evidence. He disclaims any view that the UFO problem is a nonsense problem; rather, he suggests that it is one of keen scientific interest because it compromises a body of phenomena from which careful study of the plasma-hypothesis will generate valuable new knowledge of atmospheric physics and atmospheric electricity.

One puzzling and far from understood phenomenon of atmospheric electricity that does seem to lie in the plasma category is ball lightning. Only within about the past decade has ball lightning been admitted as a real phenomenon rather than some kind of illusion. In this sense, the history of ball lightning studies is amusingly parallel to that of UFOs. It can be stated unequivocably that, as of 1968, students of atmospheric electricity have not yet succeeded in developing an adequate theoretical understanding of the baffling phenomena reported under this heading.

The fact that ball lightning reports, like UFO reports, come largely from untrained observers who happen to become witnesses to the phenomenon, hampers data-gathering. Also, it is sufficiently uncommon that it has been discoura- ging to try to set up special recording systems to gather instrumental data on the phenomenon, as is true also for UFOs. And the range of ball lightning behavior characteristics is so wide that no single mathematical model has fit very satisfactorily the reported effects as well as the known atmospheric electrical facts.

There are even parallels to the UFO problem in the sense that a semantic difficulty arises. One is not at all sure, in looking at published summaries of ball lightning reports, that one is dealing with a single phenomenon. One suspects that, mixed into the alleged ball lightning sample, are other quite different phenomena, so that one may be trying to explain more than is necessary.

Summaries of ball lightning reports have been given (see references 19, 20, 21, and 22). Ball lightning models have been discussed by so many that no catalog of individual papers is in order here. Dewan (reference 23) has pre- sented a brief summary of models developed up to about 1963, and other notions are to be found in a volume edited by Coroniti (reference 24). None of these models, nor those subsequently offered by others such as Uman and Helm- strom (reference 25) can be viewed as entirely satisfactory.

however, one major feature of reports and mathematical models is that the majority suggests that ball lightning is a phenomenon closely related to ordinary thunderstorm lightning.

Fair Weather Ball Lightning

Klass has developed the notion that ball lightning can be generated in fair weather free of all thunderstorm activity, and he has defended it on the grounds that, in the literature of atmospheric electricity, one can find a hals-doezen or so reports of lightning discharges in clear air. He also defends it on the grounds that, in some of the above cited summaries of ball lightning reports, there are luminous masses that were called ball lightning by the witness or data-collector, yet occured in the absence of thunderstorms. This is a confusing situation. We do not yet know precisely what we shall mean by ball lightning, we do not know how Nature produces it, and we have to concede that we may be lumping diverse phenomena under one heading.

To illustrate, consider Klass' citing an observation made from a USAF F-100 flying over the British Isles at 11,000 feet near midday, where a luminous orange ball with a tail streaming beyond it "somewhat like a flaming meteorite" was sighted by the pilot under clear-weather conditions (reference 18, p. 121). Klass uses that observation to support his assertions that ball lightning can not only occur under clear-air conditions, but can move through the atmosphere at relatively high speeds. It is by no means obvious that it is correct to call this a ball lightning report. Far more reasonable would be to call it an observation of a bright daylight meteor, many of which are on record. The very fact that the original account compares the tail to that of a meteorite ought to prompt this identification in preference to the ball lightning identification. I urge serious students to read Klass' book in full to see that just such easy slipping of a wide range of odd observations into his plasma category has led his arguments seriously astray.

The suggestion which Klass makes that ball lightning can form under fair-weather conditions is, like many of his other suggestions, shown to be quantitatively absurd by some elementary computations. The fair weather earth-air current is known (reference 28, p. 150) to average about 10^-12 amp/m^2, and the fair-weather potential gradient averages about 100 V/m.

If then, we ask for the area of the earth's surface over which we would have to collect current to have Joule-heating within a slab, say, 100 meters deep in amount equal to a modest estimate of 100 watts (cf., reference 25, where 1000 watts is taken as perhaps more representative), we obtain an area of 10,000 km^2 as our answer! Obviously the assumption of a slab 100 meters deep was quite arbitrary, but it would seem to give benefit of the doubt to Klass' argument, so the figures suffice to make the notion of fair-weather ball lightning seem rather far-fetched.

At no place in his book does Klass defend his assumption that plasmoids can move through the atmosphere as speeds of hundreds of meters per second, except in one special and quite interesting case (when they are electrically attracted to aircraft bearing tribo-electrically induced charges). Let us examine that notion now.

Attraction of Plasma-UFOs to Aircraft

Klass takes note of the fact that UFOs have been seen following aircraft in flight, and proposes a theory to explain this. Remarking that aircraft often develop strong net charges due to contact with snow, rain, or dust particles, he suggests (reference 18, p. 124) that "an airplane having a strong positive charge comes within reaction distance of a plasma whose surface has a negative charge" with the result that "the two will be attracted to each other, like two magnets." He goes on to say that, since the aircraft has far greater mass than the plasma, the latter "will be drawn towards the aircraft rather than the reverse."

Does Klass subject this argument to any quantitative assay? No. Let's examine that idea quantitatively here, then. For simplicity, assume a spherical plasmoid, with the greatest allowable surface charge density, namely, that which brings the surface electric field intensity to the dielectric breakdown strength of air E of the order of 20,000 V/cm at typical aircraft altitudes. Similarly, let the aircraft be roughly modeled as a sphere, also charged (which assumed opposite sign) to that same breakdown limit. This will actually overestimate net aircraft charge by about one order of magnitude, giving more benifit to Klass' assumed model. Since the surface charge density omega will satisfy E = 4 Pi x omega, each object will then hold a charge Q = R^2 E (esu) where R is the object radius and E is taken as 20,000 V/cm = 65 esu/cm. If d is the separation of the centers of aircraft and plasmoid, the the force F (cgs) acting between the two entities is:

F = Qa Qp/D² = Ra² Rp² E²/d²

where subscripts a and p correspond respectively to aircraft and plasmoid. For present rough purposes, we may generously set both radii equal to ten meters, and we may let the plasmoid tag along behind the aircraft that is dragging it (on Klass' assumption) through the air at lag-distance d=100 meters. We get, then, F=4x10^7 dynes.

To fulfill Klass' requirements, this Coulomb attraction F must equal the effective aerodynamic drag force D, to which the fast-moving plasmoid is subjected (if it is not to be torn apart or brought to rest). Calling the drag coefficient C, the air density omega, and speed of the aircraft and the trailling plasmoid V, we have,

D = 1/2 omega V² C Pi Rp²

Setting D=F to determine the allowed airspeed V,

V² = (2 Ra² E²) / (Pi omega C d²)

Thus the radius of the UFO plasmoid disappears from the V-relation.

Using omega=7x10^-4 g/cm³, C=0.2 for the high Reynolds number regime here involved, and the previously suggested values for the other parameters, we get,

V = 4x10² cm/sec = 9 mph

Thus, even upon assuming a large maximally-charged aircraft and plasmoid and limiting the trailing distance to no more than 100 meters, we obtain so low a value for the allowed V that it is absurd.

But the conclusions are even more negative for Klass' hypothesis that is suggested by the limit of V=9 mph, since it is known from experience with the aircraft charging (references 26, 27), that steady leakage of autogenous charges keeps surface field strengths down to values generally under 10^3 V/cm (a factor of twenty lower than assumed here for the aircraft) and even that value would not be found in flying through clear air free of snow or dust. Neither Klass nor I have proposed any basis for assuming that his airborne plasmoids will be so-decidedly non-neutral as to have surface charge densities anywhere near the breakdown limit, as assumed in the above calcula- tion giving Klass full benefit of the doubt on that score. When some allowance is made for those factors, it is seen that a plasmoid could not be drawn through the atmosphere at the pace of even a very slow walk by the Coulomb interactions which Klass invokes to fit his hypothesis of plasma-UFOs, hence his ideas on plasma-UFOs pacing aircraft are quantitatively untenable. He states that they do not come very close to the charged aircraft because the aircraft's "windstream serves as a protective sheath," another ad hoc assumption that can now be seen as irrelevant.

In another one of his articles (reference 17), Klass explains the inability of jet interceptors to close on UFOs as resulting from the circumstance that aircraft and plasma have the same charge, so that the interceptor repels the plasma-UFO and can never catch up with it. This is equally absurd.

Other objections could be raised: Klass fails to confront his hypothesis with cases where UFOs were neither attracted or repelled by aircraft, yet UFOs have made close passes coming from all relative directions and exhibited many unusual maneuvers not fitting his model. For example, a very famous sighting, the July 24, 1948 Chiles-Whitted sighting over Montgommery, Alabama, is briefly alluded to on page 118 of his book, so Klass must know that Chiles and Whitted saw the object come almost directly at their DC-3 on a near-collision course before it passed them and then did an abrupt pull-up before disappearing. He must also know they described a double row of windows, a length compared to a B-29, a cherry-red wake, and a blue glow from nose to tail along its undersurface. Coulomb attractions at work? Innumerable other aircraft-observed UFOs could be cited that would not fit Klass' Coulomb-attraction model, even if it did make quantitative sense for trailing UFOs.

Not only does Klass suggest that "highly charged aircraft" can attract his plasma-UFOs, but also (reference 18, p. 125-126) suggests that charged automobiles attract "low-altitude UFOs." Carrying his idea to its full absurdity, he proposes that a charged pedestrian "who encounters a very low altitude UFO may find it drawn slowly toward him or that it backs off as he approaches it." The question of wether it shall be attracted or repelled depends, he adds, on the sign of the charge of the UFO and that "of the very slight charge on the person." To make such assertions without any attempt at inserting numbers into the elementary calculations that discloses their low plausibility is quite typical of Klass.

[It might be added in this final version of the draft presented at the Montreal CASI meeting, that my use of the figure of 20,000 V/cm in my rough check of Klass' aircraft-pacing model was challenged from the floor by Klass himself. He stated that this figure must obviously be incorrect, for he had information that helicopters flying over dusty terrain can be charged up to 500,000 volts (see reference 18, page 171). As I pointed out by the way of clarification, Klass was confusing "volts" with "volts per centimeter," and to reconcile his figure with mine we need only be sure that the helicopter had a clearance above the ground of at least 25 cm (since 25 cm multiplied by 20,000 V/cm equals 500,000 volts). Here again, one is startled to encounter confusion over such elementary electrical concepts. That the dielectric breakdown strength of air is if the order of 10,000 to 30,000 V/cm, depending on electrode geometry and air pressure, is certainly not open to question.]

Formation of Plasma-UFOs in Wingtip Vortices

For the most part, Klass offers his readers no hint of the origin of the plasmoids with which he wishes to equate UFOs. But one case on which he appears to offer an idea of origin is in connection with aircraft. Klass has the idea that pollution products exert a helpful influence in plasma-formation. Aircraft engines emit pollution products. Therefore Klass suggests that pollutants, along with the charges which he believes are collected in the tip vortices, somehow form a plasma-UFO )reference 18, p. 168).

Let's go over that in more detail. First, impact charging of aircraft in clear, particle-free air is negligible. One must have rain, snow, or dust impacting on the aircraft surfaces to generate strong autogenous charges (refe- rences 26, 17), so Klass is in serious initial trouble on this score alone. Furthermore, when an aircraft is undergoing such impact-charging. what actually occurs is that the surface charge densitities build up to an equilibrium value such that the leakage-rate just equals the charging rate. One great value of charge-dissipating whips on wing trailling edges is that they boost the effective discharge rate to so high a value that the steady-state values of total aircraft charge are low. Under the steady state that is quickly attained on entering a dust or a snow cloud, the air passing off the wing has zero net charge, since the leakage charge just balances the residue left over from the impact charging. Thus, Klass will not get plasmoids bearing any significant net charge by such a process, and so his aircraft-chasing UFOs are not accounted for by the only model that he offers his reader to get his plasmoids airborne.

But the difficulties are much more serious that the absence of significant net charge. To have a plasmoid in the usual sense of the term requires high concentrations of free electrons, whereas all that will be sweeping off the trailing edge of an aircraft wing when flown under conditions favoring charging (dust, snow, rain) will be "ions" in the sense employed in atmospheric electricity. All free electrons will attach to oxygens in microseconds, and exhaust pollutants will further demobilize the small ions that are thus formed. Between this and ordinary ion-recombination processes, nothing remotely resembling a luminous plasmoid can possibily be expected to appear within the trailing vortices of an aircraft. When Klass states (reference 18, p. 168) that "an aircraft would accumulate electrical energy and focus it into periodic discharges which could create a plasma UFO in its wake when conditions were right," and then adds that these plasmoids would be left behind so that "another pilot flying along the same airway a few minutes later might encounter a glowing plasma," he is using arguments that would collapse if he were to try to put numbers into them. The temporal and spatial instability of plasmoids is one of their most outstanding characteristics. Klass accounts neither for their formation nor for their survival in this context of aircraft-related plasmas.

Diurnal Variations of UFOs

Klass suggests that UFOs are a mystery of atmospheric electricity. Students of that subject will certainly find some surprising mysteries of an atmospheric-electrical nature in Klass' book (reference 18, pp. 164-167). Klass cites Vallee's evidence for an evening maximum of low altitude UFO sightings, between siz and ten p.m., roughly. Klass notes that Brand (reference 19) finds a diurnal peak frequency of ball lightning sightings at 5 p.m. Klass feels that this rough temporal correlation indicates a genetic relation between ball lightning and UFOs. Meteorologists could suggest to him that a 5 p.m. peak in ball lightning observations would match the generally lateafternoon peak of thunderstorm activity. I believe that the early evening peak of UFO reports is the result of greater likelihood of detecting a luminous object at night than a non-luminous object by day. I gather that Klass shares some of the latter view; but he proceeds to a further idea that plasmas are formed with a diurnal peak frequency in the early evening. The route by which he gets there is curious indeed.

First, he discusses the diurnal variation of the atmospheric electric field-strength near the earth's surface and calls attention to a tendency for most land-stations to have a maximum of field-strength near 7 p.m. He glosses over the point that more UFOs are seen in summer than in winter, and that during the summer most land-stations have a strong maximum of field strength in the mid-morning. But where his physics goes astray is that he mistakenly attri- butes the peak field-strength to a concurrent maximum of radon gas that produces much of the air-ionization in the lowest atmosphere.

The actual situation is that increased ionization would, per se, increase the air's conductivity and thus decrease the observed atmospheric electric field strength (reference 28), precisely the opposite of what Klass claims. Briefly, the earth-ionosphere potential difference may be treated here as a constant (we may ignore the well-known universal diurnal variation), where vertical current densities will remain sensibly constant so long as diurnal factors only alter the conductivity in a relatively shallow air layer near the earth's surface. But with constant current density, the atmospheric electric field intensity must adjust itself to vary inversely with air con- ductivity. Pollutants decrease air conductivity; ionization processes increase it. The well-known evening increase in field intensity is due to development of an evening low-level inversion that traps pollutants, the pollutants attach small ions to generate large ions of low mobility, the air conductivity consequently goes down, and the observed field intensity must, to maintain fixed current density, go up.

If radon-trapping were the dominating factor here, as Klass evidently thinks, evening would be a time of minimal, not maximal field intensity!

He extrapolates the above to a claimed explanation for the higher frequency of UFO sightings in rural areas vs. urban areas; but again it is based on the above misconception of the role of inversions, so that this deduction of Klass' is also invalid.

But even beyond the confusion engendered by Klass' thoroughly confusing the physics of the diurnal variations of conductivity and potential gradient, there lie further basic shortcommings that warrant emphasis. One must ask, just what does he have in mind in talking about all this? How does it relate to the formation of luminous, active plasmas? Evidently the answer (reference 18, p. 166) is an assertion that these cyclic variations of "pollution and electrification" serve to set the stage "for the chance triggering of a plasma-UFO by a corona discharge on a high-tension line or perhaps by a brief power surge in a high-power TV or radio transmitter. Let's examine these two categories seperately.

One can only conclude that Klass believes that an increase of atmospheric ionization by the small factor (less than about 2) which he had in mind when he became confused over the foregoing diurnal-variations arguments, can exert an important "triggering" action on power-line corona. That he is not clear as to the physics of corona formation seems evident when he states earlier (page 22) that "under freak conditions an electrical avalanche occurs." He must be unaware the corona discharge from power structures is not dependent upon unusual concentrations of atmospheric ions, but only upon establishing sufficiently strong field strength that the continually forming free electrons (ejected by cosmic-ray or air-radioactivity bombardment of neutral air molecules) shall be accelerated within one free path to energies sufficiently high to cause an additional impact-ionization event. Being confused on this point, he draws the erroneous inference that if he could account for some extra air-ionization, he'd account for extra corona discharge on a high-tension line. Also, coronas don't detach from power lines.

Next, consider the idea of a "brief power surge in a high-power TV or radio transmitter." A clear-channel audio broadcasting station is permitted to 50,000 watt output. TV stations are typically operated at outputs in the neighberhood of 150,000 watts, though some can legally emit as much as twice this wattage. Let's take a generously large value of 300,000 watts for the power output from an elevated TV antenna, and, for wavelength reasons, we'll be generous to Klass in assuming an effective emitting area of only 1 M^2. From the Poynting equation, we then wish to estimate the maximum electric field strength prevailing near the antenna with a flux density of 3x10^5 watts/m^2. Since P = 1.3 X 10^-3 Eo^2 (P in watts/m^2, Eo in V/m), we find by this order-of-magnitude estimate that Eo = 150 V/cm. Even after allowing for the reduction in dielectric strength of air at the radio frequencies involved, this generously high estimate of 150 V/cm is more than an order of magnitude too low (in fact, probably about two orders too low) to initiate rf-breakdown and plasma-formation (see for example, reference 35, p. 185, and reference 36, p. 156). Thus, far more than a "brief power surge" will be required to cause plasmas to appear around an antenna. A mere two-fold variation of air-ionization would be entirely inconsequential in abetting this improbable event. So Klass appears to be in difficulty here, too, even if he has not made the prior mistakes with respect to diurnal variations in atmospheric-electrical parameters that led him into all this.

Air Pollution as a Plasma Promoter

In the foregoing, there have been several allusions to an underlying idea that runs through much of Klass' book: Air pollutants are alleged to aid in the formation of plasma-UFOs. This is such a curious idea, and the source of this notion is treated to casually by Klass (reference 18, p. 153) that few readers are likely to realize how it arose. Because Klass weaves it into so much of his argument, it warrants closer examination.

Klass contacted Dr. J. R. Powell concerning some interesting lab work done at Brookhaven National Laboratory (APS abstract in BNL 10625, entitled Laboratory Production of Self-sustained Atmospheric Luminosities, by Powell, Zucker, Manwarring, and Finkelstein). Using a 75 Mhz rf arc discharge as the primary power source, and feeding its output into a walk-in sized resonant cavity filled with selected gases at atmospheric pressure, the Brookhaven group were studying luminosities with radii in the decimeter range and lifetimes of the order of a second or more after shutoff of the rf power supply. Early work indicated that such luminosities could be produced in the air, N2, O2, or N2O, though not in A or CO2. It was hypothesized that the rf "pumping" stored energy in certain energetically accessible long-lived (metastable) states of N2, or O2, or N2O, and that vaporized electrode atoms (e.g., Cu) produced the visible radiation after acquiring energy in collisions of the second kind with the excited chamber-gas atoms. Possible relations to the ball lightning problem were noted by the investigators.

The important points to note here are that this experiment appears to involve three crucial features; a tuned cavity, an rf power source feeding into it, and a gas, filling the cavity as 1 atm pressure and selected to have metastable states with lifetimes of the order of seconds such as to constitute an energy reservoir upon which the light-emitting species (metal vapor atoms) can feed repetitively during the post-shut-off glow period. Wether the interpretations put on this promising experimental work stand the test of time need not bother us here; they do appear plausible.

Upon hearing of this laboratory work, Klass jumped via several erroneous steps to his idea that pollutants from aircraft, cars, and factories will enhance the likelihood of forming plasma-UFOs.

His first error lay in mistakenly identifying what he terms "nitrous oxides" (his plural) with the "nitrogen oxides" of air pollution literature (reference 18, p. 153). As a matter of fact, nitrous oxide (N2 O) is a natural constituent of air, not considered an atmospheric pollutant (reference 29, p. 156), and is therefore not even mentioned in most air pollution literature on the problem of the nitrogen oxides (reference 20, p. 3-12; ref 31, p. 83). NO is copiously produced in all combustion processes, including those in aircraft and automobiles, and oxidizes quickly in air to NO2, the primary photon-acceptor in photo-oxidation air pollution of the Los Angeles type. N2O, a rather stable compound, always present in concentrations about twice that of all other nitrogen oxides characterizing polluted atmospheresm plays no part at all in any pollution problems, since it is "dangerous only in concentrations of about 90 per cent and then has mainly an anoxic effect" (reference 32, p. 149).

Indeed, chemical analysis of the nitrogen oxides in polluted atmospheres was not meaningful until tests such as the phenodisulfonic acid method (reference 29, p. 159) were developed to react to all N-oxides except N2O! Briefly, through an error of interpretation of elemetary chemical terminology, Klass misidentified the N2O of the Brookhaven experiments with true pollutants and was off on one of the many chainsof error that so weaken his treatment of the UFO problem.

Next, he failed to appreciate relevant quantitative aspects concerning the "air pollutants" he thus began to discuss. Average concentrations of N2O at sea level are near 0.5 ppm (parts per million by volume). Average concentrations of all pollutant-N-oxides in Los Angeles run about half that (reference 31, p. 84). To suggest that any gas present in such trace quantities could play the energy reservoir role of the test-gases with which the Brookhaven group filled their tuned cavity is to miss completely a basic quantiative aspect of the experiments.

Yet this is what Klass suggests; so here we have the next stage in his error-compounding. If the metal atoms have to make a million or more collisions, on the average, before finding one of Klass' pollutant molecules, not much light would be comming from the system.

In fact, once one understands what Powell and his co-workers think happens in their chamber, it becomes somewhat unreasonable to talk about adding to ordinary air by the way of abetting the processm for thet clearly assert that the N2 and O2 of ordinary air do quite well in providing suitable metastable energy levels to make the process work. In view of this point, all of Klass' discussion about diurnal variation in pollutant concentrations, about pollu- tants swepts into tip vortices, and about alleged concentrations of pollutants nearh highways is seem to be irrelevant and based on a network of misconceptions.

But finally, the most basic error of Klass' attempts to fit the Brookhaven experiments into his thesis lies in ignoring the very special nature of the energy source used in the lab work, and in casually overlooking the complete absence of anything even roughly similar to it in outdoor environments in which he claims plasma-UFOs are being formed. The buildup of fields in the standing-wave pattern of the Brookhaven tuned cavity fed at the resonant frequency (75 Mhz) provides excitation conditions that simply cannot be blandly assumed to exist aft of a wing-tip, or under an inversion in a rural area, or above an automobile speeding down a highway, or even near a high-power TV antenna.

In the light of the preceeding points, it is interesting to re-read the kinds of inferences Klass attempts to draw: He asks (reference 18, p. 153) if it is "merely coincidence" that "both air pollution and UFOs have experienced a dramatic increase within the past two decades," and then goes on in a similar vein. "Is it also merely a coincidence that many low-altitude UFOs are seen near highways, where growing number of autos spew their pollution products? And is it coincidence again that many of the high-altitude UFOs are reported by pilots while flying along well-travelled airways, where aircraft also leave a trail of combustion-engine pollution in their wake?"

Other Misconstrued Laboratory Experiments

Although it is the Brookhaven experiments that Klass misuses most extensively in his book, three other experiments are discussed in a manner purporting to provide support for his plasma-UFO hypothesis. Because in each instance Klass fails to recognize quantitative factors that render the laboratory results irrelevant to the case he is trying to make, brief comments on all three seem in order.

First, he cites some demonstration experiments devised by A. F. Jenzano, director of Morehead Planetarium in North Carolina, and displays photos in support of the contention that erratically moving cigarand disc-shaped UFOs may result from open-air counterparts of the planetarium experiments (reference 18, p. 68 and plate 3b; also reference 17, p. 57 and 61). But when one reads the nature of the experiments in question, they prove to be low-pressure glow discharges carried out under pressure conditions and with externally varying capacitance quite unrelated to anything involved in UFO sightings. To make his point, Klass would have to show that something resembling the electric field strengths and near-vacuum gas pressures used in these demonstrations occurs at times of UFO sightings in the atmosphere; but such confrontation with relevant quantitative considerations is absent here, as elsewhere in Klass' treatment. Jenzano is quoted as saying he uses the device to simulate the Northern Lights; this is rather more reasonable. But UFOs and the aurora are certainly two quite different matters.

Secondly, Klass cites (reference 18, p. 132) laboratory work of W. H. Bostick on small moving plasmoids. Klass quotes Bostick as saying "the plasma travels not as an amorphous blob, but as a structure (called a plasmoid) whose form is determined by the magnetic field it carries along with itself." He also quotes a passage that may seem to some readers to still further support the Klass plasma hypothesis for UFOs: "The two plasmoids seemed to seek each other out unerringly and attach themselves to each other." The implication is that Bostick's work has some bearing on the UFO problem. However, on consulting the original papers (e.g., reference 33), one finds that to get the ob- served phenomena Bostick worked at gas pressures of 10^-5 mm HG (about a hundred-millionth of an atmosphere), except when the pressure was raised to that of a "poor vacuum (10^-3 mm HG) in order to slow the plasmoid down." And about equally remote from any conditions prevailing in situations where UFOs have been reported, Bostick used externally applied DC magnetic fields ranging from 500 to 2000 Gaus. The geomagnetic field has a strength of a few tenths of a Gauss. Despite Klass' intimations, the Bostick laboratory experiments bear no relation to the problem of explaining UFOs, their sometimes startling fast movements, and their sometimes high luminosity.

Thirdly, Klass recounts (reference 18, p. 284) some lab experiments which the press featured as possibly explaining UFOs. Workers as Melpar, Inc., reportedly obtained luminous emissions from a mixture of ammonia and oxygen after spark-ignition (reference 34, p. 16). Neither cited account permits a reader to decide wether this was some slow combustion process or perhaps chemiluminescence. Klass states that, on triggering the Process with the spark, "a glowing saucer-shaped object would form, providing the mixture had the right proportions ... Sometimes the glowing objects would hover horizontally; at other times, the tiny UFO would pulsate mysteriously and flip over onto its rim or turn upside down." Interesting, from a scientific point of view; but what can this have to do with the UFO problem? Klass answers that question: "The ammonia gas that Melpar used in its experiments could be found over newly fertilized farmlands, another possible reason why UFOs are more frequently seen in rural areas." Here is one more good illustration of omitting highly relevant quantitative considerations.

The Melpar experiment is not described in terms one would require in order to make precise statements; but it seems clear that partial pressure of NH3 in their reaction vessel is a fair fraction of the atmosphere. Lacking data on maximum NH3 concentrations over farm barnyards, I will appeal to the fact that public health officials seem never to have expressed concern over the safety of farmers exposed to hazardous concentration of that gas, so that barnyeard concentrations presumable fall well under the 100 ppm "maximum allowable concentration" set as the industrial safe limit (reference 29, p. 24). This would be three to four orders of magnitude below the partial pressures likely to be involved in the Melpar demonstration. Not only would reaction rates be slowed down by something like 3-4 orders of magnitude by virtue of that adverse concentration ratio, but it seems entirely out of the question that it could be self-sustaining in such concentrations, even if there were a spark-source near every barnyard to provide the requisite ignition. Actually, it seems so unreasonable to suggest that farm concentrations of NH3 could yield effects comparable to those obtained in the Melpar laboratory demonstration that the proper reaction would seem to be astonishment that any such suggestion should have been made in the first place.

Argumentation by Concatenation-Thunderstorms, Dust Devils, and Ball Lightning

Throughout his book, Klass uses a very curious type of argumentation. Noting that there exists some vague relation between concept A and concept B, he next passes on to observe another remote relation between B and C. Then C may have something or other in common with D, and Klass is soon asserting that A and D are related. Put in that abstract form, the only criticism that could be made is that stringing such claims may be dangerous. But seen in the form of particular instances, Klass' use of this mode of deduction appears almost ludicrous. A good illustration has already been cited, that concerning the chain of steps by which Klass went from the diurnal variation of potential gradient as land stations to a conclusion that his bears on the diurnal variation of UFO reports, via pollutants and inversions and radon gas.

Another example of this non-scientific mode of argument leads him to the following conclusion (reference 18, p. 113): "The dust devil and the kugelblitz (ball lightning), which a few weeks earlier had seemed poles apart, now were beginning to show signs of a possible family tie, at least on some occasions. Nature, I was beginning to realize, offers an even wider range of explanations for UFOs than I had first imagined."

Let's trace back through the concatenation of remarks that led to that statement.

He gets into it by attempts to explain the many daytime sightings in which UFO witnesses have asserted that the object looked metallic. This, Klass feels, can be understood if the UFOs are flowing plasmas (p. 108). Briefly, the observer is fooled into thinking that the self-glow is "metallic reflection" of sunlight. Leaving asside objections to that conclusion, we next find (p. 109) that he is bothered by a UFO sighting in which "dark crescents" were seen on an otherwise white or silvery UFO; so Klass asks himself what might render a plasma-UFO dark in spots. "The most obvious answer popped into my mind: dust particles."

Next he cites a model of ball lightning due to E. L. Hill, in which it had been suggested that ball lightning might consist of "electrically charged dust particles and groups of molecules which somehow are electrically separated into positively and negatively charged clusters by the action of a lightning stroke," a model which most students of the ball lightning problem would regard as unpromising. But that model has dust and it has spin, and that's the direction of chain that Klass is stringing out.

By way of seeming to confirm the notion that dust may be involved in the UFO phenomena, Klass then cites (p. 111) a UFO sighting in which beams of light from the UFO's eight large "windows" were described as shining so brightly that air-dus could be seen in the beams. (See reference 3, p. 69 for the complete account that is very abbreviated in the summary given by Klass. This sighting was made by a minister and his wife in Cleveland in the early evening of Nov. 5, 1955; the object hovered for an estimated ten minutes at a height of about 500 feet and a distance of about a half mile, before it began to slowly move away and pass out of sight. Out of this all, Klass takes the point that dust was visible in the beams reportedly shining out of the apertures of some sort of the object, and builds that point into his chain. The fact that this plasma lasted ten minutes and had eight bright spots is ignored. The important point for the idea-chain is that dust was present.)

So next (p. 111), Klass ponders "swirling, charged dust particles, interacting in complex ways with charged air particles in a plasma (which could) explain the mysterious, moving, dark crescent-schaped areas" in the sighting that started the chain. This is a preparation for the next jum: "This suggested still another phenomenon that I ought to investigate - dust devils." So he then spoke with several persons who gave him information about the well-known fact that dust-devils and dust storms can disturb the fair-weather potential gradient by virtue of strong frictional electrification (reference 28, p. 122). When one of his informants remarked that dust devils are some- times formed around the outflowing cool air that spreads out from thunderstorm downdrafts in summer storms over the arid Southwest, the last link in the chain was forged. Klass notes, with an almost audible "ah-hah!" implicit in the italicized windup that "thunderstorms are the most frequent sources of ball lightning." That, in brief, is how Klass arrived at establishing a bond between dust devils and ball lightning, with swirling, dust-laden vortical plasmoids created out of the rethorical exercise.

The term "vortex" is one Klass likes to conjure with; it comes up repeatedly throughout the book, and is woven into his model of the plasma-UFO in several ways, almost invariably without paying attention to scale-factors, as in the above case of dust-devils and ball lightning. One sees that same casual neglect of disparate scale factors, the same word-play in a later discussion where concatenative argumentation takes Klass from tornadoes to spinning UFOs. At one intermediate step of that particular chain (reference 18, p. 157), he begins a paragraph speaking about tornadoes in the ordinary sense of the word, and shifts to an idea proposed by one investigator of the radar-angel problem, namely, that some angels are small airborne vortices, which that investigator dubbed "micro-tornadoes." Because Klass has elsewhere (p. 89) intimated that probably angels are often caused by plasma-UFOs (thus clearing up many cases where UFOs were tracked on radar), one comes out of the cited paragraph on p. 157 with the impression that Klass does indeed infer that "tornadoes and at least some UFOs may be distantly related members of the same family," and evidently "micro-tornadoes" and angels are also in that family. If in approaching problems of meteorology and geophysics, scientists customarily employed that kind of logic, casually ignored important scale considerations, and rested entirely on verbal arguments almost wholly devoid of quantitative considerations, they could easily show that volcanoes are related to hurricanes and earthquakes to blizzards.

UFOs and Radar ==============

From a chapter so labeled in Klass' book, one can draw additional instances of the author's failure to understand much of what he is talking about. He remarks correctly that plasmas can be seen on radar, re-entry plasma sheaths around space capsules and satellite debris being a well-known example. From that qualitatively correct beginning, he proceeds to explain instances of UFOs seen on radar.

Citing (quite incompletely) a case from Hall (reference 3, p. 85) in which an unknown object whose radar return suggested it was as big as "any of our larger transport planes," was followed for over 30 minutes from an East coast USAF radar installation, Klass proceeds to the conclusion that this was just a plasma. The important item of information concerning duration of the radar sighting was omitted by Klass; it was a clear moonlit night in the fall, and plasmoids lasting 30 minutes are rather difficult to explain. The radar tar- get was described as moving, then stopping and remaining fixed (for the 30- minute period). An Air Force C-124 transport that came into the radar-coverage area was vectored towards the unknown. Both blips remained on the scope until the C-124 came to within a distance that the radar operator estimated at about a half-mile from the unknown, at which juncture the unknown suddenly disappeared from the scope.

Klass explains the fact that the C-124 crew could not see the plasma as due to its being "on its last legs," so that "it did not have sufficient energy to be luminous and thus was not visible." its sudden disappearance from the radar scope Klass seems as having resulted from the fact that "the proximity of the large metal aircraft hastened the plasma's demise, serving to drain off its residual energy in much the same way that a lightning rod attracts a lightning stroke."

This kind of easy argumentation makes it possible to assert that casually that a plasma too weak to yield a visible glow is at so high an electrical potential relative to an ungrounded aircraft that it sends out a stroke over the half-mile gap separating it from the aircraft. And it permits Klass to ignore all considerations of rcombination-times as he glosses over the 30+ minutes' duration of the reported radar sighting. Considering sighting returns on radar gives a much fairer comparison than the plasma-sheated re- entry vehicles. The latter draw steadily upon the kinetic energy of the entering object to maintain the plasma against recombinative losses. In lightning strokes, howeverm no such "steady" energy source is available. The result is that spotting lightning strokes on radar is rather rare (though definitely well-know) occurence. Why? Because to get a discernible radar return demands that the electron concentration in the lightning channel shall imply a "plasma frequency" greater than the radar frequency. For the frequencies employed in conventional radar practice, the requisite electron concentration runs from about 10^10 to 10^12 electrons/cm^3. But recombination processes go on at rates that rise very rapidly (roughly as the square) with increasing free electron concentration, so that lightning channels quickly quench out to radar-invisibility (reference 37, p. 108). Estimated durations of radar visibility of lightning run well under a second. The sweep-periods of typical search radar are so long compared with this time that the probability of seeing a lightning stroke on radar is rather low.

All the same, basic physics musy apply to any plasmoid that one hopes to see on radar. If it lacks a sustaining steady energy source (virtually all of Klass' plasmoids suffer from that deficiency), then their lifetimes relative to radar visibility must closely parallel that of lightning channels, of the order of a second or less. An unknown that gives a radar-return as intense as that of a large transport aircraft over a period exceeding 30 minutes can, therefore, be explained as a plasma only if one accounts for a continuing source of energy. Klass does not do so.

Sudden disappearance of unknowns from radar screens, following unconventional behaviorm is encountered in many UFO radar cases. Significantly, "sudden" disappearance in the sense of getting out of sight in a few seconds, is even more common among cases of visual sightings by credible observers. As has often been remarked before, anything that could move many miles in a few seconds would seem to disappear "suddenly" from all surveillance radars with sweep periods greates than a number of seconds.

Another example of misunderstanding of radar principle from the cited chapter concerns anomalous propagation effects (reference 18, p. 88-89). Klass seems to be under the misimpression that spurious returns occur with anomalous propagation only if an aircraft is flying in the vicinity to provide an airborne relecting agent. He also seems to feel that "motions and turbulence in the atmospheric layers" cause ground-returns, bounced off the Aircraft, to shift and move erratically, yielding the impression that the radar observer's vicinity "is being invaded by dozens of UFOs." This particular set of misconceptions appears suspiciously like a garbled version of Menzel's misconceptions about anomalous propagation and aircraft reflections (reference 11, p. 153- 171). The reader familiar with radar propagation physics is urged to study both of these treatments and judge for himself. A detailed recounting of Klass' version of the matter does not seem worth presenting here.

He aruges (reference 18, p. 89) that because 67 per cent of NICAP's UFO radar sightings (reference 3) fell in the months of May, July, August, September, and November, when radar "angels" prove to be most common, it follows that the NICAP radar cases "are classic radar angels," for there would have been "only 42 percent in these five months had the UFO radar cases been equally distributed throughout the year." Evidently Klass has very scant knowledge of statistical sampling theory, too. He intimates that the famous July, 1952 Washington National Airport UFO radar-visual sightings might have been plasma-UFOs, and closes with the comment that complete analysis is difficult fifteen years later. Not so. The data on that famous sighting, as I indicated earlier here, can be re-examined quite meaningfully even today, including the erroneous USAF claims that anomalous propagation and mirage effects accounted for its main features. Neither the latter, nor plasma-UFOs match convincingly the events of those two famous nights in UFO history.

Klass asks, finally, why all of our surveillance radar nets never see UFOs. My reply to that is to ask why he feels so sure that they do not?

Spinning Plasmas

As noted above, Klass seems to place considerable emphasis upon rotation of his plasmoids. He notes that extensive survey og ball lightning witnesses (references 21, 22) find that from a fourth to a third of the ball lightning reports involve mention of a noticeable spinning motion. His arguments about dust devild, tornadoes, and micro-tornadoes, plus other similar arguments dispose him to view that UFO-plasmas will often (perhaps usually) be spinning.

On page 160, he accepts a qualitative suggestion that rotation of a doughnut-shaped plasmoid might store enough energy as rotational kinetic energy to account for its characteristics. But suppose we hope thereby to extract lumi- nous energy at the modest rate of 100 watts for the reasonable time of 10 seconds, i.e., we ask for 10^10 ergs. The result is a spin rate of about 1000 rev/sec. Clearly, no human eye could discern angular motions at so extremely high a speed. Angular motions do not constitute a particularly attractive storage mode for energy of plasmoids.

Klass turns to an experiment by Vonnegut, Moore and Harris (reference 38) which, to fill his needs, he identifies as one relating to vortex motion of the outer shell of a plasma. On reading the original paper, one finds that it is only very distantly related to Klass' idea of plasma-UFOs, for it actually concerns the favorable effects of a vortex on maintenance of an arc discharge struck along the axis of air rotation. The inward-directed buoyancy-forces, the author note, convectively force the hot arc gases into the center of the vortex, reducing sinuous excursions of the arc and permitting an arc to exist stably over arc -- spacings about twice the spacings attainable without the vortex. Clearly the vortical effects employed here bear stability of the high-temperature gasses in an arc discharge, but have no obvious bearing on stability of ball lightning or UFOs, since no one believes that arc discharge is involved in either of those phenomena. One more instance wherein Klass either fails to understand what he is talking about or else crowds it into his mold, probably the former.

The just-cited section of the book is followed by another curiosity. Klass suggest next that "this same vortex motion also helps to explain some of the weird movements reported both for ball lightning and UFOs, such as their right-angle turns, because it would make them behave like gyroscopes (reference 18, p. 161)." He next remarks that a spinning gyro "does not move in the direction of the push" that one applies to it, "instead, its gyroscopic properties cause it to move at right-angles to the direction of the push." He then suggests that "if a plasma-UFO is spinning at moderately high speed when it comes near a metal object or a source of electromagnetic fields, the elec- trical interaction in combination with its gyroscopic properties could cause it to move at right angles to the direction of its previous motion, as is frequently reported."

Here, as before, Klass gets demerits for ignorance of undergraduate physics. It is torques, not gross body forces, which produce the notoriously perverse reactions of gyros. A fast-spinning gyro acted upon by an external force moves in entirely direct response thereto, and not at 90 degrees to that force, as Klass evidently assumes.

Plasmas as Nature's Rorschach Blots

To meet the objection that many witnesses have reported seeing machine-like UFOs, sometimes with ports, domes, leg-like structures, etc., Klass offers the proposal that a plasma would act like a Rorschach ink blot (reference 18, p. 77). Without wishing to become embroiled in arguments of primarily psychological nature, I would object that projective tests of the Rorschach type do not function by virtue of the illusory mechanism Klass adduces. Normal persons arrive at their Rorschach answers by dint of requested interpretation of the unstructured blots displayed before them. To suggest, as Klass does, that light and dark areas on his alleged plasmoids are illusorily converted by observers into fanciful ports and domes is to introduce something well beyond Rorschach factors.

I cite this because it is the closest Klass seems to come to confronting the very important point that, in many highly credible UFO reports, structured and craft-like objects are described in terms that fail to square with an amorphous blob of glowing plasma. I would suggest that his Rorschach idea be dropped as unreasonable. The best observations of machine-like UFOs are daylight observations where no glow is even involved, so the Rorschach-plasma idea seems to fail completely. See, for example, the Powell sighting of May 21, 1966 (reference 8) for a single example which Klass has heard directly from the witnesses, at the same time that I did. An 18,000-hour pilot, with a second witness, saw a domed disc pass his light plane at an estimated distance of a hundred yards in midday, whith excellent visibility. it was opaque, and was described as having quite distinct edges and a sharply contrasting white dome over red disc.

Mesmeric Properties of Plasma-UFOs

Not only does Klass propose that his plasma-UFOs are Rorschach blots, but also he intimates (reference 18, p. 227) that perhaps they have a "hypnotic effect on some observers, especially if the UFO were seen at close quarters in darkness." Commenting on use of lights in cincentrating a subject's attention in hypnotic experiments, he notes that "the plasma-UFOs, with its intense glow, its flashing pockets of color, and its changing shape, certainly would focuss the observer's attention. This could deprive his brain of its normal contact with the outside world, especially for night sightings when the object is in a remote spot."

There is one very striking similarity between Klass' plasma-UFOs and Menzel's meteorological-optical phenomena; both are stretched to cover a most astonishing range of UFO events. The stretching and straining of scientific principles found in their writings on UFOs is parallelled in the crackpot literature on UFOs. Indeed, if some of the unreasonable argumentation which they employ were found in something by, say George Adamski, it would be regarded as scientifically hilarious. As it is, such warping of familiar scientific principles seems only depressing.

Interference of Non-Coherent Light Sources

Another bothersome example of failure to understand rather elementary physical principles is to be found in Klass' discussion of a sighting in which a chemist, having the presence of mind to try viewing a UFO through his Polaroid glasses, discerned a series of concentric light and dark rings around the airborne UFO (reference 18, p. 99). Klass, ignoring the basic requirement of having coherent light sources if one is to generate interference effects, offers the suggestion that interference between polarized sky light and the light being emitted by the object caused the light and dark circles reportedly seen by Webb, the chemist. Not realizing that his argument was already lost, Klass continues to suggest that the reason that the light from the UFO was polarized was that the motions of charges in the plasma that it really was generated magnetic fields that caused the polarization of the emitted light that then interfered with sky light when viewed through the chemist's Polaroid sunglasses. With an argument like that, one might hope to show that the moon is a plasmoid.

Cold Plasmas of Ice Crystals

Perhaps the most bothersome general feature of Klass' book is the way it repeatedly tends to carry the unwary through what may appear to be reasonable deductions, but which involve large leaps of unustified nature when you examine them closely.

A good example concerns his discussion of "cold plasmas" (reference 18, pp. 114-115). let me quote his conclusion first, and then go back over the arguments that purportedly support it. "One thing that was emerging as absolutely certain. Nature has a surprisingly large bag of atmospheric electrical tricks with which it can create unusual "flying objects." Working backwards, one sees some intermediate remarks about "cold plasmas" of charged ice crystals, and working still further back one arrives at a reference to a short note by Vonnegut in the October, 1955 issue of Weather. Reading Klass' version of it, one gets the impression that electrical discharges in thunderclouds can so alter electrical forces on charged ice crystals as to make them change attitude relative to the sun that marked reflectivity or transmissivity of the cloud could result, and that this "would cause the ice cloud to appear solid (because no sunlight passes through) and could even give a silhouette effect." Then, in a non sequitur he adds that "the raw materials for such a phenomenon, beyond those provided by nature, could come from the growing numbers of high-altitude jet aircraft," and seems to intimate that the charges are to come from jet turbine blades!

Returning to the foundation on which the above series of steps rests, let see just what Vonnegut actually reported in the cited note. What he reported was a pilot observation of a bright band that propagated across the top of a thunderhead, a ground observation of a bright streamer of cloud that built up slowly and then disappeared suddenly at the moment oflightning discharge within the thunderstorm, and finally, some field observations by Vonnegut on brightness changes (amounting to a mere few tenths of a per cent) of thunderclouds at instant of lightning discharge within the cloud (as detected by radio-frequency noise gear). What in all of this remotely suggests UFOs to Klass? One could start talking about a very large variety of cloud-physical effects of unusual nature and remain equally far from the area of UFOs. Yet after juxtaposing the foregoing, Klass leaves his reader with the conclusion that "Nature has a surprisingly large bag of atmospheric electrical tricks with which it can create unusual "flying objects." What flying objects?

In earlier discussion of Vonnegut's note (reference 17), Klass went even farther from such slim supporting evidence. Introducing without any atmospheric-physical basis the notion of a "vortex of ice crystals," he merges it with Vonnegut's idea of electrical orientation effects as follows: "If the angle of incidence of sunlight playing on a vortex of ice crystals aligned by electrical fields were such that reflected light was directed away from an observerm it could conceivablt produce a silhouette effects ... and if the airborne vortex contains charged dust particles, similarly aligned by electric fields, a very pronounced silhouette could result. If electric discharge is taking place within the vortex between charged dust particles, as has been suggested by some ball lightning theories, it could easily create the illusion of a solid spacecraft with small lighted windows." All of this suggests the conclusion that if someone sets out to create UFOs out of almost thin air, he can do so.

Mirror Images and the Car-Stopping Problem

Klass evidently accepts, as I do, the reality of a puzzling number of instances where observers have reported engine and headlight failure coincident with a close passage of a UFO (reference 18, p. 96). Klass suggests that "because a plasma contains a cloud of electrified particles, there is no doubt that if an auto battery were enveloped by such a plasma, the battery could be short-circuited. But is is difficult to explain how a UFO-plasma could gain entry to the car battery in the engine compartment without first dissipating its energy to the metal body of the car."

However, he then comes up with an extremely curious suggestion that may be some measure of the scientific level of Klass' analyses. He needs to have his plasma ions inside the hood to short the battery. So he remarks that "an electrical charge in the vicinity of a conducting surface, such as a car's hood, creates a mirror image of itself on the opposite side of the conducting surface." Quite clearly, Klass is under the impression that "image charges" are real charges, and that the "image charge" induced on the inside of the hooded engine compartment can short-circuit the battery and cause other real effects. This is a puzzlingly erroneous misconception to be held by an electrical engineer.

Aeronautical engineers can appreciate the parallel to another closely similar situation where boundary-conditions can be handled by a similar ruse: the use of "image objects" in flow problems near solid, plane boundaries. For instance, the enhanced lift that accounts for the familiar flare-out as an aircraft comes down to within a few feet of an airstrip can be treated, mathematically, in terms of an identical aircraft imagined to be upside down and moving along at a distance below the real aircraft's true distance above the groundplane. In fact, wind-tunnel tests of flow problems near the ground-plane are actually conducted with real model-pairs mounted in this mirror-image attitude. To suggest that a real automobile battery could be shorted out by image charges induced in the hood is comparable, then, to suggesting that flare-out on landing results from the fact that a real aircraft is actually flying upside down, just underneath the airstrip.

Summary-Critique of Klass' Plasma-UFO Thesis

In the foregoing sections, I have pointed out a number of serious scientific errors and misconceptions that mark Klass' writings on UFOs. Although he has diligently pursued the subject of UFOs, his handling of the scientific questions involved reveals so many misunderstandings, often of elementary principles, that his principal thesis (that a substantial portion of the UFO cases can be explained by plasmas) cannot be regarded as supported.

It is important to note that Klass does not claim that all UFOs are plasmoids (reference 18, p. 282); he feels that meteors, balloons, optical phenomena, planets, and other misidentified phenomena account for many UFO reports. He does indicate, however, tht he feels he has "identified most if not all of the previously unexplained UFOs as atmospheric electrical phenomena, using NICAP's most convincing cases" (reference 18, p. 174). By the latter, he refers to the more than 700 cases in Hall's UFO Evidence (reference 3). Such a claim is fatuous; there are hundreds of cases that could not even be remotely reconciled with Klass' plasma-UFO hypothesis on any reasonable scientific grounds. Even considering the small sampling of those NICAP cases that are specifically cited in Klass' book, I would say that only perhaps two or three cases could even be tentatively viewed as some atmosphe- ric-electrical plasmoid phenomenon.

Klass asserts (reference 18, p. 286) that "it is time that these two influential organizations (NICAP and APRO) encouraged their members to open their minds to the possibility that UFOs may be only freak atmospheric electrical phenomena." He adds that NICAP and APRO should "more fully inform their members about the plasma theory," evidently thinking that this will lead them to accept his hypothesis. As a matter of fact, members of NICAP and APRO had weighed and rejected hypotheses similar to Klass long before he developed an interest in the UFO problem. Three communications cited in his book (reference 18, p. 55, 58, 177) from NICAP members contain more reasoned reactions to that hypothesis than one finds in all of Klass' writing.

The provocative UFO cases are low-altitude, close-range sightings of structured, machine-like objects of entirely unconventional nature, reported by witnesses of unquestionable credibility. The nearest Klass comes to confronting such cases is to suggest hypnotic effects or Rorschach-projective effects that make the witness see plasmoids as if they were structured vehicular objects with domes, panel, ports, markings, etc. Having interviewed so many witnesses who have seen such objects, I can only smile weakly at the unreasonableness of Klass' intimation that he has "identified" such UFOs as plasmoids.

Furthermore, implicit in Klass' plea that NICAP, APRO, and the rest of those whom he labels as "UFOrians" should be made "fully informed" about the plasma theory, is the tacit assumption that Klass, himself, is so informed. The many instances wherein Klass completely misconceived pertinent aspects of the plasma physics he was attempting to talk about make such a plea quite hollow. The net effects of further study of plasma theory by any UFOrians will be to make still clearer that Klass has written a book filled with sometimes ludicrous errors concerning plasma theory and related physics.

The principal points of critique of Klass' plasma-UFO theory are the following:

1. He fails to put numbers into his hypotheses where numbers are readily inserted. The result is that he presents what may appear to be plausible arguments because they contain some qualitatively plausible elements. In this regard, Klass resembles Menzel. Quantitative evaluations reveal serious difficulties, sometimes outright absurdity, in the writings of these two principal proponents of the notion that UFOs are only misidentified natural phenomena.
2. Plasmas are notoriously unstable and evanescent, except when suitably contained and provided with sustaining energy sources. Klass appears to be almost unaware of these prime characteristics of plasmas, for he casually ad- duces plasma-explanations in UFO incidents for which he offers no suggestion as to what provides the continuing energy sources of his plasmas, often over periods that run into the tens of minutes.
3. In the one or two instances where Klass does actually propose something resembling an energy source (powering corona, TV antennas, aircraft charge- leakage), it has been shown above that there are fatal difficulties with his position.
4. Through a quite astonishing series of minsunderstandings, Klass builds up a thesis to the effect that air pollutants are favorable to plasma-formation, amd from this, makes repeated deductions of exorbitant nature, such as greater incidence of high-altitude UFOs because of more jets polluting the airways.
5. Through failure to understand elemtary principles of atmospheric electricity, he builds an error-chain extending from diurnal variation of atmospheric electrical potential gradient to diurnal variation of UFOs, and deduces therefrom an "explanation" of excess of rural over urban sightings. For someone claiming to have uncovered an intriguing new phenomenon of atmospheric electricity, Klass' ignorance of fundamentals of that subject seems startling.
6. His claim to have accounted for the high frequency with which pilots observe UFOs following aircraft falls apart completely on subjecting the idea to quantitative assessment. His related intimations that charged automobiles and charged pedestrians also attract plasma-UFOs are absurd. It is to be stressed that the quantitative evaluation of that hypothesis involves only elementary physics and, say electrical engineering, yet no such evaluation was made by Klass. Also, he overlooks dozens of well-reported cases wherein UFO maneuvers would defy explanation in terms of his Coulomb-attraction hypothesis.
7. It seems entirely fair to suggest that part of the reason for the credence and attention given Klass' plasma-UFO hypothesis in the press and non-scientific journals rests on his being an electrical engineer as well as having a senoir editorial position within a well-known aviation-aerospace magazine. In this light, his almost incredible misconceptions about "mirror-image charges" in connection with UFO car-stopping, and the instance where he was clearly confusing voltage and voltage gradient, both deserve the emphasis of critique.
8. Finally, the most pervasively disturbing feature of Klass' book is the frequency with which it relies on argument by innuendo, argument by concatenation, argument by juxtaposition -- that is, his specious assembly of what to many an unwary reader will look like a clever series of related deductions, carried out in detective-story atmosphere. After giving that annoying feature of his writing a good deal of thought, and after reflecting on the high frequency of scientific errors, it is my guess that these arguments are probably not deviously contrived to fool the reader, but constitute reflection on the lack of preparation of the author.

The reason that they need exposure, however, is that at the present time, the UFO problem is not yet being fought-out in the usual context of serious scientific discussion. The present major difficulty still remains that of convincing a large number of persons (in the scientific community, in federal science-related agencies, in Congress, and in the general public) that the UFO problem is an extremely serious scientific problem. For this reason, the kind of easy acceptance already given to Klass in the press cannot be viewed as unimportant. Menzel's role in helping to foster the impression (for many years now) that UFOs are all explainable in quite conventional terms has had very deleterious influence on the UFO problem. Klass will now join Menzel in extending that influence if the serious deficiencies of his thesis are not held up to careful scrutiny. It is for this reason that I have devoted so much space here to what ought perhaps to be regarded as so unscientific an exposition as to need no comment.

Summary and Conclusion

Returning now to more positive considerations, let me stress that my own studies of the UFO problem have forced me to the conclusion that it is an international scientific problem of potentially enormous importance.

In my view, the hypothesis of an extraterrestrial origin for UFOs appears, via argument by elimination of many alternative hypotheses, to be the most satisfactory hypothesis to account for the impressive body of observational evidence that has accumalated over the past two decades of UFO sightings. If there is admitted to be even a very slim possibility that UFOs are extraterrestrial surveillance devices of some type, then it should be obvious that a very energetic scientific investigation of that possibility ought to be launched.

Instead, to date, world scientific opinion still leans predominantly in the direction that UFOs constitute a nonsense problem, a bothersome host of reports of misidentified natural phenomena. One finds that the spokesmen who most strongly emphasize that view are (with almost no exceptions) quite uninformed as to the real nature of the UFO evidence. Ridicule and official mishandling of the problem have kept the true nature of the UFO evidence well out of sight. As one American writer recently quipped, "The Air Force is not telling the American public the truth about UFOs."

Investigators in countries other than the U.S. may have a superior opportunity to make progress towards clarification of the UFO problem because they will not be working against the long-standing prejudices so visible in official U.S. handling of the subject. New, independent, vigorous UFO investigatory programs are sorely needed to delve vigorously and imagineatively into the fascinating and potentially world-shaking problem of the UFOs.

UFOs are the greatest international scientific problem of our times.