RR0/rr0.org

<!--#include virtual="/header-start.html" -->
<title>Déclaration du Dr. Carl Sagan</title>
<link href="." rel="start" title="Symposium sur les Objets Volants Non Identifiés">
<link href="contents_fr.html" rel="contents" title="Sommaire">
<meta content="https://www.project1947.com/shg/symposium/sagan.html" name="url"/>
<!--#include virtual="/header-end.html" -->
<ol>
  <li><a href="#biog">Biographie</a></li>
  <li><a href="#stmt0">Déclaration orale</a></li>
  <li><a href="#artcl">Article Read into the Record</a></li>
  <li><a href="#questions">Questions des Membres du Comité</a></li>
</ol>
<p>(Suit la biographie du Dr. <span class="people" title="Carl Sagan">Sagan</span>: ) </p>
<h2><a id="biog"></a>Dr Carl Sagan</h2>
<p>
  Le Dr. <span class="people">Carl Sagan</span> est Professeur Adjoint en Astronomie au Centre de Radiophysique et de
  Recheche Spatiale de l'Université de Cornell, Ithaca, New York. Il a obtenu ses A. B. et B.S., une M. S. en Physique
  et son Ph. D. en Astronomie et Astrophysique, tous de l'Université de Chicago. Il a depuis tenu des positions à
  l'Université de Californie, Berkeley; à l'Ecole Médicale de l'Université de Stanford (en tant que Professeur Adjoint
  de Génétique); et à l'Université d'Harvard et à l'Observatoire Astrophysique Smithsonian. </p>
<p>
  Les principaux intérêts de recherche du Dr. Sagan sont sur la physique et la chimie des atmosphères et surfaces
  planétaires, l'origine de la vie sur Terre, et l'exobiologie. Il a joué un rôle primordial en établissant, par
  exemple, que la surface de <a href="/place/systeme/solaire/planete/venus">Vénus</a> est très chaude et que des grandes
  différences d'altitude existent sur <a href="/place/systeme/solaire/planete/mars/index.html">Mars</a>, et a été un
  principal exponent of the view that organic molecules are to be found on Jupiter. </p>
<p>
  Dr. <span class="people">Sagan</span> a servi dans de nombreux groupes de conseil de l'<a href="/org/us/nasa">Administration
  Nationale de l'Espace et de l'Aéronautique</a> et de l'<a href="/org/us/NAS.html">Académie Nationale des Sciences</a>,
  ainsi que des organisations internationales telles que le COSPAR et l'<em>International Astronomical Union</em>. Il a
  été membre du Comité visant à réexaminer le <a href="/org/us/dod/af/amc/atic/projet/bluebook">Projet Blue Book</a>
  pour le <a href="/org/us/dod/af/AFSAB.html">Comité de Conseil Scientifique de l'Armée de l'Air</a>. </p>
<p>
  Lauréat du Prix Smith à Harvard en <a href="../../../../4/index.html">1964</a> et Condon Lecturer dans l'Etat de
  l'Oregon en <a href="../../../index.html">1968</a>, le Dr. <span class="people">Sagan</span> is shortly to assume
  additional duties as Editor of the planetary sciences journal, ICARUS. He has been active in educational innovations,
  regularly teaches in the South, and is a lecturer in the astronaut training program in Houston.</p>
<p>
  En plus de bien plus d'une centaine d'articles scientifiques, et plusieurs articles écrits pour les <em>Encyclopedias
  Britannica</em> et <em>Americana</em>, le Dr. <span class="people">Sagan</span> est co-auteur de <em>The Atmospheres
  of Mars and Venus</em> (1961), <em>Planets</em> (1966) et <em>Intelligent Life in the Universe</em> (1966).</p>
<h2><a id="stmt0"></a>Déclaration du Dr Carl Sagan, Département d'Astronomie de l'Université de Cornell à Ithaca (New
  York)
</h2>
<p>
  <b>Dr. <span class="people">Sagan</span></b>. Merci beaucoup, Congressman Roush.

</p>
<p>
  Tel que je le comprends ce que le comité voudrait de moi, c'est une discussion sur la probabilité de vie
  extraterrestre intelligente, et since this estimate is to be made in this symposium, clearly it is the hypothesis that
  unidentified objects are of extraterrestrial origin which the committee must have in mind.

</p>
<p>
  I'm delighted to tell about contemporary scientific thinking along these lines, but let me begin by saying that I do
  not think the evidence is at all persuasive, that UFO's are of intelligent extraterrestrial origin, nor do I think the
  evidence is convincing that no UFO's are of intelligent extraterrestrial origin.

</p><p>
  I think as each of the preceding speakers has mentioned, but perhaps not sufficiently emphasized, that the question is
  very much an open one, and it is certainly too soon to harden attitudes and make any permanent contentions on the
  subject.

</p><p>
  I find that the discussion, like elsewhere, is best evaluated if we consider the question of life on earth. I suppose
  that if you had all your prejudices removed and were concerned with the question of whether the earth was populated by
  life of any sort, how would you go about finding out?

</p><p>
  If, for example, we were on some other planet, let's say Mars, and looking at the Earth, what would we see?
  Fortunately we now have meteorological satellite photographs of the earth at various resolutions, so we can answer the
  question. The first large slide.

</p><p>
  This is a photograph of the earth. That is the full earth, which you are looking at which is primarily cloud cover.
  This is the Pacific Ocean. You can see southern California in the upper right, and, as advertised by the local chamber
  of commerce, you can see it is cloud free. [Laughter.]

</p><p>
  <b>Dr. </b><b><span class="people">Sagan</span></b>. Now, it is clear that very little information about the earth,
  much less possibility of life on it, is obtained by a picture at this resolution.

</p>
<p>
  The next large slide is a TIROS photograph of the earth at about 1-mile resolution, that is, things smaller than a
  mile cannot be seen, and very prolonged scrutiny of the entire eastern seaboard of the United States shows no sign of
  life, intelligent, or otherwise.

</p><p>
  We have looked at several thousand photographs of the earth, and you may be interested to see that there is no sign of
  life, not only in New York or Washington, but also in Peking, Moscow, London, Paris, and so on.

</p><p>
  The reason is that human beings have transformed the earth at this kind of scale very little, and therefore the
  artifacts of human intelligence are just not detectable photographically in the daytime with this sort of resolution.

</p>
<p>
  The next slide shows one of the few successful finds of intelligent life on earth that we made; down toward the lower
  left you can see a kind of grid, a kind of crisscross pattern, a rectangular area. This is a photograph taken near
  Cochran, Ontario, in Canada. What we are looking at are swaths cut by loggers through the forest. They cut many swaths
  in parallel, then another parallel sequence of swaths at right angles. Then the snow fell, heightening contrast, so
  that is the reason for the tic-tac-toe pattern. The sequence of straight lines there is anomalous. You would not
  expect it by geological processes. If you found that on another planet you would begin to expect there is life there.
  This is a photograph at about a tenth of a mile resolution, and is far better than the best photographs we have of
  Mars. The photographs we have of Mars are, of course, better than of any other planet. Therefore, to exclude
  intelligent life on another planet photographically is certainly premature. We could not exclude life on earth with
  this same sort of resolution.</p>
<p>
  However, there are other reasons why intelligent life on the other planets of this solar system are moderately
  unlikely.

</p><p>
  To continue this sequence of photographs, I should say there are only about one in a thousand photographs where this
  resolution of the earth gives any sign of life.

</p><p>
  The next photograph, however, shows a resolution about three times better. That is a Gemini capsule in the lower
  left-hand corner and we are looking at the vicinity of the Imperial Valley in California. You are just on the verge of
  resolving the contour patterns of fields, for agricultural purposes.

</p><p>
  The next slide shows us an area between Sacramento and San Francisco, which has a very clear geometric pattern. It is
  quite obvious that this is the result of some intelligent activity on the earth.

</p><p>
  You can see an airport, a railway, the monotonous pattern of housing developments in the upper right. You can see the
  patterns of contour fields. And this is such a highly geometrized picture, that it is clearly the result of some
  intelligence.

</p><p>
  However, a photograph taken of this same area, only let's say 100,000 years ago, when there certainly was lots of life
  on earth, would show none of these features, because these are all the signs of our present technical civilization.

</p><p>
  So even though the earth was full of life, and human beings were very much in evidence 100,000 years ago, none of this
  would be detectable by such photography. To detect individual organisms on earth, we have to have a photographic
  resolution about 10 times better than this, then we occasionally see things like these in the next slide. All those
  little dots casting shadows are cows in a field in California.

</p><p>
  There are other ways of detecting intelligent life on the earth. From the vantage point of Mars, detecting, say, the
  lights of cities at night, is extremely marginal, and in fact the only way of doing it would be to point a small radio
  telescope at the earth, and then as the North American Continent turned toward Mars, there would be this blast of
  radio emission from domestic television transmission that prolonged scrutiny would indicate some sign of intelligent
  life on the earth.

</p>
<p>
  In fact, it is radio communications which is the only reasonable method of communications over very large distances.
  It is a remarkable fact that the largest radio telescope on the earth at the present time, the Arecibo dish in Puerto
  Rico, is capable of communicating with another dish, similarly outfitted if one existed at the incredible distance of
  1,000 light years away, a light year being about 6.6 trillion miles, and the distance to the nearest star being a
  little over 4 light years.</p>
<p>
  Now, let me then go to the question of the cosmic perspective of where we are.

</p><p>
  We are, of course, sitting on a planet, the third from the Sun, which is going around the Sun, which is a star-like,
  and the other stars visible on a clear night to the naked eye.

</p><p>
  The first small slide will give an impression of what happens when you point a moderate telescope in the direction of
  the center of the Milky Way Galaxy.

</p><p>
  This is a photograph of a star cloud. You are looking at tens of thousands of suns here. In fact, the number of suns
  in our galaxy is about 150,000 million.

</p><p>
  They are collected into a disk-shaped pattern, shown in the next slide; the next slide will show a photograph of the
  nearest galaxy like our own. That fuzzy spiral thing in the middle is M-31, that is also known as the Great Galaxy
  Andromeda, and if that were a photograph of our galaxy, we would be situated extremely far out, in fact, a little far
  off the slide, very much in the galactic boon docks. The Sun is nowhere near the center of the galaxy. It is a very
  out-of-the-way rural location we happen to be in.

</p><p>
  Now, in [the] collection of 150,000 million stars in the Milky Way Galaxy, our sun is just one, and there are at least
  billions of other galaxies, and the last slide, will show you what happens if you point a telescope away from the
  obscuring dust and stars in the galaxy. You then start seeing dozens of other galaxies, everyone of those funny-shaped
  spiral and irregular-shaped things there, and some of the spherical-shaped ones, are other galaxies, each of which are
  containing about 100 billion stars as well.

</p><p>
  So it is clear that there are in the accessible universe, some hundreds of billions of billions of stars, all more or
  less like our own.

</p><p>
  Now, if we want to assess the likelihood that there are intelligent civilizations somewhere in advance of our own, on
  planets of other stars in our own galaxy, we have to ask questions which cover a variety of scientific subjects, some
  of which are fairly well known, some of which are extremely poorly known. For a numerical assessment of whether there
  is likely intelligence in other parts of the galaxy in a form we do not have at present, let me indicate the kinds of
  things we know. It depends on the rate of star formation.

</p>
<p>
  It depends on the likelihood that the given star has planets. It depends on the likelihood at least one of those
  planets is at a position from the essential star which is suitable for the origin of life. It depends on the
  likelihood that the origin of life actually occurs on that planet. It depends on the probability life once arisen on
  that planet will evolve to some intelligence. It depends on the likelihood that intelligence, once emerged, will
  develop a technical civilization. And it depends on the lifetime of the technical civilization, because technical
  civilization of a very short lifetime, will result in very few technical civilizations being around at any given time.
  We know something about some of these. There is some reason to believe that planets are a reasonable likely
  accompaniment of star formation, that the solar system in other words is a fairly common event in the galaxy and is
  not unique. There are laboratory experiments on the origin of life, in which the early conditions on earth have been
  duplicated in the laboratory. It turns out that at least the molecules fundamental to living systems, are produced
  relatively easy [sic], physics and chemistry apparently made in such a way that the origin of life may be a likely
  event.</p>
<p>
  Beyond that it is difficult to do laboratory experiments, because evolution takes billions of years, and scientists
  aren't that patient. Therefore, it is just a question of intelligent and knowledgeable estimates.

</p><p>
  Here, some scientists believe that the evolution of intelligence and technical civilization is very likely. Others
  believe it is a very remarkable and unusual event and by the merest fluke did it happen here.

</p><p>
  I don't think that this is the place to go into this very difficult question in any great detail. Let me merely say
  that much more important than these uncertainties is the question of the life of a technical civilization, judging
  from the events on the earth, one might say the likelihood of our civilization lasting only a few decades more, might
  be a fairly high probability, and if that is typical of other civilizations, then it is clear there aren't any other
  humans around.

</p><p>
  On the other hand, if civilizations tend to have very long lifetimes, it may be there are large numbers of technical
  civilizations in the galaxy.

</p><p>
  Now, one thing is clear, which is this: If there are other technical civilizations, any random one of them is likely
  to be vastly in advance of our own technical civilization. For example, we are only 10 or 15 years into having the
  technology of interstellar communication by radio astronomy. It is unlikely there is any other civilization in the
  galaxy that is that backward in their technical expertise.

</p><p>
  <b>Mr. Miller</b>. Doctor, didn't Sir Bernard Lovell receive electrical pulses he can't explain?

</p><p>
  <b>Dr. Sagan</b>. Yes, sir. There are now five objects in the heavens called pulsars, which are objects which are
  sending out radiation which is modulated with a frequency of about one per second; also there are sub-modulations.
  There are a variety of hypotheses to explain these things, some of which involve the oscillations of very old stars.
  There are certain difficulties with each hypothesis. The first suggestion made by the British at Cambridge, when they
  encountered this phenomenon was perhaps it was a beacon of some extraterrestrial civilization. That is not now their
  favored hypothesis. It is not clear that that is totally absurd, but in fact the scientific method to be used in that
  case is rather similar to the one to be used in this case. That is, it is a puzzling phenomenon. One therefore
  excludes all physical explanations that one possibly can before going to the much more hypothetical possibility of
  intelligence being involved.

</p><p>
  So, that is the present state of work in that field. For data gathering to get better information, and the refinement
  of the purely physical hypothesis.

</p><p>
  Well, I was saying that if there are other civilizations, many of them are likely to be far in advance of our own, and
  this, therefore, raises the question of how likely it is that they can traverse interstellar space and come from
  planets or some other star to here.</p>
<p>
  I should first emphasize that the distances between the stars are absolutely huge. Light, faster than which nothing
  can travel, takes 4½ years to get from here to the nearest star.

</p><p>
  <b>Mr Roush</b>. Excuse me, isn't that a rather arbitrary statement?

</p><p>
  <b>Dr. Sagan</b>. I don't think so. Perhaps you can tell me why you think it might be, then I can tell you why I think
  it isn't.

</p><p>
  <b>Mr. Roush</b>. In my opening statement I referred to the new audacity of imagination John Dewey had spoken of. I'm
  thinking of imaginative terms, not factual terms.

</p><p>
  <b>Dr. Sagan</b>. Let me say in a sentence, why most physicists believe no material object can travel faster than
  light. That takes us into questions of the theory of relativity, which has had previous encounters with congressional
  committees, and perhaps we don't want to go into that in very great detail.

</p><p>
  But the essential point is, that in making a few, very few assumptions, one of which was, the one we are talking
  about, nothing goes faster, Einstein was able to then derive a whole body of predictions which are confirmed in vast
  detail. Therefore, if someone says that is not a good idea, that things can travel faster than light, then they have
  to come up with a physical theory which explains everything we know in a way that is consistent with the idea that you
  can travel faster than light. No one has succeeded in doing that. Many physicists have tried. Therefore, the present
  belief is that you can't. But that, of course, is a time-dependent statement. It may be that this isn't the ultimate
  truth.

</p><p>
  In physics, as in much of all science, there are no permanent truths, There is a set of approximations, getting closer
  and closer, and people must always be ready to revise what has been in the past thought to be the absolute gospel
  truth. If I might say, to revise opinions, is one which is frequent in science, and less frequent in politics.
  [Laughter.]

</p><p>
  <b>Dr. Sagan</b>. So, in the context of contemporary science, I'm obviously speaking in that context, one cannot
  travel faster than light.

</p><p>
  So the distances between the stars are extremely large. Of course, any contemporary space vehicle would take a
  ridiculous amount of time to get from here to anywhere else, but we are not talking about contemporary space vehicles.
  The question, "Is there any conceivable method of traveling from one place to another very close to the speed of
  light, and therefore get reasonable transit times?" involves extrapolations of technology of a very difficult sort.
  However, let me merely say at least some people who have looked into the subject have concluded that it is not out of
  the question, even with contemporary principles of science, to imagine vehicles capable of traveling close to the
  speed of light, between the stars.

</p><p>
  This doesn't mean that it happens. There may in fact be insuperable engineering difficulties we don't know about, but
  there is nothing in the physics that prohibits interstellar space flight.

</p><p>
  So any estimate of how likely it is that we would be visited by an extraterrestrial intelligent civilization, depends
  not only on how many of them are there, but on what kind of transport they have, and how often they launch their space
  vehicles, even very optimistic estimates for all these numbers, gives a conclusion that an advance civilization comes
  here very rarely. But I again emphasize the great uncertainty in any of these numerical estimates, as they involve
  parts of science we don't know very much about.</p>
<p>
  So, to conclude what I understand is the main reason why this committee has asked me to testify, it is not beyond any
  question of doubt that we can be visited. There are great difficulties from our present point of view. They are not
  insuperable. And if Dr. McDonald, for example, were to present me with extremely convincing evidence of an advanced
  technology in a UFO, I could not say to him that is impossible, because I know you can't get from there to here, or I
  can't say to him that is impossible because I know there aren't any other guys up there.

</p><p>
  On the other hand, I would of course demand very firm evidence before I would say, well, that seems to be a very
  likely hypothesis. So I would like to spend Just a few minutes to come more closely to the subject of this symposium.

</p><p>
  First of all, I think it is clear to the committee, but this point should be emphasized very strongly, that there are
  very intense, predisposing, emotional factors in this subject.

</p><p>
  There are individuals who very strongly want to believe that UFO's are of intelligent extraterrestrial origin.
  Essentially to my view, for religious motives; that is, things are so bad down here, maybe somebody from up there will
  come and save us from ourselves. This takes all sorts of subtle and not so subtle forms. There are also predisposing
  emotional factors in the other direction; people who very much want to believe UFO's are not of intelligent
  extraterrestrial origins, because that would be threatening to our conception of us as being the pinnacle of creation.
  We would find it very upsetting to discover that we are not, that we are just a sort of two-bit civilization.

</p><p>
  It is clear that the scientific method says you don't take either of those views, and you simply keep an open mind and
  pursue whatever facts are at hand with as many diverse hypotheses as possible, and try to eliminate each suggested
  hypothesis, and see if you are lucky with any one.

</p><p>
  I might mention that, on this symposium, there are no individuals who strongly disbelieve in the extraterrestrial
  origin of UFO's and therefore there is a certain view, not necessarily one I strongly agree with -- but there is a
  certain view this committee is not hearing today, along those lines.

</p><p>
  Finally, let me say something about the question of priorities, which Congressman Rumsfeld asked us for, and the
  question of significance. Now, the possibility of discovering something about extraterrestrial life, life originated
  on some other planet, is of the very highest interest for biology and in fact for all science. A bona fide example of
  extraterrestrial life even in a very simple form, would revolutionize biology. It would have both practical and
  fundamental scientific benefits, which are very hard to assess, it would truly be immense.

</p><p>
  Now, if the answer to this sort of profound scientific question lies right at hand, it would be folly to ignore it. If
  we are being visited by representatives of extraterrestrial life, just stick our heads in the sand, would be a very
  bad policy, I think.

</p><p>
  On the other hand, to mount a major effort to investigate these things, I think requires some harder evidence than is
  now at hand.

</p>
<p>
  It is clear that if such an effort were mounted, some information on atmospheric physics would be forthcoming. I think
  some information on psychology would certainly be forthcoming. I have the impression that the capability of human
  populations to self-delusion, has not been accorded appropriate weight in these considerations. There is an
  interesting book published about a century ago by McKay called "Extraordinary Popular Delusions and the Madness of
  Crowds" which I commend to the committee. It goes into such things as alchemy, and witchcraft. After all, there have
  been centuries in which these things were considered to be as obviously true as anything, and yet we now know that
  this is really nonsense. </p>
<p>
  So the possibility of these sort of delusions having a kind of contemporary guise as UFO's should not be thrown out
  altogether. I do not think that explains most or all of the unidentified settings.

</p><p>
  Since the funds are so painfully tragically short for science today, the priority question boils down to this: In the
  search for extraterrestrial life there is a high risk, high possibility, that is the one we are talking about today;
  namely, UFO's -- there is a high risk that they are not of extraterrestrial origin, but if they are, we are sure going
  to learn a lot.

</p><p>
  Compared to that, there is a moderate risk, significant return possibility, and that is, looking for life even simple
  forms on nearby planets, and searching for intelligent radio communications by the techniques of radio astronomy. Here
  it is clear there will be significant paydirt of one sort or another for what I gather is a comparable sort of
  investment.

</p><p>
  So if Congress is interested, and I'm not sure it is, I think it might very well ought to be, but if Congress is
  interested in a pursuit of the question of extraterrestrial life, I believe it would be much better advised to support
  the biology, the Mariner, and Voyager programs of NASA, and the radio astronomy programs of the National Science
  Foundation, than to pour very much money into this study of UFO's.

</p><p>
  On the other hand, I think a moderate support of investigations of UFO's might very well have some scientific paydirt
  in it, but perhaps not the one that we are talking about today.

</p><p>
  Mr. Chairman that concludes my statement except that I request that you include for the record a statement entitled
  "Unidentified Flying Objects" that I prepared for the Encyclopedia Americana.

</p><p>
</p>
<a id="artcl"></a>
<h2>Objets Volants Non Identifiés*</h2>
<p>(par Carl Sagan) </p>
<p>
  Objet Volant Non Identifié (OVNI*s [In Encyclopedia Americana (New York: Grolier) and In Bull Atom. Sci, 23, (6), 43,
  1967.]) est le terme générique pour les phénomènes aériens ou célestes en déplacement, détectés visuellement ou par
  radar, dont la nature n'est pas immédiatement comprise. L'intérêt pour ces objets va de la spéculation que certains
  d'entre eux sont les produits de civilisations au-delà de la Terre, et des réfléxions psychologiques sur les problèmes
  humains comtemporains que cette interprétation, fournit. </p>
<p>
  Observations. Unidentified flying objects have been described variously as rapidly moving or hovering; disc-shaped,
  cigar-shaped, or ball-shaped; moving silently or noisily; with a fiery exhaust, or with no exhaust whatever;
  accompanied by flashing lights, or uniformly glowing with a silvery cast. The diversity of the observations suggests
  that UFO's have no common origin and that the use of such terms as UFO's or "flying saucers" serves only to confuse
  the issue by grouping generically a variety of unrelated phenomena. </p>
<p>
  In the United States, popular interest in unidentified flying objects began on June 24, 1947, when a group of rapidly
  moving, glistening objects was observed from the air in daytime, near Mount Rainier, Washington. The observer, a
  Seattle resident, dubbed them "flying saucers." The sighting received extensive publicity. Somewhat similar sightings
  have been reported ever since. The differences among these observations, however, are as striking as the observations
  themselves. </p>
<p>
  Investigations. Because of its national defense responsibility, the U.S. Air Force investigates reports of
  unidentified flying object over the United States. The number of sightings investigated in 1947-65 is shown in the
  following table.</p>

<table class="right" cols="7">
  <caption>
    Reported sightings of UFO's, 1947-65 <span class="source">[Lawrence, J. Tacker, <em>Flying Saucers and the U.S. Air Force</em> (Princeton, N.J. (1960), et Bibliothèque du Congrès, Faits sur les Objets Volants Non Identifiés (Washington 1966)] </span>
  </caption>
  <tbody>

  <tr>
    <th>Année</th>
    <th>Nombre</th>
  </tr>

  <tr>
    <td>1947</td>
    <td>79</td>
  </tr>

  <tr>
    <td>1948</td>
    <td>143</td>
  </tr>

  <tr>
    <td>1949</td>
    <td>186</td>
  </tr>

  <tr>
    <td>1950</td>
    <td>169</td>
  </tr>

  <tr>
    <td>1951</td>
    <td>121</td>
  </tr>

  <tr>
    <td>1952</td>
    <td>1501</td>
  </tr>

  <tr>
    <td>1953</td>
    <td>425</td>
  </tr>

  <tr>
    <td>1954</td>
    <td>429</td>
  </tr>

  <tr>
    <td>1955</td>
    <td>404</td>
  </tr>

  <tr>
    <td>1956</td>
    <td>778</td>
  </tr>
  <tr>
    <td>1957</td>
    <td>1178</td>
  </tr>
  <tr>
    <td>1958</td>
    <td>473</td>
  </tr>
  <tr>
    <td>1959</td>
    <td>364</td>
  </tr>
  <tr>
    <td>1960</td>
    <td>557</td>
  </tr>
  <tr>
    <td>1961</td>
    <td>591</td>
  </tr>
  <tr>
    <td>1962</td>
    <td>474</td>
  </tr>
  <tr>
    <td>1963</td>
    <td>399</td>
  </tr>
  <tr>
    <td>1964</td>
    <td>572</td>
  </tr>
  <tr>
    <td>1965</td>
    <td>886</td>
  </tr>

  </tbody>
</table>

<p>
  Evaluation of these reports is difficult. Observations frequently are sketchy, and different reports of the same
  phenomenon are often dissimilar, or even irreconcilable. Observers tend to exaggerate. Deliberate hoaxes, some
  involving double-exposure photography, have been perpetrated. After allowances are made for these factors, the
  accepted scientific procedure is to attempt an explanation of the observations in terms of phenomena independently
  observed and understood. Only if an observation is rigorously inexplicable in terms of known phenomena does the
  scientist introduces alternative hypotheses for which there is no other evidence. Such hypotheses must still be
  consistent with all other available scientific information. </p>
<p>
  The identity of most UFO's has been established as belonging to one of the following categories: unconventional
  aircraft; aircraft under uncommon weather conditions; aircraft with unusual external light patterns; meteorological
  and other high-altitude balloons; artificial earth satellites; flocks of birds; reflections of searchlights or
  headlights off clouds; reflection of sunlight from shiny surfaces; luminescent organisms (including one case of a
  firefly lodged between two adjacent panes of glass in an airplane cockpit window); optical mirages and looming;
  lenticular cloud formations; ball lighting; sun dogs; meteors, including green fireballs; planets, especially Venus;
  bright stars; and the aurora borealis. </p>
<p>
  Radar detection of unidentified flying objects has also occurred occasionally. Many of these sightings have been
  explained as radar reflections from temperature inversion layers in the atmosphere and other sources of radar
  "angels." </p>
<p>
  Considering the difficulties involved in tracking down visual and radar sightings, it is remarkable that all but a few
  percent of the reported UFO's have been identified as naturally occurring -- if sometimes unusual phenomena. It is of
  some interest that the UFO's which are unidentified do not fall into one uniform category of motion, color, lighting,
  etc., but rather run through the same range of these variables as the identified UFO's. In October 1957, Sputnik I,
  the first earth-orbiting artificial satellite, was launched. Of 1,178 UFO sightings in that year, 701 occurred between
  October and December. The clear implication is that Sputnik and its attendant publicity were responsible for many UFO
  sightings. </p>
<p>
  Earlier, in July 1952, a set of visual and radar observations of unidentified flying objects over Washington, D.C.,
  caused substantial public concern. Government concern was reflected in the creation in November of that year of a
  special panel to evaluate these reports. The panel was established by the Office of Scientific Intelligence of the
  Central Intelligence Agency, and was headed by the late Professor H. P. Robertson of the California Institute of
  Technology. The Robertson panel, after a thorough investigation of the UFO reports to that date, concluded that all
  were probably natural phenomena, wrongly interpreted. </p>
<p>
  The most reliable testimony is that of the professional astronomer. Professor Jesse L. Greenstein of Mount Wilson and
  Palomar Observatories (author of the <i>ASTRONOMY</i> article on pages 90-95) has pointed out that a vehicle 100 feet
  (30.5 meters) in diameter, at an altitude of 50 miles (80.5 km), would leave a broad track on photographic plates of
  the sky taken with large telescopes. This track could be distinguished easily from those of ordinary astronomical
  objects such as stars, meteors, and comets. Nevertheless, it appears that such tracks or unambiguous visual
  observations of classical UFO's have never been made by professional astronomers. </p>
<p>
  For example, in the Harvard Meteor Project performed in New Mexico during the period 1954-56, extensive photographic
  observations were made by Super-Schmidt cameras, with a 60° field of view. In all, a surface area of about 3,000
  square miles (7,700 sq km) was observed to a height of about 50 miles (80 km) for a total period of about 3,000 hours.
  Visual and photographic observations were made which could detect objects almost as faint as the faintest objects
  visible to the naked eye. These observations by professional astronomers were made in a locale and period
  characterized by extensive reports of unidentified flying objects. No unexplained objects were detected, despite the
  fact that rapidly moving objects were being sought in a study of meteors. Similar negative results have been obtained
  by large numbers of astronomers and help to explain the general skepticism of the astronomical community towards
  flying saucer reports. </p>
<p>
  A series of puzzling and well-published flying saucer sightings in the mid-1960's again led to the appointment of a
  government investigating panel, this time under the aegis of the <a href="/org/us/dod/af/AFSAB.html">Air Force
  Scientific Advisory Board</a>. It is significant that this panel was convened not at the request of the operational or
  intelligence arms of the Air Force, but in response to a request by the Air Force public relations office. The panel,
  under the chairmanship of Brian O'Brien, a member of the board, met in February 1966, and restated the general
  conclusions of the Robertson panel. It was recommended that the Air Force make a more thoroughgoing effort to
  investigate selected UFO reports of particular interest. although the probability of acquiring significant scientific
  information (other than psychological) seemed small. The O'Brien panel suggested that the Air Force establish a group
  of teams at various points within the United States in order to respond rapidly to UFO reports. The panel recommended
  that each team should consist of a physical scientist familiar with upper atmospheric and astronomical phenomena, a
  clinical psychologist, and a trained investigator. </p>
<p>
  In October 1966 the University of Colorado was selected by the Air Force Office of Scientific Research to manage the
  program, and to prepare a thoroughgoing analysis of the UFO problem. The National Academy of Sciences agreed to
  appoint a panel to review the report when it is completed in early 1968. </p>
<p>
  Hypotheses of Extraterrestrial Origin. Repeated sightings of UFO's, and the persistence of the Air Force and the
  responsible scientific community in explaining away the sightings, have suggested to some that a conspiracy exists to
  conceal from the public the true nature of the UFO's. Might not at least a small fraction of the unexplained few
  percent of the sightings be space vehicles of intelligent extraterrestrial beings observing the earth and its
  inhabitants? </p>
<p>
  It now seems probable that the earth is not the only inhabited planet in the universe. There is evidence that many of
  the stars in the sky have planetary systems. Furthermore, research concerning the origin of life on earth suggests
  that the physical and chemical processes leading to the origin of life occur rapidly in the early history of the
  majority of planets. From the point of view of natural selection, the advantages of intelligence and technical
  civilization are obvious, and some scientists believe that a large number of planets within our Milky Way galaxy --
  perhaps as many as a million -- are inhabited by technical civilizations in advance of our own. </p>
<p>
  Interstellar space flight is far beyond our present technical capabilities, but there seem to be no fundamental
  physical objections to it. It would be rash to preclude, from our present vantage point, the possibility of its
  development by other civilizations. But if each of, say, a million advanced technical civilizations in our galaxy
  launched an interstellar spacecraft each year (and even for an advanced civilization, the launching of an interstellar
  space vehicle would not be a trivial undertaking), and even if all of them could reach our solar system with equal
  facility, our system would, on the average, be visited only once every 100,000 years. </p>
<p>
  UFO enthusiasts have sometimes castigated the skeptic for his anthropocentrism. Actually, the assumption that earth is
  visited daily by interstellar spacecraft is far more anthropocentric -- attaching as it does some overriding
  significance to our small planet. If our views on the frequency of intelligence in the galaxy are correct, there is no
  reason why the earth should be singled out for interstellar visits. A greater frequency of visits could be expected if
  there were another planet populated by a technical civilization within our solar system, but at the present time there
  is no evidence for the existence of one. </p>
<p>
  Related to the interstellar observer idea are the "contact" tales, contemporary reports of the landing of
  extraterrestrial space vehicles on earth. Unlike the UFO reports, these tales display a striking uniformity. The
  extraterrestrials are described as humanoid, differing from man only in some minor characteristic such as teeth,
  speech, or dress. The aliens -- so the "contactees" report -- have been observing earth and its inhabitants for many
  years, and express concern at "the present grave political situation." The visitors are fearful that, left to our own
  devices, we will destroy our civilization. The contactee is then selected as their "chosen intermediary" with the
  governments and inhabitants of earth, but somehow the promised political or social intervention never
  materializes. </p>
<p>
  Psychological Factors. The psychologist Carl Jung pointed out that the frequency and persistence of these contact
  tales -- not one of which has been confirmed by the slightest sort of objective evidence -- must be of substantial
  psychological significance. What need is fulfilled by a belief that unidentified flying objects are of
  extraterrestrial origin? It is noteworthy that in the contact tales, the spacecraft and their crews are almost never
  pictured as hostile. It would be very satisfying if a race of advanced and benign creatures were devoted to our
  welfare. </p>
<p>
  The interest in unidentified flying objects derives, perhaps, not so much from scientific curiosity as from
  unfulfilled religious needs. Flying saucers serve, for some, to replace the gods that science has deposed. With their
  distant and exotic worlds and their pseudoscientific overlay, the contact accounts are acceptable to many people who
  reject the older religious frameworks. But precisely because people desire so intensely that unidentified flying
  objects be of benign, intelligent, and extraterrestrial origin, honesty requires that, in evaluating the observations,
  we accept only the most rigorous logic and the most convincing evidence. At the present time, there is no evidence
  that unambiguously connects the various flying saucer sightings and contact tales with extraterrestrial
  intelligence. </p>
<p>
</p>
<a id="bibliography">BIBLIOGRAPHY</a>
<p>
  Jung, Carl G., <i>Flying Saucers: A. Modern Myth of Things Seen in the Skies</i> (New York 1959). </p>
<p>
  Menzel, D. H. and Boyd, L. G., <i>The World of Flying Saucers: A. Scientific Examination of a Major Myth of the Space
  Age</i> (New York 1963). </p>
<p>
  Ruppelt, Edward J., <i>The Report on Unidentified Flying Objects</i> (New York 1956). </p>
<p>
  <span class="people" title="Josef Samuelovitch Shklovsky">Shklovsky, Iosif S.</span> and Sagan Carl, <i>Intelligent
  Life in the Universe</i> (San Francisco 1966). </p>
<p>
  Tacker, Lawrence J., <i>Flying Saucers and the U.S. Air Force</i> (Princeton 1960). </p>
<p>
  Vallee, Jacques, <i>Anatomy of a Phenomenon</i> (Chicago 1968). </p>
<p>
</p>
<hr size="2">
CARL SAGAN, <i>Department of Astronomy, Cornell University.</i>
<p>
</p>
<a id="questions"></a>

<p>Thank you.

</p><p>
  <b>Mr. Hechler</b>. Dr. Sagan, there have been some recent experiments at Green Bank, W. Va., with its 300-foot
  telescope, in an attempt to synchronize this with the Arecibo dish, in such a way as you might in effect produce
  almost a 2,000-mile diameter collecting surface for trying to receive signals from the pulsars.

</p><p>
  I wonder if this isn't the type or specific activity in radio astronomy that could utilize some additional support in
  order to ascertain the truth about terrestrial life and signals therefrom ?

</p><p>
  <b>Dr. Sagan</b>. Congressman Hechler, as a member of the faculty at Cornell that runs the observatory, I would find
  some problem answering that.

</p><p>
  <b>Mr. Hechler</b>. But not of West Virginia, however?

</p><p>
  <b>Dr. Sagan</b>. That is right. The study of pulsars, as I indicated to Chairman Miller, is relevant. The development
  of a long base-line parameter of the sort you talked about is of great interest to many areas of radio astronomy, and
  conceivably to the area we are talking about.</p>
<p>
  However, there has not been since Project OXMA, which occurred in Green Bank some 7 years or so ago, any systematic
  effort in this country to look for signals of intelligent extraterrestrial origin.

</p><p>
  There is at the present time a fairly major effort under way in the Soviet Union, but at least in this country there
  are no such efforts directed specifically to this question.

</p><p>
  It may be if we ever do detect intelligent signals from elsewhere, it will be an accidental byproduct of some other
  program. There is at the present time no effort to search for extraterrestrial signals.

</p><p>
  <b>Chairman Miller</b>. Are they trying to do things in Australia?

</p><p>
  <b>Dr. Sagan</b>. To the best of my knowledge there is no such work being done.

</p><p>
  <b>Chairman Miller</b>. The Mills-Cross program is also connected with Cornell, isn't it?

</p><p>
  <b>Dr. Sagan</b>. The Cornell-Sydney Astronomy Center, yes, sir.

</p><p>
  <b>Chairman Miller</b>. Is that all, Mr. Hechler?

</p><p>
  <b>Mr. Hechler</b>. I was hoping you would suggest something more specific, for our future consideration.

</p><p>
  <b>Dr. Sagan</b>. Let me say, and again let me emphasize that it is by no means demonstrated that radio astronomical
  searches for extraterrestrial intelligence have anything whatever to do with UFO's, but if we were interested, as some
  of us are, in examining the possibility of extraterrestrial intelligence, sending signals to Earth, then relatively
  modest programs, of say less than a, million dollars, could be organized, using largely existing instruments with only
  small modifications in the things you hook up to the radio telescope, which would be ideal for this purpose.

</p><p>
  There are in fact many radio astronomers who are privately interested in this sort of thing, but it carries something
  of the same sort of stigma that both the previous speakers mentioned about UFO's. It is unconventional. It is in many
  senses radical. Many astronomers prefer to have nothing to do with it.

</p><p>
  <b>Mr. Pettis</b>. Mr. Chairman.

</p><p>
  <b>Mr. Roush</b>. Mr. Pettis.

</p><p>
  <b>Mr. Pettis</b>. I would like to ask the doctor, or any other member of the panel. Is there any indication that any
  other Government, particularly the Russians, are interested in this subject?

</p><p>
  <b>Dr. Sagan</b>. I cannot speak about the UFO program. Perhaps Dr. Hynek can say something about that. As far as the
  question that I just mentioned, the radio search for extraterrestrial intelligence, there is a state commission in the
  Soviet Union, for the investigation of cosmic-radio intelligence. There is a fairly major effort that has been
  mustered for the last few years along these lines.

</p><p>
  And there is only some information about that; that we have gotten out of the Soviet Union.

</p><p>
  I don't know anything about their activities on UFOs. Perhaps Dr. Hynek would like to comment on that.

</p><p>
  <b>Dr. Hynek</b>. May I, Mr. Chairman, preface my remark, in answer to that, by pointing out a danger here that we may
  be putting the cart before the horse in the consideration of extraterrestrial intelligence.

</p><p>
  Speaking of horses, suppose someone comes here and tells us, or announces to us there is a report of a horse in the
  bath tub.</p>
<p>
  I think that it would be rather pointless to then ask, what is the color of the horse, what does he eat, how could be
  have gotten there, who installed the bath tub? The question is is there a horse in the bath tub? This is a question I
  think we should direct ourselves to first. Is there anything to these reports?

</p><p>
  Now, coming to the question of the Russian situation, I do know from my visits behind the Iron Curtain, or as they
  like to speak of it, the Socialist countries, there have been sightings behind the Iron Curtain.

</p><p>
  In fact, if you were to have good translations, it would be difficult to distinguish between a UFO report from Russia,
  from Brazil, from Argentina, from Japan, or from the United States. There is a rather rough pattern.

</p><p>
  Now, the Russians, to the best of my knowledge, have given no official recognition to the problem, but I do know, from
  personal information, that there is sort of a ground-swell interest, or a latent interest, that pops up here and
  there, but apparently they have as much difficulty in getting official recognition as we do.

</p><p>
  <b>Mr. Roush</b>. I would first point out that I realize that a visit to Russia doesn't necessarily make a person an
  expert or give him all the information. A year ago June I did visit Russia. I had conversations with a few of their
  people, including, my pronunciation may not be correct, Dr. Millionshchikov and the head of their weather bureau, I
  believe it is Petrov, and several others, and I repeatedly asked the question, "Do you believe in unidentified flying
  objects" In each instance they merely laughed. That was the response that I got. Since then, however, I have observed
  there have been papers published in Russia discussing the phenomena, and discussing it in scientific terms.

</p><p>
  It seems to me that any discussion such as ours today raises the question of the existence of extraterrestrial life.
  That is one reason we asked Dr. Sagan to come here. I'm not real sure, Dr. Sagan, whether you stated whether there is
  or whether there is not extraterrestrial life. I was watching for that, and I don't believe I heard you say it.

</p><p>
  <b>Dr. Sagan</b>. Congressman Roush, I have enough difficulty trying to determine if there is intelligent life on
  Earth, to be sure if there is intelligent life anywhere else. [Laughter.]

</p><p>
  If we knew there was life on other planets, then we would be able to save ourselves a lot of agony finding out. It is
  just because the problem is so significant, and we don't have the answers at hand we need to pursue the subject. I
  don't know. It beats me.

</p>
<p class="question"><b>Roush</b> : I believe you coauthored a book with a Russian, is that correct?</p>
<p class="answer">That is correct.</p>
<p class="question"><b>Roush</b> :Does Dr. <span class="people" title="Josef Samuelovitch Shklovsky">Shklovsky</span>
  share your views?</p>
<p class="answer">I think he shares my restraint.<br/> I think both of us would say we think this is an extremely
  important subject, that we are on the frontier of being able to find out, but that neither of us knows whether there
  is or isn't life out there. Let me say if it turns out there isn't life on Mars, that is almost as interesting as if
  we find there is life on Mars, because then we have to ask, what happened different on Mars than on the Earth, so that
  life arose here and not there. That will surely give us a very profound entry into the question of follow-up of
  evolution and the cosmic context.</p>
<p class="question"><b>Roush</b> :Suppose we discover there is life on Mars, in some form, wouldn't this almost cinch
  your case, and you could say there is extra-terrestrial life?</p>
<p class="answer">Yes, sir; it certainly would, but not cinch our case about extraterrestrial intelligence. Conceivably,
  there might be a low form on Mars. If there is Martian life, it is of interest how low it is. If there is intelligence
  on Mars -- but we don't know there is intelligence on Mars -- then we don't have to grasp that evolution process.</p>
<p class="question"><b>Roush</b> :I would like to finish this mornings session just by telling of a cartoon I saw which
  I think Dr. Hynek perhaps saw and enjoyed as much as I did. It showed a flying saucer hovering over the Earth, with
  little green men looking down, and one turned to the other and said, "Do you suppose it is swamp gas?" [Laughter.]</p>
<p class="answer"><b>Dr. Hynek</b>. That is a good statement to close the session on.</p>
<p class="question"><b>Roush</b> :We shall reconvene at 2 o'clock this afternoon.</p>
<p>(Là où, à 12 h 15, l'audition fut recessed to reconvene à 14 h)</p>
<!--#include virtual="/footer.html" -->