VENUS AND
DR. VELIKOVSKY

SCIENTISTS, like other human beings, have their hopes and fears, their passions and despondencies—and their strong emotions may sometimes interrupt the course of clear thinking and sound practice. But science is also self-correcting. The most fundamental axioms and conclusions may be challenged. The prevailing hypotheses must survive confrontation with observation. Appeals to authority are impermissible. The steps in a reasoned argument must be set out for all to see. Experiments must be reproducible.

The history of science is full of cases where previously accepted theories and hypotheses have been entirely overthrown, to be replaced by new ideas that more adequately explain the data. While there is an understandable psychological inertia—usually lasting about one generation—such revolutions in scientific thought are widely accepted as a necessary and desirable element of scientific progress. Indeed, the reasoned criticism of a prevailing belief is a service to the proponents of that belief; if they are incapable of defending it, they are well advised to abandon it. This self-questioning and error-correcting aspect of the scientific method is its most striking property, and sets it off from many other areas of human endeavor where credulity is the rule.

The idea of science as a method rather than as a body of knowledge is not widely appreciated outside of science, or indeed in some corridors inside of science. For this reason I and some of my colleagues in the American Association for the Advancement of Science have advocated a regular set of discussions at the annual AAAS meeting of hypotheses that are on the borderlines of science and that have attracted substantial public interest. The idea is not to attempt to settle such issues definitively, but rather to illustrate the process of reasoned disputation, to show how scientists approach a problem that does not lend itself to crisp experimentation, or is unorthodox in its interdisciplinary nature, or otherwise evokes strong emotions.

Vigorous criticism of new ideas is a commonplace in science. While the style of the critique may vary with the character of the critic, overly polite criticism benefits neither the proponents of new ideas nor the scientific enterprise. Any substantive objection is permissible and encouraged; the only exception being that ad hominem attacks on the personality or motives of the author are excluded. It does not matter what reason the proponent has for advancing his ideas or what prompts his opponents to criticize them: all that matters is whether the ideas are right or wrong, promising or retrogressive.

For example, here is a summary—of a type that is unusual but not extremely rare—of a paper submitted to the scientific journal Icarus, by a qualified referee: “It is the opinion of this reviewer that this paper is absolutely unacceptable for publication in Icarus. It is based on no sound scientific research, and at best it is incompetent speculation. The author has not stated his assumptions; the conclusions are unclear, ambiguous and without basis; credit is not given to related work; the figures and tables are unclearly labeled; and the author is obviously unfamiliar with the most basic scientific literature …” The referee then goes on to justify his remarks in detail. The paper was rejected for publication. Such rejections are commonly recognized as a boon to science as well as a favor to the author. Most scientists are accustomed to receiving (somewhat milder) referees’ criticisms every time they submit a paper to a scientific journal. Almost always the criticisms are helpful. Often a paper revised to take these critiques into account is subsequently accepted for publication. As another example of forthright criticism in the planetary science literature, the interested reader might wish to consult “Comments on The Jupiter Effect” by J. Meeus (1975)^* and the commentary on it in Icarus.

Vigorous criticism is more constructive in science than in some other areas of human endeavor because in science there are adequate standards of validity that can be agreed upon by competent practitioners the world over. The objective of such criticism is not to suppress but rather to encourage the advance of new ideas: those that survive a firm skeptical scrutiny have a fighting chance of being right, or at least useful.

EMOTIONS IN THE scientific community have run very high on the issue of Immanuel Velikovsky’s work, especially his first book, Worlds in Collision, published in 1950. I know that some scientists were irked because Velikovsky was compared to Einstein, Newton, Darwin and Freud by New York literati and an editor of Harper’s, but this pique arises from the frailty of human nature rather than the judgment of the scientist. The two together often inhabit the same individual. Others were dismayed at the use of Indian, Chinese, Aztec, Assyrian or Biblical texts to argue for extremely heterodox views in celestial mechanics. Also, I suspect, not many physicists or celestial mechanicians are comfortably fluent in such languages or are familiar with such texts.

My own view is that no matter how unorthodox the reasoning process or how unpalatable the conclusions, there is no excuse for any attempt to suppress new ideas—least of all by scientists. Therefore I was very pleased that the AAAS held a discussion on Worlds in Collision, in which Velikovsky took part.

In reading the critical literature in advance, I was surprised at how little of it there is and how rarely it approaches the central points of Velikovsky’s thesis. In fact, neither the critics nor the proponents of Velikovsky seem to have read him carefully, and I even seem to find some cases where Velikovsky has not read Velikovsky carefully. Perhaps the publication of most of the AAAS symposium (Goldsmith, 1977) as well as the present chapter, the principal conclusions of which were presented at the symposium, will help to clarify the issues.

In this chapter I have done my best to analyze critically the thesis of Worlds in Collision, to approach the problem both on Velikovsky’s terms and on mine—that is, to keep firmly in mind the ancient writings that are the focus of his argument, but at the same time to confront his conclusions with the facts and the logic I have at my command.

Velikovsky’s principal thesis is that major events in the history of both the Earth and the other planets in the solar system have been dominated by catastrophism rather than by uniformitarianism. These are fancy words used by geologists to summarize a major debate they had during the infancy of their science which apparently culminated, between 1785 and 1830, in the work of James Hutton and Charles Lyell, in favor of the uniformitarians. Both the names and the practices of these two sects evoke familiar theological antecedents. A uniformitarian holds that landforms on Earth have been produced by processes we can observe to be operating today, provided they operate over immense vistas of time. A catastrophist holds that a small number of violent events, occupying much shorter periods of time, are adequate. Catastrophism began largely in the minds of those geologists who accepted a literal interpretation of the Book of Genesis, and in particular the account of the Noahic flood. It is clearly no use arguing against the catastrophist viewpoint to say that we have never seen such a catastrophe in our lifetimes. The hypothesis requires only rare events. But if we can show that there is adequate time for processes we can all observe operating today to produce the landform or event in question, then there is at least no necessity for the catastrophist hypothesis. Obviously both uniformitarian and catastrophic processes can have been at work—and almost certainly both were—in the history of our planet.

Velikovsky holds that in the relatively recent history of the Earth there has been a set of celestial catastrophes, near-collisions with comets, small planets and large planets. There is nothing absurd in the possibility of cosmic collisions. Astronomers in the past have not hesitated to invoke collisions to explain natural phenomena. For example, Spitzer and Baade (1951) proposed that extragalactic radio sources may be produced by the collisions of whole galaxies, containing hundreds of billions of stars. This thesis has now been abandoned, not because cosmic collisions are unthinkable, but because the frequency and properties of such collisions do not match what is now known about such radio sources. A still popular theory of the energy source of quasars is multiple stellar collisions at the centers of galaxies—where, in any case, catastrophic events must be common.

Collisions and catastrophism are part and parcel of modern astronomy, and have been for many centuries (see the epigraphs at the beginning of this chapter). For example, in the early history of the solar system, when there were probably many more objects about than there are now—including objects on very eccentric orbits—collisions may have been frequent. Lecar and Franklin (1973) investigate hundreds of collisions occurring in a period of only a few thousand years in the early history of the asteroid belt, to understand the present configuration of this region of the solar system. In another paper, entitled “Cometary Collisions and Geological Periods,” Harold Urey (1973) investigates a range of consequences, including the production of earthquakes and the heating of the oceans, which might attend the collision with the Earth of a comet of average mass of about 10¹⁸ grams. The Tunguska event of 1908, in which a Siberian forest was leveled, is often attributed to the collision with the Earth of a small comet. The cratered surfaces of Mercury, Mars, Phobos, Deimos and the Moon bear eloquent testimony to the fact that there have been abundant collisions during the history of the solar system. There is nothing unorthodox about the idea of cosmic catastrophes, and this is a view that has been common in solar system physics at least back to the late-nineteenth-century studies of the lunar surface by G. K. Gilbert, the first director of the U.S. Geological Survey.

What, then, is all the furor about? It is about the time scale and the adequacy of the purported evidence. In the 4.6 billion-year history of the solar system, many collisions must have occurred. But have there been major collisions in the last 3,500 years, and can the study of ancient writings demonstrate such collisions? That is the nub of the issue.

VELIKOVSKY has called attention to a wide range of stories and legends, held by diverse peoples, separated by great distances, which stories show remarkable similarities and concordances. I am not expert in the cultures or languages of any of these peoples, but I find the concatenation of legends Velikovsky has accumulated stunning. It is true that some experts in these cultures are less impressed. I can remember vividly discussing Worlds in Collision with a distinguished professor of Semitics at a leading university. He said something like “The Assyriology, Egyptology, Biblical scholarship and all of that Talmudic and Midrashic pilpul is, of course, nonsense; but I was impressed by the astronomy.” I had rather the opposite view. But let me not be swayed by the opinions of others. My own position is that if even 20 percent of the legendary concordances that Velikovsky produces are real, there is something important to be explained. Furthermore, there is an impressive array of cases in the history of archaeology—from Heinrich Schliemann at Troy to Yigael Yadin at Masada—where the descriptions in ancient writings have subsequently been validated as fact.

Now, if a variety of widely separated cultures share what is palpably the same legend, how can this be understood? There seem to be four possibilities: common observation, diffusion, brain wiring and coincidence. Let us consider these in turn.

Common Observation: One explanation is that the cultures in question all witnessed a common event and interpreted it in the same way. There may, of course, be more than one view of what this common event was.

Diffusion: The legend originated within one culture only, but during the frequent and distant migrations of mankind, gradually spread with some changes among many apparently diverse cultures. A trivial example is the Santa Claus legend in America which evolved from the European Saint Nicholas (Claus is short for Nicholas in German), the patron saint of children, and which ultimately is derived from pre-Christian tradition.

Brain Wiring: A hypothesis sometimes also known as racial memory or the collective unconscious. It holds that there are certain ideas, archetypes, legendary figures, and stories that are intrinsic to human beings at birth, perhaps in the same way that a newborn baboon knows to fear a snake, and a bird raised in isolation from other birds knows how to build a nest. It is apparent that if a tale derived from observation or from diffusion resonated with the “brain wiring,” it is more likely to be culturally retained.

Coincidence: Purely by chance two independently derived legends may have similar content. In practice, this hypothesis fades into the brain-wiring hypothesis.

IF WE ARE TO ASSESS critically such apparent concordances, there are some obvious precautions that must first be taken. Do the stories really say the same thing or have the same essential elements? If they are interpreted as due to common observations, do they date from the same period? Can we exclude the possibility of physical contact between representatives of the cultures in question in or before the epoch under discussion? Velikovsky is clearly opting for the common-observation hypothesis, but he seems to dismiss the diffusion hypothesis far too casually; for example, he says (page 303^*): “How could unusual motifs of folklore reach isolated islands, where the aborigines do not have any means of crossing the sea?” I am not sure which islands and which aborigines Velikovsky refers to here, but it is apparent that the inhabitants of an island had to have gotten there somehow. I do not think that Velikovsky believes in a separate creation in the Gilbert and Ellice Islands, say. For Polynesia and Melanesia there is now extensive evidence of abundant sea voyages of lengths of many thousands of kilometers within the last millennium, and probably much earlier (Dodd, 1972).

Or how, for example, would Velikovsky explain the fact that the Toltec name for “god” seems to have been teo, as in the great pyramid city of Teotihuacán (“City of the Gods”) near present-day Mexico City, where it is called San Juan Teotihuacán? There is no common celestial event that could conceivably explain this concordance. Toltec and Nahuatl are non-Indoeuropean languages, and it seems unlikely that the word for “god” would be wired into all human brains. Yet teo is a clear cognate of the common Indoeuropean root for “god,” preserved, among other places, in the words “deity” and “theology.” The preferred hypotheses in this case are coincidence or diffusion. There is some evidence for pre-Columbian contact between the Old and New Worlds. But coincidence is also not to be taken lightly: if we compare two languages, each with tens of thousands of words, spoken by human beings with identical larynxes, tongues and teeth, it should not be surprising if a few words are coincidentally identical. Likewise, we should not be surprised if a few elements of a few legends are coincidentally identical. But I believe that all of the concordances Velikovsky produces can be explained away in this manner.

Let us take an example of Velikovsky’s approach to this question. He points to certain concordant stories, directly or vaguely connected with celestial events, that refer to a witch, a mouse, a scorpion or a dragon (pages 77, 264, 305, 306, 310). His explanation: divers comets, upon close approach to the Earth, were tidally or electrically distorted and gave the form of a witch, a mouse, a scorpion or a dragon, clearly interpretable as the same animal to culturally isolated peoples of very different backgrounds. No attempt is made to show that such a clear form—for example, a woman riding a broomstick and topped by a pointed hat—could have been produced in this way, even if we grant the hypothesis of a close approach to the Earth by a comet. Our experience with Rorschach and other psychological projective tests is that different people see the same nonrepresentational image in different ways. Velikovsky even goes so far as to believe that a close approach to the Earth by “a star” he evidently identifies with the planet Mars so distorted it that it took on the clear shape (page 264) of lions, jackals, dogs, pigs and fish; and in his opinion this explains the worship of animals by the Egyptians. This is not very impressive reasoning. We might just as well assume that the whole menagerie was capable of independent flight in the second millennium B.C. and be done with it. A much more likely hypothesis is diffusion. Indeed, I have in a different context spent a fair amount of time studying the dragon legends on the planet Earth, and I am impressed at how different these mythical beasts, all called dragons by Western writers, really are.

As another example, consider the argument of Chapter 8, Part 2 of Worlds in Collision. Velikovsky claims a world-wide tendency in ancient cultures to believe at various times that the year has 360 days, that the month has thirty-six days, and that the year has ten months. Velikovsky offers no justification in physics for this, but argues that ancient astronomers could hardly have been so poor at their trade as to slip five days each year or six days each lunation. Fairly soon the night would be brilliant with moonlight at the astrologically official new moon, snowstorms would be falling in July, and the astrologers would be hung by their ears. Having had some experience with modern astronomers, I am not as confident as Velikovsky is in the unerring computational precision of ancient astronomers. Velikovsky proposes that these aberrant calendrical conventions reflect real changes in the length of the day, month and/or year—and that they are evidence of close approaches to the Earth-Moon system by comets, planets and other celestial visitors.

There is an alternative explanation, which derives from the fact that there are not a whole number of lunations in a solar year, nor a whole number of days in a lunation. These incommensurabilities will be galling to a culture that has recently invented arithmetic but has not yet gotten as far as large numbers or fractions. As an inconvenience, these incommensurabilities are felt even today by religious Muslims and Jews who discover that Ramadan and Passover, respectively, occur from year to year on rather different days of the solar calendar. There is a clear whole-number chauvinism in human affairs, most easily discerned in discussing arithmetic with four-year-olds; and this seems to be a much more plausible explanation of these calendrical irregularities, if they existed.

Three hundred and sixty days a year provides an obvious (temporary) convenience for a civilization with base-60 arithmetic, as the Sumerian, Akkadian, Assyrian and Babylonian cultures. Likewise, thirty days per month or ten months per year might be attractive to enthusiasts of base-10 arithmetic. I wonder if we do not see here an echo of the collision between chauvinists of base-60 arithmetic and chauvinists of base-10 arithmetic, rather than a collision of Mars with Earth. It is true that the tribe of ancient astrologers may have been dramatically depleted as the various calendars rapidly slipped out of phase, but that was an occupational hazard, and at least it removed the mental agony of dealing with fractions. In fact, sloppy quantitative thinking appears to be the hallmark of this whole subject.

An expert on early time-reckoning (Leach, 1957) points out that in ancient cultures the first eight or ten months of the year are named, but the last few months, because of their economic unimportance in an agricultural society, are not. Our month December, named after the Latin decem, means the tenth, not the twelfth, month. (September = seventh, October = eighth, November = ninth, as well.) Because of the large numbers involved, prescientific peoples characteristically do not count days of the year, although they are assiduous in counting months. A leading historian of ancient science and mathematics, Otto Neugebauer (1957), remarks that, both in Mesopotamia and in Egypt, two separate and mutually exclusive calendars were maintained: a civil calendar whose hallmark was computational convenience, and a frequently updated agricultural calendar—messier to deal with, but much closer to the seasonal and astronomical realities. Many ancient cultures solved the two-calendar problem by simply adding a five-day holiday on at the end of the year. I hardly think that the existence of 360-day years in the calendrical conventions of prescientific peoples is compelling evidence that then there really were 360 rather than 365¼ rotations in one revolution of Earth about the Sun.

This question can, in principle, be resolved by examining coral growth rings, which are now known to show with some accuracy the number of days per month and the number of days per year, the former only for intertidal corals. There appears to be no sign of major excursions in recent times from the present number of days in a lunation or a year, and the gradual shortening (not lengthening) of the day and the month with respect to the year as we go back in time is found to be consistent with tidal theory and the conservation of energy and angular momentum within the Earth-Moon system, without appeal to cometary or other exogenous intervention.

Another problem with Velikovsky’s method is the suspicion that vaguely similar stories may refer to quite different periods. This question of the synchronism of legends is almost entirely ignored in Worlds in Collision, although it is treated in some of Velikovsky’s later works. For example (page 31), Velikovsky notes that the idea of four ancient ages terminated by catastrophe is common to Indian as well as to Western sacred writing. However, in the Bhagavad Gita and in the Vedas, widely divergent numbers of such ages, including an infinity of them, are given; but, more interesting, the duration of the ages between major catastrophes is specified (see, for example, Campbell, 1974) as billions of years. This does not match very well Velikovsky’s chronology, which requires hundreds or thousands of years. Here Velikovsky’s hypothesis and the data that purport to support it differ by a factor of about a million. Or (page 91) vaguely similar discussions of vulcanism and lava flows in Greek, Mexican and Biblical traditions are quoted. There is no attempt made to show that they refer to even approximately comparable times and, since lava has flowed in historical times in all three areas, no common exogenous event is necessary to interpret such stories.

Despite copious references, there also seem to me to be a large number of critical and undemonstrated assumptions in Velikovsky’s argument. Let me mention just a few of them. There is the very interesting idea that any mythological references by any people to any god that also corresponds to a celestial body represents in fact a direct observation of that celestial body. It is a daring hypothesis, although I am not sure what one is to do with Jupiter appearing as a swan to Leda, and as a shower of gold to Danaë. On page 247 the hypothesis that gods and planets are identical is used to date the time of Homer. In any case, when Hesiod and Homer refer to Athena being born full-grown from the head of Zeus, Velikovsky takes Hesiod and Homer at their word and assumes that the celestial body Athena was ejected by the planet Jupiter. But what is the celestial body Athena? Repeatedly it is identified with the planet Venus (Part 1, Chapter 9, and many other places in the text). One would scarcely guess from reading Worlds in Collision that the Greeks characteristically identified Aphrodite with Venus, and Athena with no celestial body whatever. What is more, Athena and Aphrodite were “contemporaneous” goddesses, both being born at the time Zeus was king of the gods. On page 251 Velikovsky notes that Lucian “is unaware that Athene is the goddess of the planet Venus.” Poor Lucian seems to be under the misconception that Aphrodite is the goddess of the planet Venus. But in the footnote on page 361 there appears to be a slip, and here Velikovsky for the first and only time uses the form “Venus (Aphrodite).” On page 247 we hear of Aphrodite, the goddess of the Moon. Who, then, was Artemis, the sister of Apollo the Sun, or, earlier, Selene? There may be good justification, for all I know, in identifying Athena with Venus, but it is far from the prevailing wisdom either now or two thousand years ago, and it is central to Velikovsky’s argument. It does not increase our confidence in the presentation of less familiar myths when the celestial identification of Athena is glossed over so lightly.

Other critical statements which are given extremely inadequate justification, and which are central to one or more of Velikovsky’s major themes, are: the statement (page 283) that “Meteorites, when entering the earth’s atmosphere, make a frightful din,” when they are generally observed to be silent; the statement (page 114) that “a thunderbolt, when striking a magnet, reverses the poles of the magnet”; the translation (page 51) of “Barad” as meteorites; and the contention (page 85) “as is known, Pallas was another name for Typhon.” On page 179 a principle is implied that when two gods are hyphenated in a joint name, it indicates an attribute of a celestial body—as, for example, Ashteroth-Karnaim, a horned Venus, which Velikovsky interprets as a crescent Venus and evidence that Venus was once close enough to Earth to have its phases discernible to the naked eye. But what does this principle imply, for example, for the god Ammon-Ra? Did the Egyptians see the sun (Ra) as a ram (Ammon)?

There is a contention (page 63) that instead of the tenth plague of Exodus killing the “first born” of Egypt, what is intended is the killing of the “chosen.” This is a rather serious matter and at least raises the suspicion that where the Bible is inconsistent with Velikovsky’s hypothesis, Velikovsky retranslates the Bible. The foregoing queries may all have simple answers, but the answers are not to be found easily in Worlds in Collision.

I do not mean to suggest that all of Velikovsky’s legendary concordances and ancient scholarship are similarly flawed, but many of them seem to be, and the remainder may well have alternative, for example diffusionist, origins.

With the situation in legend and myth as fuzzy as this, any corroboratory evidence from other sources would be welcomed by those who support Velikovsky’s argument. I am struck by the absence of any confirming evidence in art. There is a wide range of paintings, bas-reliefs, cylinder seals and other objets d’art produced by humanity and going back to at least 10,000 B.C. They represent all of the subjects, especially mythological subjects, important to the cultures that created them. Astronomical events are not uncommon in such works of art. Recently (Brandt, et al., 1974), impressive evidence has been uncovered in cave paintings in the American Southwest of contemporary observations of the Crab Supernova event of the year 1054, which was also recorded in Chinese, Japanese and Arab annals. Appeals have been made to archaeologists for information on cave painting representations of the earlier Gum Supernova (Brandt, et al., 1971). But supernova events are not nearly so impressive as the close approach of another planet with attendant interplanetary tendrils and lightning discharges connecting it to Earth. There are many unflooded caves at high altitudes, distant from the sea. If the Velikovskian catastrophes occurred, why are there no contemporary graphic records of them?

I therefore cannot find the legendary base of Velikovsky’s hypothesis at all compelling. If, nevertheless, his notion of recent planetary collisions and global catastrophism were strongly supported by physical evidence, we might be tempted to give it some credence. If the physical evidence is not, however, very strong, the mythological evidence will surely not stand by itself.

LET ME GIVE a short summary of my understanding of the basic features of Velikovsky’s principal hypothesis. I will relate it to the events described in the Book of Exodus, although the stories of many other cultures are said to be consistent with the events described in Exodus:

The planet Jupiter disgorged a large comet, which made a grazing collision with Earth around 1500 B.C. The various plagues and Pharaonic tribulations of the Book of Exodus all derive directly or indirectly from this cometary encounter. Material which made the river Nile turn to blood drops from the comet. The vermin described in Exodus are produced by the comet—flies and perhaps scarabs drop out of the comet, while indigenous terrestrial frogs are induced by the heat of the comet to multiply. Earthquakes produced by the comet level Egyptian but not Hebrew dwellings. (The only thing that does not seem to drop from the comet is cholesterol to harden Pharaoh’s heart.)

All this evidently falls from the coma of the comet, because at the moment that Moses lifts his rod and stretches out his hand, the “Red Sea” parts—due either to the gravitational tidal field of the comet or to some unspecified electrical or magnetic interaction between the comet and the “Red Sea.” Then, when the Hebrews have successfully crossed, the comet has evidently passed sufficiently farther on for the parted waters to flow back and drown the host of Pharaoh. The Children of Israel during their subsequent forty years of wandering in the Wilderness of Sin are nourished by manna from heaven, which turns out to be hydrocarbons (or carbohydrates) from the tail of the comet.

Another reading of Worlds in Collision makes it appear that the plagues and the Red Sea events represent two different passages of the comet, separated by a month or two. Then after the death of Moses and the passing of the mantle of leadership to Joshua, the same comet comes screeching back for another grazing collision with the Earth. At the moment that Joshua says “Sun, stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon,” the Earth—perhaps because of tidal interaction again, or perhaps because of an unspecified magnetic induction in the crust of the Earth—obligingly ceases its rotation, to permit Joshua victory in battle. The comet then makes a near-collision with Mars, so violent as to eject it out of its orbit so it makes two near-collisions with the Earth which destroy the army of Sennacherib, the Assyrian king, as he was making life miserable for some subsequent generation of Israelites. The net result was to eject Mars into its present orbit and the comet into a circular orbit around the Sun, where it became the planet Venus—which previously, Velikovsky believes, did not exist. The Earth meantime had somehow begun rotating again at almost exactly the same rate as before these encounters. No subsequent aberrant planetary behavior has occurred since about the seventh century B.C., although it might have been common in the Second Millennium.

That this is a remarkable story no one—proponents and opponents alike—will disagree. Whether it is a likely story is, fortunately, amenable to scientific inquiry. Velikovsky’s hypothesis makes certain predictions and deductions: that comets are ejected from planets; that comets are likely to make near or grazing collisions with planets; that vermin live in comets and in the atmospheres of Jupiter and Venus; that carbohydrates can be found in the same places; that enough carbohydrates fell in the Sinai peninsula for nourishment during forty years of wandering in the desert; that eccentric cometary or planetary orbits can be circularized in a period of hundreds of years; that volcanic and tectonic events on Earth and impact events on the Moon were contemporaneous with these catastrophes; and so on. I will discuss each of these ideas, as well as some others—for example, that the surface of Venus is hot, which is clearly less central to his hypothesis, but which has been widely advertised as powerful post hoc support of it. I will also examine an occasional additional “prediction” of Velikovsky—for example, that the Martian polar caps are carbon or carbohydrates. My conclusion is that when Velikovsky is original he is very likely wrong, and that when he is right the idea has been pre-empted by earlier workers. There are also a large number of cases where he is neither right nor original. The question of originality is important because of circumstances—for example, the high surface temperature of Venus-which are said to have been predicted by Velikovsky at a time when everyone else was imagining something very different. As we shall see, this is not quite the case.

In the following discussion, I will try to use simple quantitative reasoning as much as possible. Quantitative arguments are obviously a finer mesh with which to sift hypotheses than qualitative arguments. For example, if I say that a large tidal wave engulfed the Earth, there is a wide range of catastrophes—from the flooding of littoral regions to global inundation—which might be pointed to as support for my contention. But if I specify a tide 100 miles high, I must be talking about the latter, and moreover, there might be some critical evidence to counterindicate or support a tide of such dimensions. However, so as to make the quantitative arguments tractable to the reader who is not very familiar with elementary physics, I have tried, particularly in the Appendices (following the References), to state all the essential steps in the quantitative development, using the simplest arguments that preserve the essential physics. Perhaps I need not mention that such quantitative testing of hypotheses is entirely routine in the physical and biological sciences today. By rejecting the hypotheses that do not meet these standards of analysis, we are able to move swiftly to hypotheses in better concordance with the facts.

There is one further point about scientific method that must be made. Not all scientific statements have equal weight. Newtonian dynamics and the laws of conservation of energy and angular momentum are on extremely firm footing. Literally millions of separate experiments have been performed on their validity—not just on Earth, but, using the observational techniques of modern astrophysics, elsewhere in the solar system, in other star systems, and even in other galaxies. On the other hand, questions on the nature of planetary surfaces, atmospheres and interiors are on much weaker footing, as the substantial debates on these matters by planetary scientists in recent years clearly indicate. A good example of this distinction is the appearance 1975 of Comet Kohoutek. This comet had first been observed at a great distance from the Sun. On the basis of the early observations, two predictions were made. The first concerned the orbit of Comet Kohoutek—where it would be found at future times, when it would be observable from the Earth before sunrise, when after sunset—predictions based on Newtonian dynamics. These predictions were correct to within a gnat’s eyelash. The second prediction concerned the brightness of the comet. This was based on the guessed rate of vaporization of cometary ices to make a large cometary tail which brightly reflects sunlight. This prediction was painfully in error, and the comet—far from rivaling Venus in brightness—could not be seen at all by most naked-eye observers. But vaporization rates depend on the detailed chemistry and geometrical form of the comet, which we know poorly at best. The same distinction between well-founded scientific arguments, and arguments based on a physics or chemistry that we do not fully understand, must be borne in mind in any analysis of Worlds in Collision. Arguments based on Newtonian dynamics or the conservation laws of physics must be given very great weight. Arguments based on planetary surface properties, for example, must have correspondingly lesser weights. We will find that Velikovsky’s arguments run into extremely grave difficulties on both these scores, but the one set of difficulties is far more damaging than the other.