“I came upon the idea that traditions and legends and memories of generic origin can be treated in the same way in which we treat in psychoanalysis the early memories of a single individual. I spent ten years on this work. I found that the collective memory of mankind spoke of a series of global catastrophes that occurred in historical times. I believed that I could even identify the exact times and the very agents of the great upheavals of the more recent past. The conclusions at which I arrived compelled me to cross the frontiers into various fields of science, archaeology, geology, and astronomy”.
In the preface to Worlds in Collision, Velikovsky summarized his arguments:
Worlds in Collision is a book of wars in the celestial sphere that took place in historical times. In these wars the planet earth participated too. […] The historical-cosmological story of this book is based in the evidence of historical texts of many people around the globe, on classical literature, on epics of the northern races, on sacred books of the peoples of the Orient and Occident, on traditions and folklore of primitive peoples, on old astronomical inscriptions and charts, on archaeological finds, and also on geological and paleontological material.
“I have endeavoured to show that two series of cosmic catastrophes took place in historical times, thirty-four and twenty-six centuries ago, and thus only a short time ago not peace but war reigned in the solar system.”
“We maintain also that one planet — Venus — was formerly a comet…
“… that it joined the family of planets within the memory of mankind”
“We conjectured that the comet Venus originated in the planet Jupiter”
“From the fact that Venus was once a comet we learned that comets are not nearly immaterial bodies”
“We claim that the earth’s orbit changed more than once and with it the length of the year;”
“… that the geographical position of the terrestrial axis and its astronomical direction changed repeatedly”
“… the polar regions shifted, the polar ice became displaced into moderate latitudes, and other regions moved into the polar circles.”
“… electrical discharges took place between Venus, Mars, and the Earth when, in very close contacts, their atmospheres touched each other;”
“… that the magnetic poles of the earth became reversed only a few thousand years ago”
“… and that with the change in the moon’s orbit, the length of the month changed too, and repeatedly so”
“In the period of seven hundred years between the middle of the second millennium before the present era and the eighth century the year consisted of 360 days and the month of almost exactly thirty days, but earlier the day, month, and year were of different lengths.”
“We offered an explanation of the fact that the nocturnal side of Venus emits as much heat as the sunlit side”
“… we explained the origin of the canals of Mars and the craters and seas of lava on the moon as brought about in stress and near collisions.
“… excessive evaporation of water from the surface of the oceans and seas, a phenomenon that was postulated to explain the excessive precipitation and formation of ice covers, was caused by extraterrestrial agents.”
“We recognized that the religions of the peoples of the world have a common astral origin.”
“We learned why there are common ideas in the folklore of peoples separated by oceans”
“The accounts given in this book about planets changing their orbits and the velocities of their rotation, about a comet that became a planet, about interplanetary contacts and discharges, indicate a need for a new approach to celestial mechanics.”
“The theory of cosmic catastrophism can, if required to do so, conform with the celestial mechanics of Newton.”
The book proposed that around the 15th century BCE, a comet or comet-like object (now called the planet Venus), having originally been ejected from Jupiter, passed near Earth (an actual collision is not mentioned). The object changed Earth’s orbit and axis, causing innumerable catastrophes which were mentioned in early mythologies and religions around the world. Fifty-two years later, it passed close by again, stopping the Earth’s rotation for a while and causing more catastrophes. Then, in the 8th and 7th centuries BCE, Mars (itself displaced by Venus) made close approaches to the Earth; this incident caused a new round of disturbances and disasters. After that, the current “celestial order” was established. The courses of the planets stabilized over the centuries and Venus gradually became a “normal” planet.
These events lead to several key statements:
Venus must be still very hot as young planets radiate heat.
Venus must be rich in petroleum gases, and hydrocarbons.
Venus has an abnormal orbit in consequence of the unusual disasters that happened.
Velikovsky suggested some additional ideas that he said derived from these claims, including:
Jupiter emits radio noises.
The magnetosphere of Earth reaches at least up to the moon.
The sun has an electric potential of approximately 1019 volts.
The rotation of earth can be affected by electromagnetic fields.
Velikovsky arrived at these proposals using a methodology which would today be called comparative mythology – he looked for concordances in myths and written history of unconnected cultures across the world, in particular following a rather literal reading of their accounts of the exploits of planetary deities. In this book, he argues on the basis of ancient cosmological myths from places as disparate as India and China, Greece and Rome, Assyria and Sumer. For example, ancient Greek mythology asserts that the goddess Athena sprang from the head of Zeus. Velikovsky identifies Zeus (whose Roman counterpart was the god Jupiter) with the planet Jupiter. Velikovsky identifies Athena with the planet Venus, although the Greek counterpart of the Roman Venus was Aphrodite and not Athena. This myth, along with others from ancient Egypt, Israel, Mexico, etc. are used to support the claim that “Venus was expelled as a comet and then changed to a planet after contact with a number of members of our solar system” (Velikovsky 1972:182).
Critical reaction and controversy
The plausibility of the theory was summarily rejected by the physics community, as the cosmic chain of events proposed by Velikovsky was regarded as simply contradicting the basic laws of physics.
Velikovsky’s ideas had been known to astronomers for years before the publication of the book, partially by writing to astronomer Harlow Shapley of Harvard, partially through his 1946 pamphlet Cosmos Without Gravitation, (Friedlander 1995:11), and partially by a preview of his work in an article in the August 11, 1946 edition of the New York Herald Tribune. An article about the upcoming book was published by Harper’s Magazine in January 1950, which was followed by an article in Newsweek (Bauer 1984:3-4) and Reader’s Digest in March 1950.
Shapley, along with others such as astronomer Cecilia Payne-Gaposchkin (also at Harvard), instigated a hostile campaign against the book before it was even published. Initially, they were highly critical of a publisher as reputable as Macmillian publishing such a seemingly disreputable book, even as a trade book, and then their disapproval was re-invigorated when Macmillan included it among other trade books of possible interest to professors listed under the category “Science” in the back of a textbook catalog mailed to college professors. Within two months of the book’s initial release, the publishing of the book was transferred to Doubleday, which has no textbook division.
The fundamental criticism against this book from the astronomy community was that its celestial mechanics were irreconcilable with Newtonian celestial mechanics, requiring planetary orbits which could not be made to conform to the laws of conservation of energy and conservation of angular momentum (Bauer 1984:70). Velikovsky conceded that the behavior of the planets in his theories are not consistent with Newton’s laws of motion and universal gravitation. He proposed that electromagnetic forces could be the cause of the movement of the planets, although such forces between astronomical bodies is essentially zero (Friedlander 1995:11-12).
Velikovsky tried to protect himself from criticism of his celestial mechanics by removing the original Appendix on the subject from Worlds in Collision, hoping that the merit of his ideas would be evaluated on the basis of his comparative mythology and use of literary sources alone. However this strategy did not protect him: the appendix was an expanded version of the Cosmos Without Gravitation monograph, which he had already distributed to Shapley and others in the late 1940s — and they had regarded the physics within it as egregious.
Carl Sagan wrote that the high surface temperature of Venus was known prior to Velikovsky, and that Velikovsky misunderstood the mechanism for this heat.  Velikovsky believed that Venus was heated by its close encounter with the Earth and Mars. He also did not understand the greenhouse effect on Venus, which had earlier been elucidated by astronomer Rupert Wildt. Ultimately, Venus is hot due to its proximity to the sun; it does not emit more heat than it receives from the sun, and any heat produced by its celestial movements would have long dissipated. Sagan concludes: “(1) the temperature in question was never specified [by Velikovsky]; (2) the mechanism proposed for providing this temperature is grossly inadequate; (3) the surface of the planet does not cool off with time as advertised; and (4) the idea of a high surface temperature on Venus was published in the dominant astronomical journal of its time and with an essentially correct argument ten years before the publication of Worlds in Collision” (p. 118).
Carl Sagan has also noted that “Velikovsky’s idea that the clouds of Venus are composed of hydrocarbons or carbohydrates is neither original nor correct.”  Sagan notes that the presence of hydrocarbon gases (such as petroleum gases) on Venus was earlier suggested, and abandoned, again by Rupert Wildt, whose work is not credited by Velikovsky. Also, the 1962 Mariner 2 probe was erroneously reported in the popular press to have discovered hydrocarbons on Venus. These errors were subsequently corrected, and Sagan later concluded that “[n]either Mariner 2 nor any subsequent investigation of the Venus atmosphere has found evidence for hydrocarbons or carbohydrates” (p. 113).
Tim Callahan, religious editor of Skeptic, presses the case further in claiming that the composition of the atmosphere of Venus is a complete disproof of Worlds in Collision. “. . . Velikovsky’s hypothesis stands or falls on Venus having a reducing atmosphere made up mainly of hydrocarbons. In fact, the atmosphere of Venus is made up mainly of carbon dioxide–carbon in its oxidized form–along with clouds of sulfuric acid. Therefore, it couldn’t have carried such an atmosphere with it out of Jupiter and it couldn’t be the source of hydrocarbons to react with oxygen in our atmosphere to produce carbohydrates. Velikovsky’s hypothesis is falsified by the carbon dioxide atmosphere of Venus.”
Velikovsky’s hypothesis is also falsified, according to astronomer Philip Plait, by the presence of the Moon with its nearly circular orbit for which the length of the month has not changed sensibly in the 5,800 years the Jews have used their lunar calendar. “If Venus were to get so close to the Earth that it could actually exchange atmospheric contents [i.e., closer than 1,000 kilometers (600 miles) from the surface of the Earth],” as Velikovsky claimed, “. . . the Moon would have literally been flung into interplanetary space. At the very least it orbit would have been profoundly changed, made tremendously elliptical. . . . Had Venus done any of the things Velikovsky claimed, the Moon’s orbit would have changed.”
Regarding Jupiter’s radio emissions, Sagan noted that “all objects give off radio waves if they are at temperatures above absolute zero. The essential characteristics of the Jovian radio emission – that is is nonthermal, polarized, intermittent radiation, connected with the vast belts of charged particles which surround Jupiter, trapped by its strong magnetic field – are nowhere predicted by Velikovsky. Further, his ‘prediction’ is clearly not linked in its essentials to the fundamental Velikovskian theses. Merely guessing something right does not necessarily demonstrate prior knowledge or a correct theory.” Sagan concluded that “there is not one case where [Velikovsky’s] ideas are simultaneously original and consistent with simple physical theory and observation.”
By 1974, the controversy surrounding Velikovsky’s work had permeated US society to the point where the American Association for the Advancement of Science felt obliged to address the situation, as they had previously done in relation to UFOs, and devoted a scientific meeting to Velikovsky. The meeting featured, among others, Velikovsky himself and Carl Sagan. Sagan gave a critique of Velikovsky’s ideas and attacked most of the assumptions made in Worlds in Collision. His criticisms are present in his book Broca’s Brain: Reflections on the Romance of Science and is much longer than that given in the talk. Sagan’s arguments were aimed at a popular audience and he did not remain to debate Velikovsky in person, facts that some have taken to undermine Sagan’s analysis. Sagan rebutted these charges, and further attacked Velikovsky’s ideas in his PBS television series Cosmos.
Later in November 1974 at the Biennial Meeting of the Philosophy of Science Association held at the University of Notre Dame, Michael W. Friedlander, professor of physics at Washington University in St. Louis, confronted Velikovsky in the symposium “Velikovsky and the Politics of Science” with examples of his “substandard scholarship” involving the “distortion of the published scientific literature in quotations that he used to support his theses”. For example, contrary to Velikovsky, R.A. Lyttleton did not write “the terrestrial planets, Venus included, must [emphasis added] have originated from the giant planets. . . .” Rather, Lyttleton wrote “. . . it is even possible. . . .” As Friedlander recounts, “When I gave each example, [Velikovsky’s] response was ‘Where did I write that?’; when I showed a photo copy of the quoted pages, he simply switched to a different topic.”
A thorough examination of the original material cited in Velikovsky’s publications, and a severe criticism of its use, was published by Bob Forrest. Earlier in 1974, James Fitton published a brief critique of Velikovsky’s interpretation of myth, drawing on the section “The World Ages” and the later interpretation of the Trojan war, that was ignored by Velikovsky and his defenders whose indictment began: “In at least three important ways Velikovsky’s use of mythology is unsound. The first of these is his proclivity to treat all myths as having independent value; the second is the tendency to treat only such material as is consistent with his thesis; and the third is his very unsystematic method.” A short analysis of the position of arguments in the late 20th century was given by Dr. Velikovsky’s ex-associate C. Leroy Ellenberger, a former senior editor of Kronos (a journal to promote Velikovsky’s ideas) (Bauer 1995:11), in his essay. Almost ten years later, Ellenberger criticized some Velikovskian and neo-Velikovskian qua “Saturnist” ideas in an invited essay.
The storm of controversy that was created by Velikovsky’s works, especially Worlds in Collision, may have helped revive the Catastrophist movements in the last half of the 20th century; it is also held by some working in the field that progress has actually been retarded by the negative aspects of the so-called Velikovsky Affair.
More recently, the absence of supporting material in ice core studies (such as the Greenland Dye-3 and Vostok cores), bristlecone pine tree ring data, Swedish clay varves, and many hundreds of cores taken from ocean and lake sediments from all over the world has ruled out any basis for the proposition of a global catastrophe of the proposed dimension within the later Holocene period.[Citation needed] Also, the fossils, geological deposits, and landforms in Earth in Upheaval, which Velikovsky regards as corroborating the hypothesis presented in Worlds in Collision have been, since their publication, explained in terms of mundane noncatastrophic geologic processes.[Citation needed] So far, the only piece of the geologic evidence, which has shown to have a catastrophic origin, are coral-bearing conglomerates found within the Hawaiian Islands. These conglomerates are now attributed to mega-tsunamis generated by massive landslides created by the periodic collapse of the sides of the islands. In addition, these conglomerates, as many of the items cited as evidence for his ideas in Earth in Upheaval are far too old to be used as valid evidence supporting the hypothesis presented in Worlds in Collision.
Henry Bauer notes that:
“Macmillan had followed the normal procedure of having the manuscript of Worlds in Collision evaluated by outside readers. We know the identities of two of them: O’Neill, science editor of the New York Herald Tribune, and Atwater of the Hayden Planetarium and the American Museum of Natural History. [..] when Shapley protested before Worlds in Collision was actually published, Macmillan sought reviews from three new and impartial referees. [..]
“The reviewers’ letters, now available in the Macmillan files at the New York Public Library, reveal that none of the three actually recommended against publication. In addition to C. W. van der Merwe, professor of physics at New York University, the readers were Clarence S. Sherman, associate professor of chemistry at Cooper Union College, and E. M. Thorndike, head of the physics department at Queens College. Though there are no statements against publication of the book, two of the three letters contain strong criticisms on some points of science. (The Macmillan files also reveal that similarly strong criticisms on points of science had been made by O’Neill, who was one of the first readers of the manuscript originally submitted by Velikovsky to Macmillan.)”
“Under the weight of many arguments, I came to the conclusion–about which I no longer have any doubt–that it was the planet Venus, at the time still a comet, that caused the catastrophe of the days of Exodus.”
“When Venus sprang out of Jupiter as a comet and flew very close to the earth, it became entangled in the embrace of the earth. The internal heat developed by the earth and the scorching gases of the comet were in themselves sufficient to make the vermin of the earth propagate at a very feverish rate. Some of the plagues [mentioned in Exodus] like the plague of the frogs…or of the locusts, must be ascribed to such causes.”
“The question arises here whether or not the comet Venus infested the earth with vermin which it may have carried in its trailing atmosphere in the form of larvae together with stones and gases. It is significant that all around the world people have associated the planet Venus with flies.”
Immanuel Velikovsky, Worlds in Collision, New York:NY,