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:
1. Venus must be still very hot as young planets radiate heat.
2. Venus must be rich in petroleum gases, and hydrocarbons.
3. 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:
1. Jupiter emits radio noises.
3. The Sun has an electric potential of approximately 1019 volts.
4. 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."
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, 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 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.
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.