Velikovsky was born in Vitebsk, Russia. As a child he learned several languages, and excelled in mathematics. In 1913 he travelled to Europe, visiting Palestine, briefly studying medicine at Montpelier, France, and taking premedical courses at the University of Edinburgh.
Just before the outbreak of World War I, Velikovsky returned to his homeland and enrolled in the University of Moscow, where he received a medical degree in 1921. From there he went to Berlin, where he married a young violinist and became the general editor of the journal, Scripta Universitatis. During this time he became acquainted with Albert Einstein, who edited the journal's mathematical-physical section. Velikovsky shifted to Palestine in 1924 and practiced psychoanalysis for the next 15 years. Some of his writings appeared in Freud's Imago.
In 1940, Velikovsky studied a number of natural disasters that occur in the Bible, such as the parting of the Red Sea and the eruption of Mt. Sinai. When he compared these biblical passages to similar entries in some obscure Egyptian texts, he became convinced they were describing the same catastrophes, and went about reconstructing ancient Middle Eastern time-lines to make both sides fit.
After studying other historical records, he became convinced that many catastrophes were linked to a single global cataclysm, and that Venus was involved. In 1939 he shifted to the United States and for the next ten years he researched these topics, the result being two separate books: Ages in Chaos - a historical reconstruction covering the years 1450 BC to 840 B.C, and Worlds in Collision.
In 1950 Macmillan published Worlds in Collision. It described how 3,500 years ago Venus was ejected from Jupiter as a comet - then started a wayward path through the solar system. Its gravitational field moved other planets out of their orbits or affected their rotation - including Earth's. Macmillan, who publish many textbooks, came under fire from scientists and academics who considered Velikovsky's ideas to be unacceptable - ideas at odds with uniformitarianism. The book was consequently banned from many academic institutions. Although it was at the top of the New York Times non-fiction bestseller list, Macmillan gave in and transferred the book to Doubleday. In 1952 Doubleday pub1ished Velikovsky's Ages in Chaos.
As an answer to his critics, Velikovsky's third book, Earth in Upheaval (1955), presented raw data that would validate any global cataclysm theory:
"I have excluded from [these pages] all references to ancient literature, traditions, and folklore; and this I have done with intent, so that careless critics cannot decry the entire work as "tales and legends". Stones and bones are the only witness."
It was fully referenced and designed to gain the support of orthodox science - however academia had already determined that anything he ever wrote would automatically be unacceptable.
Meanwhile Velikovsky had been maintaining contact with Einstein - he would send him letters and manuscripts and Einstein would return them, usually with comments written in the margins. With regards to Earth in Upheaval, Einstein accepted all the evidence of sudden violence upon the Earth, but he rejected Venus as being the cause. Nine days after their final meeting Einstein died, and a copy of Worlds in Collision was found open on his desk. He was rereading it because latest discoveries concerning Jupiter had confirmed one of Velikovsky's predictions.
It is currently accepted that a comet wiped out the dinosaurs, yet in the 1950s, when Velikovsky suggested similar ideas, he was rejected. In fact many of his radical ideas that orthodox science originally laughed at, due to their lack of scientific foundation, have become proven facts:
Velikovsky deduced each of these facts many years before mainstream science found ways to prove them. He also stated that after its close encounters with Earth, Mars and the Sun, Venus would have a much higher than expected temperature, would be enveloped in hydrocarbon clouds (remnants of its comet's tail), and would have an anomalous rotation. The scientists' predictions - a similar temperature to Earth, an atmosphere of carbon dioxide or water and standard rotation - have all since been shown to be wrong. Venus has a surface temperature of 750 degrees Kelvin - hot enough to melt lead. Its atmosphere is full of hydrocarbons and its rotation is in an opposite direction to all the other planets.
· Jupiter periodically becomes unstable and ejects excess mass.
· Jupiter emits non-thermal radio noise.
· Comets can be rich in hydrocarbons, with highly energetic electrical tails.
· The Moon has had recent surface melting, seismic and volcanic activity, none of which should be true for a body that had supposedly been dead for 4.5 billion years.
With hindsight, academia should be re-examining his work, for more of his startling ideas could also be correct. Here is Velikovsky's hypothesis on what may have previously happened to our planet:
".that under the impact of a force or the influence of an agent - and the earth does not travel in an empty universe - the axis of the earth shifted or tilted. At that moment an earthquake would make the globe shudder. Air and water would continue to move through inertia; hurricanes would sweep the earth and the seas would rush over continents, carrying gravel and sand and marine animals, and casting them on the land. Heat would be developed, rocks would melt, volcanoes would erupt, and lava would flow from fissures in the ruptured ground and cover vast areas. Mountains would spring up from the plains and would travel and climb on the shoulders of other mountains, causing faults and rifts. Lakes would be tilted and emptied, rivers would change their beds; large land areas with all their inhabitants would slip under the sea. Forests would burn, and the hurricanes and wild seas would wrest them from the ground on which they grew and pile them, branch and root, in huge heaps."
"Water evaporated from the oceans would rise in clouds and fall again in torrential rains and snowfalls. Clouds of dust, ejected by numerous volcanoes and swept by hurricanes from the ground.all this dust would keep the rays of the sun from penetrating to the earth."
Perhaps the extra-terrestrial agent was a force such as an electromagnetic field? The Earth is a giant magnet, and the fields would act upon each other. Duration would not be a factor - if the strength of this field were strong enough to tip the earth over, it would happen instantly, triggering the effects Velikovsky listed above.
Note to self - the above para could become an entire chapter
 Immanuel Velikovsky, Earth in Upheaval (1955), preface.
 Immanuel Velikovsky, Earth in Upheaval (1955), p.120-121