NOTICE: This is the author's version of the work. It is posted here by permission of the AAAS for personal use, not for redistribution. The definitive version was published in Science 338, no. 6104 (12 October 2012), doi:10.1126/science.1227959 Heterodoxy and Its Discontents by Alex Wellerstein (Associate Historian, Center for the History of Physics, American Institute of Physics, College Park, Maryland; wellerstein@gmail.com) Review of: Michael D. Gordin, The Pseudoscience Wars: Immanuel Velikovsky and the Birth of the Modern Fringe (Chicago: University of Chicago Press, 2012). The history of bad ideas is as interesting, and as important, as the history of good ideas. Books on the histories of Creationism, eugenics, and Lysenkoism — to pick just a few famously bad ideas — have proven illuminating to those who want to know how science functions (or doesn’t) on the margins, and how it is co-opted into popular (and political) ends. Princeton historian of science Michael Gordin’s The Pseudoscience Wars explores a lesser-known 20th-century movement, Velikovskyism, and uses this as a lens with which to understand the power of pseudoscience in an age where scientific authority and funding have never been higher. Gordin observes anecdotally that the name Immanuel Velikovsky is essentially unknown to anyone under the age of fifty. (It was meaningless to me.) Nonetheless, there is a story of great historical and present import in the history of Velikovsky’s unusual ideas and the efforts of mainstream scientists to explain their erroneous nature to what they perceived to be an unwitting and easily misled public. That such an interesting story could emerge out of what superficially appears to be a very obscure topic is one of unexpected joys of Gordin’s book. The thesis of Velikovsky’s major book, Worlds in Collision, published in 1950, sounds so ludicrous that it’s immense popularity seems incredible: at the same time as the events in the book of Exodus, the planet Jupiter ejected a massive comet that became trapped in a gravitational and electromagnetic interaction with Earth. For the next several decades, these interactions caused the supernatural events described in the Old Testament (the “manna from heaven” were hydrocarbons rained down by the comet’s tail, for example), as well as similar catastrophes described in other religious traditions. Eventually the comet settled into a stable orbit and as such became the planet we now know as Venus. For evidence of these extraordinary claims, Velikovsky cited meticulously correlated myths from ancient history (much of which had been re-dated according to his own chronology), as well as his own idiosyncratic electromagnetic theory of gravity, and a distinctly Freudian approach to the study of history. Moreover, Velikovsky was convinced that these catastrophes (again, in a nod Freud) had been repressed as a form of collective amnesia, which explains (conveniently) why 1