In the late 1960s, American scientists scrambled to catch up with their counterparts in the Soviet Union, who had identified an astonishing and potentially dangerous substance - a new form of water.
Polywater was an anomalous variant of normal water that was more viscous, boiled at higher temperatures and froze at lower ones. There was some concern that if it were released from containment, it might catalyze a reaction that would transform all normal water in the world into a form incapable of supporting life. If that sounds familiar, that's because it's almost exactly the plot of Kurt Vonnegut's 1963 novel Cat's Cradle, in which the fictitious substance Ice-Nine transforms liquid water into an alternate form that is solid at room temperature.
The popular press began to take notice. The New York Times wrote in 1969:
Water is so essential, so abundant, so simple in composition and so intensively studied over the centuries that it seems a most unlikely substance to provide a major scientific surprise. Nevertheless, this is precisely what has recently occurred. American chemists have confirmed that there is a form of water with properties quite different from that of the fluid everyone takes for granted.
It took a concerted research effort to determine that America and the world could breathe easy. Polywater wasn't a threat to the planet. Polywater didn't exist.
This "discovery" of a non-existent substance has since become a case study in pathological science, in which scientific rigor is subverted by human cognitive errors.