I’m reading Most Secret War by R. V. Jones, an English physicist’s account of his intelligence work in the Air Staff during World War II. I’m only up to the beginning of 1941, but it’s been a terrific read so far, with many enlightening anecdotes. A few dealing with erroneous assumptions were particularly good.

Much of Jones’s work dealt with radio and radar and similar phenomena. At the outbreak of WWII, we were just beginning to understand and develop this technology, and nobody knew for certain what was possible and what was not. As a result, some fairly incredible rumors were taken quite seriously. Early plans for a radio wave death ray were scrapped after calculating the necessary power output were too great, but there were still rumors that the the Germans had developed an engine killing beam of some sort.

The story, as the English heard it, was that the Germans were testing a new radio tower that could disable nearby combustion engines. Somebody would be driving by the hill in the part of the countryside where the testing was being done and their car would stop. A German soldier would come out and apologize, explaining that testing was in progress and they wouldn’t be able to proceed for twenty minutes. After a short while, the soldier would return and send the driver on his way.

The English were understandably quite concerned about this device. If the Germans perfected it and improved the range, it would be a devastating anti-bomber defense. But how does it work? It sounds incredible today. (OK, so modern cars have all sorts of electronics and radio connected computers, so actually more than credible, but given the low tech nature of carbureted cars at the time, how would radios interfere?)

Eventually a Jewish emigree from Germany explained the situation. The Germans were indeed testing a new radio tower, but in order to obtain precise measurements, they needed to eliminate interference in the area. So they posted a guard by the road and when a car approached, he would come out and ask the driver to turn off their engine. Then after testing, he’d permit the driver to continue. The radio tower wasn’t interfering with the cars’ engines, the cars’ engines were interfering with the radio tower. A minor transposition of events in the telling of the story entirely changed the conclusion.

There is an entire fallacy devoted to incorrectly inferred causation, post hoc ergo propter hoc. Combined with the fallibility of human memory and the likelihood of subtle errors introduced in the retelling, a little bit of suspected correlation can lead to a lot of assumed causation.

I found myself thinking of modern examples. Did Hulu show me an ad for milk because my smart fridge told it I just finished the carton? Much like radio tech in the prewar period, I don’t know exactly how this works, but given the dark mysteries of adtech, it could happen, right? But what if maybe I saw an ad before finishing the milk and ignored it, remembering only the ad I saw afterwards? The precise order of events matters quite a bit, but am I confident I have remembered everything precisely as it occurred? How can I know my smart fridge isn’t spying on me? Probably because I don’t actually own a smart fridge.

Another story concerns the possibility that the Germans had developed short wavelength radio transmitters. Short wavelengths would be much more effective for radar, although at the time there was a widespread belief that it was impossible to generate them. Experimenters had been attempting to create such waves, without success, for years. Eventually they developed a theory to explain their failure. The time taken for electrons to travel through the electronic valve was greater than the period of the waves to be generated. There is no basis for this theory, and it is quite incorrect, but it was accepted nevertheless because it fit what the scientists wanted to believe. This mistake was summarized as Crow’s Law.

Do not think what you want to think until you know what you ought to know.

Solid advice. There’s a lot more to the book, but these two stories stood out.