The FBI leads US domestic counterintelligence, so during the Cold War it isn't surprising that someone from a Warsaw Pact country who seems to travel randomly a

The FBI leads US domestic counterintelligence, so during the Cold War it isn't surprising that someone from a Warsaw Pact country who seems to travel randomly around, moving within (and staying at the homes of!) a group of intelligentsia whose work is foundational for cryptography, hydrodynamics, and celestial mechanics, would have had a fair amount of resources devoted to them. > All mathematics is divided into three parts: cryptography (paid for by CIA, KGB and the like), hydrodynamics (supported by manufacturers of atomic submarines) and celestial mechanics (financed by military and other institutions dealing with missiles, such as NASA). —VIA (Pedantry: the FBI also does some drugs stuff, but Erdős would've been way too small for them to bother) Lagniappe: https://simonsingh.net/books/fermats-last-theorem/wacky-fermat-stuff/devilish-short-story/ https://simonsingh.net/books/fermats-last-theorem/wacky-ferm...