Two stories about tacit knowledge
Freeman Dyson&#x27;s autobiography tells how in 01956 he joined General Atomics, a nuclear-reactor startup, and his small team designed and built a new kind of nuclear reactor in two years, the TRIGA; Teller was one of the team members.  The prototype operated for 39 years, 33 of them were manufactured, some are still in operation, and none of them has ever had a nuclear accident.<p>A few years after that, when Project Orion was canceled, he stopped working on nuclear reactors.  He said it just wasn&#x27;t fun anymore.  And I imagine he&#x27;s right; since about that time, working on nuclear reactors enmeshes you in the national security state, where promotion depends on political favor as much as technical competence, and rank is measured by headcount and by project classification level.  There&#x27;s a certain kind of person that&#x27;s fun for, but it&#x27;s usually not the kind of person who spends his Christmas vacation working problems from a calculus textbook.  It&#x27;s not the kind of person who discovers a lot of new things.  Atomic Energy merit badges went out of style.<p>About 20 years later, at the end of the 01970s, the costs of building new nuclear reactors started to skyrocket, which is another way of saying that our productivity at building nuclear reactors started to collapse.<p>I just read <i>Atlas Shrugged</i>, which tells a story of a technological society strangled by regulation, unpredictable kleptocracy, and a brain drain (&quot;draining the brains&quot;, the book said, 6 years before the Royal Society coined the term &quot;brain drain&quot;).  This aspect of the book resonated with me, although many others did not, perhaps in part because I live in Argentina, whose technological development is strangled by regulation, unpredictable kleptocracy, and a brain drain, though the brain drain is to the US and Europe rather than to a secret conspiracy.  We had a famous fusion energy program, Project Huemul, which turned out to be a scam.<p>I wonder if the same thing happened to nuclear engineering?  Maybe the potential Tellers and Freeman Dysons born in the 01960s and later never got involved in nuclear physics, except for David Hahn, who ended up with paranoid schizophrenia after his mother committed suicide, and died at 39 of an overdose of opiates.  Maybe nuclear engineering had a brain drain to electrical engineering, computer science, and related fields.