In the book The Uranium People, Leona Marshall Libby Woods, Fermi's assistant at Chicago and famously the only woman, describes a moment when, having found a mistake in Fermi's calculations, they presented him with the correct calculation. He said, as he was prone to, affectionately, "You see, just as I said".
She describes a moment when a group of them stood, dumbfounded, as he casually listed a series of the most obscure and infrequented neutron interaction cross sections.
"In science, particularly in physics or engineering education, a Fermi problem, Fermi question, or Fermi estimate is an estimation problem designed to teach dimensional analysis, approximation, and the importance of clearly identifying one's assumptions."
As I stared at his chair at the B reactor at Hanford, knowing that he knew exactly what they were doing, I wondered...clearly identify one's assumptions.
