Pakistan, Aug. 1 -- There are men whose obituaries read like a catalogue of postings and pensions, and there are men whose passing empties a room that had, until that moment, felt permanently full. Pervez Butt belonged to the second kind. To the nation he served for over four decades, he was Chairman of the Pakistan Atomic Energy Commission, an engineer decorated with the Nishan-e-Imtiaz, the Hilal-e-Imtiaz, and the Sitara-e-Imtiaz. To me, he was something far less official and far more irreplaceable, the man who called my Abba, 'Shahjee - The Great'. I do not think I ever heard Uncle Pervez use that title lightly, and I never once heard my father correct him out of modesty. It was a private joke that had calcified, over decades, into sim...