Two young geniuses argued physics by mail
Ibn Sina (Avicenna) and al-Biruni — two of the towering minds of their age, born within seven years of each other — carried on a written debate as young men in Central Asia around 998 CE. Across eighteen questions on Aristotle's physics and cosmology, the roughly 25-year-old al-Biruni pressed objections and the roughly 18-year-old Ibn Sina fired back, one of the most remarkable scientific correspondences of the medieval world.
How we know
IPM Today "Avicenna and al-Bīrūnī" (ipmtoday.com); Free Library "Ibn Sina–Al-Biruni correspondence" (thefreelibrary.com); LMU DFG project "The Philosophical Correspondence of Avicenna and al-Bīrūnī" (philosophie.lmu.de); birth/death years from graph (al-Biruni 973–1048, Ibn Sina 980–1037)
One of many fact-checked wonders across eight traditions at The Spring of Wisdom.