The Size of the Universe – Belief and Knowledge Through 2,500 Years

Abstract

Erik Høg takes the reader on an intellectual journey from ancient cosmologies to modern astrometry. From Anaxagoras and Ptolemy to Tycho Brahe and today's measurements, he shows how our idea of the Universe's size has gradually expanded—both conceptually and numerically. The article highlights the tension between faith, philosophy, and observation, and demonstrates how precise measurements of parallax, Cepheids, and redshift revolutionized our worldview. For physicists, it's a reminder that methodical progress—not least in instruments—drives understanding. The text also puts today's cosmological distance scale into perspective and shows just how radically our understanding has changed in only a few centuries. It's a reflection on the expansion of knowledge alongside the Universe.