# Ships, Dinosaurs, and Nuclei: It's the Scales that Count

**Jim Friar**

T-16, LANL

The question, "Were dinosaurs warm blooded?", will be explored by appealing to scales and dimensional analysis, as will be the question, "What was the Royal Navy's secret weapon in the 19th century?". The question, "What is a nucleus?" is discussed from the perspective of scales. Chiral symmetry is introduced by examining the Rutherford experiment, and the influence of that symmetry on nuclear physics is discussed. Power counting (a form of dimension alanalysis) and "naturalness" are introduced and are used to assess the importance of many-body forces, and to answer the question, "Is nuclear physics tractable?". An appeal is made to Gilbert's Law of Magnetism to judge the complexity of calculations in light nuclei. Recent benchmarks in our understanding of systems are reviewed.

************************************************************** **This is NOT a regular seminar**, but a colloquium that I will give at the University of Arizona. I will try to show in simple terms how nuclear physics"works", using illustrative examples from the history of science, paleontology, optics, and movie trivia.