This book grew out of notes from physics lessons for the liceo scientifico, gathered over years of teaching in the third and fourth years. It is not meant to replace a traditional textbook: the excellent texts on the market cover the syllabus with care and completeness, and it often refers to them. The approach here is different. Each chapter is a narrative reconstruction of how one arrives at a result, an experiment, a formula, with the pace of a lesson delivered aloud in class.
The underlying idea is that physics is not a list of formulae to be filed away, but a way of reasoning that can be reconstructed every time. For this reason the text shows the path, not just the destination: the hesitations, the questions, the attempts that usually disappear in the tidied-up version of the result.
Three principles guide the exposition.
- Understand first, remember later. Formulae come after a physical motivation, never before. An equation that is understood does not need to be memorised: it can be reconstructed when needed, because its meaning is known.
- Show how one thinks, not just what one thinks. Proofs, examples and problems are written as complete lines of reasoning, including the steps that are usually skipped. The aim is for the student to be able to retrace the path alone, not merely check that the sums add up.
- Connect. The book insists on the analogies between phenomena that superficially seem unrelated. The harmonic oscillator, for example, reappears everywhere: from springs to LC circuits, from light to quantum particles. Recognising the same pattern under different disguises is half of a physicist’s job.