= Theoretical physics
<Theoretical physics> develops physical models, derives their consequences and identifies observations that can test them. It uses mathematics to connect assumptions with predictions: a <Lagrangian> can determine <equations of motion>, while a <symmetry> can imply a <conservation law>.
An ideal <simple pendulum> is a small but complete example. Its assumed constraint and <gravitational force> determine an equation; the <small-angle approximation> gives a tractable <oscillation period>; comparison with larger-amplitude measurements tests that approximation. A successful calculation and a physically adequate model are connected achievements, but one does not automatically establish the other.
Back to article page
