Part 5/14:
A key concept in modern physics is symmetry. Emmy Noether’s groundbreaking work showed that symmetries imply conservation laws—for example, rotational symmetry leads to conservation of angular momentum, and time invariance leads to conservation of energy.
In quantum field theory, gauge symmetries are fundamental. They dictate how particles interact via force-carrying bosons (called Bzons). For instance, the electromagnetic force arises from the U(1) gauge symmetry, associated with electric charge, mediated by massless photons.