Question: Do complex numbers play a part in Physics? If so, what areas?

Arttu Rajantie answered on 24 Jun 2011:

Quantum mechanics looks much simpler when one uses complex numbers. Quantum mechanics is a funny theory and many of the quantities that appear in calculations are not actually observable. The observable quantities are all real.

Some things in electromagnetism are also simpler when you use complex numbers, but not to the same extent as in quantum mechanics.