What makes quantum physics different to classical physics? In classical physics, you can know everything there is about a system and predict the future with certainty, but the future in the quantum world is less than certain. In quantum physics, things can be both waves and particles at the same time, and particles can exist in all places at once until they are measured and observed.

One of the founders of modern-day quantum mechanics is Erwin Schrödinger - an Austrian physicist, who lived from 1887 to 1961. Schrödinger is famous for his equation, the Schrödinger equation. This is one of the most famous equations in all of Physics - but what does it tell you, and what is it useful for?

The Schrödinger equation tells you how quantum systems - e.g. atoms, electrons, photons - behave and interact with each other. It allows us to understand how quantum mechanical systems evolve, and to make predictions about the states of systems. The Schrödinger equation is fundamental to all areas of quantum mechanics and plays a key role in quantum communication and quantum computing. These rely on the principles of entanglement and superposition, which were famously discussed by Schrödinger using his "cat in the box" thought experiment.

### Want to learn more?

Quantum mechanics and the study of the Schrödinger equation is a core part of the physics program at Heriot-Watt University. Students study quantum mechanics courses in the 3^{rd} year (B29QS Quantum Theory & Spectroscopy), 4^{th} year (B20QD Quantum Theory & Solid State Physics) and 5^{th} year (B21QM Quantum Mechanics & Statistics). This extensive coverage reflects the enormous importance of quantum phenomena in modern physics. Additionally, during summer internships there are opportunities to get involved with cutting edge research exploiting quantum effects, including quantum cryptography - a field in which Heriot-Watt employs several world-leading scientists.