# Can't understand what's psi

1. Aug 26, 2014

### quawa99

I just started reading the quantum theory.I came across the wave particle duality experiments and just after that the book had the Schrödinger equation.I don't understand what psi is exactly in that equation and what a wave function is and how it differs from a wave equation mathematically.can anyone explain what it is in simple terms please?

2. Aug 26, 2014

### Staff: Mentor

Which book? You'll get better answers from us if we know which book you're working through.

The function $\psi(x,t)$ is the unknown in the Schrodinger equation. Once you know what it is, $\psi(x,t)\psi^*(x,t)$) is the probability of finding the particle at position $x$ at time $t$.

3. Aug 26, 2014

### JohnPrior3

Wavefunction describes the quantum state. When I took my first quantum mechanics course, I had a lot of trouble with stuff so I can probably understand it's ambiguity. So basically, the most important idea of quantum mechanics is measurements and how they change a system. The quantum state describes the information of the given particle i.e. spin. These mathematics behind the wave function deals with complex numbers and probability. The difference between the wave equation and the wave function is that the wave equation describes a wave in classic mechanics and the wave function is quantum mechanics. You get definitive answers through the wave equation, but the wave function has values that are probabilities. Have you studied the Stern Gerlach experiment? Tackling Schrödinger would be a little easier if you have those basics down.