# A linear theory (quantum theory)?

1. Mar 16, 2008

### xylai

Some textbooks say that quantum mechanics is a linear theory. I don't know why?
How can we decide a theory is a linear theory?
Thank you!

2. Mar 16, 2008

### Staff: Mentor

The governing equation (the Schrodinger Equation) is a linear differential equation. One consequence of linearity is that if $\psi_1$ and $\psi_2$ are both solutions, then so is $\psi_1 + \psi_2$.

3. Mar 16, 2008

### xylai

Thank you!

4. Mar 16, 2008