- #1
Kyle.Nemeth
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Homework Statement
In Griffiths Introduction to Quantum Mechanics textbook, he shows that for any wave function that is time-dependent (which implies that the state of any particle evolves with time), the wave function will stay normalized for all future time. There is a step in the proof that I seem to intuitively understand, but seems like it may be invalid as it would violate the product rule of differentiation.
2. Homework Equations
Here is what he does in the book,
[tex] \frac {\imath\hbar}{2m}(\Psi^*\frac {\partial^2\Psi}{\partial x^2}-\frac {\partial^2\Psi^*}{\partial x^2}\Psi)=\frac{\partial}{\partial x}[\frac {\imath\hbar}{2m}(\Psi^*\frac {\partial\Psi}{\partial x}-\frac {\partial\Psi^*}{\partial x}\Psi)][/tex]
The Attempt at a Solution
Since the partial derivatives are operators, it doesn't make sense to me to have them factored out and sort of "skipping over" the psi* function (well, I mean the partial derivative that's being factored out of that first time with the psi* in it). Is it that the psi* and the derivative being multiplied to it are commutative, so that it might make more sense to factor out a partial derivative after switching their order?