# Probability of zero in stationary wave state

1. Sep 22, 2006

### knightpraetor

What is it that causes the probability of stationary waves ( or waves in general) to be zero at a particular point? I mean, when i look at a stationary wave state there are places that there are zero probability of the particle being at with a particular energy, but i don't understand why there is zero probability there

2. Sep 22, 2006

### dextercioby

I'm sure you're confusing the probability density with the probability itself. By "stationary waves" (in QM perhaps) do you mean "plane waves" ? They describe particles with definite energy & momentum.

Daniel.

3. Sep 22, 2006

### masudr

By stationary wave, I think he/she means stationary state: i.e. an energy eigenstate (which is, therefore, independent of time, assuming a time-independent Hamiltonian).

4. Sep 23, 2006

### Meir Achuz

Take a high speed photo of a vibrating string in its second harmonic.
The center will never move.

5. Sep 23, 2006

### masudr

And as for the "what causes it..." part of the question, the answer is simple: boundary & continuity/smoothness conditions.