Modern 2:Overview of Chapter 3

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Here is a fundamental result '''which you should prove''':
 
Here is a fundamental result '''which you should prove''':
<math> \langle \vec{p} _x \rangle _ t  = -i \hbar \int \psi^*(\vec{r},t) \partial _x \psi(\vec{r},t) d^3 r  </math> (3.4 these numbers refer the equation numbers in the book)
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<math> \langle \vec{p} _x \rangle _ t  = -i \hbar \int \psi^*(\vec{r},t) \partial _x \psi(\vec{r},t) d^3 r  </math>     '''(3.4)'''
  
 
<math> \partial _x </math> means partial with respect to <math>x</math>.
 
<math> \partial _x </math> means partial with respect to <math>x</math>.
  
 
The vector form of
 
The vector form of

Revision as of 00:21, 24 February 2006

Overview of Chapter 3

 2/24/06 
  • The state of a system is system is described by a wavefunction. ψ(r,t). The wavefunction evolves deterministically according to the Schrodinger equation. However, we give a probabilistic interpretation to the wave function that allows us to predict the measurement of a given physical quantity.
  • On the other hand, if we perform an experiment, the system will be in some state. How do we obtain as much information about this state.
  • Finally, we may wish to perform an experiment on a system in a given state; i.e., one that is prepared experimentally to have well-defined properties.

Reminder

 \langle \vec{r} \rangle _ t  = \int \vec{r} \  |\psi(\vec{r},t)|^2 d^3 r

 \langle \vec{p} \rangle _ t  = \int \vec{p}  \ |\phi(\vec{p},t)|^2 d^3 p

But we can also compute the expectation of p in position space. This is essential if we want to be able to treat variables such as angular momentum, which involve both position and momentum: \vec{L} = \vec{r} \times \vec{p}

Here is a fundamental result which you should prove:  \langle \vec{p} _x \rangle _ t  = -i \hbar \int \psi^*(\vec{r},t) \partial _x \psi(\vec{r},t) d^3 r  (3.4)

 \partial _x means partial with respect to x.

The vector form of

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