- #1
ehrenfest
- 2,020
- 1
Homework Statement
I am so confused about propagators:
[tex]K(x,t;x',0) = \int |E\rangle e^{-iEt/\hbar} \langle E| dE[/tex]
I understand the RHS of that equation perfectly: it just decomposes the time-independent state into its eigenstates and then propagates each of the eigenstates individually.
I would understand the LHS if and only if the ";x'," were removed from it. I simply do not understand why you need to get rid of the prime after you propagate the state? Why can you not propagate a time-independent wave-function of x' and get a time-independent wavefunction of x not x'?
EDIT: here is another equation from the wikipedia site on propagators:
[tex]\psi(x,t) = \int_{-\infty}^\infty \psi(x',0) K(x,t; x', 0) dx'[/tex]
I think I am starting to understand this better. So, the reason you have an x and an x' is that the x' is summed over (continuously) if we want to think of the propagator just as a huge summation. But still why don't other operators like the Hamiltonian have an (x,x') attached to them? You can think of the Hamiltonian as a matrix operator as well.