- #1
FredMadison
- 47
- 0
In a Hilbert-space whose dimensionality is either finite or countably infinite, we have the discrete resolution of identity
[tex]
\sum_n |n\rangle \langle n| = 1
[/tex]
In many cases, for example to obtain the wavefunctions of the discrete states, one employs the continuous form of the resolution of identity, namely
[tex]
\int dx |x\rangle \langle x| = 1
[/tex]
It doesn't seem quite valid to apply a continuous operator in a discrete Hilbert space. How can one justify it?
[tex]
\sum_n |n\rangle \langle n| = 1
[/tex]
In many cases, for example to obtain the wavefunctions of the discrete states, one employs the continuous form of the resolution of identity, namely
[tex]
\int dx |x\rangle \langle x| = 1
[/tex]
It doesn't seem quite valid to apply a continuous operator in a discrete Hilbert space. How can one justify it?