eigenvalues of normal operators
Let be a Hilbert space![]()
and the algebra of bounded operators
![]()
in . Suppose is a normal operator. Then
- 1.
- If is an eigenvalue

of , then is an eigenvalue of (the adjoint operator of ) for the same eigenvector

.
- 2.
- Eigenvectors of associated with distinct eigenvalues are orthogonal

.
Remark - It is known that for any linear operator![]()
eigenvectors associated with distinct eigenvalues are linearly independent
![]()
. 2 strengthens this result for normal operators.