The operator is hermitian if  = †
The operator is anti-hermitian if Â=-ņ

where the operation † means taking hermitian conjugate defined such that the inner product = for all functions f, g.

Demonstrate that the expectation value of the anti-hermitian operator is imaginary.

Consider two less-than-desirable options. in the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. in the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. which of these two situations would result in the greatest impact force?