Checking if Momentum Operator is Hermitian - Integration

In summary, the momentum operator in quantum mechanics is a mathematical representation of momentum, denoted by the symbol p, and is defined as the derivative of the wave function with respect to position. An operator is considered Hermitian if its adjoint is equal to itself, and this property is important in quantum mechanics as it is associated with observable physical quantities. To check if the momentum operator is Hermitian, its adjoint is compared with the original operator using an integration by parts method. It is important for the momentum operator to be Hermitian as it ensures that momentum is an observable quantity and allows for the application of mathematical techniques. If the momentum operator is not Hermitian, it would make it difficult to interpret experimental results and could
  • #1
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Homework Statement



I'm checking to see if the momentum operator is Hermitian. Griffiths has the solution worked out, I'm just not following the integration by parts.

Homework Equations



int(u dv) = uv - int(v du)

The Attempt at a Solution



I've attached an image of my work.

It seems there should be an additional 'dx' with my 'v' term, but then the 'uv' portion would have a 'dx', which wouldn't make much sense to me.

Thanks for your time.
 

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  • #2
If you set ##u = f^*##, then
$$
\frac{du}{dx} = \frac{df^*}{dx}
$$
hence
$$
du = \frac{df^*}{dx} dx
$$
 

1. What is the momentum operator in quantum mechanics?

The momentum operator is a mathematical representation of the physical quantity of momentum in quantum mechanics. It is denoted by the symbol p and is defined as the derivative of the wave function with respect to position.

2. What does it mean for an operator to be Hermitian?

An operator is considered Hermitian if it satisfies the condition that its adjoint is equal to itself. In other words, the Hermitian operator is equal to its complex conjugate. This property is important in quantum mechanics because it is associated with observable physical quantities.

3. How do you check if the momentum operator is Hermitian?

To check if the momentum operator is Hermitian, we need to calculate its adjoint and compare it with the original operator. If they are equal, then the operator is Hermitian. In the case of the momentum operator, we need to perform an integration using the integration by parts method to show that it is Hermitian.

4. Why is it important for the momentum operator to be Hermitian?

The Hermitian property of the momentum operator ensures that the physical quantity it represents, momentum, is an observable quantity in quantum mechanics. This means that the momentum operator has real eigenvalues, which can be measured experimentally. It also allows for the application of mathematical techniques such as the spectral theorem.

5. What are the implications if the momentum operator is not Hermitian?

If the momentum operator is not Hermitian, it means that the physical quantity it represents, momentum, is not an observable quantity in quantum mechanics. This would make it difficult to apply mathematical techniques and interpret the results of experiments. It could also lead to inconsistencies and contradictions in the theory.

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