Page13 on Griffiths quantum mechanics

In summary, when proving the Schrodinger equation preserves normalization, the book suggests taking the complex conjugate of the equation. This means changing any aspect of the equation that contains an imaginary component to minus said component. This is based on the assumption that V is real and ψ is complex. The complex conjugate of a product is the product of the complex conjugate, and the complex conjugate of a derivative is the derivative of the complex conjugate. This can be found in more detail on the wiki page for complex conjugates.
  • #1
Frank0
4
0
In the prove of the Schrodinger equation preserves the normalization I don't understand the step
from

∂ψ/∂t=ih/2m ∂2ψ/∂x2- i/h Vψ

to

∂ψ*/∂t=-ih/2m ∂2ψ/∂x2+ i/h Vψ* (h represents h bar)

the book says "taking complex conjugate equation" but I don't see how.

Thanks in advance.
 
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  • #2
Frank0 said:
In the prove of the Schrodinger equation preserves the normalization I don't understand the step
from

∂ψ/∂t=ih/2m ∂2ψ/∂x2- i/h Vψ

to

∂ψ*/∂t=-ih/2m ∂2ψ/∂x2+ i/h Vψ* (h represents h bar)

the book says "taking complex conjugate equation" but I don't see how.

Thanks in advance.

Welcome Frank, it says it's your first post~

Alright so we literally just change any aspect of the equation which contains an imaginary component to minus said component.

For example...
[itex]e^{-iHt/ \hbar} [/itex]
goes to

[itex]e^{iHt/ \hbar} [/itex]

We make the assumption that V is real and that ψ is complex.

Given the above should help, I'm sure you're familiar but, just in case ψ* refers to the complex conjugate of ψ.

Let me know if I missed what you were asking some how, though I'm sure someone can answer a little more cleanly.

http://en.wikipedia.org/wiki/Complex_conjugate
The wiki page provides the general information on conjugating as well.
 
  • #3
If you have some equation a = b then you can take the complex conjugate of both sides and get a* = b*. Then you just have to know that the complex conjugate of a product is the product of the complex conjugate; the complex conjugate of a derivative is the derivative of the complex conjugate; the complex conjugate of i is -i; etc.
 

1. What is the main concept of Page 13 in Griffiths quantum mechanics?

The main concept of Page 13 in Griffiths quantum mechanics is the introduction of the fundamental postulates of quantum mechanics, including the wave function, the measurement postulate, and the time evolution postulate.

2. How does Griffiths explain the wave function on Page 13?

On Page 13, Griffiths explains the wave function as a mathematical representation of a quantum system, which contains all the information about the possible states of the system. It is described by the Schrödinger equation and can be used to calculate probabilities of different outcomes.

3. What is the role of the measurement postulate on Page 13?

The measurement postulate, introduced on Page 13, states that upon measurement of a quantum system, the wave function will collapse into one of its possible states with a probability given by the square of the amplitude of that state in the wave function. This postulate explains the probabilistic nature of quantum mechanics.

4. How is time evolution addressed on Page 13 in Griffiths quantum mechanics?

On Page 13, Griffiths introduces the time evolution postulate, which states that the wave function of a quantum system will change over time according to the Schrödinger equation. This postulate allows for the prediction of the future state of a system based on its current state.

5. Are there any limitations or criticisms of the postulates presented on Page 13 in Griffiths quantum mechanics?

Yes, there are some limitations and criticisms of the postulates presented on Page 13 in Griffiths quantum mechanics. For example, the measurement postulate has been criticized for not addressing the issue of wave function collapse and the time evolution postulate has been criticized for being unable to fully explain the concept of measurement in quantum mechanics. Additionally, there are alternative interpretations of quantum mechanics that do not necessarily align with these postulates.

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