Why are even and odd functions orthogonal in quantum mechanics?

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Discussion Overview

The discussion revolves around the concept of orthogonality in the context of wave functions in quantum mechanics, particularly focusing on the relationship between even and odd functions. Participants explore the implications of orthogonality, its mathematical definition, and the challenges of visualizing these concepts.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants express difficulty in visualizing the orthogonality of wave functions, particularly when considering functions like shai4 and shai100.
  • One participant questions whether understanding orthogonality extends beyond vectors to functions, indicating a need for clarification.
  • Another participant suggests that while visualizing orthogonality is challenging, it is a generalization of the concept from vectors to functions, with examples like Hermite polynomials.
  • It is mentioned that wave functions exist in an infinite-dimensional Hilbert space, complicating the visualization of their orthogonality.
  • A participant notes that the mathematical definition of orthogonality involves the integral of the product of two functions equating to zero, which differs from traditional geometric interpretations of perpendicularity.
  • One participant introduces the idea that all odd functions are orthogonal to all even functions in a periodic context, referencing Fourier analysis as a potential explanation.

Areas of Agreement / Disagreement

Participants generally agree on the mathematical definition of orthogonality but express differing views on the visualization and interpretation of this concept in the context of wave functions. The discussion remains unresolved regarding how to intuitively grasp the orthogonality of functions.

Contextual Notes

Limitations include the challenge of visualizing abstract mathematical concepts in infinite-dimensional spaces and the dependence on specific definitions of orthogonality that may vary across contexts.

hasanhabibul
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shai n and shai m are mutually orthogonal ...where n and m can any numerical value...but i can't imagine it how they can be perpendicular to one another ... (to me the worst thing is to think shai4 and shai100 are perpendicular) and what is the advantage or reason of it...can anyone help me to make me imagine orthogonality of wave function??
 
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Do you understand what it means when two mathematical (forget physics for the moment) functions are orthogonal?
 
I know about orthogonality of two vectors... Does it contain more?
 
I can easily picture shai4 is perpendicular to shai5 ... But is it also Perpendicular to shai100? Then it makes me difficult to picture up.
 
hasanhabibul said:
I know about orthogonality of two vectors... Does it contain more?

Yes, functions can also be orthogona, it is a generalization of orthogonality of vectorsl. A good example would be Hermite polynomials; but there are many, many others. This is something you would study in a course in linear algebra.

Also, I don't think you can -in general- "visualize" orthogonality.
My suggestion would be that you start by taking a look at the wiki for "orthogonal functions".
 
Since wave-functions exist in the infinite-dimensional Hilbert space, I don't think you can actually visualize them being orthogonal...
 
Well, in simple terms you can't imagine a wave function. Usually if your dealing with a vector space, the concept of orthogonal is merely the fact that the dot products between two such vectors equal 0. Heres the killer, in quantum mechanics you would be wrong to think that you can even imagine a physical interpretation of the abstract vectors that represent the state of a wave function. Much of the mathematical abstraction that you get with quantum mechanics were made up by rules that have no physical sense except in very specific cases.

In your case you are wondering why an even and odd function are considered orthogonal or even what it means. When two functions are orthogonal it means that the integral of the two functions product over a period equals 0. It has nothing to do with how you'd imagine something to be perpendicular in the traditional sense. That is a mathematical definition.

The reason why all odd functions are orthogonal to all even functions that are periodic can be explained by simple Fourier analysis. I'm sure wiki would have an ok explanation.
 

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