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Quantum Mechanics

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Comments

  • Registered Users, Registered Users 2 Posts: 3,038 ✭✭✭sponsoredwalk


    Hi, I've started to watch some lectures on quantum mechanics & they're going well except for the fact that some of it makes no sense. Basically I just don't see how |ψ|²dτ represents the probability of finding a particle described by ψ in the volume element dτ. Most likely it's due to me having missed something in the development of the material thus far or maybe it's because the answer to this question hasn't been fully given yet - or maybe I'm just missing some elementary logic. I think it's best to briefly state exactly what's been done in the course:

    History
    Defined Schrodinger Equation
    Mentioned, without justification, the Born Interpretation:
    - The element |ψ|²dτ represents the probability of finding the particle described by ψ in the volume element dτ
    Derives the 1-Dimensional Schrodinger equation & momentum operators
    Evaluates some Gaussian integrals
    Gives four representations of the dirac delta function
    - via a Rectangle function
    - via the Heaviside step function
    - via a Gaussian function
    - via the sinc function (using this to give an integral representation)
    Goes through Fourier's integral theorem
    Derives Parseval's identity (Also known as the normalization condition)
    Inserts the Debroglie relation into the integral representation of the Dirac delta function & uses Parseval's identity to derive a relationship between position & momentum
    Derives a solution to the 1-D Schrodinger equation for a free particle
    Shows how the equation of continuity can be derived from the Schrodinger equation
    Mentioned the commutator [a,b] = ab - ba
    Just started to derive material related to expected values
    (If any of this is too short I'll expand on it)

    So I can see how normalizing the integral ∫|ψ|²dτ due to the linearity of the Schrodinger equation is a way to get ∫|ψ|²dτ = 1 & that this obviously relates things to probability but I mean to make such a definitive claim about what |ψ|²dτ stands for seems a bit much.


  • Registered Users Posts: 100 ✭✭IRWolfie-


    Because they are entangled, information can theoretically be passed between them faster than the speed of light ( or so my understanding of the subject goes),

    No, entanglement can not be used to transmit information in any way.


  • Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    So I can see how normalizing the integral ∫|ψ|²dτ due to the linearity of the Schrodinger equation is a way to get ∫|ψ|²dτ = 1 & that this obviously relates things to probability but I mean to make such a definitive claim about what |ψ|²dτ stands for seems a bit much.

    images?q=tbn:ANd9GcTbd9AHZ9DuMZr5s3yLo4MsyLPx1M0B_BURSrAFmKrgoDyxdG6A


  • Registered Users, Registered Users 2 Posts: 4,080 ✭✭✭EoghanIRL


    I'm reading a few books on quantum mechanics at the moment . How can quantum entanglement occur after particles exsist?


  • Closed Accounts Posts: 519 ✭✭✭thecatspjs


    Hi there, I have an assignment due but I'm having trouble getting started. Maybe someone can help?!

    A quantum wire in an infinite potential well has a length of 12 Angstroms. The well contains a superposition of the 3 lowest energy states. The mixing ratios are 4:12:87.

    Determine the normalized amplitude coefficients for each of the 3 states.


    I don't want the answer, just some help. The mixing ratios thing is throwing me off. I don't know/see how these come into it or what they are.


  • Registered Users Posts: 15 morison4642


    could make up some of these things your self


  • Registered Users, Registered Users 2 Posts: 566 ✭✭✭adrian92


    Just a thought , if anyone thinks worthy of a response.


    Is there any merit, do you think, in pursuing the possibility of electrical power generation via the interaction of the earth's magnetic field together with the moving conductor (viz sea water) , on principle?

    (I have not done, nor do I have the ability to, any analysis on the energy yield)


  • Registered Users, Registered Users 2 Posts: 1,891 ✭✭✭SlowBlowin


    I don't think the fish would be happy ?

    SB


  • Registered Users, Registered Users 2 Posts: 3,457 ✭✭✭Morbert


    I have unstuck this thread for now, as I'm not sure how useful it is as a reference.

    But I am open to suggestions.


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