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classes:2009:fall:phys4101.001:q_a_1030 [2009/10/30 11:22] – fitchclasses:2009:fall:phys4101.001:q_a_1030 [2009/11/30 16:32] (current) – youmans
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 ====chap0326 - 9:44 - 10/26/09==== ====chap0326 - 9:44 - 10/26/09====
 I'm still a little confused as to how we can show that <f_p'|f_p> = d(p-p') and what the so called Dirac orthonormality is really saying.  I'm still a little confused as to how we can show that <f_p'|f_p> = d(p-p') and what the so called Dirac orthonormality is really saying. 
 +
 +===Hardy 11:20 - 11/01/09====
 +I also have a hard time to understanding the math inside this equation. It turns out to be equivalent to the proof of equation [3.31] in our textbook. I think the technique used in the proof must be very tricky and just a matter of math.
 +
 +===Blackbox 2:10 - 11/01/09====
 +Yes, it' a kind of Fourier trick. If you look at the equation 2.144, then you would understand how this proof has been made.
 +
 +=== Can 10:48 11/06/09 ===
 +For Chap <f_p'|f_p> = d(p-p'), look at this equation, if p'=p, then d(p'-p)=d(0), and d(p'-p)=0 otherwise. Mathematically, d(0)=1, the physical meaning behind it is the orthonormal of wave function in momentum space.
  
 ====ralph - 11:10AM 10/29/09==== ====ralph - 11:10AM 10/29/09====
 In problem 3.13 we had to show three parts.  I'm a little confused as to how they are related.  Particularly, is part a (the commutator identity) somehow relevant to part c? In problem 3.13 we had to show three parts.  I'm a little confused as to how they are related.  Particularly, is part a (the commutator identity) somehow relevant to part c?
- 
 ====ralph - 11:10AM 10/29/09==== ====ralph - 11:10AM 10/29/09====
 Now that I'm getting a better understanding of the new notation, can someone explain to me if it's possible to have multiple eigenvalues for the same state?  I vaguely remember hearing something like this before I fully understood its implications.  How does this work statistically? Now that I'm getting a better understanding of the new notation, can someone explain to me if it's possible to have multiple eigenvalues for the same state?  I vaguely remember hearing something like this before I fully understood its implications.  How does this work statistically?
  
 +===Hardy - 11:30 - 11/01/09===
 +I think it can't be possible for a same state to have multiple eigenvalues. Because the state is determined by 
 +<math>(B-\lambda I)|X>=|0></math>
 +===Andromeda 10:51 11/01/09===
 +the degenerate states of some operator share the same eigenvalues. for example in an atom two or more different configuration of electrons can have the same energy. 
 ====ralph - 11:10AM 10/29/09==== ====ralph - 11:10AM 10/29/09====
-My understanding is that the space-momentum uncertainty principle is analogous to the time-energy one.  What are the implications of this?  Should I change my understanding of how momentum and energy are related?  Particularly, I'm having trouble understanding how the concept of mass...  Maybe I'm just way overthinking it, or maybe my grasp on relativity is just not strong enough. +My understanding is that the space-momentum uncertainty principle is analogous to the time-energy one.  What are the implications of this?  Should I change my understanding of how momentum and energy are related?  Particularly, I'm having trouble understanding how the concept of mass fits in...  Maybe I'm just way overthinking it, or maybe my grasp on relativity is just not strong enough. 
- +===Andromeda 10:59  11/01/2009=== 
- +i think i might be overthinking this too but i am having trouble understanding the whole explanation of how energy time form of the uncertainty principle is a "consequence" of the position momentum one. he talks about how this is a good way of thinking about it in relativistic situations and at the end of paragraph he says the resemblance is quite misleading!!! can anyone clarify this a bit? 
- +
  
 +== prest121 23:10 11/1/2009 ==
 +I think the point Griffiths is trying to make is that the momentum-position uncertainty principle resembles the energy-time uncertainty principle, primarily because the uncertainty for both is <math>\hbar/2</math>.  Although the two uncertainty principles are correlated in special relativity, the quantum mechanics we are dealing with is nonrelativistic, so they are very different.  Specifically, the energy-time uncertainty principle deals with time, which we typically consider to be an independent variable.
  
 +====Dagny====
  
 +What is a good method for finding the determinant of an nxn matrix? Do you think we will need to be able to find such a determinant in this class? Why or why not?
  
 +====Jake22 4:30 11/30/2009====
 +Must all non-degenerate energy eigenfunctions be parity eigenfunctions?
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-**Q&A for the next lecture: [[Q_A_1103]]** +**Q&A for the next lecture: [[Q_A_1102]]**
classes/2009/fall/phys4101.001/q_a_1030.1256919732.txt.gz · Last modified: 2009/10/30 11:22 by fitch

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