Recent content by plxmny

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    Klein's Paradox

    I am interested in learning more about Klein's paradox. My QM book said you need QFT to treat it properly. I did a quick internet search but found no expository materials. Even Wikipedia had no mention. This forum had very little of substance that I could find on the subject. Maybe someone can...
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    SL(2,C) etc

    Thanks James - I really appreciate your effort. I will read through your answer carefully. I posted a similar question under linear algebra but didn't get a serious answer. What prompted this was the fact that 1 0 0 1 0 1 -1 0 work like complex numbers so I wondered what the whole...
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    What is this ring called?

    repeat after me ... "I don't know" ... all together now ... "I don't know"....
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    What is this ring called?

    NateTG, 0 is just 0 0 0 0 and + is just matrix addition and x is just matrix multiplication. I found some stupid wikipedia thing where these 4 were given names like K0 K1 K2 K3 but no references were given so that was a dead end. I'm at work so I can't look it up in my books.
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    What is this ring called?

    Thanks, NateTG, for taking the time to respond. That is what I thought until I realized that it had to be a RING for closure. So then I thought I would like to know the NAME of it, at least.
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    What is this ring called?

    This set of four matrices: 1 0 | 0 1 | -1 0 | 0 1 0 1 | 1 0 | 0 1 | -1 0 are closed under multiplication. What is it called? I know that it is not those silly quaternions
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    SL(2,C) etc

    When people discuss the Lorentz transformation, the start talking about "groups " of transformations SL(2,C), SO(1,3) etc. Looks impressive! Where can I learn this stuff too? I asked a similar question in the Linear Algebra section but it gets less traffic
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    Boundary Conditions for Fermi Gas

    Hi I am new to solid state. I just read about fermi gas in a cube. For some reason the author used periodic boundary conditions? Why didn't they choose finite well potential where the height of the well is related to the work function?
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    Undergrad Lab Experiment

    Thanks, Creator - I will definitely check that out! I appreciate your help!:smile: (Amazing how many non-answers I get on these silly forums)
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    Undergrad Lab Experiment

    The average answer seems to be "tunneling diode" but it is difficult to see how one could demonstrate tunneling with such a device - other than to point at it and say "there's tunnelin' in that thar device!" ;)
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    Undergrad Lab Experiment

    Thank you very much for both of your replies. I have seen the "photon tunneling on your kitchen table". Someone else is doing that. Yes, we have access to a semiconductor fabrication lab! Just tell me what you have in mind and I can get it rolling!
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    Undergrad Lab Experiment

    Hi Y'all, I would like to demonstrate electron tunneling in my Modern Physics lab class. Does anyone know of how to set such an experiment up? We have a lot of equipment and $$$ available, so that's not a problem. I don't want to ask the prof beforehand because he's kinda dumb.
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    Need mental picture

    Well I am just learning this stuff and it's pretty clear that there is a lot of obfuscation going on. So I am taking very small bites. I can definitely visualize a linear transformation. Maps a vector to another vector. Period.
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    Need mental picture

    Hmm. I take it you've never read David Hume. Anyways, I thought a little about this on my lunch break. I came up with "a linear combination of linear combinations". Doesn't seem like a concept worth worrying about.
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    Need mental picture

    Hello Gals, I know what a scalar is. I know what a vector is. I know what a linear transformation is. But what in the name of sweet aunt petunia is a rank 3 tensor? Love, Plx Mny
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