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Photo of Enrico Fermi includes math/physics I do not understand

  1. Jun 12, 2013 #1
    The attached jpeg shows Enrico Fermi at the blackboard.

    There is a geometric drawing and some math I do not understand.

    Can you point me in the right direction?

    I have searched for a discussion of what he is presenting but cannot find one.

    The photo may be familiar because it was used by the US Postal Service for a stamp honoring Enrico Fermi on the 100th anniversary of his birth.

    Thank you!

    Attached Files:

  2. jcsd
  3. Jun 12, 2013 #2


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    This is an infamous photo of Fermi that had been discussed by many people. There is an error in the equation that was written (presumably by him) on the board.

  4. Jun 12, 2013 #3

    Does the geometry relate to some aspect of physics? Perhaps something to do with nuclear physics?
  5. Jun 12, 2013 #4
    Well two problems with the first equation. One, as written it's meaningless - the two operators don't really have a meaning unless they're operating on some state, so the omission of [itex] \Psi [/itex] is somewhat strange to me... second, he's missing a factor of [itex] -\hbar^2[/itex] infront of the momentum operator.

    The equation he's written is the time-dependent Schrödinger equation for a Coulomb potential, like that of a hydrogen atom. I don't really know what the diagram he's drawing has to do with it except perhaps depicting a coordinate system.
  6. Jun 12, 2013 #5
    Thank you, dipole and zapper for your responses. Very helpful.

  7. Jun 12, 2013 #6


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    No, there is no missing factor of ##-\hbar^2##. That factor comes from writing the momentum operator out as ##p = -i\hbar \nabla##.
  8. Jun 12, 2013 #7
    Mute, do you agree that the other math on the board has no apparent connection to the geometry drawing?
  9. Jun 12, 2013 #8
    Doh, that's true.
  10. Jun 13, 2013 #9


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    Without more information it's hard to say for sure. It could be a coordinate system, as dipole suggests; I could imagine it might be a diagram to help illustrate a scattering problem.

    He could also just be writing things for a photo op.
  11. Jun 13, 2013 #10


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    Go home, Enrico. You're drunk.
  12. Jun 13, 2013 #11

    It would be a great stretch to associate the drawing with something about quantum mechanical angular momentum. Maybe that was the idea, but it certainly doesn't look anything like the orthodox representations in most textbooks:

  13. Jun 13, 2013 #12
    He was just trolling.
  14. Jun 14, 2013 #13
    He was probably thinking, "This circle/triangle thing will definitely drive someone bonkers in 100 years."
  15. Jun 14, 2013 #14


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    He doesn't draw very good circles. It took some strategic posing and some cropping of the frame to get a half decent picture.
  16. Jun 14, 2013 #15
    This link shows another picture of Fermi, younger in age, with same circle drawing on blackboard, but in this version the circle drawing also is associated with energy equations.

    http://photos.aip.org/history/Thumbnails/fermi_enrico_a16.jpg [Broken]
    Last edited by a moderator: May 6, 2017
  17. Jun 14, 2013 #16
    Well, I see a Coulomb potential. So maybe the drawing is a water molecule?
  18. Jun 14, 2013 #17


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    He is definitely younger on one of these pictures, probably even by several minutes.
    Last edited by a moderator: May 6, 2017
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