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

JLBRECKENRIDGE
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!

#### Attachments

• enrico fermi small.jpg
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ZapperZ
Staff Emeritus
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.

Zz.

JLBRECKENRIDGE
Zapper,

Does the geometry relate to some aspect of physics? Perhaps something to do with nuclear physics?

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 $\Psi$ is somewhat strange to me... second, he's missing a factor of $-\hbar^2$ 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.

JLBRECKENRIDGE

Joseph

Mute
Homework Helper
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 $\Psi$ is somewhat strange to me... second, he's missing a factor of $-\hbar^2$ infront of the momentum operator.

No, there is no missing factor of ##-\hbar^2##. That factor comes from writing the momentum operator out as ##p = -i\hbar \nabla##.

JLBRECKENRIDGE
Mute, do you agree that the other math on the board has no apparent connection to the geometry drawing?

No, there is no missing factor of ##-\hbar^2##. That factor comes from writing the momentum operator out as ##p = -i\hbar \nabla##.

Doh, that's true.

Mute
Homework Helper
Mute, do you agree that the other math on the board has no apparent connection to the geometry drawing?

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.

lisab
Staff Emeritus
Gold Member
Go home, Enrico. You're drunk.

He was just trolling.

He was probably thinking, "This circle/triangle thing will definitely drive someone bonkers in 100 years."

BobG
Homework Helper
He doesn't draw very good circles. It took some strategic posing and some cropping of the frame to get a half decent picture.

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]

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Well, I see a Coulomb potential. So maybe the drawing is a water molecule?

Borek
Mentor
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]

He is definitely younger on one of these pictures, probably even by several minutes.

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