- #1

Demystifier

Science Advisor

- 10,611

- 3,352

## Main Question or Discussion Point

I have just found out that Feynman also (re)discovered (some essential aspects of) Bohmian mechanics a long time ago, in his "Feynman Lectures on Physics" part III. Namely, in the last chapter devoted to superconductivity as macroscopic manifestation of quantum mechanics, he derives equations that are exactly equal to the Bohmian equations of motion (with classical electromagnetic field). Yet, he does not mention Bohm in this context, so I presume that he was not aware that these equations have already been discovered earlier by Bohm (and much more earlier by de Broglie). Indeed, Feynman's equations (21.19) and (21.31) are the Bohm equations for velocities. Likewise, Feynman's equation (21.38) is the Bohm equation for the acceleration, including the term with the quantum potential. In fact, Feynman even calls it "mystical quantum mechanical potential".

Another interesting feature of the Feynman discussion is the fact that he interprets these velocities as MACROSCOPIC velocities of an electron current in a superconductor. Since such a current is macroscopic, it suggests that it might be MEASURABLE. In fact, Feynman points out that the quantum correction to the classical acceleration is not very big EXCEPT AT THE JUNCTION BETWEEN TWO SUPERCONDUCTORS. I don't know if a measurement of that kind has already been performed (the Feynman's book is quite old), but it would be truly remarkable to look for an experimental evidence of a macroscopic effect directly related to Bohmian mechanics.

Does anybody know more about measurements of electric currents in superconductors? If yes, are they compatible with Eqs. (21.19) and (21.31), or with (21.38)?

Another interesting feature of the Feynman discussion is the fact that he interprets these velocities as MACROSCOPIC velocities of an electron current in a superconductor. Since such a current is macroscopic, it suggests that it might be MEASURABLE. In fact, Feynman points out that the quantum correction to the classical acceleration is not very big EXCEPT AT THE JUNCTION BETWEEN TWO SUPERCONDUCTORS. I don't know if a measurement of that kind has already been performed (the Feynman's book is quite old), but it would be truly remarkable to look for an experimental evidence of a macroscopic effect directly related to Bohmian mechanics.

Does anybody know more about measurements of electric currents in superconductors? If yes, are they compatible with Eqs. (21.19) and (21.31), or with (21.38)?