I will of course explain why I think there's a simple solution, but only after seeing if there's something simple (but apparently hard to find) already out there. So, help me out here folks: Does anyone know for sure what Feynman's solution to this little puppy was? Along those lines, is Laurie M Brown from Northwestern by any chance linked into this group? I can't imagine anyone who knows more about Feynman's published works! He was after all trying to teach freshmen, and he honestly seemed to think they would all figure it out with a bit of thought!

I also think that Feynman's solution was very likely to have been relatively simple, and not some kind of tremendously detailed exercise in relativistic corrections. But I can't easily back off, because the solution is a bit too straightforward once you look at it the right way. My problem is this: I more-or-less accidentally came up with what seems to be a pretty good resolution of the paradox, and it ain't the one described in any of the papers I've seen on it. McDonald (Princeton) (Warning: I can see the paper, but it may have access restrictions for others.)

Many of these are summarized in a paper that was written and updated a decade ago by John Belcher (MIT) and Kirk T. In the decades since then, that lack of resolution has produced a surprisingly large number of published attempts to solve the Feynman Disc Paradox. As a result, I was one of many people who years ago discovered to my chagrin that he never bothered to answer his own question, at least not in any source I've ever seen. Needless to say, you can't have it both ways!įeynman, bless his heart, seemed to have an extraordinarily optimistic view of the ability of others to decipher some of his more cryptic physics puzzles. However, you could also argue that since the collapsing magnetic field will create a strong circular electric field that is tangential to the perimeter of the disc, the static charges will be pushed by that field and the disc will necessarily begin to rotate. The paradox is this: Conservation of angular momentum says that after the field collapses, the disc must of course remain motionless. The disc is permitted to warm up until the magnetic field collapses. However, the magnetic field is was generated by a small superconducting current.

The disc with its embedded static charges and magnetic field is initially at rest. The disc in it also has a strong magnetic field whose north-south axis is parallel to the rotation axis of the disc. 17-4, 'A paradox,' describes a problem in electromagnetic induction that did not originate with him, but which has nonetheless become known as 'Feynman's Disc Paradox.' It works like this: A disc (Feynman's spelling) that is free to rotate around its axis has set of bead-like static charges near its perimeter. Richard Feynman in Lectures on Physics Vol.

The feynman lectures on physics vol ii