At 10:30 PM 1/3/2013, Terry Blanton wrote:
On Thu, Jan 3, 2013 at 9:54 PM, Harry Veeder
<<mailto:hveeder...@gmail.com>hveeder...@gmail.com> wrote:
Terry, fill us in.
Did Feynman regard the concept of a negative temperature meaningless?
<http://www.openseti.org/Docs/HotsonPart1.pdf>http://www.openseti.org/Docs/HotsonPart1.pdf
Be sure to read the sidebar:
Terry quoted some of the sidebar. I'll quote more of it.
The Hotson "family business" is English literature. Mr. Hotson's
father and uncle had Harvard Ph.D.s in the subject, and his late
uncle was a famous Shakespeare scholar. Mr. Hotson, however,
always intended a career in physics. Unfortunately, he could not
resist asking awkward questions. His professors taught that conservation
of mass-energy is the never-violated, rock-solid foundation
of all physics. In "pair production" a photon of at least 1.022
MeV "creates" an electron-positron pair, each with 0.511 MeV of
rest energy, with any excess being the momentum of the "created"
pair. So supposedly the conservation books balance.
But the "created" electron and positron both have spin (angular
momentum) energy of h/4p. By any assumption as to the size
of electron or positron, this is far more energy than that supplied
by the photon at "creation."
"Isn't angular momentum energy?" he asked a professor.
"Of course it is. This half-integer spin angular momentum is
the energy needed by the electron to set up a stable standing wave
around the proton. Thus it is responsible for the Pauli exclusion
principle, hence for the extension and stability of all matter. You
could say it is the sole cause of the periodic table of elements."
"Then where does all this energy come from? How can the 'created'
electron have something like sixteen times more energy than
the photon that supposedly 'created' it? Isn't this a huge violation of
your never-violated rock-solid foundation of all physics?"
"We regard spin angular momentum as an 'inherent property'
of electron and positron, not as a violation of conservation."
"But if it's real energy, where does it come from? Does the
Energy Fairy step in and proclaim a miracle every time 'creation'
is invoked, billions of times a second? How does this fit your
never-violated conservation?"
"'Inherent property' means we don't talk about it, and you
won't either if you want to pass this course."
Well, this answer sounded to him like the Stephen Leacock
aphorism: "'Shut up,' he explained." Later Mr. Hotson was taken
aside and told that his "attitude" was disrupting the class, and
that further, with his "attitude," there was no chance in hell of his
completing a graduate program in physics, so "save your money."
He ended up at the Sorbonne studying French literature, and later
became a professional land surveyor.
However, he has retained a lifelong interest in the "awkward
questions" of physics, and with Dirac's Equation has found
some answers.
There are "professors" like that. They "profess" to be scientists.
However, we are hearing this story from the student. What I notice
is, indeed, what the professor talked about. "Attitude." This is a
story being recalled, I assume, years later, and we tend to remember
what we made events mean, not what actually happened.
What I notice first of all about this story is that Hotson *believed*
the professor about completing a graduate program. Hotson based his
entire future on one a**hole. On the other hand, it's possible that
Hotson totally misunderstood what the professor was saying to him. In
the exchange, the professor was warning him, say, that the question
was beyond his level, and he had a lot to learn first. That is
consistent with the later comment; which could mean that a
know-it-all would be unable to progress.
True or not, it's possible. This is not a judgment on Hotson's
theories, which I have not reviewed, nor is it anything conclusive
about that story. In the story -- told by Hotson -- the professor
comes off peculiarly direct. Jerk-off professors are rarely so witty.
I think the "inherent property" comment is totally brilliant!
But if Feynman, my own college level physics professor, had said that
to me, I suspect that I'd have figured out a way to mention "inherent
property" as many times as possible, and I'd have studied the
material intensely, to give the professor no excuse to give me
anything less than an A. But that, of course, is just me imagining
myself in that situation.
Professor: "The math of many-body problems is too difficult to allow
exact calculations, so we rely on approximations to estimate energy levels."
Student: "Oh, they are inherent properties, then?"
My high school physics teacher was probably my best friend. He might
well have told me I wasn't ready to understand something, though I
don't actualy recall that, but he would also have told me to keep
asking questions, and don't be afraid to be wrong. Sometimes the
answer to a question is, "Hmmm. You have a point there. We don't
know. See me after the class. Now, about today's assignment...."
And, after the class: "That was a great question. Would you like to
write a paper on this mystery, for extra credit? If you'd like any
help, just ask. Oh, by the way. Some people won't like you asking
these questions. You should know to be careful!"
I've been confronted by smart-ass students, on occasion. I just
explained the stuff, pointing out that there were things they just
hadn't studied yet, and explaining what I could of it for them.
If we take the story as real, the professor was a smart-ass himself,
but essentially wrong. People who ask inconvenient questions make the
best physicists, if they learn to moderate their belief in their own
rightness and start to become more open to learning. That does
involve, sometimes, shutting up for a while.
