Please do not send mail to the University, as it may be considerably
Email sent to my university account will probably be deleted unread; there is too much spam to delete by hand, so I delete everything unless I'm expecting a message.
For contact information, click here.
Click on the next link for my bibliography.
Here for pages of reviews of books and papers. (The "papers" page has become a sort of blog.)
Essays: Over the years I have written essays on topics which have puzzled me and put them on the "papers" page.
As the page grew, the essays became more and more difficult to locate.
Following is a list with brief descriptions.
"Restoring the quantum state after a measurement"
According to current quantum theory, a measurement applied to a system in a given state
usually changes the state. The problem addressed is whether it is possible to recover
the initial, premeasurement state. This is impossible for nontrivial projective measurements,
but can be possible for the more general so-called POVM measurements. The essay discusses
when it is possible and how to do it. It also questions some misleading statements in the literature
on this problem.
"Analysis of the famous experiment of Grangier, Roger, and Aspect supposedly establishing the existence of the photon"
This 1986 experiment is frequently
cited as establishing the existence of the photon. The analysis presented
in the essay
leads to the opposite conclusion: if the photon hypothesis it true, then there is a vanishing probability
of obtaining the experimental results.
This does not mean that the
photon hypothesis is wrong (and I doubt that it is wrong), only that the
is inconsistent with it. The essay also discusses in less detail an experiment by an undergraduate group Thorn, et al.,
which obtains results consistent with the photon hypothesis. The results of Thorn, et al. differ by an order of magnitude
from those of Grangier, Roger, and Aspect (GRA). Despite characterizing the GRA experiment as "an experimental tour-de-force,
Thorn, et al., never mentions this inconsistency!
For me, the interest in the essay is
how the GRA experiment came to be regarded as definitively establishing
the existence of the photon. For about 30 years, seemingly nobody noticed the discrepancy. It makes me wonder
how trustworthy are claims about modern physics experiments (not just photon experiments).
"A second look at P. Riley's 'On the probability of occurrence of extreme space weather events' "
P. Riley's 2012 paper "On the probability of occurrence
of extreme space weather events" concludes that the probability
of a geomagnetic storm as bad as the worst known (the so-called "Carrington event" of 1859) in the next decade is on
the order of 12%. Given that such a storm might cause trillions of dollars in damages, this is alarmingly high.
This essay points out some surprising anomalies in Riley's data and analysis. The anomalies are so serious that
I would go so far as to say that there is no reasonable scientific basis for the 12% figure. No one can say with
any reasonable degree of certainty what the actual probability is, but my personal estimate would be at least an order of magnitude lower.
Following is a link to my personal website .
Recent revisions of the papers page:
October 27, 2013.
An essay entitled "Restoring the quantum state after a measurement"
was added to the
October 23 entry on the "papers" page. The October 27 entry reports on the nearly final results of
two years of effort to obtain correction in the literature of erroneous papers of Dressel and Jordan.
December 6: 2013. A recent paper of Emerson, Serbin, Sutherland, and Veitch is recommended for
its transparent presentation of the Pusey/Barrett/Rudolph result.
February 9, 2014. (1) Reservations are expressed about a much-discussed paper "Direct measurement of the