June 4, 1999
"Quantum Optics" (QO) seems to me to epitomise what is wrong with the orthodox quantum theory (QT) approach to fundamental physics. It has evolved as a system of rules for predicting the outcomes of experiments, but it does not attempt any real physical explanations. Interference is supposed to happen as a result of interference between "probability amplitudes", not as a result of real superpositions of wave properties such as "electric displacement". Where interference produces a dark fringe in a pattern, this is supposed to mean that no "photons" reach that point. But consider the similar case with water waves: there is no question of anything of real physical significance being present at the points of high amplitude and absent at stationary points in an interference pattern. The constituent waves just flow through all points. It is meaningless (sorry - I may have to eat my words later, as this sounds too dogmatic!) to build a theory around just parts of a wave.
Optics - at least, the low-energy optics that I am concerned with - involves waves that are spread out in space and time, and that split into other waves at devices such as beamsplitters. To try and model them as particles is bound to lead to problems!
Looking at QO experiments as an outsider, I have the impression that experimenters have always felt free to manipulate the apparatus so as to achieve the predicted result, and there have sometimes been several possible ways of doing this. They can, for example, chose to alter the intensity of a laser, or the sensitivity of a detector, or the band width of a filter. Results that do not match prediction have only occasionally reached publication, for the publication system demands that experiment be backed by theory. What can they do with results that do not fit? These are in fact the very results that are potentially valuable, telling us what is really happening, but they tend to be discarded as an embarrassment.
The whole collection of experiments in any given area is thus rather confusing, giving the appearance of uninterrupted confirmation of predictions, but in fact achieving this as a result of an underlying hotch-potch of ad hoc experimental adjustments! Within the QO community, there seems also to be a very polite and considerate attitude towards other people's work. The first person to produce a "story" that seems to hang together seems to acquire a monopoly that nobody else will challenge. If some of the "evidence" backing that story is not quite as strong as it should be, who is going to say so?
But enough of politics, psychology and criticisms! What about the science - the facts that have led me to these views?
My first contributions are my essay, The Nature of Light, and various papers, such as "EPR, Magic and the Nature of Light" , that mention that I am not happy with the QT ideas on atomic cascades. The two are not unrelated. Many of my ideas came from study of Alain Aspect's thesis, in which QT ideas on atomic cascades led him to make assumptions that led to the infamous "non-local effects"!
26:5:99: I've just written Part II of my paper on PDC and realised that I have not given any links to Part I! If people are interested, the draft (in Latex) of a paper with the maths in it is available on request. This work challenges some of the predictions of SED, as well as QT. Part I covers some features of the "degenerate case" of situations where the vertically and horizontally polarised outputs are separate. Part II is concerned with the special case in which they are superimposed physically.
It might be advisable first to read the relevant section from my contribution to the Instantaneous Action at a Distance book first. PDC is a field that is rather difficult at first to break into, but once you've made a start I'm sure that my rational approach must be easier than the QT one! I have problems in that, as mentioned above, the experimenters have felt free to use any method that comes to hand (well, almost!) to achieve "correct predictions", and it is not always possible to deduce from the published reports exactly what is happening. One can only deduce this from reading "between the lines" from many related reports. One can, of course, also directly ask the experimenters for supplementary information, and this I have done. I propose to include some of my correspondence in the essay.
PDC is an area in which realism should be able to win! It does not need particle accelerators to do the experiments, which can be done in an ordinary laboratory. If you are interested in this subject, please do get in touch. Young people are especially welcome, with fresh brains, as my own is becoming just slightly confused! Too many hypotheses; experiments too limited in scope.
4:6:99: See also my various Suggestions for experiments. They include what some people will find most interesting, my latest ideas for refuting claims that Nature really is nonlocal: "EPR" experiments obey local realism!