As far as the philosophical issue that result already required you reject either locality, realism about the physical properties of an object before measurement, or that we could choose experimental conditions (measurement angle) without having that choice spied on by the experiment we were about to perform,

]]>A lot of people want to define ‘photons’ as some sort of ‘excitations’ of waves. If you do you can then start assuming all sorts of properties to them, not only a ‘frequency’.

“According to the wave model of light, the speed of the electrons should be related to the intensity of the light. But that’s not what happens. In reality the speed of the electrons depends only on the frequency of light, and the light intensity determines the number of electrons that fly off.” (about the photoelectric effect.)

To me a photon is a photon, not a wave though.

]]>And does it make a sense to distinguish between photons ?

last not least : “Each photon then interferes only with itself. ” this statement is defintely wrong !!

]]>“Some time before the discovery of quantum mechanics people realized that the connexion between light waves and photons must be of a statistical character. What they did not clearly realize, however, was that the wave function gives information about the probability of one photon being in a particular place and not the probable number of photons in that place. The importance of the distinction can be made clear in the following way. Suppose we have a beam of light consisting of a large number of photons split up into two components of equal intensity. On the assumption that the intensity of a beam is connected with the probable number of photons in it, we should have half the total number of photons going into each component. If the two components are now made to interfere, we should require a photon in one component to be able to interfere with one in the other. Sometimes these two photons would have to annihilate one another and other times they would have to produce four photons. This would contradict the conservation of energy. The new theory, which connects the wave function with probabilities of one photon, gets over the difficulty by making each photon go partly into each of the two components. Each photon then interferes only with itself.

Interference between two different photons never occurs.

The association of particles with waves discussed above is not restricted to the case of light, but is, according to modern theory, of universal applicability.”

]]>Apparently a third paper on this issue appeared and somehow I missed it 😉

http://arxiv.org/PS_cache/arxiv/pdf/1111/1111.6597v1.pdf

The abstract reads:

“Given the wave function associated with a physical system, quantum theory allows us to compute predictions for the outcomes of any measurement. Since, within quantum theory, a wave function corresponds to an extremal state and is therefore maximally informative, one possible view is that it can be considered an (objective) physical property of the system. However, an alternative view, often motivated by the probabilistic nature of quantum predictions, is that the wave function represents incomplete (subjective) knowledge about some underlying physical properties. Recently, Pusey et al. showed that the latter, subjective interpretation would contradict certain physically plausible assumptions, in particular that it is possible to prepare multiple systems such that their (possibly hidden) physical properties are uncorrelated. Here we present a novel argument, showing that a subjective interpretation of the wave function can be ruled out as a consequence of the completeness of quantum theory. This allows us to establish that wave functions are physical properties, using only minimal assumptions. Specifically, the (necessary) assumptions are that quantum theory correctly predicts the statistics of measurement outcomes and that measurement

settings can (in principle) be chosen freely.”

Perhaps you saw this already.

]]>“As far as I can see, this paper is a fairly straightforward extension of PBR, but I only think that one of the weakened constraints is conceptually interesting. The original proof required a factorizability condition, i.e. for product states you have a Cartesian product of ontic state spaces and the distribution is independent over the factors. This can be replaced by a “local compatibility” condition, which is just the condition that if lambda is a possible ontic state for a single copy of a bunch of different states, then n copies of lambda is possible for any tensor product of n states chosen from that set. This drops the independence part of the assumption. Why this is true is very easy to see, since this is the only property of factorizability used in the original PBR result.

Hall also claims to have weakened this further to a condition of “compatibility”. This is supposed to go beyond reductionist models, which say that each system has its own individual ontic properties and the properties of composite systems are simply the collection of properties of all the parts. Hall tries to go beyond this by allowing the ontic state space of two systems to be arbitrarily different from the cartesian product of the ontic state spaces of the individual systems. I don’t think this has been achieved, since one still needs to know how the properties of the global system are related to the properties of the subsystems. Hall says that if we know that lambda is compatible with some states of one system, then we need only know that lambda is compatible with n-fold products of those states. However, since the state spaces are completely distinct, I don’t think that it makes sense to consider lambda as a possible ontic state for both a subsystem and the full composite system. This is not the case in the original theorem, or in the version with local compatibility, in which case the state on the global system is n copies of lambda rather than just one. Therefore, I don’t think that this part of the paper makes much sense.

Hall also points out that the probability distribution over the ontic state need not be independent of the choice of measurement, since only one measurement is considered for each pair of states. Whilst this is true, and perhaps interesting because it places a constraint on certain types of retrocausal theory, it does not allow the original PBR conclusion to be drawn. If another choice of measurement were made then the distributions could overlap and the quantum state would be epistemic. It is this loophole that I hope to exploit in developing an epistemic retrocausal theory. Perhaps this is worth saying, but it is certainly not groundbreaking.”

]]>http://arxiv.org/abs/1111.6304

Scott, does this impact your previous conclusions?

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