Flaw in Anton Zeilinger article (Rev. Mod. Phys., Vol. 71, No. 2, Centenary 1999) This Thread is a continuation from the “Cramer new experiment” thread (see DrC post origin) to separate out comments on an Anton Zeilinger article from the discussion on Cramer ‘Transactional Interpretation’ & "retrocausality". Dr Chinese, I have to give you credit, when you make me look closer at something I at least find some deeper information and potential meanings, and learn more. I doubt Zeilinger has tried the experiment he imagines in Part III of his foundations paper you linked us too. In fact I rather regard him like Einstein considered some of his Professors, inconsistent and not in touch with the information he is presenting, at least in this section. But he does reference a source experiment later in Part III, from a 1998 Ph.D thesis by B Dopfer (University of Innsbruck), from which he claims: The key is no correlation or knowledge of the other entangled photon is considered at all. IMO this gives a condition that not even QM can explain. It means that an experimenter given a beam of light without knowing its source, could determine whether or not it was entangled based solely on the beam and no other information. If we send him light from a Laser he can generate double slit patterns. But if we send him just one beam of entangled photons with no access to the entangled beam we are to believe he would discover the beam is entangled as attempts to generate that pattern will fail. Balderdash! There is no such wave state of an entangled beam that can do that. THE PROBLEM IS the B Dopfer thesis does NOT make that claim!! A hard document to find, in its original language it can be found at;Birgit Dopfer. Figure 4.6 (Abbildung 4.6) is clear enough in any language that the lack of a pattern with the double slit is shown WITH a registration, and correlation of detections in the other beam. That is you must look at the other photon to get a no pattern view. IMO a rather embarrassing detail for the Zeilinger paper, and that section of his paper is clearly flawed. I really would like to be able to read the Dopfer paper; it has data and ideas in the figures hard to explain. (I still need to understand just what a Heisenberg Lens does). If anyone comes across a English translation of the 146 page Dopfer paper I'd like to read it. Also he figure on Page 12 of the thesis also confirmed my expectation that the shape of a Type I SPDC is significantly different than a Type II. I can see why polarization entanglement tests use Type II. Good cartoon at opening of Dopfer paper.