Quantum Mechanics and Reality

Physics is quite familiar with macroscopic properties that can’t be possessed by individual atoms or molecules. As Susan Stebbing questioned in her philosophy and the physicists, where the common sense notion of solidity imply the metaphysics of continuous substances, and whether scientific substances by the scientific account of the solidity of macroscopic objects is incompatible with the common sense notion of it. Science is not concerned with the underlying truth of the theories but at the same time is concerned with the comprehensive explanation of its appearance. A theory is empirically plausible if the observational effects are true. Many differ from positivists, who hold that theoretical statements can be translated into purely observational ones, and instrumentalists, who hold that theoretical statements are merely part of meaningless algorithms that enable us to get from true observation statements to other true observational statements, and hence to predictions.

Take the case of quantum mechanics:

Bell proved a theorem in the form of an inequality, called the Bell’s inequality.


This inequality would hold if the amount of correlation was due to the probability of spin ½ in the right expression correlating with –½ in the left hand expression because they depended ( perhaps probabilistically ) on earlier sharp values of the spin when the atoms shot out particles in the opposite directions originally. Bell also showed that if Bohr’s idea did not have sharp values in the absence of experimental determination of them was correct, the correlation would be greater for certain infinite classes of values of the variable @

1) Bell’s argument requires as a premise an axiom of locality, to the effect that there is no sort of action at a distance, whereby what happens in an experiment at a space time point X can’t affect what happens at a space time point Y where XY lies outside the light-cone. The arbitrariness of simultaneity in special relativity makes this locality principle very much plausible; if there is action at a distance, we may have to ask what type of axes in the Minskowski space determines the simultaneity of the events X and Y. Even so locality could be denied, there might be preferred set of inertial axes in the Minkowski space. It might be singled out by cosmological considerations, as a frame of reference in which the cosmic background radiation is equal in all directions. Admittedly this would be worrying as electromagnetic and mechanical phenomenon would be Lorentz invariant and Bell type phenomenon would not be Lorentz invariant, but it would not be impossible.



2) Even though non-commuting quantum mechanical variables might not simultaneously have sharp values something might be made up of real propensities.

3) Even on the Bohr view, the tree in the quad exists when no one saw it, it did not combine this view with mind-body dualism and if one merely regarded an experiment as an interaction in the macroscopic object.

4) Theoretical physicists seem to disagree with one another on quantum mechanics as much as philosophers do on the issue on realism and idealism.

 Natural history is the study of rough generalizations and not of tight laws. Consistency is a necessary condition for truth , but is it the sufficient one?



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