Na.C3.AFve and scientific realism or direct and indirect realism Naïve realism

realism in physics refers fact physical system must have definite properties whether measured/observed or not. physics 19th century implicitly , explicitly taken based on philosophical realism.

scientific realism in classical physics has remained compatible naïve realism of everyday thinking on whole there no known, consistent way visualize world underlying quantum theory in terms of ideas of everyday world. general conclusion in quantum theory naïve realism, although necessary @ level of observations, fails @ microscopic level. experiments such stern–gerlach experiment , quantum phenomena such complementarity lead quantum physicists conclude [w]e have no satisfactory reason ascribing objective existence physical quantities distinguished numbers obtained when make measurements correlate them. there no real reason supposing particle has @ every moment definite, unknown, position may revealed measurement of right kind... on contrary, maze of contradiction inject quantum mechanics such concepts carried on language , philosophy of our ancestors... more exact if spoke of making measurements of this, that, or other type instead of saying measure this, that, or other physical quantity . no longer possible adhere both principle of locality (that distant objects cannot affect local objects), , counterfactual definiteness, form of ontological realism implicit in classical physics. interpretations of quantum mechanics hold system lacks actualized property until measured, implies quantum systems exhibit non-local behaviour. bell s theorem proved every quantum theory must either violate locality or counterfactual definiteness. has given rise contentious debate of interpretation of quantum mechanics. although locality , realism , in sense of counterfactual definiteness, jointly false, possible retain 1 of them. majority of working physicists discard counterfactual definiteness in favor of locality, since non-locality held contrary relativity. implications of stance discussed outside of microscopic domain thought experiment of schrödinger s cat illustrates difficulties presented. quantum mechanics applied larger , larger objects one-ton bar, proposed detect gravity waves, must analysed quantum mechanically, while in cosmology wave function whole universe written study big bang. difficult accept quantum world somehow not physically real, quantum mechanics forces abandon naïve realism , though can argued counterfactual definiteness realism of physics more specific notion general philosophical realism.

[w]e have give idea of realism far greater extent physicists believe today. (anton zeilinger)... realism, means idea objects have specific features , properties—that ball red, book contains works of shakespeare, or electron has particular spin... objects governed laws of quantum mechanics, photons , electrons, may make no sense think of them having defined characteristics. instead, see may depend on how look.

yet many scientists mathematical realists, , since there several competing interpretations of quantum mechanics there little reason contemporary realists worry anti-realist interpretations of quantum strangeness.