T]here is . . . no question of a mechanical disturbance of the systemunder investigation . . . [but] there is essentially the question of an influ-ence on the very conditions which define the possible types of predictionsregarding the future behavior of the system.This fragment of his longer article is virtually the entire point of his earlier very briefresponse,8

he puts it this way:It is true that in the measurements under consideration any direct me-chanical interaction of the system and the measuring agencies is ex-cluded, but a closer examination reveals that the procedure of measure-ments has an essential influence on the conditions on which the verydefinition of the physical quantities in question rests.

[T]heoretical assumptions often allow one to say with certainty, on thebasis of the outcome of a certain experiment, what “would have hap-pened” if an alternative possible apparatus had been used.

Mermin gets involved in questions of definitions and meanings, as didBohr. But Bohr had to involve himself with such matters because he wasconfronted by a characterization of “physical reality” that was basically aliento what arises from his own knowledge-based approach. Hence he was forced,in effect, to redefine this key term to bring it into line with his own philosophy.

The central question in judging the adequacy of Bohr’s reply is whetherthe faster-than-light influence that he claims exists, within his knowledge-based framework of thinking, can be both sufficiently real to block the ap-plication of the EPR criterion of physical reality, yet sufficiently unreal toproduce no mechanical disturbance. That is the problem that troubled Bell,and probably everyone else who is troubled by Bohr’s argument

By this argument Bohr disputes the key EPR claim that performinga measurement on one of two correlated—but currently non-interacting—systems does not “disturb” the other.So the point of Bohr’s argument is to assert that within his knowledge-based and prediction-oriented Copenhagen framework there IS an action-at-a-distance influence, and the existence of this action-at-a-distance influenceblocks the EPR (implicit) claim that there is none, thereby blocking appli-cation of the EPR criterion of reality

hus, from Bohr’s perspective, in which the meaningof “physical reality” is tied to our acquiring the knowledge needed to makepredictions about it, measuring q1 does disturb the other system because itproduces “an influence on the very conditions which define the possible typesof predictions regarding future behavior of the [other] system.” Thus if wemeasure q1 then we cannot make a prediction about p2

predictions about theoutcomes of our later possible observations, then performing one of the earlierpossible measurements may exclude the possibility of performing an alterna-tive possible one

contains an ambiguity

The meaning of Bohr’s argument has been much debated. Mermin citesPlotnitsky’s book7 for a “thoughtful critique of Bell’s statements about Bohr’sviews”. Plotnitsky roundly condemns Bell as completely failing to under-stand Bohr. Bell himself admits to not understanding Bohr’s argument, butwith the implication that Bohr’s argument does not make sense

However, the term“influence events” contains an essential ambiguity.

The meaning and validity of Bohr’s reply has been muchdebated. Karl Popper5 claims that Einstein, not Bohr, won that famousbattle. John Bell6 likewise has questioned the rationality of Bohr’s argument.

he same as the nonlocal influ-ence deduced by Bohr, and used by him to block the application ofthe criterion of physical reality proposed by Einstein, Podolsky, andRosen

As I read Bohr, he too was broadly interestedin questions of definition and meaning

the influence that Bohr does identify: an influence onthe possibility of making valid predictions

Nowhere, however, do the terms“nonlocal” or “faster-than-light” or “action-at-a-distance” appear in Bohr’s reply to EPR

It is interesting to recall here the commentmade by Gell-Mann[132]: ((Niels Bohr brainwashed a whole generation ofphysicists into believing that the problem had been solved fifty years agog>

It is this notion which Bohm refers to as unbroken wholeness that isassociated with a system of two correlated quantum particles. This may seemsimilar to Bohr's idea of individed wholeness but there is an important differ-ence. Bohm's approach implies that the ((whole~>is analysable in thought (e.g.,through the concept of nonclassical but causal trajectory of a particle acted onby the quantum potential); in constrast, Bohr maintained that the entireexperimentally relevant situation was inherently an unalysable whole aboutwhich nothing could be said at all

o primeiro modelo que descreve a estrutura quântica do átomo de hidrogênio

Physicist Niels Bohr won the Nobel Prize for his quantum model ofthe atom,