It is not my intention to enter here into the extensive debate on the conceptual foundations of quantum mechanics. Suffice it to say that anyone who has seriously studied the equations of quantum mechanics will assent to Heisenberg's measured (pardon the pun) summary of his celebrated uncertainty principle:
Along the same lines, Niels Bohr wrote:
We can no longer speak of the behaviour of the particle independently of the process of observation. As a final consequence, the natural laws formulated mathematically in quantum theory no longer deal with the elementary particles themselves but with our knowledge of them. Nor is it any longer possible to ask whether or not these particles exist in space and time objectively ...
When we speak of the picture of nature in the exact science of our age, we do not mean a picture of nature so much as a picture of our relationships with nature. ...Science no longer confronts nature as an objective observer, but sees itself as an actor in this interplay between man [sic] and nature. The scientific method of analysing, explaining and classifying has become conscious of its limitations, which arise out of the fact that by its intervention science alters and refashions the object of investigation. In other words, method and object can no longer be separated.
An independent reality in the ordinary physical sense can ... neither be ascribed to the phenomena nor to the agencies of observation.Stanley Aronowitz has convincingly traced this worldview to the crisis of liberal hegemony in Central Europe in the years prior and subsequent to World War I.
A second important aspect of quantum mechanics is its principle of complementarity or dialecticism. Is light a particle or a wave? Complementarity ``is the realization that particle and wave behavior are mutually exclusive, yet that both are necessary for a complete description of all phenomena.'' More generally, notes Heisenberg,
the different intuitive pictures which we use to describe atomic systems, although fully adequate for given experiments, are nevertheless mutually exclusive. Thus, for instance, the Bohr atom can be described as a small-scale planetary system, having a central atomic nucleus about which the external electrons revolve. For other experiments, however, it might be more convenient to imagine that the atomic nucleus is surrounded by a system of stationary waves whose frequency is characteristic of the radiation emanating from the atom. Finally, we can consider the atom chemically. ...Each picture is legitimate when used in the right place, but the different pictures are contradictory and therefore we call them mutually complementary.And once again Bohr:
A complete elucidation of one and the same object may require diverse points of view which defy a unique description. Indeed, strictly speaking, the conscious analysis of any concept stands in a relation of exclusion to its immediate application.This foreshadowing of postmodernist epistemology is by no means coincidental. The profound connections between complementarity and deconstruction have recently been elucidated by Froula and Honner, and, in great depth, by Plotnitsky.
A third aspect of quantum physics is discontinuity or rupture: as Bohr explained,
[the] essence [of the quantum theory] may be expressed in the so-called quantum postulate, which attributes to any atomic process an essential discontinuity, or rather individuality, completely foreign to the classical theories and symbolized by Planck's quantum of action.A half-century later, the expression ``quantum leap'' has so entered our everyday vocabulary that we are likely to use it without any consciousness of its origins in physical theory.
Finally, Bell's theorem and its recent generalizations show that an act of observation here and now can affect not only the object being observed -- as Heisenberg told us -- but also an object arbitrarily far away (say, on Andromeda galaxy). This phenomenon -- which Einstein termed ``spooky'' -- imposes a radical reevaluation of the traditional mechanistic concepts of space, object and causality, and suggests an alternative worldview in which the universe is characterized by interconnectedness and (w)holism: what physicist David Bohm has called ``implicate order''. New Age interpretations of these insights from quantum physics have often gone overboard in unwarranted speculation, but the general soundness of the argument is undeniable. In Bohr's words, ``Planck's discovery of the elementary quantum of action ... revealed a feature of wholeness inherent in atomic physics, going far beyond the ancient idea of the limited divisibility of matter.''