QUANTUM METAPHYSICS - E-thesis

mathematical equations of natural science no longer describing nature, but only our knowledge
of it. In saying this, he did not mean that we only address our own thinking and that our portrayal
of nature could not via further knowledge evolve.
The Copenhagen group saw that the illusion of an observer independent external world adopted
at the turn of the modern era fell apart when the observational events and the system being
investigated are interwoven (entangled) at the microscopic level. It was no longer possible to
speak in an unproblematic way about atomic particles without also considering the measurement
situation . When waves are observed in one situation and particles are observed in another, the
thought that the most fundamental level of reality consists of material particles moving in spacetime
becomes a problem. The concept of an ’object’ at the microscopic level becomes obscure.
According to Heisenberg, the question of whether particles ”as such” exist in space and time
could no longer be constituted in such a form, because it was necessary for us to conclude the
particle’s behaviour from those events which occurred when it was in interaction with some
other system like another microscopic entity or a macroscopic measurement device. Descartes’
division into res cogitans and res extensa and the world’s old division between objective events
in space and time and, on the other hand, the mind or soul in which these events are reflected,
was no longer a suitable starting point for an understanding of modern science. 591 When different
situations produced different phenomena, human beings were not only passive observers but, by
manipulating the boundary conditions, they also designed or shaped the distribution of
obtainable outcomes. This was something that Descartes could not have attained. It made sharp
separation between the world and the I impossible. 592
The Copenhagen group adopted the probability interpretation of the wave function presented by
Max Born, in which the square of the wave function gave each point a probability that a particle
could be observed at given position. Unanimity on a more accurate characterisation of the wave
function could not however be achieved. Born himself thought that the wave function was in
some way connected with reality, while Bohr took it more as a mathematical device which gave
a symbolic portrayal of a microscopic world that could not be observed. For his part, Heisenberg
speculated that the wave function addressed some world of potential possibilities, while Pauli
linked the wave function to the psychic side of reality as some kind of irrational or creative
element. On occasions, the wave function was presented as portraying nothing more than our
591 Heisenberg 1955, 12, 21.
592 Heisenberg 1962, 81.
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