FoundationalConceptsNeuroscience

quantum mechanics.
Quantum mechanics represents a radically different description
of what might be called physical reality. In pre-quantum (so-called
classical) physics, the objects of analysis and the properties of physical
systems are conceived as having an existence independent of observa-
tion. The properties of matter and energy are inherent qualities of the
universe that may be fathomed by our observations but are not in any
way dependent upon observations. In quantum physics, interaction is
crucial to defining the properties of a system. In part, this stems from
the fact that atomic and molecular systems are so small that the act
of observation necessarily perturbs the system in unexpected ways,
changing its properties. However, it goes beyond this in complicated
ways, with the interaction we humans have as observers seemingly
playing a new and critical role in defining the properties of systems
being measured, a concept completely unanticipated in classical
physics.
Figure 4.1 shows the créme de la créme of early twentieth-century
physicists at a conference in Belgium in 1927. Front and center in the
photo is Albert Einstein. To Einstein’s right are Hendrik Lorentz, Marie
Curie (the only person in the group to have received two Nobel Prizes),
and Max Planck. The folks in the rows behind Einstein include Erwin
Schrédinger, Wolfgang Pauli, Werner Heisenberg, Paul Dirac, Louis de
Broglie, Max Born, and Niels Bohr. They had come together to discuss
the rapid developments in the new physics of quantum mechanics.
Niels Bohr (1885-1962) was one of the most influential physicists
in the development of quantum mechanics; some say he was second
only to Einstein in his impact on twentieth-century physics. Both
Bohr and Einstein were deeply interested in what physics can say
about the nature of reality. Einstein maintained that there is an un-
derlying physical reality to the universe that exists independent of