Quantum Mechanics is one of the most successful theories of nature. It accounts for all known properties of matter and light, and it does so with an unprecedented level of accuracy. On top of this, it generated many new technologies that now are part of daily life. In many ways, it can be said that we live in a quantum world. Yet, quantum theory is subject to an intense debate about its meaning as a theory of nature, which started from the very beginning and has never ended. The essence was captured by Schrödinger with the cat paradox: why do cats behave classically instead of being quantum like the one imagined by Schrödinger? Answering this question digs deep into the foundation of quantum mechanics. A possible answer is Dynamical Collapse Theories. The fundamental assumption is that the Schrödinger equation, which is supposed to govern all quantum phenomena (at the non-relativistic level) is only approximately correct. It is an approximation of a nonlinear and stochastic dynamics, according to which the wave functions of microscopic objects can be in a superposition of different states because the nonlinear effects are negligible, while those of macroscopic objects are always very well localized in space because the nonlinear effects dominate for increasingly massive systems. Then, microscopic systems behave quantum mechanically, while macroscopic ones such as Schrödinger’s cat behave classically simply because the (newly postulated) laws of nature say so. By changing the dynamics, collapse theories make predictions that are different from quantum-mechanical predictions. Then it becomes interesting to test the various collapse models that have been proposed. Experimental effort is increasing worldwide, so far limiting values of the theory’s parameters quantifying the collapse, since no collapse signal was detected, but possibly in the future finding such a signal and opening up a window beyond quantum theory.
Steven R. Brown
Q methodology was introduced in 1935 and has evolved to become the most elaborate philosophical, conceptual, and technical means for the systematic study of subjectivity across an increasing array of human activities, most recently including decision making. Subjectivity is an inescapable dimension of all decision making since we all have thoughts, perspectives, and preferences concerning the wide range of matters that come to our attention and that enter into consideration when choices have to be made among options, and Q methodology provides procedures and a rationale for clarifying and examining the various viewpoints at issue. The application of Q methodology commonly begins by accumulating the various comments in circulation concerning a topic and then reducing them to a smaller set for administration to select participants, who then typically rank the statements in the Q sample from agree to disagree in the form of a Q sort. Q sorts are then correlated and factor analyzed, giving rise to a typology of persons who have ordered the statements in similar ways. As an illustration, Q methodology was administered to a diverse set of stakeholders concerned with the problems associated with the conservation and control of large carnivores in the Northern Rockies. Participants nominated a variety of possible solutions that each person then Q sorted from those solutions judged most effective to those judged most ineffective, the factor analysis of which revealed four separate perspectives that are compared and contrasted. A second study demonstrates how Q methodology can be applied to the examination of single cases by focusing on two members of a group contemplating how they might alter the governing structures and culture of their organization. The results are used to illustrate the quantum character of subjective behavior as well as the laws of subjectivity. Discussion focuses on the broader role of decisions in the social order.
A. W. Thomas
The strong force that binds atomic nuclei is governed by the rules of Quantum Chromodynamics. Here we consider the suggestion the internal quark structure of a nucleon will adjust self-consistently to the local mean scalar field in a nuclear medium and that this may play a profound role in nuclear structure. We show that one can derive an energy density functional based on this idea, which successfully describes the properties of atomic nuclei across the periodic table in terms of a small number of physically motivated parameters. Because this approach amounts to a new paradigm for nuclear theory, it is vital to find ways to test it experimentally and we review a number of the most promising possibilities.