# Are there Quantum Jumps?

## – Speakers –

- Stephen L. Adler: Effective Theories, Fundamental Theories, and State Vector Reduction

I discuss the role of effective theories in physics, and the interpretation of the GRW/CSL theories of state vector reduction as effective theories. I then briefly describe ideas for a fundamental pre-quantum theory underlying the GRW/CSL theories.

- David Albert: Quantum Mechanics and Metaphysics

Over the past twenty-five years, the Quantum-Mechanical Measurement Problem has been transformed from something almost mystical into an ordinary, tractable, scientific problem - and the achievements of Giancarlo Ghirardi and his collaborators have been decisive in this transformation. These developments re-open, for the first time in nearly a century, the possibility of a complete scientific account of nature, and of a scientifically informed metaphysics built out of and around such an account. I will explore some of the promise, and some of the problems, of such a metaphysics here.

- Giovanni Jona-Lasinio: Recent Progress in Understanding Irreversible Processes

For over seventy years our understanding of irreversible processes has been based on Onsager's 1931 papers which have provided the tools to analyze experiments in physics and physical chemistry. Onsager's approach however is valid only near equilibrium. In particular it does not require to define non equilibrium thermodynamic functionals. Recently progress has been achieved via an extension of Einstein's theory of thermodynamic fluctuations to non equilibrium dynamical situations without the restriction of being close to equilibrium. We shall illustrate in simple terms some of the basic ideas and results.

- Roger Penrose: Relativistic Quantum Realism and Minimalistic Quantum State Reduction

Although EPR effects provide impressive demonstrations of the kind of non-locality that is hard to square with a both realistic and relativistic view of state vector evolution, such issues arise already with the position measurement of a single quantum particle. It will be argued that this conflict is resolved by the non-locality of twistor quantum geometry. The actual mechanism of quantum state reduction is a much more serious matter, and, for this a minimalistic approach is proposed in which (provisionally) the speed of light is taken to be infinite. Nevertheless, a desire for Einstein's equivalence principle to have foundational significance drives one to a particular scheme for the time scale of quantum state reduction.

- Alberto Rimini: Genesis of the Spontaneous Localization Approach to Quantum Measurement

The motivations for introducing models of spontaneous reduction are briefly discussed. Then the genesis and the evolution of models based on spontaneous localization are reviewed. In particular the transition from discontinuous to continuous processes, the introduction of models for systems of identical particles and for systems of several kinds of identical particles are described. Some final considerations include a discussion of the difficulties encountered in introducing relativistic generalizations of the spontaneous localization models.

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