Quantum Worlds

Quantum probability and many worlds

We discuss the meaning of probabilities in the many worlds interpretation of quantum mechanics. We start by presenting very briefly the many worlds theory, how the problem of probability arises, and some unsuccessful attempts to solve it in the past. Then we criticize a recent attempt by Deutsch to derive the quantum mechanical probabilities from the non-probabilistic parts of quantum mechanics...

Drift-Diffusion in Mangled Worlds Quantum Mechanics

In Everett’s many worlds interpretation, where quantum measurements are seen as decoherence events, inexact decoherence may let large worlds mangle the memories of observers in small worlds, creating a cutoff in observable world size. I solve a growthdrift-diffusion-absorption model of such a mangled worlds scenario, and show that it reproduces the Born probability rule closely, though not exac...

Worlds in the Everett Interpretation

This is a discussion of how we can understand the world-view given to us by the Everett interpretation of quantum mechanics, and in particular the rôle played by the concept of ‘world’. The view presented is that we are entitled to use ‘many-worlds’ terminology even if the theory does not specify the worlds in the formalism; this is defended by means of an extensive analogy with the concept of ...

On Schizophrenic Experiences of the Neutron or Why We Should Believe in the Many-worlds Interpretation of Quantum Theory

There are many interpretations of quantum mechanics, and new ones continue to appear. The Many-Worlds Interpretation (MWI) introduced by Everett (1957) impresses me as the best candidate for the interpretation of quantum theory. My belief is not based on a philosophical affinity for the idea of plurality of worlds as in Lewis (1986), but on a judgment that the physical difficulties of other int...

When Worlds Collide: Quantum Probability From Observer Selection?

Deviations from exact decoherence make little difference for large-amplitude quantum states, but can make a big difference for small-amplitude states. This may provide a rationale for ignoring small-amplitude states when deriving the Born measurement probabilities from the many worlds interpretation. Interactions between large and small worlds may destroy the memory of observers in small amplit...

Many Worlds : Quantum Theory and Reality ?