Observational Consequences of Many-Worlds Quantum Theory

Abstract

Contrary to an oft-made claim, there can be observational distinctions (say for the expansion of the universe or the cosmological constant) between "single-history" quantum theories and "many-worlds" quantum theories. The distinctions occur when the number of observers is not uniquely predicted by the theory. In single-history theories, each history is weighted simply by its quantum-mechanical probability, but in many-worlds theories in which random observations are considered, there should also be the weighting by the numbers or amounts of observations occurring in each history.

8 pages, no figures, LaTeX. Messages from Jerry Finkelstein and Jacques Mallah have led me to realize that, although I stand by my prediction that in a many-worlds theory you will be alive in the year 2100 in some worlds, paradoxically the evidence you will have then will not support many-worlds quantum theory over single-history quantum theory, since in either theory it will be evidence of very low measure and likelihood for a random observation. Therefore, I deleted this part of the paper (and shortened other parts)