## Relative state formulation of quantum mechanics, in Reviews of Modern Physics, 29, 1957, 454-462 [FIRST EDITION IN ORIGINAL WRAPS OF HUGH EVERETT'S FAMOUS MANY-WORLDS INTERPRETATION OF QUANTUM MECHANICS]

1957. 1st Edition. FIRST EDITION IN ORIGINAL WRAPS OF HUGH EVERETT'S FAMOUS "MANY-WORLDS INTERPRETATION" OF QUANTUM MECHANICS, an interpretation in which (to use Schrodinger's thought experiment) the universe splits in two: in one view we see a cat, in another we see ourselves seeing the cat. Though Everett's ideas remain controversial, they have been accepted in some form by many prominent physicists, among them Hawking and Feynman. Everett was fascinated by many of the paradoxes seemingly inherent in traditional quantum theory (Peacock, The Quantum Revolution, 152). He did not accept Bohr's "collapse of the wave-function;" whereas Schrodinger's thought experiment posited a cat both alive and dead until the opening of a box. Everett's theory splits the universe into two states: in one we see a cat; in another we see ourselves seeing the cat.

"In 1957, working under the direction of his Ph.D. supervisor John A. Wheeler, Everett produced a novel solution to the measurement problem of quantum mechanics. This problem is to explain how it is that quantum states in superpositions appear to experimenters who interact with them as if they have definite classical outcomes. Like many physicists, Everett was unhappy with the von Neumann collapse postulate and the arbitrary quantum classical divide, and he proposed that the simplest way to resolve the measurement problem was to suppose that reality is nothing more than a quantum wave function, and that wave function does not collapse. As Schrodinger emphasized, if classical measuring device interacts with a system that is in a superposition, the wave function of the measuring device (and the experimenter who runs it) becomes correlated with each component of the superposition. What bothered Schrodinger is that real observers do not see superpositions, but only definite results (such as either a definitely alive cat or a definitely dead cat).

Everett's answer was simplicity itself: the observer together with his or her apparatus actually does split into two components (one who perceives a dead cat, the other who perceives a living cat) - but each version of the observer is correlated with the corresponding component of the cat. That is, the new state is a superposition of two states, one with an observer perceiving a live cat, and one with an observer perceiving a dead cat. Each observer seems to perceive a definite cat-state and not a superposition. However, these two components do not interact with each other in any way. It is exactly as if the universe has split in two. Every time one system becomes correlated with another system that is in a superposition, the world splits into as many versions as there are components of the observed system, and so on, ad infinitum. "Everett at first called his theory the relative state formulation of quantum mechanics. By this he meant that every observer could be in a number of different states, each one defined relative to a state of the system being measured. This later became known as the Many-Worlds Interpretation of quantum mechanics; [in] this view there literally is a colossal multiplicity of universes, multiplying exponentially or faster into more universes, with each universe playing out every possibility that is consistent with the laws of physics" (ibid, 152-153). Item #648

CONDITION & DETAILS: Original wraps. Lancaster: American Physical Society. Volume 29, Number 3, July 1957. (10.5 x 8 inches; 263 x 200mm). This is not an ex-libris copy, thus there are no markings whatsoever; no writing or ownership marks at all. Near fine condition inside and out.

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Price:
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