Various solutions to the "measurement problem" associated with wave-function collapse have been proposed. Some physicists maintain that the classical or macro-world does not suffer from quantum ambiguity because it can store information and is subject to an "arrow of time", whereas the quantum or micro-world is alleged to be unable to store information and time-reversible (Pagels, 1983). A more extravagant approach is the many-worlds hypothesis, which claims that the universe splits each time a measurement (or measurement-like interaction) takes place, so that all the possibilities represented by the wave function (e.g. a dead cat and a living cat) exist objectively but in different universes. Our own consciousness, too, is supposed to be constantly splitting into different selves, which inhabit these proliferating, non-communicating worlds.
Other theorists speculate that it is consciousness that collapses the wave function and thereby creates reality. In this view, a subatomic particle does not assume definite properties when it interacts with a measuring device, but only when the reading of the measuring device is registered in the mind of an observer (which may of course be long after the measurement has taken place). According to the most extreme, anthropocentric version of this theory, only selfconscious beings such as ourselves can collapse wave functions. This means that the whole universe must have existed originally as "potentia" in some transcendental realm of quantum probabilities until selfconscious beings evolved and collapsed themselves and the rest of their branch of reality into the material world, and that objects remain in a state of actuality only so long as they are being observed by humans (Goswami, 1993). Other theorists, however, believe that nonselfconscious entities, including cats and possibly even electrons, may be able to collapse their own wave functions (Herbert, 1993).
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