The box measures the cat
The following definition is taken verbatim from this website
A measurement is an interaction, usually irreversible, between subsystems that correlates the value of a quantity in one subsystem with the value of a quantity in the other subsystem. The interaction may trigger an amplification process within one object or subsystem with many internal degrees of freedom, leading to an irreversible high-level change in the same object. If the course of the amplification is sensitive to the initial interaction then we can designate the system containing the amplified process as the “measuring apparatus”, since the trigger is sensitive to some (often microphysical) quantity or parameter of the one of the other subsystems, which we designate the “object” system. Eg the detection of a charged particle (the object) by a Geiger counter (the measuring apparatus) leads to the generation of a “click” (high-level change). The absence of a charged particle does not generate a click. The interaction is with those elements of the charged particle’s wavefunction that passes between the charged detector plates, triggering the amplification process (an irreversible electron cascade or avalanche), which is ultimately converted to a click.
A measurement, by this definition, does not require the presence of an conscious observer, only of irreversible processes.
This is important because consciousness is a poorly defined quantity — so whenever people try to import it into physics AS IF IT WAS WELL DEFINED it allows a kind of slight of hand that leads to bad ideas. Being poorly defined doesn’t mean that “it doesn’t exist”, only that it is possible to subtly shift meanings when using it in deductive structures, rendering the results of those structures suspect. So, for instance, when someone says that “consciousness collapses the waveform” — what that means, and weather it means anything at all, is highly dependent on a private definition of consciousness. That private definition means that such claims are NOT science, which is exclusively concerned with PUBLIC definitions and falsifiable hypotheses.
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