The first question of course is whether Erwin the Schrödinger was a cat lover or a cat hater. Or neither (then why'd he choose a cat?). I don't know the answer to that question (those questions). Some people might say, "Does it matter?" in a rather irritated voice, like Judith at the dinner table when Larry mentions that their next door neighbor, Mr. Brandt, is mowing part of their yard. Well, no, it doesn't matter! But I'd still like to know.
Schrödinger did mention in his description of setting up the thought experiment that the equipment involved "must be secured against direct interference by the cat," which he described as "penned up in a steel chamber” with a flask of hydrocyanic acid that would be broken by a hammer released by a mechanical relay switch activated by the radioactive decay of a nucleus that is specified to have an equal probability of decaying or not decaying in one hour.
At the end of the hour, the experimenter looks inside the steel box, and by doing so determines if the cat is dead or alive. During the hour before the box is opened, however, according to the Copenhagen interpretation of quantum theory, the cat is both dead and alive, because the wavefunction (or state vector) of the atomic nucleus has equal components of decayed-state and non-decayed state and only by a measurement is the wavefunction put into either one state or the other. Thus only by a measurement is the cat put in one state or the other.
The semantics gets a little tricky, though, when you consider that looking in the box is more of an observation than a measurement. Can you say what the difference between an observation and a measurement actually is? Looking at your speedometer while you're driving, for instance, or weighing yourself. You're looking at a numerical reading produced by an instrument. More about all that later!
The semantics gets a little tricky, though, when you consider that looking in the box is more of an observation than a measurement. Can you say what the difference between an observation and a measurement actually is? Looking at your speedometer while you're driving, for instance, or weighing yourself. You're looking at a numerical reading produced by an instrument. More about all that later!
