Redefining Reality - The Intellectual Implications of Modern Science

This is what makes the thought experiment called Schrödinger’s cat
so troubling.
We can create pairs of electrons such that when we do not
look at them, both are in superposed states of clockwise and
counterclockwise spin, but as soon as we observe one, both
collapse into a single state such that one is always the opposite
of the other, but we never know which will be which.
Imagine that we attach the apparatus that creates these pairs to
a spin detector that will observe the spin of one of the particles.
We then attach the detector to a circuit connected to a poison
gas canister. If the detected particle is spinning clockwise, then
the circuit does nothing. If it is spinning counterclockwise, the
canister is opened, allowing the gas to escape. Finally, we place
the canister in a closed box containing a cat.
We push a button, a correlated pair of electrons is emitted,
and the detector determines the spin of one. If the electron
collapsed from its superposed state into a clockwise spin, the
cat lives. If the electron collapsed from its superposed state into
a counterclockwise spin, then the gas escapes, and the cat dies.
But suppose we do not look in the box? The detector is a physical
thing subject to the laws of quantum mechanics. If we have not
observed the detector, its atoms will be in their superposed state,
which is now entangled with that of the emitted electron.
Likewise, the circuit is just more atoms that are unobserved
and, thus, are entangled with the state of the larger system.
And it is the same with the canister of gas and the cat. All are
just atoms, all unobserved, all in superposed states in a grand
entangled system.
When we do not observe the system, it is in one superposed
state, meaning that the cat is in the superposed state of alive
and dead. But the instant we open the box to look, we see either
a dead or live cat.
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