Schrodinger's cat is a flawed thought experiment. The cat is not in a super-position of live-dead just because the decay (or absence of a decay) hasn't been observed by a human. Observation just means "interaction". If one particle interacts with another, it has been "observed".
Schrodinger's cat is a flawed thought experiment. Observation just means "interaction"
The way I learned it, Bohr would say "the atom is in a superposition of states until it is observed". Schrödinger used the cat thought experiment to show the absurdity of Bohr's position: "... and then, when I look at the cat, it is forced to take a stand, poof it goes 'alive', or 'dead'"
As far as I know, we still don't understand what, exactly, constitutes an "observation". Quoth Bell (the guy from Bell's experiment):
... current interest [in questions of foundations of
quantum mechanics] is small. The typical
physicist feels that they have long been answered,
and that he will fully understand just how if he
ever can spare twenty minutes to think about it.
The thing is, you don't actually need to postulate that the cat goes "poof" at the point of observation. Suppose this didn't happen. Then the state of the world before observation is this:
(Normalization dropped.) This isn't weird. What would be weird is if these two states could interfere with each other.
I did some work a few years back which argues that interference between these states is virtually impossible - they live too far away from each other in configuration space.
Ultimately the argument goes all the way back to David Bohm in the 50's. The novelty of what I did is cooking up a plausible experiment for which the calculations are tractable.
Cool. How do you deal with the double slit experiments if there is no interference? Aren't you back to a fully deterministic worldview, from the observer's perspective?
There is interference - my model is merely the many body schrodinger equation, after reduction to a two-particle NLS.
The key observation is that a measurement apparatus involves N particles, each moving a distance O(1). Thus, the distance (in configuration space) between both wavepackets (i.e., |cat dead, observer sad> and |cat alive, observer happy>) is O(sqrt(N)).
Because the two wavepackets are so far apart, they can't interfere. This is true with or without the observer, since the cat still has O(10^23) particles.
On the other hand, if there were no observer, and the system were merely an electron, the distance between wavepackets would be O(1) and interference would be possible.
