I'd like to contribute some clarifying thoughts on the Schrödinger's Cat Experiment:

I think it's correct that this hypothetical experiment was meant to expose to ridicule the idea of macroscopic entities behaving in a quantum manner. The description of the experiment describes what would be if cats behaved like particles, but clearly exposes this not to be the case, because

  • First of all, it doesn't take a human observer to make the cat decompose, literally. It so happens the cat takes billions of observers into the box with it - its body fauna. Assume that you leave the cat in the box (with enough food and water, let's not be too cruel) for two months, and let's assume the particle decays and kills the cat after one month. When you open the box, you will be made drastically aware that the cat has been dead for weeks; it's quite obvious it would not have just dropped into that state when you opened the box.
  • Unlike a particle, a cat interacts with its environment in a complex way. A particle bouncing off another particle will leave no lasting effect apart from a very fleeting change of momentum, impossible for the current state of our art to trace back after a few nanoseconds. The cat will leave claw marks in the box that won't go away, and whose accumulation could give an indication of how much time passed.
  • Even absent microorganisms and effects on the environment, the cat has a complex and continuously varying state of its own. Part of this is its C14 content, which stays (roughly) constant and which starts to decrease once the cat stops living (and eating). Granted, carbon dating won't work too well in a timeframe of weeks, but you get the idea.
Unlike a particle, a cat is a complex system, interacting with its macroscopic environment in intricate ways. The cat's environment will, in an inanimate and unconcerned way, take almost immediate note of the cat's passing, thus completely eliminating the possibility of the cat existing in a superimposed quantum state.

What's to be learned from this? Quantum mechanics (generally) apply to the microscopic realm, and the whackiness that exists on that plane is rarely observed at the "human" level. A few experiments, such as those with boson fluids, form interesting exceptions.