Erwin Schrödinger's intention for his infamous cat-killing box was to discredit certain implications of the quantum mechanics, of which his wave mechanics was the first mathematical formulation. Werner Heisenberg's matrix mechanics was shown to be isomorphic with wave mechanics, producing identical physical predictions, including his uncertainty principle.
This thought experiment is widely misunderstood. It suggests that quantum mechanics implies the simultaneous (and obviously contradictory) existence of a live and dead cat. Technically it claims only the superposition of coherent wave functions for the probability amplitude of finding a live or dead cat when the box is opened and an observation is made. Moreover, it points clearly to our solution to the
problem of measurement, that human observers are not required to make measurements (if not "observations").
The details of the tasteless experiment include a bit of radioactive material with a decay half-life likely to emit an alpha particle during the experiment, a Geiger counter, which produces an avalanche of electrons when the alpha particle passes throught it, and an electrical circuit energized by the electrons to open a bottle of a deadly nitric acid gas. The gas will kill the cat, but the time of death is unpredictable with quantum indeterminacy.
If we open the box at a time when there was a 50% probability of an alpha particle emission, the best a physicist can say is that there is a 50% chance the cat will be observed as dead or dying. If the alpha particle decay occurred at an earlier time, Schrödinger misleadingly suggests that the mixture of nuclear wave functions describing decay and no decay can be magnified to the macroscopic world and describe a similar mixture of live cat and dead cat wave functions.
As soon as the alpha particle sets off the avalanche of electrons (an irreversible event with a significant entropy increase), new information is created in the world. For example, a simple pen chart recorder could record the time of decay. Even without that, the cat's death sets in motion biological processes that are equivalent, if gruesome. An autopsy will tell us Schrödinger's cat died hours or days ago. There was never a superposition of live and dead cats.