I never had a problem with the whole "fast zombie vs. slow zombie" debate, as technically you could have fast zombies in the first 6-12 hours, before rigor mortis set in. Then you'd start having the classic variety of zombie.

My biggest problem is figuring out how zeds move after death in the first place. Muscles require ATP (adenosine triphosphate) in order to move; it is the primary and only fuel that muscles use. ATP is broken down from glycogen; glycogen is produced by the liver from the carbs, fat and proteins in the food you eat. In order for glycogen to get from your liver to your muscles, your heart has to pump it through your circulatory system. But if our current clinical definition of death is no cardiac activity, then how do zombies move?

i agree with cybrbeast, in that the "observer" is miscategorized. in order to be the observer, you must be able to accurately detect change. the minute the steel box is closed in this experiment, the reliability of the human-as-observer falls to pieces. two points that are of interest to me:

1. if the click of the Geiger counter could be heard, it could be argued that the atomic decay state and thus the state of the cat remain binary and knowable. obviously this defeats the point of the steel box in obscuring observation, but it also circumvents the erroneous assumption that "observation" is the hinge upon which the state of an object rests. measuring the state of an object does not determine the state itself; it simply allows the state to be quantified for human application.

2. we must rely on the observer's observation of the cat being alive or dead as accurate, which it may not be.

the use of cyanide as the killing agent in the experiment makes the assertion that a cat cannot be "both alive and dead" debatable. cyanide inhibits cytochrome c oxidase, which is used in the electron transport system to make adenosine triphosphate (used by the body for energy) in an oxygen-dependent way. simply said, cyanide makes breathing useless and paralyzes everything in the body that needs oxygen. those things that need oxygen the most to live will die first. and since all tissue and organs in the body require oxygen at a different rate, there is an arbitrary, unknown time at which exactly half of the cells in the cat's body would be dead, and half alive. this would not coincide with the cat's brain or cardiac activity, since those are both highly oxygen-dependent tissues. so it could be said that if the exact moment the cat fell over from cardiac failure the steel door happened to be opened, the observer could observe a truly dual state of the cat's existence and still misclassify it as being in the state of "dead".

again, the observed state is independent of the actual state.

on a more humorous note, would the now-dead cat have muffled it's own sound upon falling?