Schrödingers cat paradox
Question 1 
What is the shortest description of Schrödingers cat paradox which clearly explains the paradox. 
Question 2 
How important is probability in order to explain the Schrödingers cat paradox. 
Purpose
The purpose of the question is the following:
 In the Schrödingers cat paradox many things are involved which maybe are not important. Should it be a cat in a box?
 What is the paradox?
 What is the importance of the paradox? what does it try to explain? (I do not like the word prove)
Description
The Schrödingers cat paradox consists of a cat in a box. In the box there is a glass container which contains poisonous.
The Schrödingers cat paradox is based around two events and two states: dead_and_alive and dead_or_alive
 The first event is a random event. This is the release of a poisonous gas by a radioactive particle, which will kill the cat.
 The second event is an observer who will look inside the box.
 The state dead_and_alive is a superposition of two states dead or alive. Accordingly to Quantum mechanics the cat in the box is in the superposition state dead_and_alive before the observer looks inside the box.
 The state dead_or_alive is the state of the cat after the observer has looked inside the box and he or she knows that the cat is either dead or alive.
Exactly what the paradox is I do not know. I expect that the paradox is: how can the cat be both dead and alive.
The problem is what does this mean. IMO the major problem with the concept of superposition is that it is not clear.
Answer Question 1 A
A simpler description of the Schrödingers cat experiment is to remove the cat in the story and to perform the experiment only with a radio active element and a counter. The release of a radioactive particle increases the counter. When you start the experiment the counter is reset (=zero).
 One state of this experiment is the value of the counter after you have looked inside the box.
 A different state of this experiment is the value of the counter before you have looked inside the box. This a superposition of the values 0 and 1 and 2 and 3 and 4 etc.
The question is what is the physical importance of this superposition state? IMO zero.
When the box has a glass window you can continuously monitor the state of the counter.
Answer Question 1 B
An even simpler description is as follows:
Consider yourself inside the smallest room. There is a queue of people in front of the door.
You put your ear against the door and you hear one person say to an other:

The man inside the smallest room is in a superposition state of both live and dead.
Same question as above.
Answer Question 2  Probability
The concept of probabilty has nothing to do with physics.
The reality is that if you perform any experiment often more than one or a range of answers are possible.
The central issue of the Schrodinger's Cat Paradox is the decay of a radioactive element. Radioactivity is described by the concept of half life time. To calculate that number you need a counter which counts each decay particle. When you know how many particles have decayed in for example 1 hour you can calculate the average time between each decay. If you know how many radioactive elements there are you can calculate the time that 50% of all the elements have decayed and that is the half life time.
In such an experiment no probability is involved.
The outcome of many experiments is not identical. When you repeat an experiment which includes radioactive elements each time a slightly different answer is possible. That means a range of answers are possible. When you count the number of answers which are in a specific range you get what is called a probability function. However that does not mean that probabilty has something to do how and when radioactive elements decay. It does not.
Reflection 1
We all agree that you only know what is inside the box when you open the box and you look inside. This is a strictly human operation.
The question of course is can you say anything meaningfull about what is (the state) in the box before you open the box.
The answer is Yes, however to claim that the cat is in both states together is rather ambiguous.
The problem is first that in reality a cat if either living or dead is not in one state but a collection of many. If you close the box and look again the cat is in a different state.
Second, Suppose you do the same experiment 99 times and every time you measure the same results A and B. When you do this experiment again and now you only measure A you can be "sure" that the other part is B.
You do not need the Schrödingers cat paradox to make this deduction.
Reflection 3
For some the solution of the paradox lies in a wave function. When you look inside there is a collapse of this wave function.
The problem with this "solution" that the ambiguous concept of being in both states is replaced by a new ambiguous concept: the collapse of a wave function.
Feedback
26/4/96 You can compare Schrödingers cat paradox with a circular polarized photon through a vertically polarizer filter.
Before the photon(~the cat) passes, it is both vertically (~cat alive) and horizontally (~cat dead) polarized.
After the photon is observed through the filter, it decides by a chance of 50% to pass through the filter (~cat alive) or to be absorbed (~cat dead).
So the photon decides to be in a definite state as it is observed.
Comment: I have some doubts with this comparison. A cat is first in one state (alive) and has then a certain chance of going to a different state (dead). The change of state happens independent if we make an observation.
A photon is in a combination of two states, partial horizontal and partial vertical polarized. The decision which state is preffered is only know if we do an experiment, ie the photon has to go through the filter.
For a discussion about Schrodingers Cat in Usenet 2003 read this: Schrodinger's Cat Paradox??
For an evaluation about an article in Scientific American read this: Quantum Weirdness? It's all in your mind
Last modified: 1 May 1997
Modified 25 May 2013
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