It might have been some years ago. I was working at my desk when suddenly a cat jumped on my table. It was a beautiful deep black cat and his silhouette seems to radiate a spooky blue light. Surprised I cried "Hey where're you coming from?!" because the room was closed and this cat I have never seen before. Especially not today, not in this room. The creature looked at me with an intelligent gaze that has nothing catlike no more. To my uttermost surprise he answered.
"No idea" he said (well, let's suppose it's a he) and looked serene at me while he laid himself down on my paperwork. For some time I stared at the animal that was so familiar and at the same time so strange, while my thoughts and feelings were seeking a new equilibrium. Finally I said: "What are you?!" For a moment there was silence. Then the cat said: "I am a Schrödinger Cat". Another silence fell.
"But you died long ago in that physics experiment didn't you?" I asked with a sigh. Once again the cat looked silent at me for quite some time, as serene and silent as a cat could look at something.
"Do you want to know how it really happened?" the cat asked.
"Yes please" I replied immediately. "I would be very delighted! Everybody think you're dead!"
The cat looked up and said: "Okay. As you know the radioactive nucleus would soon decay. The registration of the emitted particle then would release the poison that would kill me immediately."
Here the cat hesitated for a moment and looked at me with a glaze I couldn't interpret otherwise than as a silent reproach. I remembered the experiment. The clue was the nucleus in fact couldn't decay: the forces that make it cohere are too strong. Only because a particle suddenly is present outside the nucleus - just like that, from one moment upon the next - it escapes from the strong nuclear force. The mutual repulsion of the electrical charges then gets grip on the particle and push the particle away and so it escapes. It "tunnels" quantum mechanically through the barrier that in fact it never can take, only because quantum mechanically there was a change - however it isn't a big one - the particle had its position outside the nucleus instead of inside it.
"Because the precise moment of decay was fundamentally indeterminate" the cat continues, "it was fundamentally indefinite after some time whether I was alive or not." I did remember, just as the fact that after the elapse of on half-life of the nucleus the poison-releasing mechanism was shut off. That was the time the cat just mentioned.
""Well!" I interrupted him, in an attempt to excuse myself, "when the box after two years still was there we assumed you were dead".
"But did you never looked in it?!" the cat cried out.
"Nobody dared to take the risk" I confessed softly. "Neither did I."
"Well good heavens!" the cat said. He was silent for quite a moment. Then he cried out:
"that was quite stupid of all of you! If you did had a look you would have seen I wasn't in there any more!"
"But the box was perfectly closed, wasn't it?" I asked softly to myself. In my mind I pictured the box that was hermetically closed since the beginning of the experiment. Now it showed off in a showcase in the Physics Museum with the caption "Box with Schrödinger Cat. Most probably dead."
"Yes" the cat replied, "It was indeed. But there was happening something else. Soon after I was locked up in the box with the whole contraption, it became clear the gravitational waves that spherically emitted from my beating heart with light speed, always would betray whether I was alive or not. The atoms of the researchers were waved through by them, whether they want it or not. And nothing shields off gravitational waves. So I had to become smaller and smaller until those waves were too weak to be detected. In fact I had to become that small the quantum character of the gravitational waves itself prevented the waves from transferring interpretable information of my state. By that time it did took me little effort - in fact no effort at all - to tunnel through the wall. And as soon as that happened I ran away."
"Yes, suppose you would tunnel back inside before you did!" I said.
"Exactly" the cat replied. "And it succeeded. Wherever I came, no more in the box! And then it was only a matter of regaining strength."
The cat had finished his story.
"Ghee!" I cried, "Fantastic! Great! And what now?"
"Well, I think I just go on like this now", he said. "You know, I never completely lost my indeterminacy, strange enough. I still left some quantum mechanical power and you can't imagine how funny that can be! Mousses thinking they hide behind a skirting-board and suddenly Piouw! there I am through the wall. Fridges and store cupboard just lying open for me. Butchers, chicken houses! And when they drove me in a scrape: Piouw!"
I smiled at the picture of that. So that was how he came in.
"But isn't it still an uncertain existence?" I said.
"Doesn't hold that for everyone?" the cat replied and that I had to admit that. Besides, his existence had gained some probability since, I guess.
"Maybe you want a little bit milk?" I asked.
"Yes" the cat said, "Maybe".
Most probably he drunk the milk of the dish until it was empty and, after a last cattish "Miouw!" he disappeared, just like that from one moment upon the next. I was glad the Schrödinger Cat was still alive. Most probably, I guess.