Schrödinger's cat serves to demonstrate the apparent conflict between what quantum theory tells us is true about the nature and behaviour of matter on the microscopic level and what we observe to be true about the nature and behaviour of matter on the macroscopic level.
Here is Schrödinger's (theoretical) experiment: We place a living cat into a steel chamber, along with a device containing a vial of hydrocyanic acid.
There is, in the chamber, a very small amount of a radioactive substance.
If even a single atom of the substance decays during the test period, a relay mechanism will trip a hammer, which will, in turn, break the vial and kill the cat.
The observer cannot know whether or not an atom of the substance has decayed, and consequently, cannot know whether the vial has been broken, the hydrocyanic acid released, and the cat killed.
Since we cannot know, the cat is both dead and alive according to quantum law, in a superposition of states.
It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive).
This situation is sometimes called quantum indeterminacy or the observer's paradox: the observation or measurement itself affects an outcome, so that it can never be known what the outcome would have been if it were not observed.
We know that superposition actually occurs at the subatomic level, because there are observable effects of interference, in which a single particle is demonstrated to be in multiple locations simultaneously.
What that fact implies about the nature of reality on the observable level (cats, for example, as opposed to electrons) is one of the stickiest areas of quantum physics.
Schrödinger himself is rumoured to have said, later in life, that he wished he had never met that cat.
Schrödinger was never able to demonstrate by experiment that his theory had validity, living as he did at a time when advanced test apparatus of sufficient accuracy and sensitivity had not been developed.
Over the past 30 years, researchers at both Oxford and Cambridge had proposed conducting suitable research using more advanced equipment but these plans were aborted owing to violent objections from the Royal Society for prevention of cruelty to animals. In addition, the Queen was not amused.
Similarly, promising preliminary work at both Yale and Harvard over the past decade had been stymied by similar objections from a powerful coalition of Animal Liberationists and the Society for Prevention of Cruelty to Animals.
However, we have recently become aware of discreet experiments being conducted by PhD students at the Angeles City University in the Republic of the Philippines.
It seems these researchers had struck a deal with one of the top ten Chinese restaurants in the city which had been developing a tasty variant of Mongolian feline and was prepared to make suitable study specimens available from its breeding stock.
Cats suitably anaesthetised and fitted with heart and respiration monitors have been placed in sealed stainless steel containers along with delicate equipment designed to release hydrocyanic gas or hydrogen cyanide (H-C?N) should the appropriate radiation activity occur.
To meet objections from cat lovers it has been pointed out that the procedure is entirely painless, hydrocyanic acid very fast acting in the rare event of it being released, and that the cats in question are grown for culinary purposes and destined for the table in any case.
Going to the table after fulfilling a serious scientific purpose would merely give a greater purpose to their short lives.
Japanese researchers are excited by these developments and are actively investigating whether their ongoing research into whales could be adapted - after all, Cats were originally proposed almost by accident, and just scaling up the apparatus, stainless steel tank, quantum of hydrocyanic acid etc is a technical challenge.
Though Japan produces first rate engineers, opticians, astronomers, car designers, electronics experts etc, their biologists have always been a particularly inept lot, no doubt drawn from the lowest intellectual strata, as they have spent nearly a century catching whales, strictly for research purposes, but have only just figured out that they are not fish but mammals.
Similarly, if hydrocyanic acid can successfully be removed from cats by appropriate cooking techniques, the Japanese are stimulated by the prospect of developing Mongolian Whale - strictly for further research purposes, of course – Honest!