Schrodinger's Cat

Schrodinger proposed a theoretical experiment to illustrate a principle in quantum theory known as superposition which theorises that for any physical entity, such as an electron, the entity is in all its possible states and a particular state is only known when observed. Schrodinger proposed that a living cat is placed inside a box along with a vial containing a lethal acid. Also in the chamber is a small amount a radioactive substance. The mechanism is so designed that should a single atom of the radioactive substance decay then a hammer is tripped that breaks the vial thus killing the cat.

 The observer cannot know whether the vial has been broken and the cat killed. Since an entity can exist in all possible states for that entity - in the case of the cat dead, alive or dead/alive - then until the box is opened and an observation made the cat is in all three (or possibly more) states. In quantum mechanics the observation affects the outcome so that any outcome does not exist until an observation is made. Whilst this may be true for electrons it is more difficult for us to accept that it can be true for such an entity as a cat. In our experience of the world a cat is alive or dead - it cannot be both at the same time. (One is reminded of the Dead Parrot sketch in Monty Pythons Flying Circus where the buyer of the parrot insists that the parrot is dead whilst the shopkeeper holds the opposite view. The sketch is funny because we 'know' that the parrot is dead or alive and the efforts of the two antagonists to prove their point of view is seen by us as ridiculous because of this 'knowledge'.

Some hold to the theory of 'many worlds'. Simply put all possible outcomes happen but in parallel worlds that do not interact so that you both married the girl of your dreams as well as being jilted at the altar - two states that cannot both be true in one world. If this is the case then everything exists in every possible state created by a particular outcome until an observation is made in one of the worlds when a particular outcome becomes part of the memory stream of that world. However it also means that it is possible for all outcomes to become part of the memory stream in all the worlds created and just to make it more complex occasionally there could be interaction between worlds such that two or more memory streams existed in one world. Before you dismiss this idea as preposterous think of the times that you and another person have believed strongly in the outcome of an event you both shared yet the two versions are incompatible. You will assume that your friend has created a false memory BUT he will have the same opinion about you.