Do you know physics is divided into two categories one is classical and another is modern physics. In classical physics by seeing behaviour of a object we can justify what is going to happened in future with that object or what has happened in past but when modern physics come it's not possible to justify because modern physics is based on quantum particles and when we are not observing quantum particles they are present in different states and when we observe them they randomly choose one of the state and show us result.

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Schrodinger does not like the quantum theory and according to him quantum theory is not applicable on big things and he also prove this in his cat experiment. 

EXPERIMENT EXPLANATION :

Schrodinger took a cat and place it in a box he also put some radioactive material, a poisonous gas bottle and a radioactive sensor in which hammer was connected. There was 50% chance of radioactive material not to decay and when radioactive material start decaying, sensor will absorb it and break the poisonous gas bottle due to which cat will be die, now when box was closed no one knows what is happening in the box, cat is alive or dead it can only be known when box will be opened.

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According to quantum principles when no one knows what was happening inside the box, cat was present in two states one is dead and another one alive. When box is opened wave function is collapsed and quantum particles choose one of the state dead or alive and that is shown to us as a result. This experiment was carried out many times and every time result was different sometimes cat was alive and sometimes dead.

In this experiment Schrodinger want to prove that cat can't be present in two states, when box was closed cat died due to poisonous gas and when box will be opened cat will already dead there will be no selection of dead or alive when box will be opened.

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Quantum physics does not work according to human mind it work differently at different time. If quantum physics is applicable on this experiment and if cat is dead in this world then cat must be alive in another world and this also indicate parallel universe.