Schrödinger’s+Cat


 * Schrödinger’s Cat **

Schrödinger asked what would happen if we were to shut a cat in a box with a device containing cyanide and a radioactive atomic nucleus. The particle emitted by the nucleus when it decays triggers a mechanism that releases the poison into the box and the cat will be instantly killed. The decay of the nucleus cannot be predicted. All we can say is that there will be a certain probability that the nucleus will have decayed after a certain time. We only can say that the cat was healthy and the nucleus has not decayed at the time when the box was closed. The nucleus has to be described by a quantum superposition. The wavefunction must be composed of two parts, describing both a decayed and a non-decayed nucleus. Since the cat is also composed of atoms, it should also be described by a wavefunction. Since the fate of the cat is now strongly correlated with that of the radioactive nucleus, we must describe the two by an entangled state. Therefore, the cat’s wavefunction will be split into a superposition of two states: one describing a live cat, and one describing a dead cat. Thus, unless we open the box to check the condition of the cat, it is both dead and alive at the same time. Some physicists believe that human consciousness is necessary to collapse quantum superpositions during measurement. Does the moon exist when we are not looking? Maybe when our back is turned, the moon smears out into a hazy superposition. With reference to the double slit experiment, we force the atom to make up its mind when we observe it. If we observe the atom, we instantly collapse the component of the wavefunction in the other arm to zero. Even if we don’t see the atom, we still force it to become a definite particle by travelling through the other arm.