Understanding Schrodingers Cat and Quantum Uncertainty

Schrodinger's Cat is a famous thought experiment that highlights the fact that matter can exist in two states at once. This article covers this basic experiment, as well as a more modern experiment in the same field.

When it was discovered that matter could exist in two states at once, Schrödinger, a well-known physicist proposed a thought experiment involving a cat in a box. He proposed that since the decay of radioactive materials was related to quantum theory and uncertainty, a particle could be in a state of having decayed radioactively and not having done so, at the same time. This is, in fact, true. After suggesting this, Schrödinger then went on to suggest that if a cat was placed in a box with a vial of cyanide and if that vial was triggered to break when a particular particle decayed, the cat would be both dead and alive at the same time, until the box was opened. This is false, but the principle of the experiment does not have a scientific reason for not holding true, which is why the ‘Schrödinger’s Cat’ remains as a useful learning tool for those interested in Quantum Mechanics.

The key result of understanding Schrödinger’s cat is that matter doesn’t have to exist in only one state at a time. Just like a photon exists in multiple places at once due to uncertainty, actual objects can be both in motion and not in motion, until some event requires the object to be in one state and not the other. A recent experiment involved setting a very small metal plate in a vacuum in to a state of vibration and non-vibration, in order to demonstrate this principle.

This experiment used the fact that at low levels of momentum, particles have higher ‘wavelengths’, the quantum effect of uncertainty responsible for making particles act like waves. Most particles have very small wavelengths because their temperatures make them vibrate, but it is possible to negate this effect by cooling an object. The typical instrument of choice for cooling an object to very low temperatures is a ‘cooling laser’ fires photons at a specific energy level, which actually take energy from the target particles as they’re deflected.

Using a cooling laser, the scientists brought the small metal plate in question to a temperature as close to absolute zero as possible, so that the uncertainty in the particle’s energy would give a probability that the particle was both at absolute zero and at a positive temperature. The physicists performing the experiment then took two separate readings without disturbing the metal plate, one of which showed that the object was vibrating, and the other showed that the plate was not doing so.

This experiment shows that as long as an object isn’t disturbed, it can go in to a ‘quantum’ state, no matter what its size is. In theory, there is no reason why large objects like busses and elephants can't go in to quantum state, but actually cooling them down and ensuring that no outside disturbances would break that state is almost impossible.

Image With Permission: http://www.morguefile.com/archive/display/66704

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