Saturday, February 7, 2009

Quanta

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Energy cannot be created or destroyed.
Energy manifests into different forms.
Energy is matter, matter is energy.
Energy governs the world.
Energy is ... God??
- The Secret

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Welcome to the world of quantum mechanics.

Law 1: The position and momentum of a particle cannot be measured with arbitrary accuracy.

In the macroscopic world, we could see where, say, a car is by looking (bouncing a light wave off) at it, or we could use radar. To determine the momentum, just measure position twice in 1 second, and we could calculate the momentum.

Not so in the quantum world.

Since a particle is point-like and extremely small, interaction - say using a photon to probe/interact with it, changes it instantaneously. We could use a photon to interact with it in order to determine its position, but the photon will give energy to the, say, electron, that will change its momentum. We could have the electron leave a path in a particle detector, which will show its momentum, but we could not determine its position at any specific time.