by Joe Mccane

Created on: February 26, 2009

Quoted from one of the greatest scientists of the 20th century, Albert Einstein, "... god does not play dice." He gave this response when Werner Heisenberg proposed the uncertainty principle, Einstein said that statement thinking the natural world does not go by probabilities. Heisenberg however, said we can not know the exact position and speed of an electron at the same time; we can only know the probability of one and the exact number of the other. Therefore, he reasoned, if you know the exact speed of the electron then the position is only a probability, not an exact position.

In quantum mechanics a particle is described as a wave instead of a particle. The position of the particle is simply where the wave is concentrated, and the speed of the particle is the wavelength divided by the frequency. The position of the particle is unknown to the degree of the amplitude of the wave. If you know anything about waves, then you should know the frequency is how many times the crest of the wave passes a point in a second. The amplitude of the wave is how far the crest extends out, finally the wave length is the length from one trough to the next, a trough is the opposite of a crest.

Waves only have a definite position when it is concentrated at one point, which means the wave length cannot be defined. On the contrary, waves only have a definite speed when there is a distinct crest and trough, which means the position cannot be exactly determined. Consequently, in quantum dynamics there is no states particles can be in that give you both the exact position and velocity, which gave rise to the uncertainty principle.

Einstein proposed a few thought experiments to disprove the uncertainty principle, the first thought experiment goes as follows. Consider a particle passing through a slit of width d. The slit introduces an uncertainty in momentum of approximately h/d because the particle passes through the wall. But let us determine the momentum of the particle by measuring the recoil of the wall. In doing so, we will find the momentum of the particle to arbitrary accuracy by conservation of momentum. Bohr's response to this thought experiment was to some extent of the wall that we are measuring the recoil from is quantum dynamic also, so the uncertainty that the wall produces is equal if not more then the uncertainty if we measured the particle in more conventional ways.

Soon after Einstein proposed another thought experiment to disprove the uncertainty principle. This

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