Thursday, 9 April 2009

The Strange World of Quantum Physics - Heisenberg's uncertainty Priciple.

A few days ago, I came across a very interesting effect of Heisenberg's Uncertianty Principle.
The theory states that it is impossible to know simultaneously with an infinte degree of accuracy both the position and velocity of a particle. In a very beautiful and exquisite way the diffraction pattern one observes in light is one of the proofs of this theory. 
Imagine that we are shining a light through a large slit so that there is a beam of light falling on a screen.
Now imagine that we are slowly making the slit smaller and smaller. The iwdth of the beam will get smaller ans smaller. But afte a certain point Heisenberg's Uncertainty Principle comes into action. since we know the position of the light  beam with greater and greater accuracy, we will know the velocity and therefore the momentum with lesser and lesser accuracy(Since P=mv). This results in the beam of light widening out and displaying a diffraction pattern as follows:

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