Quantum Mechanics: the Heisenberg Principle

Heisenberg’s principle is indeed is very, very, very not intuitive. Frankly speaking, I call it bizarre, but you can see it did not work. Suppose I have a laser beam here, and I use laser beam because of light but I could use any other lights for that matter. I make here an opening, a slits, a vertical slits, and here goes the laser beam right through the slits. Light goes on, light goes on, and here I project this on to small screen, projection screen. And what do I see? Well you see exactly what you predict. You see here this laser spot from this beam.

But now, I am going to make this vertical slit narrower and narrower and narrower. What now are you going to see? Well you are going to see exactly what you predict. You are going to cut off, the edge is off this circle and the spot is narrower and narrower and narrower but, now you come to the point that this narrow slit say is only 100 of an inch wide. And now Heisenberg principle comes in because now you know so precisely in the horizontal direction where the light is that as it immerges from this slit, the direction of the light is no longer the determined according to Heisenberg’s principle. And so now what you are going to see, it is going to spread out in the horizontal plane and therefore what you are going to see on this projection screen is going to get wider. Extremely not intuitive because what am I doing, I am making the slit narrower and narrower and narrower and narrower. And what do you see ultimately, that the beam horizontally becomes wider and wider and wider and wider and wider.

Now that is very not intuitive but it is the way the world works.


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