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Tuesday
Sep282010

Uncertainty in the world

Uncertainty in the world, from quantum mechanics to string theory... One of the most counter-intuitive concepts at the foundation of quantum mechanics is quantum uncertainty - more technically called Heisenberg uncertainty. It is a concept that the human mind seems to be inherently incapable of grasping; yet, it is simply true, it is law of Nature. When an atom slows down enough, one starts seeing its size spread with slower speeds... the screwy thing about this is the following: by "size spreading" we mean its location becomes uncertain; uncertain not simply because our measuring instrument is not precise enough, but uncertain at its core, in reality, to Nature itself... the atom is really nowhere precise in particular, but anywhere in a region all at the same time. You can study quantum mechanics for decades, and this phenomenon stays difficult to chew on and remains always disturbing. But it is simply true. One has to accept that there is inherent uncertainty or "fuzz" in Nature. The picture with this post shows a recent actual snapshot of the surface of a piece of copper by a scanning tunneling microscope at IBM. 48 atoms are arranged in a circle; within the circle, a few electrons are trapped. The water like ripples you see are the electrons... a peak in a ripple indicates high likelihood for the presence of electrons, a dip low likelihood. And that is all that Nature itself can tell about the electrons in the circle; the electrons' locations are literally nothing but a fuzz of probability, they are in many places at the same time with different likelihood - and the whole thing ripples like waves on the surface of an ocean... perhaps somewhat romantic but still very very disturbing. In recent years, and in the context of string theory, this concept of uncertainty seems to extend to space itself... there are indications that if you look at empty space at very very (very) small distances, you would expect that the concept of location or point in space gets fuzzed out as well... you simply cannot zoom into the fabric of space beyond a certain limit. If you try, you instead find yourself zooming out instead of zooming in...

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