Wednesday, July 02, 2008

Giant atoms

Remember the little solar system model of the atom that our grade school science textbooks taught us? The idea that electrons were just like little planets whizzing around their nucleus suns was the source of a number of good comic book plots. Of course, if went any further in your physics education, you soon learned that the solar system model was wrong and that scientists had known it was wrong since 1927. In fact, the solar system model was the working theory for about a dozen years. Nils Bohr proposed the solar system model in 1913 to replace the yummy, but inaccurate, plum pudding model proposed by J. J. Thomson, the discoverer of the electron, in 1897. Bohr's model won him a Nobel Prize in 1922 but by then it was already known that the model had problems.

The 1927 version, called the Copenhagen interpretation is still the dominant paradigm in physics. The Copenhagen interpretation came out of a series of meetings and collaborations aimed at incorporating quantum weirdness into a more complete understanding of fundamental physical principles. It was only partly successful. The Copenhagen interpretation resulted in the use of the mathematics of probability to model the atomic world, but did so at the expense of an easily visualizable metaphor that was accessible to laypersons. In the Copenhagen interpretation, electrons don't exist as discrete particles inside an atom. Instead they are smeared out across the electron shells in wave-like patterns that can only be described mathematically. This makes the job of textbook illustrators very difficult and they have retaliated by sicking to the old Bohr model for the past eighty years.

Now, there is a glimmer of hope for the illustrators. A Rice University-led team of physicists has built a bigger and better atom. Quite a bit bigger, in fact. One of their atoms is about the size of a poppy seed. Using lasers, the team excited potassium atoms to extremely high levels and forced the electrons to exist in real space and planet-like orbits. The result is giant Bohr atoms with real, Newtonian, billiard-ball particles.

I have no idea what use these giant atoms will have; the Rice team gave the usual answer about increasing our understanding and maybe having computer applications. I suspect they really made these atoms just because it was a cool experiment to do. As a next step in their research, I suggest shrinking a team of super scientists and sending them to explore these new electron worlds. They'll probably find dinosaurs there, because lost worlds always have dinosaurs.

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