What Uncertainty Means to Me– And You, and the Universe

In chapter 2 of How to Teach Physics to Your Dog, there’s a footnote about the ubiquity of uncertainty principle analogies in the mass media:

To give you an idea of the breadth of subjects in which this shows up, in June 2008, Google turned up citations of the Heisenberg Uncertainty Principle in (among others) an article from the Vermont Free Press about traffic cameras, a Toronto Star article citing the influence of YouTube on underground artists, and a blog article about the Phoenix Suns of the NBA. Incidentally, all of these articles also use the Uncertainty Principle incorrectly–by the end of this chapter, you should hopefully understand it better than any of them.

Add the Washington University in St. Louis psychology department to the list of institutions that don’t understand quantum mechanics as well as my dog– in an otherwise interesting New York Times article about study skills Benedict Carey writes:

Dr. [Henry L.] Roediger [III] uses the analogy of the Heisenberg uncertainty principle in physics, which holds that the act of measuring a property of a particle alters that property: “Testing not only measures knowledge but changes it,” he says — and, happily, in the direction of more certainty, not less.

Once again, that’s not really what the Uncertainty Principle says. It’s a semi-classical analogy used to make the fundamental physics of uncertainty more palatable to classically trained physicists in the 1930’s. Quantum uncertainty is really about the fundamental nature of matter, and is an unavoidable consequence of the dual particle and wave nature of quantum objects. You cannot measure both the position and momentum of a particle arbitrarily well not because the act of measuring one perturbs the system, but because those quantities do not exist.

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