Saturday, July 10, 2010

A Constant not Constant?

Back on Earth, there was an interesting story in Livescience:

Proton is Smaller Than Thought, new Measurement Finds

According to research published in the July 8 issue of NATURE, the size of the proton is 4 percent smaller than previously thought. The size of protons is thought to depend on the "Rydberg constant," a combination of values including Planck's value h and the speed of light c. This finding may indicate that the book value of the Rydberg is wrong, or something may be missing from Quantum Electrodynamics. "Either a theory must be revised or a supposed constant is wrong."

Being composed of values like h and c, a change in the Rydberg might mean that one or both of these changed. 330 years ago, in the time of Ole Roemer, many thought the speed of light infinite. Planck's value has only been measured for about a century. Recording these numbers in the pages of a book does not make them constant. The Rydberg is now a "supposed constant," preparing for a day when we may regard it as variable.

While we hear of Newton's gravitational constant and even a Hubble constant, a "speed of light constant" has never entered the vocabulary. Constant c is just a hypothesis barely 100 years old. It has spread through a school system that emphasis memorization by rote, telling students what to think but not how to think. Those who preach a constant speed of light look increasingly old and foolish. From a vantage point encompassing just a small part of the Universe, human concerns look small indeed.

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