Do physical constants fluctuate?
The ‘physical constants’ are numbers used by scientists in their calculations. Unlike the constants of mathematics, such as ¼, the values of the constants of nature cannot be calculated from first principles; they depend on laboratory measurements. As the name implies, the so-called physical constants are supposed to be changeless. They are believed to reflect an underlying constancy of nature. In this chapter I discuss how the values of the fundamental physical constants have in fact changed over the last few decades, and suggest how the nature of these changes can be investigated further. There are many constants listed in handbooks of physics and chemistry, such as melting points and boiling points of thousands of chemicals, going on for hundreds of pages: for instance the boiling point of ethyl alcohol is 78.5°C at standard temperature and pressure; its freezing point is -117.3°C. But some constants are more fundamental than others. The following list gives the seven most generally
