Changing Constants

by David Bradley

from the Royal Society

In contrast to the majority of the speakers at the meeting, Professor John Barrow FRS of the University of Cambridge is a cosmologist rather than a metrologist. His research is concerned with how the fundamental physical constants of nature might not be fixed, as some would suggest, but can change with the passage of time.

The fundamental constants play a crucial role in cosmology and many theories about the origins and the end of the universe and all that happens on a cosmological scale in between hinge on these values. Barrow explained how researchers can use astronomical observations to place strong limits on just how far the supposed "constants" of nature might change over the cosmologically significant timescales of billions of years.

He pointed out that observations of the absorption spectra of quasars, considered among the most distant, and so ancient of astronomical objects, have provided researchers with a substantial body of evidence consistent with a very slow change in one particularly relevant constant, the so-called fine structure constant (?) of electromagnetic interactions, at a level that is below the detection threshold of current scientific experiments. The fine structure constant provides a measure of the intrinsic strength of the strength of electromagnetic forces in the universe. This constant is one defined by CODATA with no units, in other words it is self-consistent and relies on knowing no other values, whether of mass, time, or space. It is a pure number and, asked Barrow, why does such a number have the value it does, are they truly fundamental and unchanging or could they have other values or change with time?

Fundamental constants are among the most accurately measured quantities in the whole of science, added Barrow, but theoretically we are yet to explain the value of any constant of nature. Some theoreticians had once hoped that a so-called "Theory of Everything" would have the values pre-programmed in, so that we could derive definitive values from this for all constants. Current wisdom implies this is certainly not the case for all constants, said Barrow, and many values may be produced by nature entirely at random.

 

Read on... Timing Fundamental Constants