Halpern, Paul, Wesson, Paul. "5 Ever-Changing Moods: Did Nature’s Constants Evolve?." Brave New Universe: Illuminating the Darkest Secrets of the Cosmos. Washington, DC: The National Academies Press, 2006.
The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
Brave New Universe: Illuminating the Darkest Secrets of the Cosmos
electric charge or a changing light speed would cause alterations in alpha as well. Although quantum theory asserts that at ordinary energies alpha remains approximately 1/137 for all times, physicists have reason to believe it could vary under extreme conditions, such as those in the very early universe.
The fine-structure constant lies at the heart of quantum electrodynamics; it gauges the strength of interactions between charged particles. Because at higher energies, virtual particles arise that shield the charges of real particles, some theoretical models suggest that alpha could have a different value in such regimes. If researchers established that it was not only energy dependent but also time dependent, this would imply a slow change in the properties of the vacuum. Earth’s evolution could consequently be affected over long periods. Hence, like changing G, variations in alpha could possibly be detected through geophysics.
In 1999 a team of astrophysicists led by John K. Webb of the University of New South Wales found evidence for evolution of the fine-structure constant in the absorption spectra of very distant quasars, extremely remote, superpowerful sources of energy, believed to serve as the dynamos of young galaxies. Webb and his colleagues found that alpha could have varied as much as 2 percent since the time of the Big Bang.
For those scientists who are of the opinion that at least some of nature’s firm footholds are really slippery sands, Webb’s results offered the tantalizing prospect of vindication. They seemed to reveal a past landscape significantly different from that of today. The study of “variable constants” kicked into high gear, with an increasing number of researchers eager to explore its exotic terrain. Among these innovative scientists was Cambridge cosmologist John Barrow, who, along with Magueijo and Håvard Sandvik, developed a model of the universe based on changing alpha.
Recent findings, however, have cast doubt on Webb’s results. In 2004 a group headed by Nobel Prize–winning physicist Theodor Hänsch reported that its four-year study of atomic emissions