Plan B for the Cosmos; January 2001; Scientific American Magazine; by João Magueijo; 2 Page(s)

Although cosmic inflation has acquired an aura of invincibility, alternative theories continue to attract some interest among cosmologists. The steady state theory, which until the 1960s was widely regarded as the main alternative to the big bang, has been kept alive by a small band of proponents. The pre-big bang theory, a reworking of inflation that has been motivated by string theory, also turns some heads. But the most promising and provocative alternative may be the varying-speed-of-light theory (VSL), which my colleagues and I have been developing for several years. If nothing else, these dissenting views add color and variety to cosmology. They also give expression to a nagging doubt: Could the enthusiasm generated by inflation and its offshoots conceal a monstrous error?

Mainstream cosmological theories such as inflation are based on a crucial assumption: that the speed of light and other fundamental physical parameters have had the same values for all time. (They are, after all, known as constants.) This assumption has forced cosmologists to adopt inflation and all its fantastic implications. And sure enough, experiments show that the presumed constants are not aging dramatically. Yet researchers have probed their values only over the past billion years or so. Postulating their constancy over the entire life of the universe involves a massive extrapolation. Could the presumed constants actually change over time in a big bang universe, as do its temperature and density?