PTOLEMY, the ancient Greek astronomer, is renowned in scientific circles for thinking up a in which the sun and planets orbit the Earth. It had to be tweaked to fit every new astronomical observation, and the end result was an elaborate system of epicycles. When Copernicus showed that the observations fitted more elegantly with a theory in which the Earth went around the sun, Ptolemy鈥檚 work became redundant. Now when scientists call a system Ptolemaic, they mean it is clunky, over-elaborate and in need of a revolution.
One theory facing such an accusation is inflation, the idea that something caused the universe to blow up rapidly moments after the big bang. When proposed it in 1980, inflation solved almost all the problems with big bang cosmology. It still does 鈥� but physicists are beginning to doubt whether it really is the answer (see 鈥淚nflation deflated鈥�).
There are two things to consider here. First, to apply the Ptolemaic label in a derogatory way is an insult to a great mind. Ptolemy鈥檚 system worked well within the limitations of his era鈥檚 knowledge: it was the best science of his time. Second, even if inflation one day goes the same way, that would not detract from its value. The theory has inspired a generation of experiments and observations that have hugely increased our understanding of the universe.
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Questioning and replacing long-held ideas is what science does best. Copernicus could not have happened without Ptolemy.
Cosmology 鈥� Keep up with the latest ideas in our .
