Other sciences … the stars look down

Although most of the journals professing to cover all sciences concentrate their attention on biology, a few still have a fair number of papers in other sciences. Most of the readers of this column probably don't have time to look at these, but I read them, and especially the ones I don't understand too well, in the hope that their very strangeness might shake up my mind to think of something new. In particular I am fascinated by astronomy and have been since the time an astrophysicist told me that he had been to a meeting to discuss what had happened in the first 10 –30 seconds of the Universe. Not knowing too much about the field. I told him that I knew the answer: if one had listened carefully, one would have heard: " Oh, damn! " These days one does astronomy to see if light can be thrown on cosmological theories, and the field is replete with amazing objects, such as black holes, invisible matter and naked singularities, the last being a great name for a cabaret group. I might as well give the dire news at once. It appears that all is not well in astronomy because it seems likely that the Universe is younger than the oldest stars. Shall I repeat that? Some stars are thought to be older than the age of the Universe, an impossibility that tells us that one, or both, of these assertions cannot be true. Readers who are interested should consult the excellent general paper entitled 'The Age of the Universe' in the encountered this problem in a paper in Scientific American in November 1992 and have felt uneasy ever since. I am amazed that referees and editors allow people to publish papers with such blatant contradictions but, as we shall see, it seems that the weightier the problem in this field, the more light-heartedly cavalier its treatment. First, I need to sketch some of the technical background. Everything depends on the value of the Hubble constant, which describes the expansion rate of the Universe and is given by the recession rate of a galaxy divided by its distance. The former is measured by the red shift of the spectral lines. The latter can be obtained by measurements of the luminosity of variable stars called Cepheid variables. The trouble is that two values of the Hubble constant have been obtained, one …