The dispute focuses on data from the orbiting Hipparcos satellite, used for viewing very distant, dim stars.
In April, a team led by Robin Catchpole at the Royal Greenwich Observatory, Cambridge, announced that results from Hipparcos in observing a class of distant stars called Cepheids, between 1,000 and 2,000 light years from Earth, showed that the conventional "rulers" for measuring distance in the universe were wrong by 10 per cent. The universe was bigger than we thought.
Now Thomas Barnes, associate director at the McDonald Observatory, at the University of Texas, has claimed that Hipparcos's observations of other "standard" stars, known as RR Lyraes, do not back that up. "It's as if the Hipparcos satellite gave us a new ruler for the universe, and it measured 11 inches for one type of star, and 13 inches for a different type," he said.
Dr Catchpole was quick to reply. "I think that some people are so desperate for funding these days that just about anything seems to them worth issuing a press release about," he commented. (The US notice was sent to the media worldwide via e-mail.) "Public debate of scientific issues is an excellent thing, but I'm not sure that's what this is."
Though an argument between American and British astronomers about the size of the universe might seem as important as one between theologians about how many angels can dance on the head of a pin, it matters to scientists trying to develop consistent theories about the formation of the universe, stars and the galaxies.
The British findings in April seemed to settle a long-standing mystery in astronomy. Different measurement systems have been used to determine the age of the universe, its speed of expansion, and the age of stars. The combination of the three led to the paradox that the universe was about 11 billion years old, while its oldest stars were up to 14 billion years old. This meant that either theories of star formation, or the universe's formation, or the measurement system, were wrong. Yet individually all seemed unassailable. The British work represented a breakthrough.
The work of Dr Catchpole and a colleague in South Africa, Michael Feast, showed that the Cepheids were further away - and so brighter, and so younger (because young stars burn more brightly) - than was thought.
Viewed in conjunction with work by scientists at the Universities of Sussex and Glasgow, which showed that the universe was certainly larger than measurements had suggested, the paradox appeared to have been resolved.
Dr Barnes was unable to suggest whose work might be at fault, telling scientists at an international meeting last month that he was "very confident" of his results.
But of the dispute his work - and press release - had created, he said: "This is great. If everybody agreed right away, there would be no advancement in our knowledge."
This is not the first time that American and British astronomers have differed over the importance of US findings. In April, the American Astronomical Society trumpeted the discovery of an "antimatter fountain" at the centre of our galaxy, the Milky Way - only for Sir Martin Rees, the British Astronomer Royal, to comment that the Americans hadn't found antimatter - only particles produced by the radioactive decay of normal matter.
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