_ Fact of the


An incredible 98 per cent of the mass of the Universe, which until recently had been unaccounted for, was ‘found’ by astronomers at the Royal Observatory, Edinburgh (ROE). The problem was that while astronomers could work out a theoretical mass for the Universe by examining the gravitational pull on large objects in space, they were only able to see around two per cent of it.

The ‘find’ was made last November, when astronomers at ROE theorised that fluctuations in the brightness of quasars, the most distant objects they can see, were not due to changes in the quasars themselves. Instead, they believe that ‘Oark Matter’ - the missing mass - is passing between the quasars and earth, acting like a giant gravitational lens which focuses light on the earth.

‘Some people disagree with us,’ admits ROE press officer Mark McCauley. ‘Stephen Hawkins was one of the people who thought more of the theory than others, but there is still a lot more theoretical work to be done.’ The find is just one of many made at ROE since it moved to Blackford Hill in 1894. Although star-gazing stopped there in the late SOs, ROE maintains three giant telescopes around the world. Two are in Hawaii, on the summit of Mauna Kea at 13,600 feet



;/ I

where the air is thin and clear. The third is the UK Schmidt telescope in Australia, which takes photographs of the sky on fifteen inch square glass plates. Each plate, covering an area the size of 150 lull moons, is shipped back to Edinburgh for analysis by the recently completed Super Cosmos computer. The machine is so sensitive it can detect images one ten-millionth of a metre across and evaluate the million or so stars and galaxies on each plate in just two hours. The plates have to be extra thin so they can bend inside the telescope. As McCauley points out, ‘The plate library is not somewhere you take a short cut through. If you break a plate it doesn’t make you too popular.’ (Thom Oibdin)

A new ROE centenary exhibition illustrating its contributions to astronomy will be opened by Patrick

Moore on Monday 4 April.

:— Remains of

the day

From identifying traces of semen to examining shipments of illicit drugs, the forensic scientist is increasingly important in solving crimes. When the full extent of the grizzly events at 25 Cromwell Street, Gloucester, is uncovered, it will be partly thanks to forensic scientists’ painstaking use of DNA identification techniques.

However, publicity surrounding the science has not always been so positive, as Professor Brian Caddy from Strathclyde University knows. He appeared for both the Maguire Seven and the Birmingham Six during their first appeals in 1987 to give his opinions on the original forensic reports, which he believed did not support the convictions.

‘Although their Lordships chose to reject part of the evidence, they had a misguided view towards the technique known as Mass Spectrometry,’ remembers Caddy. ‘Later on I was proved correct, but the problem always is with these things that the courts want an example.’ At the time, although Caddy knew in theory that compounds other than explosives could produce a positive test result, he was unable to say which ones. It later turned out that a pack of playing

5 cards was one of them. I Techniques have moved forward since then and Caddy is convinced

In the llame of the Father; the film version of the Cuildiord Four and Maguire Seven‘s story

that better methods of quality control and systems of analysis make a repeat of the Maguire fiasco unlikely. ‘Today, the problem is that forensic scientists are very good when you already have a suspect but aren’t very good at actually finding one,’ according to Caddy. The creation of a DNA database has been suggested, but Caddy admits the idea raises some ethical questions, particularly for civil liberties. (Thom Oibdin)

Professor Brian Caddy will discuss methods for analysing controlled drugs at the Old College 2 on Thurs 7 April as part of a day of talks on various aspects of forensic science.

The Science Festival runs from Friday l»—Saturday 23 April. Full programme and details on ()31 556 6446.



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The List 25 March—7 April 1994 89