Issue 42

11 March - 21 April 1997

Science insight - The reluctant cosmologist

Dr Andy Albrecht didn't want to become a cosmologist as an undergraduate at Cornell University in New York.

"Cosmology had a reputation for being more like philosophy than science," he said. "You would think big thoughts, but how would you ever know if they were right?"

But when he joined the University of Pennsylvania as a postgraduate student, he came under the influence of a "young hot shot, superstar professor" called Paul Steinhardt, realised how fascinating the subject could be and ended up doing a PhD in cosmology. For the last four years Andy has been a lecturer in the theoretical physics group at Imperial, his first teaching post, and a reader since October 1995. He now believes that cosmology is one of the most exciting fields in science.

Cosmology is being revolutionised by large, deep surveys of space which are providing vast amounts of experimental data for theoreticians like him to analyse. "My work with other members of the theory group involves producing detailed theoretical predictions which can be tested using the new data," Andy explained. "Already it is clear that this new data will reveal deep insights into the history of the universe and the physics of the hot big bang."

One of cosmologists' current aims is to trace what they call the 'redshift', or the third dimension, which represents the speed at which the galaxy is moving away from us. Soon, predicts Andy, we will have maps representing this third dimension for over a million galaxies. Knowledge will then reach beyond the galaxies towards an understanding of the history of the universe itself.

Key to this eventual understanding is the big bang theory. "It's the theory that the universe was once extremely hot and extremely dense, so dense that matter was opaque and light couldn't get through without scattering," said Andy. When cosmologists look back through space, and therefore back through time as well because light takes billions of years to reach us, they run up against that opaqueness. However, technological progress in the last decade has meant that they can now begin to overcome this obstruction.

One of the first technological advances was the Cosmic Microwave Background Explorer (COBE), a satellite funded by NASA and launched in 1989 to measure infrared and microwave radiation from the early universe. Andy is involved in many follow-up experiments, including the European Space Agency's Planck Surveyor, which he describes as "the ultimate microwave background experiment."

Before coming to Imperial, he worked as a researcher at both Fermilab outside Chicago, home of the world's most powerful particle accelerator, and at Los Alamos in New Mexico. Switching from pure research to an educational institution has proved a very worthwhile move. "IC is a very special place to do cosmology. The head of the theory group, Tom Kibble, is one of the great pioneers of modern cosmology and Michael Rowan-Robinson's astrophysics group is involved in most of the key experiments." Andy also greatly enjoys teaching, and the contribution made by his students. "Students challenge you in a way that you don't get anywhere else."

"One of my students came in and asked me a very good question. He said, 'do you really believe this stuff? When you leave your office and go home, do you really believe it?' I know what he was talking about," said Andy. "It takes quite a lot of nerve to describe the universe ten or fifteen million years ago. But what makes me take it seriously is the process by which we arrive at these ideas; it's a rigorous, demanding process. It's possible that the data will tell us that all the ideas we are working with are wrong, but even that will be progress. We're getting somewhere with this, one way or another. It isn't just flights of fancy."

PHOTO : Dr Andy Albrecht. Photography by Nick Jackson, Blackett Lab Photography and Publications.