Confirming and refining the inflationary model

Andrew Liddle is part of the 250-strong collaboration that is preparing for the launch of the Planck satellite.

His particular interest is in confirming and then refining the so-called inflationary model. This states that immediately after the Big Bang, the universe became roughly a million-trillion-trillion times bigger in less than a hundred-million-trillionth of a second.

Liddle, who is professor of astronomy at the University of Sussex, believes that tiny quantum fluctuations before inflation would have been blown up into significant local variations in density that were large enough to have acted as seeds for galaxy formation.

These ancient variations can still be detected by measuring the radiation emitted at the time, which has since largely remained unaltered.

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The Cobe satellite has already measured the radiation, but the results have been relatively crude. Planck will have much higher resolution, survey more points and collect a far greater amount of data.

While preparing for the satellite's launch, Liddle is making an effort to bring his research to a wider audience. He sees it as an important part of his job to convey the excitement of astronomy to the public.

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This year, in recognition of his research and lecturing, Liddle was asked to present the British Association's prestigious Lord Kelvin lecture.

Getting the measure of distant and ancient supernovae

Until last year, Richard Ellis was director of the Institute of Astronomy in Cambridge, but he now pursues his research interests as a professor at the California Institute of Technology in Los Angeles. He says he had difficulty conducting world-class research in Britain, where resources have been declining for many years.

Ellis is a leading member of the Supernova Cosmology Project, which attempts to measure the velocity of distant (and ancient) supernovae. Results from the project suggest that the velocities of these early supernovae are much slower than newer supernovae, so the implication is that we are in an accelerating universe - one that is expanding at an ever-increasing rate. This contradicts the accepted model, which states that gravity tries to pull objects together, slowing the rate of expansion.

An accelerating universe hints at an anti-gravity effect, a new source of energy that is driving the universe apart. However, the theory is based on observations of just a few dozen supernovae.

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"My first reaction was that there was something wrong with the data," confesses Ellis. He will be more certain after the 2006 launch of the Supernova Acceleration Probe (Snap), a satellite that will observe 6,000 supernovae.

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