Prof Anthony Hewish – “Radio-astronomy, inflation and the design of the Universe”

We were very honoured to have Professor Tony Hewish talk to us about some of the outstanding problems raised by modern cosmology. He of course has a long and distinguished career in radio astronomy and is a Nobel laureate in physics, so his audience was treated to an authoritative review of cosmology since the beginnings of his research career in Cambridge after WWII.

Working with Martin Ryle and colleagues, Tony used ex German radio equipment to build a radio telescope at Lords Bridge off the A603 and before that, an array on the playing fields behind Grange Road in Cambridge. The purpose of this was to identify strong radio sources in the sky and match them to their optical counterparts. Having achieved this with the intense radio source Sagitarius A, many other radio galaxies were identified along with quasars and pulsars as the years went on.

After this historical overview of the Cambridge research, attention was turned to the first of the two main problems with our understanding of the universe, namely the nature of dark matter. An audit of mass in the universe based on the motions of galaxies and the phenomenon of gravitational lensing implies that there must be a much larger percentage of as yet unidentified mass that has no interaction with normal matter. This ‘dark matter’ comprises about 23% of the universe, with normal atoms being only 4.6%. The remainder is a mysterious ‘dark energy’ that pervades the universe and is involved in inflation. This is the idea developed by the physicist Alan Guth that the universe rapidly expanded an infinitesimally small time after the Big Bang that started the universe. Tony Hewish had some success in explaining the complex quantum theory behind Guth’s theoretical prediction of how inflation works, but it isn’t easy for the novice. The idea that a perfect vacuum still contains energy is hard to get the head around, but it does explain the source of energy that drives inflation. We were shown a remarkable graph with data from the WMAP space observatory that measures changes in the microwave background. This was remarkable because Guth’s theoretical calculations of the expected values overlapped the experimental data to an extraordinary degree.

The talk was concluded with a discussion of String Theory in which space and time are in eleven dimensions rather than four. The theory attempts to explain gravity and dark energy, but seems to be more in the realms of mathematical philosophy. We were left with the feeling that much has happened since Tony’s first radio astronomy experiments over fifty years ago, but that actually more problems have been raised than solved. This is part of the appeal of science as well, as the challenge!

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