Bob Lambourne Lecture - Cosmic Microwave Background (CMB)

Following our AGM on 15th October we were treated to an excellent lecture from Dr. Robert Lambourne Head of the Physics & Astronomy Department at the Open University, on the Cosmic Microwave Background (CMB). Bob is well known to our Society as he has lectured to us on several occasions. 

In the 1980s' cosmologists formed the theory of "cosmic inflation," and asked did it really happen? It is still being studied today in an attempt to prove it . 

The Cosmic Microwave Background Radiation was released about 380,000 years after the "Big Bang". It is the oldest light in the universe, and we cannot see anything before this period. It is explained as the cooled down radiation in the microwave region of the spectrum left over from the early stage of development of the universe, before atoms existed and stars and galaxies formed. When the universe was young it was denser, hotter, filled with opaque gas, and developed a light pattern afterglow. It contained all the matter of the universe in a very small space (i.e. a small bubble) and is thought to be uniform in all directions. Bob said that everything we see as astronomers is within the expanded bubble. As it expanded it grew cooler and became transparent. The gas collapsed and the first stars formed about 400 million years ago, and later the galaxies and planets formed. The very short and rapid burst of growth in the very early universe may explain the large scale uniformity of our universe and the structures within it. 

We saw an all sky measurement CMBR map on screen which showed tiny fluctuations in the density of matter and temperature changes. Three space missions have been studying this . Firstly, NASA's COBE explorer in the late 1980s' showed very limited measurements due to lack of technology, the second mission NASA's WMAP in 2001 showed greater detail, and because of the highly improved technology the ESA PLANCK mission launched in 2009 gives very detailed measurements and temperatures at different frequencies across the whole sky. The differences between the three mission results could be easily seen on the graphics. The PLANCK mission is still ongoing. There are other experimental groups studying the CMB including the BICEPS South Polar telescope.

Bob's talk covered aspects of the power spectrum, dark matter, dark energy, gravitational waves and many other areas. He provided us with a very interesting and very technical physics lecture which was followed by questions from members.

We thanked Bob and look forward to future lectures from him. 

Jan Dell