Cosmic Microwave Background astronomy

described here is my own, unless specifically stated otherwise. To the best of my knowledge it has not, nor has any similar dissertation, been submitted for a degree, diploma or other qualification at this, or any other university. This dissertation does not exceed 60 000 words in length. To Isabel and Ffion ii I am not sure how the universe was formed. But it knew how to do it, and that is the important thing. Anon. (child) It is enough just to hold a stone in your hand. The universe would have been equally incomprehensible if it had only consisted of that one stone the size of an orange. The question would be just as impenetrable: where did this stone come from? Jostein Gaarder (in 'Sophie's World') Acknowledgements Firstly I would like to thank the two people who have introduced me to the immense field of microwave background anisotropies, Anthony Lasenby and Stephen Hancock. Without them I would not have begun to uncover the beauty at the beginning of time. I would also like to thank Joss Bland-Hawthorn whose supervision and enthusiasm during my time in Australia has made me more inquisitive in my field. The many collaborations involved in this project have introduced me to many people without whom this thesis would not have been written; Graca Rocha and iii I want to say a special thank you to the two women in my life that have kept me going for the last few years. Thanks to Ffion, my sister, whose insanity has kept me sane and thanks to Isabel whose support and encouragement I could not have done without and whose love has made it all worth while. deserve a special mention for making my time in the department a little more bearable. Anna Moore for putting up with me for three months in Australia. for putting up with me for the first years of my research. I could not finish thanking people without mentioning Pam Hicks and David Titterington (special thanks for all the colour overhead transparencies) who have kept the department running smoothly. I am also very grateful to PPARC for awarding me a research studentship. May they know better next time.