Physical Cosmology can be split into 2 major branches: the detailed study of how structure formed; and the investigation of the parameters which describe the entire Universe. My research involves several different parts of both of these branches.
The most extraordinary fact that we have been learning about cosmology in the last few decades is that there we can make measurements which give us direct answers to questions about the large scale nature of the Universe. Right now these quantities are being measured with increasing precision and we are in a period of rapid growth in our understanding of cosmology. Many of today's questions appear answerable on a timescale of years - and this is what makes cosmology currently so exciting!
We know that the Universe has close to flat geometry, and is dominated by a mysterious dark energy, with most of the matter also made of some as yet unknown form. The early Universe was very smooth, with low amplitude density perturbations of the sort generated in the inflationary picture of the early Universe. And we know that those perturbations grew through gravitational instability to make all the structure that we seee in the Universe today. Galaxies are the fundamental building blocks of this structure, but the details of galaxy formation are not yet understood, because it involves a huge range of physical processes on a variety of length scales and time scales.
Measuring the dozen or so cosmological parameters cannot typically be done without also measuring quantities that depend on galaxy formation and evolution. Hence the study of the two main branches of cosmology are always intimately connected. With the parameters being measured to greater and greater precision, and the physics of galaxy formation being dissected in ever increasing detail, we are still left with many unsolved puzzles. In particular: why do the parameters have the values that they do? what are the dark matter and the dark energy? did inflation really happen and can we learn anything about it? are there basic ingredients currently missing from the standard cosmological model? when exactly did the first stars form to end the cosmic dark ages? what is the history of star-formation over cosmic time? what is the relationship between supermassive black holes and the galaxies that they form inside? what will be the far future fate of the Universe and of our small part of it?
The development of structure in the Universe is a complex and multi-faceted topic. Tackling the biggest questions in the formation and evolution of galaxies and clusters of galaxies requires a combination of observational and theoretical approaches, covering the full range of the electromagnetic spectrum. A crucial and developing window is in the sub-millimetre part of the spectrum, where one can readily study star-forming galaxies at very early times. Because of this I have become involved in several projects and instruments which focus on using these wavelengths in order to conduct ambitious, deep extragalactic surveys.