The Universe's expansion is accelerating, and no one knows why. This research tackles the two biggest unknowns in cosmology: the nature of dark matter, which outweighs ordinary atoms five to one, and dark energy, the force driving cosmic acceleration. It also pursues the detection of gravitational waves—ripples in space-time predicted by Einstein but never directly observed—and investigates how planets form around other stars, a step toward finding life beyond Earth. The work combines theory with observations from satellites like Planck and Herschel, and prepares technology for future missions such as LISA, a space-based gravitational wave observatory. Better measurements of cosmological distances and the cosmic microwave background will sharpen our understanding of the Universe's composition and fate. This is fundamental science with no immediate practical application. Yet past fundamental research on the cosmic microwave background led to technologies now used in precision timing and satellite navigation. A deeper grasp of exoplanet formation could one day guide the search for habitable worlds, while gravitational wave astronomy may open an entirely new way to observe the cosmos.
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Our research in Astrophysics includes the areas of cosmology (the study of the Universe), the most distant galaxies, exoplanets (planets around other stars), and gravitational waves (distortion of space-time predicted by Einstein but so far not detected). This work will make a contribution towards answering some of the greatest questions that can be posed, including: can we find signs of life outside the solar system? and what is the fate of the Universe? Our work involves a combination of theory and observations. We use cutting-edge facilities such as the Planck and Herschel satellites, and LISA Pathfinder (to be launched in 2015), and we also develop the theory and technology that will lead to proposals for the development of the next generation of satellites and experiments. Our understanding of the nature of the Universe has changed profoundly over the past 20 years, since it was discovered that the expansion of the Universe is accelerating, and as experiments, primarily those observing the cosmic microwave background, have allowed the accurate measurement of the parameters describing the Universe - the proportions of ordinary matter (atoms), dark matter, and dark energy, and the current rate of expansion. Dark matter clumps gravitationally and outweighs ordinary matter by a factor 5, but what it consists of is unknown. The even greater mystery is dark energy, which is causing the acceleration of the Universe, and which dominates the mass-energy budget. Our work in cosmology takes different approaches to answering these problems. But the common theme in our research is the understanding that advances will come through improved experiments that measure quantities (cosmological distances, the rate of expansion) more accurately. The experiments rely on better technology (e.g. measurements of polarisation of the cosmic microwave background), better understanding of the physics under study (the properties of supernovae used to measure cosmological distances), and better data analysis techniques that improve the precision and accuracy of the results (applying rigorously the Bayesian formalism to complex large datasets). No less profound for humankind has been the discovery, again over the past 20 years, of planets around many of the nearest stars in our galaxy, and the first characterisation of other stellar systems. If the ultimate goal is to discover life on other planets this will be achieved through successive advances in understanding how different types of planet (rocky/gaseous, large/small) form around different types of star (old/young, active/inactive, hot/cool) at different radial separations, and of how the star over its lifetime can affect the conditions on its planets. Our work in this area includes theoretical work to understand the mechanisms by which planets form, as well as developing a deeper understanding of stellar variability and how this can subtly bias measurements of the atmospheres of planets (possibly leading to eroneous conclusions), as well as influence the habitability of planets. A consequence of Einstein's 1915 theory of general relativity, which describes the curvature of space-time due to mass, is that massive objects undergoing acceleration radiate energy in the form of gravitational waves, propagating the signal of the change of curvature at the speed of light. Gravitational waves have yet to be detected, but their detection is one of the great goals of physics. The effect is extremely subtle, so measurements in space away from sources of vibration and the influence of the Earth are called for. Our research on gravitational waves centres on contributing to the development of technologies for use in the planned European Space Agency mission LISA (not expected to launch before 2030), and analysis of data from the LISA Pathfinder mission, to be launched in 2015, that will test prototypes of these technologies.
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