NSAS Seminar Series - Cosmology with Professor Geraint Lewis

Research interests

Professor Geraint Lewis undertakes a broad spectrum of research.

On the largest scales, his program involves looking at the influence of dark energy and dark matter on the evolution and ultimate fate of the Universe. Another aspect of his research uses the phenomenon of gravitational lensing to probe the nature and distribution of the pervasive dark matter, and employing individual stars to magnify the hearts of quasars, the most luminous objects in the Universe. Closer to home, Geraint's research focuses upon Galactic cannibalism, where small dwarf galaxies are torn apart by the much more massive Milky Way and Andromeda Galaxy. Using telescopes from around the world, including the 10-m Keck telescope in Hawaii, he has mapped the tell-tale signs of tidal disruption and destruction, providing important clues to how large galaxies have grown over time.

Geraint's topic is:  Supermassive black holes and time in the Early Universe

Einstein’s universe, underwritten by his general theory of relativity, is a weird place. One key prediction from his mathematics is that we should see the distant universe run in slow motion, with time running slower the further back we look. But the hunt for this cosmic time dilation in some of the brightest objects, supermassive black holes known as quasars has failed to find this effect – until now! In this talk I will present our latest work on the cosmological time dilation of quasars, revealing what we found and what it means. As well as confirming that we live in an expanding universe, these findings hammer nails into the coffins of more outlandish cosmological ideas.