Cosmology with the cosmic microwave background light: then and now

Please join us before the Colloquium in Hennings 318 for coffee, tea and snacks at 2:45 pm

Cosmology enjoyed a remarkable development over the last century. Astronomical observations revealed that galaxies like our own are not distributed at random throughout space, but rather delineate a quite remarkable structure, reminiscent of the skeletal framework of a sponge. How could that be? We now have developed a compelling picture of how these galaxies and their distribution developed over time, under the influence of gravity. We trace their origin to the earliest moment of the Universe. Most effective in achieving our current understanding has been the study of the sky background light called the Cosmic Microwave Background. This light, which is invisible to the naked eye but easily measurable with modern sensors, travelled uninterrupted for 13.8 billion years throughout the Universe. It last interacted with the material content of the Universe when the Universe was very much hotter, denser, and more homogeneous than it is now. It thus bears witness to the prevailing physical conditions back then and sheds light on the process that generated the primordial seeds out of which structures grew. As a result, recent observations bring amazing confirmation of ideas put forward in the 19880s and open a window on physics over a range of scales, times and energies that were hitherto inaccessible. I will describe how we came to the arresting conclusion that we are the children of quantum fluctuations of the vacuum!