A:5. How do galaxies evolve?
Both observations and theoretical simulations show that the Universe which emerged from the Big Bang was clumpy on large-scales. These large-scale structures are assumed to have grown gravitationally, under the influence of both dark matter and dark energy, from primordial seed perturbations, possibly generated during a period of inflation in the early Universe. It is within the highest density regions of this fabric that galaxies, the fundamental building blocks of the universe, and clusters of galaxies first formed. Understanding the subsequent evolution of galaxies from the time of their formation, through cosmic time, up to the present day represents a formidable challenge in modern astrophysics. However, using a wide range of complementary techniques and wavebands we are beginning to probe the underlying mechanisms of galaxy formation such as the role of mergers and interactions and the importance of feedback from outflows driven by supernova and active galactic nuclei.