Explore the fascinating theory of cosmic inflation and its role in explaining the early universe in this comprehensive lecture by astronomer David Mulryne. Delve into the limitations of the hot big bang model and examine alternative ideas about the universe's origin. Learn about the expansion of the universe, general relativity, and key concepts like the flatness problem and horizon problem. Discover how cosmic inflation addresses these issues and potentially explains the origin of cosmic structure. Gain insights into cutting-edge cosmological research and the ongoing quest to understand what happened before the hot big bang.