Physics is defined as the study of matter, energy, and the interactions between them, encompassing the fundamental laws governing the universe. It involves the application of mathematics to describe and predict physical phenomena, with a focus on understanding how and why things interact. The discussion highlights the distinction between physics and other sciences like chemistry and biology, emphasizing that physics seeks to explain the underlying principles of nature. Some participants argue that physics has evolved into a probabilistic discipline, particularly at the subatomic level, where cause and effect become less clear. Overall, physics remains a critical field for exploring the fundamental nature of reality.