Relativity: Special Relativity Principles and Consequences

This lecture covers the principles of special relativity, focusing on Einstein's two postulates established in 1915. The instructor explains that all physical laws are the same in all inertial frames and that the speed of light is constant in a vacuum, independent of the source. The lecture discusses the implications of these postulates, including the relativity of simultaneity, time dilation, and length contraction. The instructor introduces the concept of proper time and proper length, illustrating these ideas with examples such as muons and their lifetimes in different frames. The mathematical framework of Lorentz transformations is presented, which reconciles classical mechanics with relativistic effects. The instructor emphasizes that the speed of light is a universal limit that cannot be exceeded, demonstrating this with examples of relative velocities. The lecture concludes with a discussion on how events are perceived differently in various inertial frames, highlighting the importance of understanding spacetime in the context of relativity.