Part I: Spacetime Foundations
Before Einstein, space and time were thought to be separate, absolute entities. The revolutionary insight of special relativity is that they are unified into a single four-dimensional spacetime continuum. This part explores the historical context, experimental evidence, and conceptual foundations of Einstein's theory.
Part Overview
In 1905, Albert Einstein published "On the Electrodynamics of Moving Bodies," introducing special relativity. The theory emerged from the incompatibility between Galilean relativity (classical mechanics) and Maxwell's electromagnetism. Einstein resolved this with two simple postulates that led to profound consequences: time dilation, length contraction, and the relativity of simultaneity.
Key Topics
- • Historical context: Galilean relativity and the search for the aether
- • Michelson-Morley experiment: the null result that shook physics
- • Einstein's two postulates and their radical implications
- • Time dilation: moving clocks run slower
- • Length contraction: moving objects are shortened
- • Relativity of simultaneity: "now" is observer-dependent
- • Minkowski spacetime: the geometric unification of space and time
7 chapters | Foundation for all of SR | From Galileo to Minkowski
Chapters
Chapter 1: Galilean Relativity
The principle of relativity before Einstein. Galilean transformations, inertial frames, and why classical mechanics is the same in all uniformly moving frames. The concept of absolute time.
Chapter 2: Michelson-Morley Experiment
The famous 1887 experiment that sought to detect Earth's motion through the luminiferous aether. The null result, attempts to explain it (Lorentz-FitzGerald contraction), and its revolutionary implications for physics.
Chapter 3: Einstein's Postulates
The two simple postulates at the heart of special relativity: (1) The laws of physics are the same in all inertial frames, and (2) The speed of light in vacuum is the same for all observers. Deriving the structure of spacetime from these postulates.
Chapter 4: Time Dilation
Moving clocks run slower: where . The light clock thought experiment, proper time vs. coordinate time, experimental verification (muon decay, atomic clocks on airplanes), and the twin paradox.
Chapter 5: Length Contraction
Moving objects are contracted in the direction of motion: . Proper length, the barn-pole paradox, and why this is a real physical effect, not an optical illusion. Experimental evidence from particle accelerators.
Chapter 6: Relativity of Simultaneity
Events that are simultaneous in one frame are not simultaneous in another. The train-and-platform thought experiment. Why "now" is observer-dependent. Implications for causality and the light cone structure of spacetime.
Chapter 7: Minkowski Spacetime
Hermann Minkowski's geometric interpretation: "Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality." Spacetime intervals, worldlines, light cones, timelike/spacelike/null separation, and the metric tensor .
Course Navigation
Prerequisites:
- • Basic calculus and algebra
- • Classical mechanics (Newtonian physics)
- • Basic understanding of electromagnetic waves