Albert Einstein presents his revolutionary theories of relativity, beginning with the special theory in the first part. He systematically dismantles classical mechanics by examining the physical meaning of geometrical propositions, coordinate systems, and the constancy of the speed of light. By analyzing how observers on moving trains and embankments perceive time and simultaneity differently, he demonstrates that spatial and temporal intervals are not absolute. This leads directly to the Lorentz transformation and the realization that the velocity of light serves as an absolute limiting speed in the universe, fundamentally altering our understanding of mass, energy, and momentum.
Transitioning to the general theory in the second part, Einstein addresses the limitations of classical physics regarding non-uniform motion and gravitation. He introduces the principle of equivalence, arguing that the effects of acceleration and a gravitational field are physically identical, which explains why all bodies fall at the same rate regardless of their mass. This equivalence leads to the profound realization that gravitational fields curve space and time, requiring a shift from Euclidean geometry to non-Euclidean Gaussian coordinates to accurately describe physical reality.
Einstein demonstrates the validity of his general theory by applying it to observable phenomena, most notably predicting the correct calculation for the perihelion movement of Mercury and the gravitational deflection of starlight during solar eclipses. These predictions successfully resolve long-standing astronomical discrepancies that classical mechanics could not account for, providing robust empirical support for the new framework.
In the final section, the discussion extends to the cosmological scale, exploring the structure of the universe as a whole. Einstein examines the difficulties inherent in Newton's infinite universe and proposes that space may be finite yet unbounded, behaving as a spherical continuum determined by the distribution of matter. Through these concepts, the work redefines humanity's fundamental understanding of the cosmos, replacing rigid Newtonian absolutes with a flexible, four-dimensional space-time fabric.
