Chapter 2: Basic Physics – Core Concepts

The historical progression begins with classical physics, which successfully unified mechanical and thermal phenomena, as well as electricity, magnetism, and light into electromagnetic theory. Pre-1920 physics operated within Euclidean space-time, recognizing 92 atomic elements held together by electromagnetic forces that vastly exceed gravitational strength but maintain overall electrical neutrality through charge balance. Electromagnetic fields propagate as waves across an enormous frequency spectrum, from radio waves to gamma rays, with visible light oscillating at approximately 5×10¹⁴ cycles per second. The quantum revolution fundamentally transformed this classical picture by introducing space-time as the physical stage and revealing the failure of Newtonian mechanics at atomic scales. Quantum mechanics established the uncertainty principle, which prohibits simultaneous precise measurement of position and momentum, explaining atomic stability by preventing electron collapse into the nucleus through mandatory kinetic energy requirements. This quantum framework reveals nature's inherently probabilistic character, where individual events follow statistical rather than deterministic laws, and unifies wave-particle duality as universal behavior with higher frequency waves exhibiting more pronounced particle characteristics. Quantum electrodynamics emerged as the successful theory governing light-matter interactions, providing the fundamental rules for electrical, mechanical, and chemical phenomena outside nuclear processes while predicting antimatter existence. However, nuclear physics presents ongoing challenges, with strong nuclear forces requiring separate theoretical treatment and experimental discoveries revealing complex particle classifications including baryons, leptons, and mesons that resist unified description. Contemporary physics recognizes four fundamental interactions arranged by decreasing strength: strong nuclear force, electromagnetic force, weak nuclear interaction, and gravitational force.