Physics

The fundamental science of matter, energy, and motion

What Is Physics?

Physics seeks to understand the fundamental laws governing the universe — from the smallest subatomic particles to the largest galaxy clusters. It asks: what are things made of, and what rules do they follow?

Classical Mechanics

Newton's three laws of motion (1687) describe how objects move:

• First Law (Inertia): An object at rest stays at rest; an object in motion stays in motion unless acted on by a force
• Second Law (F=ma): Force equals mass times acceleration
• Third Law (Action-Reaction): For every action, there is an equal and opposite reaction

Key Branches

• Classical Mechanics — motion of everyday objects
• Thermodynamics — heat, energy, and entropy
• Electromagnetism — electricity, magnetism, and light (Maxwell's equations)
• Quantum Mechanics — behavior of particles at the subatomic scale
• Relativity — Einstein's theories of special (1905) and general (1915) relativity
• Nuclear & Particle Physics — the building blocks of matter

Famous Equations

• F = ma — Newton's second law
• E = mc² — mass-energy equivalence (Einstein)
• Schrödinger Equation — describes quantum wave functions
• Maxwell's Equations — unify electricity and magnetism

Why It Matters

Every technology you use — from smartphones to MRI machines to GPS — exists because of physics. It's the foundation of all engineering and applied science.