Master Physics Fundamentals
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The word "physics" comes from the Greek physis (φύσις), meaning "nature." Its intellectual roots stretch back more than 2,500 years — to Thales, Democritus, and Aristotle in the 6th–4th centuries BCE. But physics as we recognize it today began in the 17th century, when Galileo Galilei (1564–1642) established experimentation as the foundation of scientific knowledge and Isaac Newton (1643–1727) published Principia Mathematica in 1687, laying out the three laws of motion and universal gravitation that would describe the physical world for the next two centuries.

The 20th century transformed physics again. Albert Einstein's theories of special relativity (1905) and general relativity (1915) redefined space, time, and gravity. Between 1900 and 1930, Max Planck, Niels Bohr, Werner Heisenberg, Erwin Schrödinger, and others built quantum mechanics — the framework describing matter at atomic and subatomic scales. These two theories, alongside Newton's classical mechanics, form the three pillars of modern physics.

At its core, physics rests on a small number of fundamental principles: the conservation of energy, momentum, and charge; the constancy of the speed of light at 299,792,458 metres per second; the four fundamental forces (gravity, electromagnetism, and the strong and weak nuclear forces); and the mathematical language — calculus, differential equations, linear algebra — used to express them.

Physics matters because everything else in science and engineering is built on it. Chemistry is applied atomic physics. Electronics is applied electromagnetism. Astronomy, materials science, medical imaging, GPS satellites, and semiconductors all rely on physical principles first worked out in a laboratory or on a chalkboard. Understanding physics fundamentals is the closest thing there is to reading the operating instructions of reality.