What Is Quantum Mechanics?
Quantum mechanics is the physics of the very small — atoms, electrons, photons. It's the most accurate theory in science, yet its implications seem impossible.
Why "Quantum"?
In 1900, Max Planck discovered that energy comes in discrete packets called quanta — not continuous streams. This was the first hint that reality at small scales is fundamentally different.
Key Concepts
#### Wave-Particle Duality
Light and matter are both waves AND particles. An electron isn't a tiny ball — it's a wave of probability until measured.
The famous double-slit experiment shows this: electrons create wave-like interference patterns, but hit the detector as individual particles.
#### Superposition
Before measurement, particles exist in multiple states simultaneously. Schrödinger's cat (a thought experiment) is both alive and dead until observed.
This isn't metaphor — it's how reality works at quantum scales.
#### The Uncertainty Principle
Heisenberg showed you cannot know both position and momentum precisely. The more precisely you measure one, the less precisely you know the other.
This isn't a measurement limitation — it's fundamental to nature.
#### Entanglement
Two particles can become "entangled" such that measuring one instantly affects the other, regardless of distance. Einstein called this "spooky action at a distance."
Why It Matters
- Computers: Transistors rely on quantum effects
- Lasers: Quantum light emission
- MRI machines: Quantum spin of atoms
- LEDs and solar cells: Quantum energy transitions
Future quantum computers may solve problems impossible for classical computers.
The Measurement Problem
When we observe a quantum system, it "collapses" from superposition to a definite state. What counts as observation? Why does this happen?
Physicists still debate interpretations — Copenhagen, Many Worlds, Pilot Wave. The math works perfectly; the meaning remains mysterious.
Related Reading
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