physics

Group theory earns its keep when a symmetry argument settles a physical question no calculation was going to answer. This lesson covers group actions and counting up to symmetry, why crystals cannot have five-fold rotation and what happened when one did, Noether's link between symmetry and conservation, and how the same idea is built into modern networks.

QKD has an unconditional security proof and almost no deployment. This lesson covers the authentication bootstrap it cannot solve, distance limits and the trusted node compromise, attacks on real hardware that the proof does not cover, why NSA and NCSC recommend against it, and where quantum genuinely delivers.

Quantum cryptography uses physics rather than computational hardness. This lesson covers the no-cloning theorem, the BB84 protocol step by step, why measurement in the wrong basis leaves a detectable trace, the error rate threshold, and the entanglement-based alternative.

Why Unity runs physics on its own 50Hz clock instead of the frame rate, and what follows from that. Covers rigidbodies and colliders, moving things correctly with forces rather than the Transform, interpolation for smooth motion, tunneling and continuous collision detection, and where physics cost actually comes from.

What a qubit actually is, why measurement destroys superposition, how entanglement links qubits, and how the quantum circuit model turns these ingredients into computation.

What it takes to fuse hydrogen isotopes — the four conditions (temperature, density, confinement time, energy gain), the three main approaches (magnetic, inertial, magnetized target), the engineering problems (tritium, neutrons, materials) that remain after the physics is in hand.

The handful of quantitative concepts that make every energy debate readable — joules and watts, energy density, capacity factor, levelized cost of energy, exergy — and what each one is good and bad at communicating.

The mathematical object behind a qubit — a complex unit vector in a two-dimensional Hilbert space — and why measurement collapses superposition. The structural difference between a quantum state and a classical bit, expressed in math.

What makes silicon work where diamond won't, why doping turns an insulator into a tunable conductor, and how slapping p-type silicon next to n-type creates the depletion region that becomes a diode. The physics every chip is built on.