In the course
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10 videos · 3 h 21 min
Explainer · YouTube
Khan Academy
Khan Academy's beginner introduction to what the quantum wavefunction is, how to use it and where it comes from. Watch for how ψ is turned into probabilities, the recipe that Parts 2 and 3 make exact.
Explainer · YouTube
Richard Behiel
A visual case for why quantum mechanics runs on complex numbers, aimed at learners who have met some quantum mechanics but find the complex numbers puzzling. Behiel pictures the phase as a generalization of plus and minus that drives interference: this section's arrows, which Part 5 puts to work. His chapter 'Plane Waves' (14:30) is this section's winding-phase wave; the closing 'U(1) Symmetry Implies Electromagnetism' (18:07) is an optional extra.
Explainer · YouTube
Professor Dave Explains
Professor Dave on what wavefunctions are, then how to normalize them and calculate expectation values: the recipes of this section and of Part 4. It assumes you have met operators and picks up bra-ket notation and inner products along the way, chapter 14's language, so treat normalization and expectation values as the payoff.
Explainer · YouTube
Looking Glass Universe
A six-minute Looking Glass Universe lesson on the rule of quantum mechanics behind much of its strangeness: interference. Keep this section's callout beside it: probabilities can only add, but amplitudes can point opposite ways and cancel.
Lecture · YouTube
Ryan O'Donnell
A short segment of Ryan O'Donnell's Carnegie Mellon course on quantum computation (15-859BB, Fall 2018), posted on his own channel and devoted to the claim in this section's first paragraph: multiplying a state by a global phase changes nothing you can measure. It is written for qubits rather than ψ(x), the same argument in vector form; relative phase, as the section shows, is another matter.
Explainer · YouTube
PBS Space Time
The title is this section's closing question, and the episode's answer is objective collapse: theories that treat the wavefunction as real and add a physical collapse to explain why big things never show quantum strangeness. It is one more answer beside the many-worlds and pilot-wave views the section names; chapter 22 weighs them all.
Lecture · MIT
MIT OpenCourseWare · Allan Adams · 2013
Allan Adams's MIT 8.04 lecture introduces the wavefunction as the fundamental description of a quantum system, states the probability rule and normalization, shows why a wave of definite momentum is equally likely to be found anywhere, and restates superposition and uncertainty in the language of wavefunctions. A university-level companion to Parts 1 to 3; expectation values arrive in his next lecture.
Lecture · MIT
MIT OpenCourseWare · Barton Zwiebach
An eight-minute segment of MIT 8.04 (Spring 2016) on what the wavefunction means: Born's probability interpretation, stated on the blackboard. Compare his notation with this section's recipe, density |ψ(x)|² times a width gives a probability.
Lecture · MIT
MIT OpenCourseWare · Barton Zwiebach
Zwiebach asks which wavefunctions can be normalized at all and whether a normalized wavefunction stays normalized as time passes: the last paragraph of this section, done properly. It looks ahead to the Schrödinger equation of chapter 10.
Interview · Institute for Quantum Computing
Institute for Quantum Computing · Urbasi Sinha
Urbasi Sinha, then a postdoctoral fellow at Waterloo's Institute for Quantum Computing, explains the triple-slit experiment that put Born's rule on trial, the 2010 test this section describes. The logic to keep in mind: squaring sums of amplitudes produces only pairwise interference, so a genuine three-path term would break the rule.