Lewin For The Love Of Physics

Working Through Lewin's Lectures Without Losing Your Mind

Lewin For The Love Of Physics has become one of the more frequently recommended free physics resources online, and honestly, it deserves the attention. The lectures cover everything from classical mechanics through quantum physics, recorded at MIT with a straightforward classroom style that cuts out the fluff. I went through the full series a few years ago while trying to fill gaps from my undergrad, and there are specific ways to make it actually work rather than just watching passively. The lectures are organized into roughly 36 sessions spanning the standard physics curriculum. Each one runs about an hour, and Lewin writes extensively on the board while working through derivations in real time. That's the key thing most people miss about this resource. He doesn't skip steps or jump ahead with hand-waving. If you sit down and actually work the math alongside him, it becomes a functioning textbook replacement. If you just watch, you'll forget half of it within a day. I ran into a specific issue with the classical mechanics lectures, particularly the section on rotating reference frames and the Coriolis effect around Lecture 8. The problem was that Lewin sets up the coordinate transformation in a way that assumes you already have comfort with vector operators in non-inertial frames. I got stuck for about three days trying to follow the derivation because my linear algebra was rusty, and the lectures move past this without explicitly connecting the pieces. The workaround was to pull up Strang's linear algebra lectures for the operator fundamentals and come back. That connection between matrix operations and vector derivatives didn't show up in the physics lectures themselves but it was absolutely necessary to follow along. Once I had that foundation, the rotating frame derivation clicked in maybe twenty minutes.

The electromagnetism section, starting around Lecture 14, is where the real value sits. Lewin handles Maxwell's equations in a way that most upper-level courses don't. He derives the wave equation from scratch using vector identities rather than just stating them. One thing that trips people up is the boundary condition work in the magnetostatics portion. He moves quickly through the discontinuity conditions for B and H fields, and beginners often skip past the derivation assuming it's obvious. It's not obviously obvious if you haven't seen the integral form applied to a pillbox surface. I recommend keeping a pen and paper ready during those sections and working through the pillbox argument yourself before he moves on. Download and access info: The lectures are freely available on MIT OpenCourseWare and YouTube. There's no official download link from MIT, but the videos are accessible through the OpenCourseWare physics page. The accompanying problem sets and exams are also posted there, and those are worth doing even if you're only watching for understanding. The problems reinforce the derivations in a way that passive viewing doesn't. Here's what nobody warns you about. The quantum mechanics lectures, starting around Lecture 28, assume a lot of mathematical maturity. Specifically, the treatment of Hilbert space and operator formalism expects you to be comfortable with bra-ket notation and eigenvalue problems before Lewin introduces them. The first two quantum lectures felt like trying to read a newspaper in a language you half-know. I skipped ahead to the Fourier analysis lecture (number 27) and did the problems in Griffiths' intro to QM for the sections I couldn't follow, then came back. The gap between classical and quantum in these lectures is genuinely wide, and Lewin doesn't bridge it explicitly.

Another counter-intuitive point: the thermodynamics lectures aren't as straightforward as they look. Lecture 24 on entropy and the second law uses a statistical mechanics approach that's concise to the point of being sparse. Lewin states the Boltzmann relation S = k ln W and moves immediately to applications without deriving it from first principles. If you want the derivation, you need a separate resource. I used Schroeder's thermal physics for that section, and it took about two hours of supplementary reading to fill the gap. The payoff was understanding why the microcanonical ensemble approach works, which made the later lectures on phase transitions much clearer. There are legitimate limitations to this resource. The video quality varies because these were recorded in actual classrooms over many years. Some lectures have poor audio, especially the earlier ones from the late 90s and early 2000s. The camera work is static, focused on the board, which means if you're at the back of the room in the original footage, you'll be squinting at chalk. This matters more than it should because missing a step on the board forces you to pause and rewind repeatedly, which fragments your focus. I found it more efficient to watch at 1.25x speed and take notes rather than constantly stopping. The note-taking is non-negotiable. These lectures reward active engagement and punish passive consumption. The series doesn't cover general relativity or particle physics in any depth. If you're looking for those topics, you'll need to supplement with other resources. String theory is completely absent. Field theory gets a brief mention but no dedicated treatment. The classical waves and optics portion is solid, though the diffraction derivations assume you already know how to set up Fresnel integrals. If you don't, spend time on that first because Lewin treats it as given.

A practical schedule that worked for me was three lectures per week with a day of problem solving sandwiched between. The information density is high enough that watching five or six in a row leads to diminishing returns. I'd estimate that working through the full series with problems takes about four to six months at a moderate pace. The real time investment is in the problems, not the watching. Factor that in upfront because people consistently underestimate it. The supplementary materials on OpenCourseWare include the full problem sets with solutions, midterm exams, and final exams with answers. Use the solutions selectively. Look at the setup and first principles of each problem before checking the answer key. If you look at the solution too early, you short-circuit the learning process and the lectures lose most of their value. I made this mistake with the Lagrangian mechanics problems and had to go back and redo about twelve of them after realizing I'd been peeking. One more thing worth noting. Lewin's teaching style favors physical intuition over rigorous mathematical proof. This is a strength for building understanding but a weakness if you need formalism for exams or research. The derivations are correct but sometimes hand-wave the convergence conditions or domain restrictions. For most people this is fine, but if you're using these lectures to prepare for graduate qualifying exams, you'll want to cross-reference with a more formal text like Jackson for E&M or Landau for mechanics. The intuition you build here will serve you well, but the rigor isn't always there.

The resource is completely free, requires no account, and the lectures are archived in high enough quality for study purposes. The main costs are time and discipline. If you can commit to working through them systematically with problems and notes, this is one of the best physics education resources available, period. If you're looking for something you can casually watch without engaging, you'll get very little out of it and probably conclude it's not worth your time, which would be a mistake on both counts.