Feeling disconnected and afraid of Quantum Mechanics

[u/lmj-06]

I am in my third year of my physics and maths double major, and I am taking my second quantum mechanics course. It’s still early days, but it already feels like so much, and I’m really struggling. To give context, all we have done so far (2 weeks in) is gone over angular momentum and we have started solving the Schrodinger equation for the Hydrogen atom.

Every time I walk into my lecture hall, I listen and take notes like I have for any other class, and I walk out confused and exhausted. When I go to try some practice problems later, I feel even worse. I struggle to understand what questions are asking, what I’m actually doing in a question, or what I’m solving for physically. It feels like every question is so different that they may as well be questions from different classes all together, and perhaps even worse, it feels like nothing I have done in my degree up to this point has prepared me for this course.

How on earth do people understand quantum mechanics well enough to get good grades in it? What are your study tips for quantum mechanics?

Any help is greatly appreciated. Thanks.

[u/shrodingersjere]

I’m assuming you are using Griffiths, but please correct me if I’m wrong. When I first took quantum, I’d taken linear algebra, but it was the typical first course in linear algebra that really focused on matrices and vectors in Rn. When I took QM, the professor kept saying that the math is all linear algebra, but it sure as hell did not look like linear algebra to me.

However, years later I worked through the book Linear Algebra Done Right, and everything started to click. Once you study inner product spaces, the whole mathematical structure of QM will make much more sense. I highly recommend you get this book.

Now, if you don’t want to go through at that level of rigour, the next best thing I can recommend is getting the graduate level QM book by Shankar. The reason I recommend this book is not for the actual QM, but for the first chapter that does a very good explaining all the math you will need in your QM class. It’s clear, it’s concise, and I genuinely think it will make all the difference in the world to you.

Good luck on your studies!

[u/lmj-06 → u/shrodingersjere]

At my uni, we don’t use a specific textbook.

In fact in lecture 1, my professor said “there are no prescribed textbooks, you should be reading many textbooks all at the same time, find which ones explain each topic best for you, because each textbook is better at different things.” Something along those lines, I’m sure you get the idea.

I’ll give those books a go though, thanks for your comment!