Reddit mentions of Introduction to Quantum Mechanics

Author of two widely used undergratuate physics texts: one for Electricity and Magnetism and one for Quantum Mechanics. He also authored the somewhat-less-widely used (perhaps mainly because it's a specialist subject in most undergrad programs) Introduction to Elementary Particles.

If you really want to learn quantum mechanics check out this intro book by David Griffiths. It assumes you know some calculus but that's about it.

Start off with a good undergraduate level book, such as Griffiths, you need a good grasp of differential equations first. (I think you can pick up partial differential equations through the course since most problems in introductory QM are separable and they walk you through the separation)

MIT has these resources, but unless you are a prodigy, I think you'll need a textbook with descriptive explanations to really get it.

If you're searching for free information, I'm not going to tell you to search torrents for "quantum mechanics" and "ebook" because that would be unethical. (being sure to select "file scan")

But a good place to start might be like this

Start with Griffiths Introduction to Quantum Mechanics.

You know how when you're spinning the wheel of a bike, it takes work to stop it, or change the direction? That property is called angular momentum and is in some sense the "angular version" of linear (plain-old) momentum (the property that makes heavier, faster things harder to stop).
The spin of a particle is an inherent angular momentum; it's a property of the particle ITSELF, not of the STATE of the particle. Yes, that's weird. It's something that's very hard to understand without quantum mechanics.

Particles that have spin not equal to 1 are even more confusing! The best way to understand spin 1/2 particles comes from an analogy that Roger Penrose came up with: imagine a closed book with a belt stuck in it like a bookmark and attached to a fixed table. If you rotate the book by 360deg about an axis parallel to the belt, the book's back to where it started, but the belt has a twist in it. You can't, without moving the book, move the belt around in any way (we say "continuously deform it") so that the twist goes away. On the other hand, if rotate the book through 720deg, we have two twists that will go away if bring the belt around the book.

Why this happens is very difficult to explain, and impossible in an ELI5 context. I recommend you get a textbook in quantum mechanics. Griffths' is the most widely used, but it's targeted at 2nd year physics majors, and [Townsend]
(http://www.uscibooks.com/townsend2.htm) has a more accessible text targeted to freshmen. Penrose's Road to Reality is layman friendly book (I often joke that even medical students might be able to understand it), but reading it is a (very rewarding) ordeal. It covers what's essentially all of physics. On the other hand, it's only ~1200pages to cover the last 4 centuries of human understanding, so it's very handwave-y.

EDIT: links

The first one can be learned from Griffiths' text, but it's definitely an 3rd/4th year physics textbook. If you have a strong background in math, though, much of the physics can probably be gleaned quickly enough from online introductory material.

As for the second, I've been told that Emmy Noether's Wonderful Theorem is a great read, but I haven't taken the time to check it out yet.

I do highly recommend Genome by Matt Ridley and A History of God by Karen Armstrong. It looks like Before the Big Bang might be a great idea too.

However, I'm noticing a bit of redundancy in your stacks and don't want you to get bored! In the presence of the other books, I would recommend Dawkins' The Ancestor's Tale in lieu of The Greatest Show on Earth. (Although, if you're actually not going to read all the other books, I would actually go the other way.) Similarly, I would probably choose either to read the God Delusion or a few of the other books there.

Other recommendations: how about The Red Queen by Matt Ridley, and The Seven Daughters of Eve by Bryan Sykes? These occupy niches not covered by the others.

The popular expositions on cosmology all look supremely awesome, but you should probably choose half of them. Another idea: read just The Fabric of the Cosmos by Greene, and if you love it, go ahead and learn mechanics, vector calculus, Electrodynamics, linear algebra, and Quantum Mechanics! Hmm...on second thought, that might actually take longer than just reading those books :)

Griffiths' Quantum Mechanics has a crash course in most of the linear algebra required to do a first course in quantum mechanics. It's not very complicated - you just need basic understanding of vector spaces, linear transformations and functionals, and inner products, with a little bit of practice using dual notation of vectors (not too much, just enough for the Dirac notation which the book explains). Griffiths' also has a good explanation of simple fourier series/transform.

The key thing is being able to do basic linear algebra without matrices since in most of the cases, the vector space is infinite dimensional. But spin is a good example where almost everything can be done with matrices.

Additionally, solving ordinary differential equations and using separation of variables for partial differential equations in 3-d quantum mechanics would help.

Group theory will be of help in more advanced classes. Dummit and Foote or Arton's books on algebra are decent introduction. They are a bit dense though. If you want a real challenge, try Lang's Algebra book. I don't know of any easier books though. My first algebra book was Dummit and Foote which can be done without any real prerequisites beyond matrix algebra, but isn't really well written.

Links to books: Griffiths, Dummit and Foote.

PS: I have ebooks of these two books in particular.

Wow, thanks for the Reddit gold, that's awesome! It's been my pleasure to have the discussion with you. As for a good textbook, I have a few suggestions. For a pretty good broad look at optics from both classical and quantum points of view, give Saleh and Teich a look. For purely quantum stuff, my undergrad textbook was by Griffiths, which I enjoyed quite a bit, though I recall the math being a bit daunting when I took the course. Another book I've read that I liked quite a bit was by Shankar. I felt it was a bit more accessible. Finally, if you want quantum mechanics from the source, Dirac is a bit of a standard. It's elegant, but can be a bit tough.

My first response is that probabilistic doesn't mean unpredictable - just the opposite in fact. It may not be possible to say with 100% certainty the outcome of any particular event but the predictions of Quantum Mechanics ultimately boil down to Newtons laws on a macroscopic scale leaving little doubt about the power of prediction. Besides there are quantum effects such as tunneling which happen but would be classically impossible (tunneling is when a particle with finite energy passes through a larger potential barrier). It's a fascinating subject and without a doubt a strange one.


The classical physics treatment is Griffiths: http://www.amazon.com/Introduction-Quantum-Mechanics-David-Griffiths/dp/0131244051

I don't know your math background but it requires a minimum of linear algebra and ordinary differential equations. In reality you need partial differential equations as well but you can get an enormous amount out of it without them. Without knowing your specific background it's hard to tell where to start and it's such a broad subject (hell I've had over a year worth of courses dedicated to the subject not to mention subatomic physics which is basically a continuation of QM and I still don't understand it all) that starting at all is impressive.


It's worth noting that there are two completely different (but equivalent) formulations of QM developed independently. One is almost entirely formulated through matrices the other being through the schroedinger equation. I am personally not deeply familiar with the matrix formulation but if you are strong in linear algebra and weak on ODE/PDE that might be a place to start.


If starting with a text book is too much (and it sure would have been for me had I not been taking it as a course) try going through wikipedia just to see what makes sense and what doesn't. If you start doing some reading and have any questions feel free to PM me and I would be happy to answer as best I can or head over to r/physics - they are generally nice guys as long as the question is fairly specific. Best of luck!