This class was extremely difficult I would recogmend not taking it with him. This class is also technically skippable. If you must take this class take it with a diffrent professor.
He is a great guy, funny, and lectures well. But his exams can be astronomically difficult.

Regan is a cool guy, I like him a lot and he clearly cares about the welfare of his students, but fuck this class is hard. I'm a CS major, I don't care about physics, and I really don't want to spend the amount of time required to do well in this class on physics. It's probably a good take if you will do physics upper divs, but it's not for me.

Regan doesn’t know the material, and doesn’t want you to know it either. 17 is supposed to be an introduction to atomic phenomena and some elements of quantum mechanics. He refuses to make a class that is in itself supposed to be easy actually digestible, by including as much content as possible, and presenting it as superficially as he can. He mentioned geometric algebra (cause I cannot use the word “taught”), only to not use it again in the remainder of the course. He usually starts using some physical concepts under the umbrella of “I’ll make it clear later” and then forgets to define it properly until everyone is utterly confused. He spent an entire lecture talking about fermion and boson statistics, which required attention to the effects of spin-coupling. He used the word “spin” about 30 times that entire lecture, without defining spin once. The first question he was asked after the class was “What is spin?” He went out of his way to give the most rigid, abstract, confusing, and mind-boggling presentation of one feature (the turning of a playing card), instead of defining it for the means of a lower division class. The student was visibly confused. They were speechless. Regan smirked and moved on. He didn’t even ask the student if it made sense. He just moved on. That happened to me too. He just doesn’t know the material profoundly enough to actually answer questions, or teach for that matter. And he enjoys confusing his students. Otherwise, he would not smirk so visibly when someone doesn’t know something.
His homework is unreasonably difficult. He always taught the concepts needed for 80% of an assignment the day it was due. Since his lectures lacked any conceptual insight and were nothing but regurgitations of formulas, the assignments felt demoralizingly difficult. And the grading was harsh and lazy. His homework problems had a lot of subsections, and if you had one typo for one, your score for that problem started from 75%. It didn’t matter if everything but your answer for one subsection out of say 5 was perfect, you still got a 75% for the problem.
His exams require literal memorization of problems, instead of conceptual understanding. Preparing for exams was a witch hunt of “What could Regan decide to test us on?” He didn’t teach what a blade in geometric algebra was. He briefly described it in some typed lecture notes on his website. We got that on our exam. And he shamed us publicly for not knowing it in the lecture notes.
Regan is too concerned with trash talking other physicists to actually do his job. He builds his personality on the hate he has for the textbook, the constants in physics, or different historical concepts. No human being should build a personality on what they hate. That is not just counterproductive, but harmful. As a physics major, I want to be encouraged by my professor’s love for physics, not their hate for what they perceive to be “stupid.”
Don’t take his class. Just don’t. As a physics major in college you deserve a professor that is knowledgeable, passionate, and sincere. Regan is none of those things.

Grading: I got an A without really understanding anything and get about the average on every midterm/final. Still very confused about that curve. The averages were around 55-65%.

Prof: Take Regan if you really understood 1B, if not, you're kind of screwed. You also have to understand the readings that were supposed to be done each week and took about ~2 hours each for me. He makes the assumption you know all that information going into lecture. Which is great if you do because then he teaches very well at that high conceptual level. If not, then you'll be in week 10 and see him write Maxwell's equations every lecture and still have no idea what they mean.

Regan: cool funny guy
tests: crazy hard
homework: ALOT
hbar: stupid human constant
don: enlightened
the curve: GNARLY

fr fr tho, prof is super dope, funny and knowledgeable. He teaches QM with his own twist, which was weird at first but later it kind of grows on you.

This class for most of the quarter was quite difficult and had me questioning my major. There were two midterms, a final, and a bunch of homework. The homework was very doable and Regan would almost always extend the deadline. The midterms were difficult but overall I would say they were fair. The final was also fair in my opinion. Some tips for future people taking this class: 1) Don't freak out if you start off the quarter not knowing wtf is going on in the class. The first lecture petrified me and I didn't think it would get better from there, but it does. 2) KNOW THE HOMEWORK. It seems that Regan really liked pulling questions from the homework to put on the midterms/final. If you really know the homework and the ideas that were covered then you will do fine on the exams. 3) Don't freak out if you do poorly on the first (or maybe second) midterms. Since Regan curves, as long as you stay near the average you should do fine. I was below average by a lot on the first midterm, around average on the second midterm, but I crushed the final, so I ended up with an A-. For me, Regan's lectures weren't that helpful, but they were entertaining. I found myself mostly self-studying for the course. Overall, study the homework/textbook really hard and don't freak out and you should do fine.

I don't really like his teaching style, which is basically just doing derivations for the full lecture. I feel like I'd probably do just as well if I didn't go to class and just studied from the book, since that's what his test questions are like. The tests have gnarly curves.

Good professor. I think many people in my class found the lectures too theoretical and boring, but I really enjoyed the thorough derivations because everything felt so connected. It's quite impressive how many things one can derive from Maxwell's equations. If you have genuine interest in physics, I highly recommend him, but if you just want to get by in the class (which I can understand), his lectures are probably not for you. He does go over a lot of material that's never even remotely tested, but regardless, I found the lectures worthwhile.

His tests were fairly challenging. I'd say half of the midterm questions were pretty straightforward, sometimes even exact homework problems, while the rest would be stuff a bit beyond the scope of the textbook that he specifically talked about in class (ex. AC circuits with complex notation, relativistic kinematics, spinning charged spheres). He does not go through many examples in class, but if he does, you can almost guarantee it will show up on an exam in some form. If you know how to do the homework problems and understand the more challenging concepts he goes over in class, you should do relatively well on the test. Take advantage of your note card and write down a tough question or two if you still have room. I thought his final was easier and most of the questions only tested a basic understanding of the topics, save for a few tough questions.

I also recommend going to discussion sections at least before the exams because sometimes the TA's will do problems that are similar to the ones on the test.

Midterm 1 average: 56
Midterm 2 average: 49
Final average: 60

Regan was very passionate about the content in the class which showed during lecture but lectures themselves weren’t helpful. Sometimes there would be a nugget of good information in one of the derivations which would help on a homework problem but the homework problems were mostly self taught. Don’t bother going to office hours, he can be really helpful when on track but most of the time it was just a hang out. The two midterms were nearly the same as the homework and the notecards were helpful. The final was brutal and the highest score was a 35%; it was not in any way similar to content we found in class. Overall my advice would be to read the chapters before you do th homework. Don’t be stressed by the first 3 weeks of the class, it’s supposed to be overwhelming. The last 3 weeks were a breeze because everything interconnected and the first 3 weeks finally made sense. I only got a B because I wrote an equation wrong on my notecard but otherwise I think I would have probably gotten an A- . I think beside the mishaps, Regan was pretty fair and reasonable.

Most difficult and stressful class I've ever taken, and it doesn't need to be, so avoid this professor if you can. Saddly he was a really entertaining lecturer, I actually enjoyed class, he also told jokes, always tried his best to answer questions, and held lots of office hours. But that doesnt make up for the fact that I thought I was gonna fail most of the quater. I walked out of both midterms and the final thinking I could have studied weeks more and not been able to get a 60%. The average grade on both midterms was around 50%, but if you stay around the average (I was below by a few percent both times) and turn in all your homework, you might be okay besides the anxiety and depression. I still don't understand how I got a B-, honestly, the curve must have been crazy. If you are a quick study, extemely knowledgable on all physics, and phenominal on creative problem solving, you might be one of the f***ers who can get an A, otherwise you're in for a wild ride.