Okay, I can see that point. I admit the language used was imprecise; I was trying to balance between describing what I was doing and keeping it short enough to work as a Slashdot snippet. Perhaps I leaned too far one way. The source article specifies "graduate level physics concepts" instead of just "graduate level physics." This was a submission issue, rather than a source material issue.

Funny, you are criticizing the lesson for the questions raised in this lesson, and then providing many of the exact answers that are coming in later lessons...

So, which parts could I have explained better?

The protons have a mass that's relatively easy to measure. The charge is very well known, as is the interaction of moving charges with magnetic fields. If you fire a proton through a magnetic field, it will be accelerated into a circular motion, and the easily-measured radius of the circle (visible in a bubble chamber) will indicate what the mass is.

For neutrons, it's much harder. Early measurements at the time were imprecise compared to today's. Now that we better understand the mechanism of radioactive decay, we can find it through a roundabout means. When a neutron is not part of a nucleus, it is unstable, and decays into a proton, an electron, and an electron antineutrino. The difference in masses between the neutron and the proton is a significant factor in the half lives of these decays, so that was used in the early days to compute the mass of a free neutron.

Griffiths' text is commonly used, but I wasn't thrilled with it. I'm of the "do the math right or not at all" mentality, and his use of the probability distribution with operators instead of the psi* operator psi proper methodology in the first few chapters forms bad habits with students. It only works because he carefully chooses examples whose operators do not involve derivatives. His electricity and magnetism textbook is fantastic, and his particle text is great, but I'm not happy with his quantum text. Joachain and Bransden made a text I much prefer (in its first edition; I haven't looked at the second edition, ISBN: 0582356911) and would recommend over Griffiths in this case.

The Bureau 42 authors don't use the site for profits. Most years, ad banner revenue is about the cost of renewing the domain name, and none of us get paid to post our stuff. We just have fun in our spare time. That's where this came from; when doing my M.Sc., I found I enjoyed teaching in labs far more than I enjoyed doing the actual research. That realization and a case of bilateral elbow tendonitis prompted me to switch to education. Now I teach K-12 (along with other tasks) at the private education company everybody in North America has heard of, which I love, but doesn't hit the higher level physics often. I wrote these lessons for fun, and shared this one with Slashdot because I thought the series came out well and that others might enjoy reading them.

Yeah, introductory quantum mechanics is introduced typically in second year, and then more detailed versions including Dirac notation show up in third and fourth year. The graduate level is where relativistic implications are usually taken into account, unless you take senior undergraduate particle physics.

Actually, I was working on the ATLAS detector that is in place at the LHC when I started writing for Bureau 42 almost 10 years ago. And I don't know how we profit off of something that's free...

My philosophy (which is in lesson nine, and probably should have come sooner; lesson one is more focused on why we need quantum mechanics, and the rest develops over time) is that the concepts and ideas of physics are represented by the math, but not defined by them. Math can certainly point out directions to look at and avenues to explore, and indicate connections between ideas we hadn't previously noticed, but as a student, I always found that the worst possible reason for a physics phenomenon was "because the math says so." This is about getting those ideas across for people who want to learn about the ideas. The ideas covered in the last two lessons are not typically introduced before grad school. (Lesson one starts at the high school level, which is all I wanted to assume from my audience.) Will you be a researcher when you're done? No. Will you have a better understanding of popular science articles relating to quantum physics? I certainly hope so.

It's hit the concepts dealt with at the graduate level, but I left the math out to make those concepts accessible to people who don't have the heavy mathematical background. I'm half way through writing next year's summer school (linear algebra, full mathematical glory, ending with tensors), and the 2012 curriculum will be Einstein's Relativity and have two parts to each lesson. The first part will be all conceptual, like this, and the second part will have all of the math. 2013 will be real analysis, 2014 assessment theory, and years beyond that haven't been pinned down. The "Bureau 42 teaches" link at the side has everything along these lines listed, with links if they've already been posted.