# What should a physics major know?

It’s summer. In academia, it’s a time to get some real research done, take a little R&R with ones family, perhaps wait in breathless anticipation of the paperback release of ones book, and most relevant to today’s discussion, to think about the successes and failures of the previous year.

In addition to my regular duties as a professor, I am also the director of Drexel’s undergraduate Physics program. Each year I have the opportunity to meet with prospective students and parents, guide admissions and curricular policies, and keep an eye on our students to see how they’re doing and where they’re going. And for the most part, our students do great things and go on to great places. For many of them, going on to do great things doesn’t necessarily mean that they go on to be physicists.

Oftentimes, when asked to talk about the value of a physics degree, I focus on how a physicist can do just about anything: finance, engineering, computing, medical school. But these outcomes suggest that the degree that many students actually go to school for — Physics — serves as nothing more than a testament to the fact that they can survive a challenging environment. We could, I suppose, simply take the view that it doesn’t matter whether they go into physics. Research skills, programming, electronic design, data analysis, mathematical rigor and so forth are useful skills for everybody. Certainly, there is a national push for so-called STEM education, and a very real recognition that these skills make a graduate employable.

I think that physics should go beyond an elite STEM accreditation field. The degree matters, even for those students (most of them, actually) who don’t go on to become physicists. They should learn what the state of the science is; they should be prepared to interpret for the world at large, to bring science and subject-specific literacy into their and others’ lives. And what else?

I have a few thoughts on that.

1. Physics education should not be “engineering light.”

Let’s start with the introductory sequences. Pick up just about any high school or calculus-based college textbook and you’ll see physics presented in almost the exact order it was discovered. (As a sidenote, you’ll also see virtually identical tables of contents, making it particularly easy for lazy instructors who don’t want to alter their lecture notes one whit to change textbooks without doing any additional work.)

Generally, there’s a first term in 17th century physics (Newton’s laws), and a second term on 19th century physics (electromagnetism), while a truly excellent teacher might spend a week or two at the end on the more esoteric chapters from the early 20th century (relativity up to $E=mc^2$ or quantum mechanics up to a vague description of the double-slit experiment). Anything more sophisticated than the bank of a racetrack or the trajectory of a basketball is generally ignored. Speeds above a few hundred mph are generally considered “fast.” This, while we have accelerators capable of accelerating protons to within a few parts in a billion of the speed of light.

These texts are written with the assumption that everyone reading them is going to be an engineer. The fact that future politicians might also be dozing in the audience is generally of only passing concern (a concern typically dealt with by putting a volcano or a bullet train on the cover ostensibly to jazz things up). This means that the T and the E in STEM get virtually all of the attention, and assumes that the S will simply take care of itself. There seems to be a societal shift away from interest in “basic science,” with the assumption that anything that’s not immediately applicable to technology is simple navel-gazing.

Introductory physics, at least for majors, but ideally for everybody else, should ideally talk about what’s going on today, with an absolutely minimal focus on pulleys and blocks on planes. Drexel’s intro sequence, we use the (imperfect, but innovative) Matter and Interaction, by Chabay and Sherwood, which focuses on 20th and 21st century physics from the outset.

2. Most majors aren’t going to be Physicists.

This is okay. It doesn’t represent a failure on the part of physics educators (though perhaps I’m being too forgiving to myself), but a reality of both people’s interests as well as the job market.

We’ve always known that students are likely to go into other fields, and we’ve treated that as an excuse to make to sure that they have lots of other skills. While I’m not arguing that we should forgo general education requirements (the etymology of University stems from Unversis meaning “whole” or “entire,” from a desire to have a universal education — a sentiment with which I wholly agree), it’s worth considering that for most physics majors, this is the end of the road, all of the physics that they’re going to see.

Degree programs that focus only on solving electric fields for configurations of charges or deriving Hamilton’s equations give students the tools of physics, but not the basis. This term I taught a “Standard Model” course for the first time. This was an advanced class officially listed for grad students, but open to undergrads which explored the basis for E&M, the weak and strong forces, open questions with regards to neutrinos, and so on, without requiring Quantum Field Theory. It was literally the most fun I’ve ever had teaching a course, and the students seemed to have a ball as well.

The more I think about it, the more I think that this is exactly the sort of course that should be required at the advanced undergraduate level. If the BS really is the terminal degree for most of our majors, then by the time they finish, they need to really see how everything fits together. And yet, courses like this seem to be the anomaly. I was only able to cobble together the course from various Classical Field, QFT, and Particle Physics textbooks, even though we were, in essence, justifying the study of just about everything else they’d seen.

In order to make a coherent (or semi-coherent) whole, I put together a set of ever-evolving course notes with the long-term goal to turn them into a textbook. If you’d like, please check them out, and be sure to send me any corrections and comments you might have. (Please be kind.)

3. “Physicist” doesn’t just mean one thing.

It never did, of course. There is an enormous push for “interdisciplinary” research and academic programs at the university level, and you’ll find few people as skeptical as me. Oftentimes, the push is made at the institutional level so that individual researchers will be eligible for federal grants that they might not be otherwise, occasionally at the cost of focus on disciplinary areas of research.

That said, the boundaries between basic research in condensed matter and applied research in materials engineering is a narrow one, as are the boundaries between biophysics and biomedical engineering, biochemistry (and several other fields). A graduate of physics can be a physicist without following the same career trajectory as even a generation ago. One approach that we take (which, admittedly, is a bit ad hoc) is to allow a much more a la carte approach to completing the degree outside of the essentials (which I’ve taken a stab at above). Physics is far too large to imagine a degree focused around course subfields or core methodologies (theorist? computational “experimentalist”? instrumentalist? You’re all physicist here.)

That said, I’d like to issue an unresolved word of caution. It’s very easy to suppose that there are no boundaries between disciplines and that a student with a particular career trajectory should simply pick and choose. Beyond the question of whether an 18 or 20 year-old is prepared to map out their future in that way, it’s worth remembering that undergraduate degrees are not a professional degree. Also, that even within those permeable membranes, there’s a lot about physics that is physics, and nothing else. And while I’d like to be able to offer a rigorous definition of what defines a physicist for the next generation, I’m afraid I’m left with Justice Stewart’s definition: “I know it when I see it.”

Hopefully, some of you can do better.

-Dave

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### One Response to What should a physics major know?

1. Seth says:

You really did leave with quoting Justice Stewart.

There’s a professor at UDel who keeps telling me a (experimental) PhD should be able to do three things:
1- design/conduct an experiment and get results (zero still counts).
2- read and understand a reported experiment (and lightly, a theory).
3- communicate their findings to others (that thing called a paper or thesis and presentations).
That the PostDoc is then able to do no.1 with a variety, not just the same thing over and over again.

Arguing against him (thinking I could be finished in 12-18 months) I plea I know nothing- but I know that I know something, I just think all of that something isn’t enough for that one thing called a PhD.

So let me tell you what I think a physics major should know, and yeah, I’ll be tooting my own and yours too: my undergraduate curriculum.

I know, but listen- the modern physics course (I had Steinberg) isn’t standard, as far as I’ve seen. And I’m *terribly* grateful for it. On top of that, the advanced lab (with Lane) gave me practical troubleshooting skills not taught in a mechanics (classical or e&m) lab. And the gripe I hear when I tell someone the first week of your intro class freshman year was particle based… The computation work freshman year with Tony﻿…. none of this seems to be standard- and I’m particularly lucky that it was compulsory.

The bonus really came junior and senior year with the special topics courses- because those really let you mind reach out and explore what is happening currently… at least to an mild/lowly graduate level lecture experience. (If you had graduate experimental courses… ) But we- students- can’t tread water without those “fundamental” courses, because they’re the supporting principles of the topics.

I’ll allow the hubris in this case: I’ve mastered the high school physics. You know- that stuff they teach to the engineers to build a toothpick bridge. Probably in part because of how many times I’ve had to teach it to someone else. But I haven’t mastered the real theoretically complicated stuff- and maybe, just maybe, if I end up teaching that to someone, I just might.

To end my rambling- I take a bit of pride knowing what I don’t know. And how to figure it out anyways. A BS in physics should be able to do at least two things:
1- figure out how to solve a problem put to them (either with theory for fundamental type problems or with a reasonable scientifically sound argument, aka pop science… why does the sun shine?)
2- teach someone unfamiliar with the subject, basic high school level physics topics. (If they can go and teach what they have learned in quantum or stat mech/thermo- give them a grant.)