So, You Want to be a Theorist? A Series on Entering the World of Theoretical Physics as an Undergrad
Maybe you loved physics since you were little and saw your favorite science fiction show for the first time, or maybe you just figured it out recently, but you are thinking about studying physics as an undergraduate, and you've heard something about eventually needing to decide whether you want to be a "theorist", or an "experimentalist". There are many different paths that can lead people to physics, and depending on which path you've taken, you may or may not have had a chance to think about this choice or found out much about it. But, perhaps, whatever you have heard, you're interested in theoretical physics and you might want to become a theoretical physicist. This series of posts is intended to serve as a rough roadmap, and offer advice about how to make the most out of your time as an undergraduate figuring out whether or you want to pursue a career in the field.
I'm going to assume that you have some interest and background knowledge of physics, and that you have a rough idea of what the differences are between theoretical and experimental physics. But, if you started out like I did, then at some point you probably felt like you didn't really know which field is more suited to your interests.
How do you choose between theoretical and experimental physics?
There's no easy answers to this question, but the best advice that I know to give is to really get a feeling for what it's like to do both jobs from as many places as you can, and use that experience to guide your choice. This series will be written primarily from the perspective of someone who early on figured out he liked theory better, but wanted to explore what it was like past the limited experience that he had at the time before getting into graduate school. However, the spirit of much of the advice here is valid for those who are not as firmly committed yet, and probably even those who are strongly interested in experimental physics.
So, if you're a beginning undergraduate interested in physics, what can you do to find out what theoretical physics is like? The first thing you should think about doing is to go find out which professors have some background in theory at your school's physics department, and ask them about it. Tell them you're thinking about choosing theory as a career, and ask what you should know. If your school has a graduate program, ask graduate students too. Depending on your personality, it could be a little nerve-wracking at first, especially as a new student, but most faculty and grad students are very interested in talking about their work. They studied physics because they enjoy it, and usually are very happy to offer advice and chat about it. The goal is to talk to people who are doing what you're thinking about doing, and doing it because they love it. Meeting these people is very important because it will help you decide if you can see yourself doing something similar and being happy with it too. You should meet and talk to as many people as possible; reading blogs written by physicists is also a good idea because it can give you some insights into what their daily lives are like. This kind of experience is what drove me into physics, and without it I do not know whether I would have pursued it or not. I can't stress enough how important it is.
Once you're at the point of taking classes, you'll most likely be enrolled in an introductory physics course. Depending on what level of physics you studied in high school, this might be a course on mechanics, electromagnetism, or maybe even a "modern" physics course or something similar. Based on my experiences, introductory physics courses are not good at giving you a feeling for what physics is like at the upper undergraduate and graduate levels. The courses are designed to give you proficiency with core 18th and 19th century physics (unless you're taking the modern physics class), and while this is very important knowledge to have, it won't necessarily give you a great idea of what 21st century theory is like. For this, there are a few small things you can start to do. First, reading about modern topics that are popularly discussed (e.g. the Large Hadron Collider, the Higgs boson, dark matter detection, observing the cosmic microwave background, etc.) will give you some idea of what is going on today. However, popular physics can be problematic in that the real work is buried behind over a century's worth of mathematics and physics that usually takes about 8 years to learn, and what is presented in magazines, online articles, and news stories can range from giving a fantastic picture of what is going on to a very misleading one. Keep all of that in mind when looking at such topics. If there are professors or students working on research that sounds interesting to you, ask them about it! They'll likely love the chance to talk about it and it will give you a first-hand picture of modern research. Getting involved in research yourself as an undergraduate is also a great idea (more on that later). Finally, if you have the time, see what upper level courses are being taught now or soon, and ask the professor if you could sit in on the lectures. There's no need to do any homework or attend every lecture (though if you want to it will probably be rewarding later when you do take the course for real), the idea is just to see what it's like, and if you find the kinds of things being discussed interesting. Just remember that if you do sit in on an upper-level course, some things will fly over your head, and this is perfectly okay. Don't get stressed about that.
Now, realize that the goal here isn't necessarily to make the decision about exactly what kind of physics you want to do while you're still an undergraduate. You will have to make this decision a year or so into graduate school (if you're pursuing a PhD or masters, at least), but your undergraduate career is about getting some broad perspectives to help you narrow down later. It might help if you do discover whether experiment or theory is better for you, but you don't need to make that decision before graduate school. However, if you are interested in exploring theory further before graduate school, what else is there that you can do? The most basic two things are take courses and do research. There are many smaller events that will happen in-between these that will shape your undergraduate experience, but those are more specific to which school you go to and your circumstances. Those small events will be the subject of future posts, but for now, let's just tackle the most universal pieces.
What about courses?
Unless you go to a university with a big physics department, your courses will likely (at least at the start) be more or less chosen for you by the program. Everyone in physics takes the basic undergraduate theory and experiment courses, regardless of what you may specialize in later. But, if your school has electives in physics (and math), then which side you're leaning on might have some influence here. If you're interested in theory, special topics courses in subjects like relativity, particle physics, solid-state physics, cosmology, astrophysics, and other topics outside of the three core courses (classical mechanics, electromagnetism, and quantum mechanics) will be useful if you can take them. Math courses in linear algebra beyond the basic course usually required for physics majors, partial differential equations, Fourier analysis, and even real analysis, among others, will more than likely come in handy. Talking to grad students with similar interests, or professors who followed a similar path to yours can be helpful when choosing electives (and of course, your advisor!). But you should also focus on electives that are interesting to you, including non-physics and non-math courses. Being an undergraduate is a unique opportunity to get some broad exposure to other ideas beyond where you're looking for a career, and that kind of exposure is important to a lot of people, including myself.
And research?
Undergraduate research used to be less prolific than it is today, and now it is almost standard to do some as a junior or senior (though I have not heard of lacking any experience seriously hurting someone later on in graduate school). However, depending on where you are, it is probably possible to get involved in research sooner than this if you're interested and willing to commit to it. However, there are a few caveats specific to doing theoretical research as an undergraduate.
You probably can't work on the Higgs Boson. I don't only mean actual work in the Higgs sector of the standard model, but also most other very well known modern theoretical physics research questions. These topics are very, very far removed from the undergraduate curriculum and require enormous amounts of work just to truly understand the underlying problem, let alone begin to solve it. I'm not trying to crush your dreams, but to say that if this kind of work is what you aspire to do, then there is a long road ahead of you. Part of what I want to do is shorten that road and help people find ways around some of the hurdles I have encountered, but doing this kind of research is not going to happen you first year at college unless you have essentially already learned the entire undergraduate curriculum before showing up.
It is possible, however, to work on interesting and modern research fairly quickly. Depending on what knowledge you have and what courses you're taking, it is possible to find professors who will bring you on board to a project in theoretical physics. This is harder than finding an experimental research project, because you usually need more background knowledge to do theoretical research. But, if you talk to professors, I think there is a good chance you will find someone to work with. You should talk to professors about research they really enjoy, because they will be more willing to (and better prepared to) help you catch up on that research. This means you might not end up doing exactly what you had in mind, and quite possibly something you'd never known about or heard of, but if you're open to it, doing this kind of research can be very rewarding. I never thought that I would be particularly interested in silver nanowires, but working on that research project has taught me an enormous amount and been a lot of fun. In graduate school, no one expects you will have already done theoretical physics research similar to what you will want to do in graduate school, so getting experience with other fields won't hurt you, and even doing experimental research projects is probably a good idea. The key thing to do is to do what is interesting to you and what will teach you and give you experience.
The first steps to getting involved in undergraduate physics research is talking to professors, and after that, probably doing at least some background reading. The next post in this series will be primarily about the details of getting involved in a research project early on, and my advice for doing this. The long term goal is for this series to offer a set of resources which will help anyone interested in theoretical physics maximize their involvement as early as possible.
This series will not be unique; there are several others who have posted similar advice:
John Baez, a mathematical physicist, has written a page on advice for the young scientist.
Philip Tanedo, now a post-doc at UCI, wrote a blog post offering a roadmap for undergraduate students.
Sean Carroll, a well-known cosmologist, wrote his own blog post on an idea for undergraduate research in theory which highlights some of the difficulties I mentioned above.
See you next time!
