How do you deal with weak background at the start of PhD?

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  • #1
MadAtom
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Hi all,

I just started in a PhD in a General Relativity related problem. Although the problems that I am going to work with are purely classical (in the sense of no QM required), I feel bad about my lack of proficiency in QFT.

I had to follow a course in some advanced topics (such as String theory and CFT), which is mandatory for the program I am in, and I was really lost. I understood the ideais, but I really struggled with the exercises, because of my lack of "experience" in QFT problems. My QFT course was really introductory and I did very few exercises.

For example, when someone asked me to apply Wick contraction, I had to go back to textbooks, because it is not something I have from top of my head, and I did not do many exercises on it at the time.

So my question is, how do you tackle this problem? The feeling that you lack some foundations, even though they are not really important to what you do, but you think that a well rounded physics should know. How do you convince yourself that "it is OK" to have these deficiencies or, rather, that it is not?

Sorry for the vagueness in this question.

MA
 

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  • #2
Choppy
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This sounds like a good topic for discussion between you and your supervisor.

I know, at the start of a PhD, you would likely rather impress your supervisor than walk in and admit that you're not as strong as you'd like to be in a particular area. But ignoring the problem or simply hoping that it won't be important in the long run doesn't seem like the best way to tackle it. At the same time, I can also appreciate that one can't be an expert in everything and at some point you have to focus. But this is why such a question is best discussed with someone who has expertise in your area. Your supervisor should have an idea of how strong your QFT foundation needs to be, even if it's just for passing your qualification and/or candidacy exams. Once you have a sense of how strong that really should be, you can develop a strategy for addressing it. That could include revisiting the prerequisite courses, finding a decent problem set to work through, auditing another course, etc. and balancing all of that with making progress on your research project.
 
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  • #3
BvU
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So my question is, how do you tackle this problem? The feeling that you lack some foundations, even though they are not really important to what you do, but you think that a well rounded physics should know. How do you convince yourself that "it is OK" to have these deficiencies or, rather, that it is not?
I sympathize. Personal story: Embarked on a PhD in high-energy physics when, just a year before, I had casually remarked that I would get my experimental physics masters pretty soon without knowing anything at all about elementary particles. Following some lectures for theoretical masters students (field theory, phenomenology of elementary particles, both given by later Nobel prize winners! :smile: ) did not help me much further. Nor did a series of lectures later on at CERN by Victor Weisskopf
One of his few regrets was that his insecurity about his mathematical abilities may have cost him a Nobel prize when he did not publish results (which turned out to be correct) about what is now known as the Lamb shift.[6]
And, still later at SLAC, a series of QFT lectures by John Dirk Walecka -- they were aimed at theoretical physics graduate students and way above my abstraction level. Couldn't finish a single execise on my own. I kept the notes and the book for fourty years but now I'm going to chuck them out (anyone a good offer for Itzykson and Zuber: QFT ?).

You simply can't know everything. But you can still achieve a PhD for what you can know and do (as you understand, I got mine -- in experimental physics).

This sounds like a good topic for discussion between you and your supervisor.
I second Choppy: you have been selected for a reason (that you apparently still have to find out). Find out what the expectations are (and manage them if unrealistic). Find your forte and thrive.

##\ ##
 
  • #4
Dr. Courtney
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Hi all,

I just started in a PhD in a General Relativity related problem. Although the problems that I am going to work with are purely classical (in the sense of no QM required), I feel bad about my lack of proficiency in QFT.

I had to follow a course in some advanced topics (such as String theory and CFT), which is mandatory for the program I am in, and I was really lost. I understood the ideais, but I really struggled with the exercises, because of my lack of "experience" in QFT problems. My QFT course was really introductory and I did very few exercises.

For example, when someone asked me to apply Wick contraction, I had to go back to textbooks, because it is not something I have from top of my head, and I did not do many exercises on it at the time.

So my question is, how do you tackle this problem? The feeling that you lack some foundations, even though they are not really important to what you do, but you think that a well rounded physics should know. How do you convince yourself that "it is OK" to have these deficiencies or, rather, that it is not?

Sorry for the vagueness in this question.

MA

I'd slow down. Focus more on passing your general exams rather than wowing your research supervisor and peers. Coming from LSU, I had a pretty weak background among my peers at MIT. After a frank discussion with both my research supervisor and academic advisor, my plan was to retake the four core undergraduate courses my first year, and focus additional independent study on the first general exam. It felt remedial taking undergrad E&M, Stat Mech, Quantum Mechanics, and Classical Mechanics over again. But I gained a level of mastery that served me well not only on the PhD qualifying exams, but throughout my research and teaching career. The course load was also light enough that I could begin being active in the research program - mostly coming up the learning curve, but making a few small contributions based more on my technical skills than on my physics knowledge.

It took me several years before I was really ready or any advanced topics. The first year was retaking undergrad courses, and the next couple were taking the meat and potatoes grad courses in prep for the 2nd PhD qualifying exam.

It was a slow start, but by my third year, I was in demand as a collaborator both in the department and beyond since my programming skills and computational prowess put some tools in my toolbox that other groups appreciated (as well as my research advisor). By the time I completed my PhD, I had been a co-author on 8 theory papers and first author on four.
 
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  • #5
MadAtom
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This sounds like a good topic for discussion between you and your supervisor.

Thank you for the input! In fact my supervisor is not too much concerned about my performance in those courses, but just on the research itself. And for the research that I am going to do, these deficiencies that I have in QFT will not weigh that much.

But it is more of a psychological burden. It weighs on my conscience not to know certain things.

But I guess I have to start becoming more comfortable with my own ignorance in order to move forward, and realize that academic life is marked by never-ending learning...
 
  • #6
MadAtom
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Find your forte and thrive.
##\ ##
Thank you for sharing this!
 

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