Back when I started my job at UBC, I remember dropping by our student’s journal club. I was happy to see that the students took initiative and had a very active club, reading and discussing review papers once a week. Good for them, I thought.
I am a great fun of such clubs. Even if your department, like the one at UBC, offers introductory graduate courses in quantum field theory, and string theory, and particle physics,etc., it is still the case that most of what you need to know as a graduate student lies outside your coursework. Along the way you’d be frequently required to pick up new skills and new knowledge, which is precisely why being a theoretical physicist is the best job in the world. Since picking up new knowledge quickly and efficiently is one of the required skills for the job, may as well start early.
Only problem was, the review articles that club was immersed in, how shall I say it gently, were not of central importance to their futures. In fact, I was kind of shocked by the amount of effort going into completely marginal topics (no examples, I realize where we are). So, I started advising this group, and future journal clubs, on what they can benefit from.
In choosing a good review article to discuss in a journal club, or to give to a graduate student, I used several criteria. First, the topic has to be important and long lasting, still relevant for research in say, 5 years. In addition, it obviously has to be well-written, and have a good selection of topics, emphasizing the ones central to the community over the author’s favorite work. Finally, it has to be fun. If you need to know what that means, go read some of Sidney Coleman’s legendary reviews, for examples those collected in his “Aspects of Symmetry”.
These were more or less the same criteria we used in coming up with the curricula for our (ongoing) summer school series “Strings, Gravity and Cosmology”. At some stage, I started collecting those references in one webpage, what every student should know. This is one of those projects I took on and never finished, so the list there is far from being comprehensive, it is a good start but it needs many more additions. Since I now have a blog, I can ask our smart and informed readers, what should I add to the list? please let me know if you can think of topics that should be covered, or specific references that cover them well. If this generates lots of good responses, maybe I’ll try to update my list and post it here sometime.
(Also, one gentle reminder: references to your recent treatise on the theory of everything do not, sadly, count as something central to students’ future. Since I am trying to protect the establishment, I’m likely to be narrow-minded and delete references to any truly revolutionary work).
What about the mathematical tools?
Topology, algebraic geometry, “advanced” differential geometry… A lot of stuff that I have to learn by myself during my phD… I know that a lot of hep-th physicists did and still do very good works with only minimal knowledge of these subjects (only a so-called “physicist knowledge”), but personally I need to grasp better the mathematics I’m supposed to use.
Representation theory is another big meal (but it is more often taught to undergrads than the former ones).
Agreed, but in my view those are better absorbed in the context of applications. Otherwise, there is the risk of being methodical and comprehensive about it, instead of being practical and picking up the tools you need. These are after all beautiful subjects, you could spend most of your life admiring them.
I would throw in some non-perturbative QFT somewhere. This tends to get short shrift in standard texts, like Peskin and Schroeder, where the emphasis tends to be on Feyman diagram-ology for particle physicists. Coleman’s lectures, as you mentioned, are great.
Also, some special topics which are worth seeing are large N field theory (Coleman again) and QFT in curved space (first couple chapters in Birrell and Davies).
And, if you mean string theory students specifically, I would say one should at least skim one of Sen’s reviews on open string tachyons.
I think anyone doing strings should learn Calabi-Yau-ology at some point, and this is an area that can get missed nowadays if you work on e.g. AdS/CFT style topics. The reason is that as well as being beautiful in itself, it connects many different branches of the subject – mirror symmetry, string phenomenology and stringy model building, exactly soluble CFTs, topology change and flops/conifold transitions, string cosmology and inflation.
There’s no one review covering all of this. Brian Greene’s review 9702155 from the 90’s is good on the geometric aspects and topology change, but doesn’t cover any of the pheno/cosmo aspects. The Douglas/Kachru review 0610102 on flux compactifications has more on the pheno side, but may assume a bit too much on CY knowledge.
piscator
The string theory people at QMUL have made life easy. Go pick! 🙂
Do you mean particularly students intending to go into string theory? For me personally in retrospect I would have loved it if I had picked up some more “irrelevant” stuff. In depth (non equilibrium) statistical mechanics, non perturbative/lattice quantum field theory, all the current developments in condensed matter physics, topological order, etc…
Unfortunately I don’t know good review articles for them either. The point being that these are all examples of methods that while not necessarily applicable/relevant directly to my work they represent the cutting edge of what is actually being used to describe observable lab systems.
Anomalies and field theory dualities. Path integral magic. Universality, critical phenomena and renormalization.
Sadly too much of what I know about renormalization has to do with hiding infinities and not enough about fixed points hot magnets.
fh: yes, I meant people interested in fields close to mine, high energy physics, gravity and cosmology, I should have been more clear. Lots of other interesting things going on, and it is a good idea to have some level of knowledge about them. But, what I meant to generate is a fairly minimal list of reviews that are indispensable. Even such a minimal list should be more than enough to take all your time, even if you don’t intend to sleep during grad school.
Lionel: Path integral magic? you mean something to do with vanishing rabbits?
I am shocked about the hiding infinities business, absolutely the wrong way to discuss renormalization, and I would have thought by now a particularly antiquated way to teach the subject. All of that should be part of the standard field theory sequence, not something to pick up by yourself. Peskin and Schroeder, among other standard texts, approaches the subject the correct way.
In my defense, I only took quantum field theory once, and just like you don’t get to choose your parents…
The standard field theory sequence thesedays seems to be a sweeping review of Wigner’s classification followed by path integrals and becoming proficient with phi^4, culminating in some Yang-Mills and Faddeev-Popov, if you’re lucky. I think you’re asking too much of those soporific fourteen weeks.
Path integral magic refers to a bag of tricks too numerous to list. I’m endlessly entertained learning about these things, like a kid in a candy store. I suppose the replica method falls under this category, although I don’t find that one particularly illuminating.
A world of physics lays hidden inside functional Jacobians.
To my defense, I had the luxury of taking field theory many times, I think 8 semesters in total. They were all different too, which is precisely your point I believe. Anyhow, we can chat if you want, lots of physics also outside functional determinants.
For people like me who are self taught and they study physics for entertainment purposes, the physics text books are really bad. In most of them there are absolutely no insights. Just the derivation of the equations with no reference to the true meaning of these equations and their physical implications. For example I bought Kiritsis’s “String theory in a nutshell”, just because he was Greek like me and because the phrase “in a nutshell” gave me the false impression that I could learn the basics of string theory fast. Needless to say it was a nightmare. The reader was pounded relentlessly with an equation after an equation and at the end he couldn’t understand what string theory is after all. I had to download many papers from the arxiv in order to start to understand the very basics.
Saying that I have a recommendation for the reader of this blog regarding the standard model and gauge theories:
All Ian Aitchison’s books: Gauge theories in particle physics Vol. I and II and supersymmetry in particle physics.
They are truly priceless.
Giotis, not all texts are all that bad, but generally reviews tend to be better. I don’t know that specific one, but my knee jerk reaction is usually against anything that involves “nutshell” in the title, though there are some exceptions.
As for string basics, maybe the following, which I discovered recently, could help:
http://www.damtp.cam.ac.uk/user/tong/string.html
There may be room for a lightly technical overview of string theory, intended for advanced laypeople, UG students, and our colleagues. I am not aware there is something like that out there at the moment. Maybe because that would be quite the project to take on…
Thanks for the link Moshe. It seems pretty good.
Regarding “String theory in a nutshell”, Kiritsis is fair and in the preface warns the reader by saying:
“It is not the purpose of this book to provide deep insights into the theory. I can only leave this to more competent colleagues”
Indeed, anybody can write down the formalism and the equations. The difficult part is to explain the deep physical meanings and implications of these equations. It is very rare to find this to text books; it requires a true talent and charisma from the author and of course a deep understanding of the things he is writing about.
I forgot to mention for the interested reader that there is also this free book of Siegel called “Fields”: hep-th/9912205 v3.
With almost 900 pages it contains practically everything from classic to quantum fields and from GR to supergravity and strings.
I have read only small parts but I’m planning to read it all when I have the time; it’s size is kind of intimidating though. Generally Siegel follows an unconventional approach in this book.
Hey I just wanted to thank you for the link and I hope you get the chance to expand it. I’ll pass it on to our journal club here at UCSB.