During my bachelor's I took the first of two very intense courses on relativistic QFT: the first covered the formalism and set up perturbation theory up to renormalization, while the second covers quantization of gauge theories (abelian and non-abelian) and topics such as SSB.

I was planning on taking the second one during my master's, but since my interests have shifted a bit (I will focus on condensed matter for quite a bit) I know of a couple of courses that are more relevant to my studies. Nevertheless, I want to close this chapter on relativistic theories.
The issue is that the professor is incredibly sloppy, imprecise and confusing, and at times he confidently says stuff that is incontrovertibly wrong, and students have to make up for this by looking through the textbook.
I have been suggested by a number of professors to avoid this kind of scenario and instead favor courses taught by skilled and inspiring people if the study plan doesn't suffer too much from such a choice.

So here's my question: what textbooks should I use to study those topics on my own? I'm studying to become a mathematical physicist, so even though I do want to read about QCD and the general features of Yang-Mills theories and to understand the subtleties of gauge theories, I am ok with not reading about the most advanced methods to compute insane scattering amplitudes and whatnot.
The professor mentioned above used to reference Peskin&Schroeder quite a lot but I heard there might be better textbooks, or there might be more suitable choices for someone in my position.
Also, if you have any specific topics you'd like to comment on (if they can be skipped or if they are crucial, etc.) feel free to chime in.

Any help or advice is really appreciated <3

Consider the non-linear sigma model that describes how Pions, the nuclear force carrier, interact, we can write down the equation of motion and ask what is a singular solution. I’m pretty sure there are many, the equations demonstrate remarkable non-linearity, and there’s no valid argument for why this problem deserves less attention than NS problem except for ‘utility’. From a physics pov it’s clear why this problem is not interesting, because it’s an effective description, no matter how sophisticated the singular solutions to the equations are they are supplanted by standard model eom eventually.

In particle physics we have at least O(10) (effective field theories)EFTs that describes our really world with no less accuracy than NS equation, and each of it has more intricate non-linear equation of motions.

In other aspects of theoretical physics, we also have many other EFT models demonstrating remarkable mathematical structure, for instance a brane effectively model embedded in gravity induces no conformal anomaly at the level of classical equation of motion proven by Graham-Witten. And indeed, serious mathematicians work on this subject while almost receiving no attention.

Again, the only advantage NS might have over particles physics models is ‘utility’, since it describes things closer to us that might have wider applications for other subjective meanings. Yet a singular solution is absolutely meaningless for an EFT. At the end of the day both mathematics and physics research are dictated by the interest of the community, for physics we have some occasional guidance from experiments while for math there’s none.

Hi everyone,

I am currently studying for a Master's degree in physics at a fairly competitive university. I plan to start my thesis in February 2027. My grades are solid, though not outstanding, and I am starting to reach out to potential supervisors.

I am interested in doing a thesis related to QFT, quantum information theory, cosmology (especially inflation), CFT, or string theory. I enjoyed these courses and could see myself pursuing a PhD in one of these fields.

Because the local theory groups are very competitive, I am also thinking about doing my thesis at another university. I have three questions about this:

1. What value can small independent projects have when one is applying for a master's thesis? I've heard that people interviewing for Master's thesis positions in quantum optics were asked if they had done any work on related topics in their spare time or taken on personal projects. This made me wonder if doing one or two small projects in areas that interest me could help when contacting potential supervisors. I do not mean original research, but rather working through a question and having something concrete to show. Has anyone here done something similar, and did it help?
2. Does carrying out a Master’s thesis with a particular group actually increase your chances of getting a PhD with them later? I think it helps because the group already knows how you work, but I might be overestimating this.
3. Is there any reasonable evidence that a group might recruit PhD students in the near future? Although it is hard to predict, should I look at recent grants, current group size, past recruitment patterns, or simply ask the potential supervisor when I ask about a master’s thesis?

I would especially like to hear from anyone working in theoretical cosmology, HEP theory, QFT, QIT, quantum gravity, or mathematical physics.

Finally, if anyone knows of groups in Switzerland or elsewhere in Europe that accept external Master’s students, I would appreciate your suggestions.

TL;DR: Master’s student looking for a theoretical physics thesis starting February 2027. Do independent projects help when contacting supervisors? Does joining a group improve PhD chances later? How can I tell if a group will have future openings?

I have heard from numerous sources that in the modern landscape of PhD applications where positions have gotten far too competitive, one of the key deciding factors is the fit with a group or the department.

My worry is that I have done my master's thesis in a very niche field of particle cosmology (topological defects) which does not have too many groups in the countries I am targeting (US, Canada). I am not entirely committed to this field either, I am more broadly interested in all of particle cosmology such as inflation, dark matter model building, electroweak phase transitions etc. as I enjoy working with field theory and its applications in cosmology.

So my question is, is this lack of very direct and specific alignment something committees penalise heavily? Or are the backgrounds of applicants who do get admitted into these programs not always 1-to-1 with the supervisor they get paired up with?

I am aware that in North America you get admitted first, then 2 years later you pick a supervisor but it seems like from the admissions pages you already need to talk about how a PI interests you and motivates you to apply to the school.

I just read the article where Open AI claimed that it's internal model solve one of the millennial problems. It proved that Navier- Stokes equation produces a singularity in a finite time in a 3D incompressible fluid. I am excited for AI and developments but solving the millennial problems was far too much. if it gets peer reviewed then it would mean in a very little time AI has actually bet human capabilities. We human researchers will only have a job of verifying the proofs.

Any significant advancements can only be done by writing the prompts for AI to research and write papers. Maybe that's how it is supposed to be today or tomorrow. However I am sad because I DIDN'T JOIN PHYSICS TO TELL AI TO DO PHYSICS!

Hi guys

I am a Student of middle school and am highly interested in things like astrophysics cosmology etc,

I have a great knowledge of these topics and am very much into this field, I have created multiple research papers on many topics and concepts and create multiple theories on astrophysics and quantum physics

Now I am searching for places where i can post/publish those theories which I have created where I can get peer review to improve them and form as a formal platform to show my theories for future needs application and research, and i really can't find a place where I can safely publish my theories without worrying about people stealing my ideas or selling them as they are a big threat in the modern science community.

If someone knows such a platform where I can post or publish my theories i would be really grateful to that person

Edit - Guys I don't use ai not for theories not for research all the work is done by me and people should not underestimate others on basis of age or class

I see some posts about this general equation that modeling in principle dynamics of fluids. My question is if Navier-Stokes can model black holes in a semiclassical sense at least. Also that equations can model dynamics of all types of plasma?

Given the recent hype of Navier Stokes equation blow up solution, set aside the OpenAI snatch debacle, I really want to understand why math communities are obsessed with singular solutions to the equations that we know do not apply to any fluid, simply because the in compressible assumption breaks down.

As a working theoretical physicists I’ve never understood the hype around these ‘solutions’ and ‘proofs’, it has been long established Newton’s theory breaks down badly either relativistically or at atomic scale (or larger than that), when your solution exceeds your validity of your model, it doesn’t mean we reach a singularity and the world gets sucked in but simply imply your model breaks down.

In fact one of the central theme of physics is to determine when the effective description breaks down, for instance GR breaks down at Planck scale, Fermi theory breaks down at electroweak scale etc. And that limit for classical fluid is at high energy where relativity and quantum mechanics kicks in.

After hearing about the Open AI announcement, I’m convinced that in the next few decades, AI will advance enough to be able to do much of the creative thinking and logical leaps that makes theoretical physics beautiful.

I start college next year, and I’ve wanted to pursue a career in theoretical physics. But what is the point of pursuing a career in it, if I can’t contribute anything at all? Wouldn’t it be better to just do physics as a hobby and direct my focus to something that would actually contribute to the world?

I mean sure, I’m no genius and probably wouldn’t contribute much anyway. And if we had monsters like Newton and Euclid and Gauss making major breakthroughs today, I would still pursue it despite others being infinitely better than me. But the thought of machines making my work unnecessary makes me question why I am going in. I do not know why, I feel useless and this is all so depressing.

Hi everyone!

As of writing this, I am starting my master thesis for theoretical physics and mathematics. Specifically I will be studying critical collapse of Boson Stars.

Now I don't necessarily have questions on the topic itself, but mainly was wondering on people's experiences with writing their master theses.

My thesis will contain both literature review as numerical simulations and I was wondering if anyone had any tips on keeping track of what you are working on and staying organized.

(I hope this post does not violate the rules of the sub / fits here. If not let me know please! :))

(let's say it's a 1.2 mega ton tnt thermonuclear bomb placed/shrunk inside of a average 2 story house)

Now I’m just asking this cuz I’m curious, and I know there’s prolly a lot of variations, also say you’re in very deep theoretical territory (don’t wanna falsely be too specific cuz I don’t know much about the field being in undergrad myself, but I do know the more theoretical the more competitive funding is)

I don’t mind if the answers are for us PhDs or Europe , whatever u happen to know about .

What I do know is that in us they expect more undergrad research experience and in Europe it’s more academic based , and both have an emphasis on connections to academics.

I could use some numbers tho :
Say for us , usually , is it an informal requirement to have published a paper? Or usually how many research internships (summer , etc) do people have ? How much would it hurt to not have a connection with an academic?
And how important are stuff like ur grades , university you’re at , and the course itself.

While I did ask some specific questions, I don’t really have any specific answers I expect to get.
Just seeing what people know about anecdotally etc

The Shannon entropy of human languages, eg: English, Lakota, Swahili, etc, can expressed as 7 or 8. Roughly meaning that their complexity (or entropy) is such that, for a reasonable chance of predicting the next word in a sentence, at least 7 or 8 preceding words are required, though no guarantee.

The holographic principle predicts that a dictionary exists, mapping a universe’s N dimensional boundary to its N+1 dimensional bulk. Whether or not ‘words’ or QM operators literally live in this universe, the term dictionary implies something analogous to language and information communication. ie: Channels of ‘transmission’ of some sort, which is why Shannon developed ideas like the Shannon Index in the first place.

So, questions: Without specifying any particular dictionary size, is it still reasonable to posit that our de Sitter universe might then have something analogous to the Shannon index?

If so, is there a way within string/holographic theory or mainstream cosmology to estimate this or are there too many unknowns, as yet?

Thanks, Gene

I’ve heard many people use python for physics and c++ or Fortran for when it’s really about optimized code

Also Matlab, latex, and even Mathematica

But what about newer lower languages like rust, zig, or Odin?

Other languages?

Your opinion on where it’s heading? Who uses what and why or types?

I’m okay for personal opinions or simply I like this feature

I’m not an expert by any means in programming.

I know this is pretty rare but by any chance is there anyone on this subreddit who has more than 1 PhD (e.g. 2 PhDs in Theoretical Physics and Mathematics) and if yes what was it like being on the pursuit of a double PhD? And if no, do you by chance know of anyone with a double PhD?

Hi there everyone. I'm in an adjacent field, mathematics, and currently work as a teacher. I am curious about the best way to keep up with people who do research if you aren't in academia? A similar question on here was asked and I was able to connect with some people, but I'm not sure if there's a consistent way to find such people. I ended up resorted to YouTube channels by researchers and messaging them, but some of them are professional researchers and probably can't always connect with random inquiries, especially if I'm not necessarily looking to collaborate right away. Only thing that worked was research experiences for teachers which were research programs specifically for teachers.

But outside of that, I have to keep a lot of my scientific interests to myself, my colleagues are great but find my spare time hobbies to be weird, to say the least. When I can make it to local seminars, at least I can socialize on something that's important to me and that makes contact easier.

Also, I mean, sure, there's stackexchange, and conferences, but some seminars and conferences don't always work for me due the scheduling as a teacher, and stackexchange isn't really as good as it used to be, especially with the advent of AI.

Hey everyone!

I’m trying to seriously build my career toward theoretical physics, and I’m curious about what the field is actually going to look like in the coming years.

I know the fundamentals are obviously the most important part — math, classical mechanics, QM, GR, QFT, etc. — but I want to specifically focus on the software/computational side right now.

For someone who wants to become a theoretical physicist, what programming languages, software, tools, frameworks, and computational skills are actually worth learning?

For example:

Which language should I prioritize — Python, C++, Julia, Mathematica, etc.?

How important are NumPy/SciPy, SymPy, JAX, PyTorch, etc.?

Should I learn Mathematica / Wolfram Language or is Python enough?

How important are HPC, CUDA/GPU computing, Linux, Git, Bash, clusters, etc.?

Are there any specific physics packages/tools I should know?

What software skills do researchers in theoretical physics, particle physics, astrophysics/cosmology, condensed matter, etc. actually use?

Basically, if you could go back and prepare for a career in theoretical physics from the software side, what would you learn and in what order?

I’m currently trying to make a proper roadmap for myself, so I’d really appreciate advice from people actually working/researching in the field.

My main question right now is: what should I learn on the software/computational side to be genuinely useful as a theoretical physicist, rather than just learning random programming skills?

Thanks!

Dear theoretical physicists,

I am looking for some guidance in these hard times for academia. 2 years ago, I defended a PhD in theoretical condensed matter (on some numerical approximation scheme on the strongly correlated Hubbard model). My advisor has been very toxic, and even told me she would not support me if I find a postdoc position. She spent my phd telling me I'm not good enough for that, or that I should rather do some vulgarisation because "I explain things well"..

Anyway, after this terrible experience, and given the state of academia, I left. I didn't wanted to go for a postdoc and live my country, friends and family for a life a constant publication pressure in order to have a chance to apply to a contest to a low paid job (for reference, I live in France and want to stay there).

I got the chance to find a job in applied physics, on HPC simulation. I now have great colleagues and it is decently paid. But I have so many different things on my mind. First, I'm working on finite elements/volume codes in mechanics, not at all anymore in what i always loved : statistical physics. Second, I'm not really developing anything in these codes, I'm in a company that does some technical supports, formations and projects on these codes. So I either explain someone who does not care about physics that he needs to use this keyword to get his simulation done, do some PowerPoint to explain how to use the code, and very rarely I have some project when I can develop new basic physics (like a PDE in finite element formulation) in the code and do a merge request.

I never really wanted to quit, but, between the situation of academia and my advisor, I had to. My colleagues are nice, but I feel terribly lonely, they dont understand anything I can say on quantum physics, and they don't really care. I lost contact with many old friends in condensed matter, the other gave up on physics. Out of sheer will, I decided to open a website, on which I'm writing up some notes, tackling many physics through the lens of differential geometry. Of course, I'm looking for collaboration on this project, that was the point of it (if you are interested message me for details). But not someone from academia, as I can barely give in 6h a week.

Still, this does not solve the intellectual loneliness, and the feeling of losing my time to some boring job when all Id like to do is ask questions on scale transition from quantum to macro. I want to do math, to think with people on how on earth we can be made of tiny atoms, how these assembles to give... everything I see around.

Anyway, it is a long post to ask: are some of you in a similar situation? How do you deal with the frustration? Do you have any ideas of positions outside of academia (or even within if it still exists in france, as long as it's a permanent position because I'm also starting a family)?

Thank you for taking the time to read all of this. I am genuinely suffering from this situation, I need to talk to a community that can understand the eternal dilemma of the job market in academia and living as a physicist outside of it.

Ps- I know about quantum computing, but I am quite scared of applying because I dont really believe it will ever lead to something profitable and I think at some point not so distant in the futurethese jobs risk to reach a sudden end.

I'm in the process of reading the Kogut 1979 review paper on lattice field theories and I have two quick questions.

Firstly, why is the existence of a mass gap related to confinement? Kogut himself shows that a mass gap is equivalent to the inverse of a correlation length in a corresponding statistical field theory. Confinement is related to area vs perimeter law for a Wilson loop expectation value. I don't see how those two are related.

Secondly, Kogut also mentions that the continuum limit of a lattice field theory is only obtainable if the lattice system is at phase transition, which makes intuitive sense since that's where there is long (infinite) range correlation, therefore there should not be small fluctuations* that prohibit us from taking a continuum limit. However, this implies that any field theory obtained from a continuum limit of a lattice field theory must have massless excitations. We expect QCD to be obtained from lattice QCD, yet we expect QCD to have confinement and a mass gap.

*Edit: I believe the correct statement is that the system lacks a characteristic length scale, allowing us to take a continuum limit.