How to Become a Good Theoretical Physicist | Hacker News Reader

How to Become a Good Theoretical Physicist

staff.science.uu.nl

157 pointsseycombi50 comments

For reference, generally people learn all this over four years of undergrad and probably the first few years of grad school (I have a BS in physics, and a PhD in a different field, so not 100% sure on the grad school work). That's 6 years of more or less full-time work, surrounded by excellent peers and mentors, where every week you read 2-4 chapters and do 10 problems per chapter. If you're motivated and talented, you'll breeze through the first few years of problems, but anecdotally, everybody hits a wall where the problems start to get really hard. I have no doubt you can replicate the undergrad education through self-study, and maybe even save money and time, but after that point, why not just go to grad school? You won't save much time doing it on your own, and you get mentorship, exposure to the research aspect (not exactly trivial to learn), credibility, and funding.

I'm pretty sure the number of high-quality researchers in theoretical physics, or any major field, who are totally self-taught is really quite small. This website feels like it's in part to dissuade amateurs from sending their "awesome result" to professionals, which the author mentions in the intro.

I'm pretty sure the number of high-quality researchers in theoretical physics, or any major field, who are totally self-taught is really quite small.

I think it's zero

It is rare (Ramanujan), but happens! [1]

[1] https://en.wikipedia.org/wiki/List_of_autodidacts

I know of at least one professor in Canada (Toronto maybe?) who was self taught and got into a graduate program on the strength of a letter of recommendation from a physicist he had been corresponding with. Can't remember the name at the moment, but I think his background had been in art.

And then there's Ed Witten, who studied history and linguistics. It's not really clear when or how he studied physics (so very possibly self-taught), though he had a famous physicist father so he would have had a ready source of advice on textbooks, etc.

Ed Witten was very good at math when he was young. He scored exceptionally well in the American Mathematics Competition. He didn't pick physics up out of nowhere, he already had a quantitively talented mind.

That might be true but op was just claiming that the number of self taught people in theoretical physics is non zero.

He was almost implying that Witten came out of nowhere with very little mathematical background and became a physics god. He implied this by saying that Witten studied history and linguistics in college, but he failed to mention his previously strong background in mathematics during his childhood. That last part is the key signal to how Witten could have even possibly become a successful physicist, although of course it is not a sufficient condition.

Could you provide a citation for the AMC score? A cursory Google search doesn't turn up anything.

My understanding is he only knew calculus before college.

I can't find it today, but I remember reading the AMC results with my own eyes many years ago. I believe he was one of the best scorers on either the AMC 8 or the AMC 10 in his state.

But these examples aren't what is being referred to as "totally self taught." Your grandparent comment acknowledges, "I have no doubt you can replicate the undergrad education through self-study..." (Of course that is pretty rare too, but what's in doubt is people who did the equivalent of grad school on their own).

FWIW, in mathematics I know there's Blake Temple, who IIRC did his undergrad in philosophy but was somehow admitted to a strong math grad program and went on to a very successful career... but again this isn't "totally self taught" in the sense here.

he was corresponding with another physicist, I do not think enough people realize no one is an island. Working, talking and communicating with others is how many things are learned and solidified because others force us to sharpen our thoughts by questioning them.

I think this is why some of the 'big' thinkers (see feynman einstein) worked at universities, it forced them to continue sharpening their skills because they had a collection of students questioning their ideas. I believe this applies to all fields... not just physics

my two cents. I agree with PaulPauper, I think it is zero as well.

freeman dyson doesn't have a phd.

Are you sure?

https://en.wikipedia.org/wiki/Freeman_Dyson

By the way, do you know that there is a series in scattering theory in quantum mechanics called Dyson series?

https://en.wikipedia.org/wiki/Dyson_series

To be frank, I doubt if you know this.

>Are you sure?

yes

>Dyson never got his PhD degree.

>By the way, do you know that there is a series in scattering theory in quantum mechanics called Dyson series?

indeed i do; i studied it in perturbation theory in undergrad.

>To be frank, I doubt if you know this.

this isn't grammatically correct. "i doubt you know this/that".

Scott Young self studied a 4 year MIT course in 1 year, although not to such a high level as you discussed: https://www.scotthyoung.com/blog/myprojects/mit-challenge-2/

That's super impressive, but there's a niggle. From his site:

> Did you grade the work yourself? Yes.

From my experience of doing CS in college, I think that's a problem.

The difference between what I believe and think I can prove to be correct, and what the professor says is correct, can be painfully stark sometimes. Especially where it comes to more advanced topics where it's easy to make your explanation of a concept sound correct, but contain crucial mistakes that invalidate your answer. Mistakes that only somebody with more intimate knowledge than yourself can spot.

We're talking fundamentals like writing out a proof that some algorithm is O(n^3) and classmates agreeing the proof does look correct, then the professor looking at it, saying "LoL, no. Watch this" and proving that it's O(n).

Not the best example. An algorithm that is O(n) is also O(n^3). If you want a tight bound you should use big theta.

I also think while it might be a bit of an issue for undergrad, by grad school at latest for math at least you should be able to tell the difference between a correct proof and incorrect proof most of the time. Usually I'd expect it after your first/second proof heavy math class (analysis/algebra/etc). Usually when I take math tests I can tell pretty precisely what grade I'll get as I know when I'm writing a proper proof or if I'm just writing for the sake of having some progress. Admittingly, my math interests are biased towards proofs/logic and I've spent time writing proofs in coq.

You're a better mathematician than I am. My experience passing mathematics exams involves a lot of "Ugh I know how this works in principle! Why doesn't it work when I apply it!? #@$%$#%!" I remember one time I was studying Newton's Method and got 5 different results for the same problem. It looked like I was applying the algorithm correctly in all of them, but the algo is very sensitive to small errors in arithmetic.

Hell, even for knowledge based tests, especially oral, I had this problem.

"How does CPU pipeline work?", prof "blahblahblah", swiz "Lol you have no idea what you're talking about" "Argh but that's what your book says!" "Nu-uh. Look, here" "Ugghhh I changed one little word!" "Yeah but that changes the meaning and now your explanation is wrong" "#@$@#%%!@#"

You know, little details I'd never realize on my own are wrong because I was 80% correct and that sounds correct enough, you can look up details when you need them. But prof is looking for 99.999% correct.

I did not graduate, as you can imagine. But I did get straight A's in coding-based classes. :)

Math is one place where I think it tends to be nice to be pedantic as you are starting to learn a topic. Generally, when I'm unsure of something proof wise it tells me I should re-read all the relevant definitions from that section/chapter. I also generally make it a goal that most important theorems are things I should be able to prove from scratch. Partly because if I can follow the proof well, then I'm less likely to misapply it. Lastly, I like how math has a heavy focus on building upon prior math so I try to review topics from previously taken classes often. I feel that cs classes are much less connected.

Some of the most amusing things I saw while I was in academia were "proofs" of various things sent in from random people. I admired their desire to contribute even while I marveled at how "not even wrong" they were.

It's a good comprehensive list, but considerably biased by the author's research interests. There are lots of good theoretical physicists that don't know much about the specifics of string theory and haven't seen general relativity since the relevant graduate course, it just depends on the field you decide to specialize in. On the math side, aside from a few things very specific to string theory, most of it is useful throughout modern theoretical physics, and it certainly helps to have at least a passing familiarity with all of the subjects listed for general erudition. The list could also be expanded with lots of things on the computational side that aren't immediately useful to string theorists but are used in many other fields.

Disclaimer: just a theoretical physics postdoc, YMMV.

http://www.staff.science.uu.nl/~gadda001/goodtheorist/primar...

I wonder, for someone like me that got a pretty terrible math education, how these free courses stack up against just using khan academy or similar.

Some of the basics - Khan academy is easy to understand and gives a good foundation. Don't even try to compare the advanced stuff. Just don't. Takes a lot of work and takes years. Even grad students run away from some of the stuff.

indeed. here is an article that was posted here not so long ago : http://m.nautil.us/issue/43/heroes/what-does-any-of-this-hav...

The stuff linked on the page is stuff you'll learn as an undergrad or before.

'Learn' can be fuzzy.

IMO, most undergrads taking an undergrad DifEq course will have little understanding of what they are actually doing and just treat it as symbol manipulation. I have seen people encounter the same problem with calculus, matrices, or even simple algebra. And you can keep pushing, but at some point if you want to progress you need to revisit older topics and hopefully gain new understanding.

It's like revisiting multiplication and division in binary and suddenly understanding why a similar process in base 10 works.

PS: Pure symbol manipulation is still powerful, but intuition takes a little more.

I'm not sure I understand any of this. The person asking is trying to understand the difference (and required effort) between Khan Academy and what's linked on the page - basically 'Maths textbooks for curious undergraduates'. That's a good and sensible question and whatever you think the answer to it is, it surely isn't (as suggested by the person responding) 40 years of ferocious training in the Arctic with Doc Savage.

To be more clear, I agree the foundation is within reach of a dedicated 20 year old student.

But, there is a huge gap between being able to pass a test on X after taking a class and being ok when someone writes the same idea in yet another notation. Or worse reading something when they go step 20 -> step 21 and yes you can get from A to B with an hour of concerted effort and step 20 -> step 21 and see what they mean and could get there the long way in a few minutes of calculation.

Now personally, I only got just enough understanding of Math to read a QM book and recognize how much work it would be to get more than a vague I kind of see what your doing thing going. But, sure if you mean the starting point for monumental effort then yea a solid undergrad math background is 'enough'.

I think he was just trying to be more clear on what we define as "learned" in the context of math. Many people "learn" math and do well on tests because they have memorized ways to manipulate equations to resolve the problem without actually understanding abstractly what is going on, and are thus often less creative with their maths. Ironically, I've found that those students who appear to excel in maths are usually the ones who are less curious about the why and how of math. Maths is usually taught in a way that it discourages the people who seem to struggle with it when they are often just trying to understand the depth of it more. I was one of these students in high school, and thought I just wasn't gifted. Fortunately I had the discipline to learn it and eventually had a really good teacher.

I got that, I just don't think it has anything to do with the question (or the bad answer I was replying to).

i'm pretty sure QFT is not undergrad

The specific page linked is 'Primary Mathematics'. There is no QFT there. The question is about the delta between that and Khan Academy, where do you think QFT comes into it?

I would love to see similiar sites set up in other disciplines of various knowledge bodies: Politcal science, economics, philosophy, computer science, etc

Yeah, an Econ one is badly needed for all the libertarian economics experts

This is a good collection of resources, but even more valuable would be the syllabi and homework sets from graduate-level theoretical physics courses, which can guide the interested learner through the vast amount of material, and help them gauge what is a reasonable pace of progress and not get bogged down (this has happened to me whenever I've tried to self-study from textbooks).

Source: Just got my PhD in theoretical high energy physics.

Very nice to see this conversation ... The list is nice and reasonably comprehensive ... it may seem long but it is not as daunting as it looks ... would like to think it is a guidance ... knowing the material does not mean one would become a good theoretical physicist, not knowing all of them does not mean one cannot become a good physicist. Since physics is an experimental science, it makes sense to know in a bit of detail how the observed facts are connected to gain one's own intuition ... this would help to make the list seem short and things become natural ... it also makes sense to know the landscape of the fields and the people in the community ... this will help one to avoid reinventing the wheel or wander into the wild with no return (to reality :-)) ... keeping these in mind, one should be able to enjoy physics or even do something meaningful at some point ...

IMHO, pick a theoretical field you like and you focus on it. Theoretical physics doesn't mean particle physics or relativity. Every field in physics can be both theoretical and experimental.

I got a graduate degree in theoretical physics, focusing on condensed matter physics. To be exact, I model the phenomenon called quantum solid, using Ginzburg-Landau theory.

Nice comprehensive list. Scares the heck out of me. The only stuff I recognize are the ones I learnt in college (math and some basic physics like EM and stuff). The rest is just plain scary. Makes me really respect Physicists. If this is just to get started then being a physicist is a lot of hard work.

Physicist here, I am sad to say that all the theoretical physicists I know are teaching physics/math to first year undergraduates. What a waste of smart people. All the jobs they could do are already taken by very old people(+65) that refuse to retire.

There's also the Chicago Undergraduate Physics Bibliography: https://www.ocf.berkeley.edu/~abhishek/chicphys.htm

Put in some decent range time, and don't underestimate crouch-jump practice

This is exactly like what I've been looking for -- a bit of a roadmap leading up to [hopefully] returning to school. I've started, but have meandered a little. And maybe less on the theoretical side, but who knows.

Thanks for this.

imho, I would start with general relativity. Most of the other stuff follows from it and you can pick up the other stuff as you go once you understand tensors and functional differential equations.

I would doubt so. I don't think you will ever understand general relativity if you don't have a good grasp on classical mechanics and classical electrodynamics.

Tensors and functional differential equations are still profound even though you might know vector calculus.

Piece of cake.

Okay, how do you become a Good Actual Physicist?

Just in case you are not joking and for anyone not familiar with the terminology: Physics, and a lot of the hard sciences, are often broadly divided into "theoretical" and "experimental" halves. Experimental physicists design and run experiments, i.e. they "get their hands dirty", or at least the hands of their graduate students and post-doctorates. Their end goal is to find some actual fact about the actual universe, usually a quantified measurement. Theoretical physicists, on the other hand, create theories: mathematical and conceptual models that hopefully explain how or why the universe is the way it is. Ideally, the created theory not only explains the measurements that the experimental physicist has already observed, but also predicts the results of new measurements not yet observed.

Don't try, most of them go into QUANT Finance.

>Unfortunately, I still have to recommend to buy text books as well

Why?

EDIT: Why buy textbooks, rather than read online resources and online textbooks?

There is a huge amount of information that has been written down. Different authors have different explanations and takes on things, and will emphasize different aspects of a topic in their presentation.

Look at the recommended texts section:

http://www.staff.science.uu.nl/~gadda001/goodtheorist/texts&...

He doesn't just cite one text on Classical Mechanics, he cites 5, and in his section on internet resources

http://www.staff.science.uu.nl/~gadda001/goodtheorist/classm...

He cites 3 more courses.

There is a lot of depth in any of these topics, and any given presentation will be a single path, of many, through the topic. Different perspectives are valuable, as they also help clarify the core of the topic, and allow you to find your own perspective. We are fortunate that there are people who have invested the effort to put some of these resources online, but not everything is currently on the internet. One day perhaps.

Also, some of the internet resources that he links to are now gone, and may or may not have been archived. Textbooks that are cited are almost certainly guaranteed to be available through some library. Given that he's also advocating that serious students attend University, proposing books to read that students can access through ILL seems reasonable.

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