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Ask HN: How to self-study physics?

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Re: Ask HN: How to self-study physics?

#61

Post by atemerev »

Mostly what other people have said here, I’ll recap:

— Solve exercises

— Learn the fundamentals (action principle, conservation laws, symmetries, statistical physics)

— With that, work on generalized coordinates, Lagrangian and Hamiltonian mechanics

— Brush up your calculus, vector calculus and linear algebra kung-fu

— Have a personal project to aim your efforts. For me, it was understanding precisely how nuclear weapons work (so I have to run many geometrical and hydrodynamic calculations). For you it might be something else.

— If you stuck with some textbook, grab another one, you will be able to return later with the new knowledge. Physics is fractal.

Best of luck!

Re: Ask HN: How to self-study physics?

#62

Post by abdullahkhalids »

jhrmnn wrote: post #56
abdullahkhalids wrote: post #52

Earlier quoted context omitted.

Absolutely. How can you claim to model something if you haven't at least looked at the thing with your own eyes, played with it with your (metaphoric) hands? Experiments teach you, that reality is complicated and models have to be simple, but with judicious choices of assumptions, one can still get accurate and precise prediction out of simple models. I am a theoretical physicist, but I would say the experimental cou…

I disagree. Perhaps in some areas, like electromagnetism or optics, but there are large fields in physics where it's not necessary (statistical mechanics, quantum mechanics, gravity, high-energy physics)

I am not saying that you should to do experiments in every area. Just that experiments in a few areas (usually mechanics/EM/optics/basic QM targeted by undergrad labs) is sufficient to give you the necessary intuition about the limitations of theory in all areas.

Re: Ask HN: How to self-study physics?

#64

Post by Myrmornis »

I've also been self-studying physics recently. Here are the books that I settled on as providing a good introduction to classical mechanics:

Classical Mechanics - John R Taylor

Structure and Interpretation of Classical Mechanics - Sussman & Wisdom https://mitpress.mit.edu/books/structure-and-interpretation-...

The Theoretical Minimum - Susskind https://theoreticalminimum.com/

Introduction to Classical Mechanics - David J Morin

Re: Ask HN: How to self-study physics?

#65

Post by thatcherc »

orbifold wrote: post #60

There are a few themes that physics revolves around: 1. Action Principle: A lot of problems in mechanics can be boiled down to writing down the correct Lagrangian. 2. Statistical physics, this teaches you about to think in terms of "Zustandssummen" and is the starting point for deriving lots of interesting laws like black body radiation. 3. Field (Gauge) Theory, turns out you can write down and derive interesting Lag…

I think points 1-6 apply best to someone with an undergrad degree (and maybe even an undergrad degree in physics), since it's hard to grasp ie the action principle and Noether's theorem without having seen at least a bit of Newtonian and classical mechanics and E&M. Certainly my high school self would have struggled here.

I really like the idea of "depth first and work backwards" though. I finished undergrad with a degree in physics about a year ago, focused mostly on AMO, but since then I've seen all these headlines about AdS-CFT correspondence and cool quantum gravity papers and trying to read them is wayyy over my head. What I realized was that to read these papers, I needed to backtrack. I kinda needed to be familiar with some of the toy models for black holes in a quantum setting, which requires quantum field theory, which requires classical field theory, which I never got around to in school.

So now I'm reading a set of classical field theory notes and loving it! Plus I get to look forward to the eventual dig all the way back down to AdS-CFT.

Re: Ask HN: How to self-study physics?

#66

Post by thatcherc »

Myrmornis wrote: post #64

I've also been self-studying physics recently. Here are the books that I settled on as providing a good introduction to classical mechanics: Classical Mechanics - John R Taylor Structure and Interpretation of Classical Mechanics - Sussman & Wisdom https://mitpress.mit.edu/books/structure-and-interpretation-... The Theoretical Minimum - Susskind https://theoreticalminimum.com/ Introduction to Classical Mechanics - Dav…

Structure and Interpretation of Classical Mechanics is so cool - I highly recommend it, especially to someone with a programming background. It's one of the main reasons I switched from CS to physics in college.

Re: Ask HN: How to self-study physics?

#67

Post by jgehrcke »

The other comments are great! Great resources and points.

I think what is crucially important is to have someone to talk to. To engage with another human being in a discussion, at every step of the learning curve.

I studied physics in Germany 2005-2010, an then did my PhD 2010-2015.

In hindsight, I must conclude that being forced to discuss things with other people at every step was what taught me the most, was long-term the most rewarding.

About my own level of understanding, about judging my abilities, about how to actually solve problems.

Examples from my time studying:

- discussion among two people: trying to grasp and crack the same exercise

- discussion in the larger study group (5 people): when helping each other out, having to admit not having understood a certain thing, and specifically trying to address the "wait, I don't get this yet"s everyone has.

- discussion in exercise class (20 people): presenting "your" solution in a concise way, seeing other solutions, discussing caveats, pros, cons, elegance, deficiencies

- discussion in seminars: presenting "old" concepts to each other, discussing them and their historical relevance

... and so on.

In hindsight these countless discussions in smaller and larger study groups were _priceless_ towards understanding what physics is about. I mean it! After all, physics is science, and in science you can only contribute in a meaningful way when you understand the mental model of your fellow scientists reasonably well, when you "speak the same language".

I understand that this might be in conflict with "self-studying physics". If it is then it's important to be aware of it, possibly to try really hard to compensate for it (to find someone to do this together with, maybe!).

Re: Ask HN: How to self-study physics?

#68

Post by impendia »

Hi hsikka,

Are you a PhD student? And if so, are you aiming at a career in academic research? I'll offer my advice as a math professor, and as someone who supervises students.

If you want to get a strong foundation in physics, then reading Halliday + Resnick, and doing a large number of the exercises, would be one good way to go about it. (Look for used copies of previous editions on Amazon -- they'll be cheap.) There are plenty of other good suggestions in the blog post you linked, and also in this thread.

However, and I hate to throw water on such a noble aspiration, are you sure that this is what you want to do? Getting a "strong foundation" takes a lot of effort. If you want to invest this effort, then great! But you might consider investing that effort into learning something closer to your field, which would both be interesting and directly help in your research.

In my observation, it is common for graduate students and professors to learn about areas outside their research area, but they don't always worry so much about getting a "strong foundation". For example, when I was a PhD student, one of my fellow students enrolled in a graduate course in physics, without worrying too much about whether he satisfied the prerequisites. It was a great experience for him, and it's one that apparently helped him a great deal in his mathematics research career.

Myself, I have invested a fair amount of time learning algebraic geometry, which is a difficult area of mathematics, different from my specialty. The results have been ambiguous -- I still don't know the field nearly as well as I wish I did. In particular, I still have only a sketchy understanding of the foundations. But, happily, I know enough to talk to algebraic geometers. Indeed, I'm currently writing a paper with a colleague in the subject, which involves both his specialty and mine -- it's not one that either of us could have written on our own.

In any case, good luck and best wishes to you!

Re: Ask HN: How to self-study physics?

#69

Post by Simon_says »

impendia wrote: post #68

Hi hsikka, Are you a PhD student? And if so, are you aiming at a career in academic research? I'll offer my advice as a math professor, and as someone who supervises students. If you want to get a strong foundation in physics, then reading Halliday + Resnick, and doing a large number of the exercises, would be one good way to go about it. (Look for used copies of previous editions on Amazon -- they'll be cheap.) Ther…

How does Halliday + Resnick compare to Young + Freedman?

Re: Ask HN: How to self-study physics?

#70

Post by adenadel »

phtrivier wrote: post #37
kobiguru wrote: post #21

Here is a guide by G. 't Hooft to learn physics. http://www.goodtheorist.science/

Looks incredibly comprehensive. Has anyone done similar work for other topics ? (biology springs to mind as something I would have no idea where to start from.)

Something somewhat similar is How to Become a Pure Mathematician (or Statistician)

http://hbpms.blogspot.com/

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