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Ask HN: How to self-study physics?

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

#51
I discovered the post by Susan Fowler a few years ago and really liked it.

I studied physics (2001-2006) and teach physics (and math) at a high school and am working through the list of proposed books (and others [1]) again, just to stay up-to-date :)

Other ressources: brilliant.org, quanta magazine,youtube channels (Veritasium/Vsauce/Physics Girl/PBS Spacetime...), ...

[1] e.g. Leonard Susskind's "The theoretical minimum" series.

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

#52
post #13

I thought I would also add my two cents, though there have been many excellent responses already. I recently defended my PhD in Physics (MIT '18). First of all - great idea! It is never too late to learn math and physics! In fact, with hard work and commitment, anybody can muster them to a high level. (1) Reading =/= understanding in math and physics. You understand a topic only if you can solve the problems. (2) Wor…

Isn't an important aspect of learning Physics is being able to conduct experiments in a lab?

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 courses I have taken were the most important courses in understanding the limitation of theory.

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

#53
post #13

I thought I would also add my two cents, though there have been many excellent responses already. I recently defended my PhD in Physics (MIT '18). First of all - great idea! It is never too late to learn math and physics! In fact, with hard work and commitment, anybody can muster them to a high level. (1) Reading =/= understanding in math and physics. You understand a topic only if you can solve the problems. (2) Wor…

Isn't an important aspect of learning Physics is being able to conduct experiments in a lab?

Short answer: not every physicist works in a lab. Theoretical & mathematical physics are entirely about working with mathematical models of phenomena that other people observed in a lab. It's enough to understand that any theory is rooted in the experimental, and should be falsifiable by it.

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

#54
post #13

I thought I would also add my two cents, though there have been many excellent responses already. I recently defended my PhD in Physics (MIT '18). First of all - great idea! It is never too late to learn math and physics! In fact, with hard work and commitment, anybody can muster them to a high level. (1) Reading =/= understanding in math and physics. You understand a topic only if you can solve the problems. (2) Wor…

A lot of good pieces of advice (especially on problem-solving, timescale, and moving on).

However, some points are IMHO superfluous, for example:

> Not all topics are equally important. Focus on the important parts.

These statements are correct and general, and most people would agree with (even having no idea the topic), but are rarely actionable (or even: make sense for a newcomer). Vide most of the motivational quotations.

In short: hard to disagree. But how the heck a newcomer knows what is important and what is not?

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

#55
post #13

I thought I would also add my two cents, though there have been many excellent responses already. I recently defended my PhD in Physics (MIT '18). First of all - great idea! It is never too late to learn math and physics! In fact, with hard work and commitment, anybody can muster them to a high level. (1) Reading =/= understanding in math and physics. You understand a topic only if you can solve the problems. (2) Wor…

I think it's essential to have a strong grasp of high school mathematics, not just high marks, but actually understand it. Gaps here are very serious. What do you think?

(not parent) Agreed. But I would also say that physics can actually help you a lot with understanding math. I learned both physics and math very organically at high school, going way ahead the curriculum, and to me it was more like a single subject. For a physicist, math is just such an essential tool. I cannot imagine having the understanding of calculus that I have without physics. (But then again that's why I'm not a mathematician.)

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

#56

Earlier quoted context omitted.

Isn't an important aspect of learning Physics is being able to conduct experiments in a lab?

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)

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

#57
post #48

I self-studied physics when I was a high-school student. I read The Feynman Lectures of Physics, and it was a great introduction (especially Vol 1 and 2; Vol 3 gives interesting insights but I wouldn't treat is like a canon of quantum physics). It is accessible online, https://www.feynmanlectures.caltech.edu/ , so go there and read chapter by chapter the pace you like. AFTER there are plenty of ways to go, but for an…

Second this. Vol 1 was the most influential physics book at high school for me. Though be prepared to go through it repeatedly. At least as a teenager with still developing abstract thinking, I had to think things through over and over again.

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

#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 Lagrangians for Electrodynamics, Fluid Dynamics and General Relativity as well.

3.1. Noethers Theorem and Symmetries allow you to get a unified view of conserved quantities.

4. Spinors, they are fundamental for understanding the quantum behaviour of matter

5. Path Integrals necessary to understand Feynman diagrams and Calculations in Quantum Field Theory.

6. Do the harmonic oscillator in as many different ways as possible, a lot of physics can be understood by solving the harmonic oscillator or coupled oscillators. Once you've understood why this is the case and the situations in which it isn't true, you will have understood a lot of physics.

I would recommend a depth first instead of breadth first approach. Pick something advanced that really interests you and work backwards what prerequisites you need to understand it. There are parts of classical physics that are super interesting but barely anyone learns about them anymore (I skimmed through Sommerfeld's lectures on theoretical physics once, they contain all kinds of super interesting problems with spinning billiard balls, tops and so on, this was at a time when Quantum Mechanics was in its infancy).

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