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So you want to learn physics (2021)
91–100 of 170 posts
Re: So you want to learn physics (2021)
#92The title should probably be: "So you want to learn theoretical physics". While generally little known and appreciated among modern theorists and mathematical physicists, physics is actually an empirical science. In other words, every single section of that reading list is based directly or indirectly on a diverse and sophisticated set of devices and measurement configurations (aka experiments). Also, most progress i…
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Re: So you want to learn physics (2021)
#93Earlier quoted context omitted.
A physics undergraduate degree is different than a lot of degrees in that it's 100% incomplete for the purpose of training towards a real profession. Nobody hires physics bachelors. It's just the four year mark of your studies to be a 8+ year trained physicist. And for that purpose of being an intermediate degree to becoming a physics PhD, Navier-Stokes isn't relevant. You don't use it in most fields that are generat…
> You don't use [Navier-Stokes] in most fields that are generating physics PhDs in the 2000s and beyond. That's because physics degrees don't include much on fluid dynamics. If someone wants to get a PhD in fluid dynamics, they probably get a PhD in some variety of engineering. This goes back to what I said about the physics curriculum seeming weird to me, as it it's not about "physics" in itself. It's more a random…
> In another comment, you said that you don't know what the Navier-Stokes equations are. Given that, I don't think you're in a good position to judge their value.
It was an exaggeration given that it never came up during my studies once. And I think that's a fantastic assessment of their value that I made it through most of a decade of studies without having to know a thing about fluid dynamics.
> I have a couple of group theory books myself, and I don't agree with your assessment that group theory should get priority over fluid dynamics.
...why? You're commenting on a physics line of education here. We don't use fluid dynamics and we extensively use group theory.
Re: So you want to learn physics (2021)
#94> they are and have been dreadfully underserved and underestimated by the academic physics community (who do not take them seriously because they aren’t studying at colleges and universities) This stuck out, pretty rigorous if all you want to satisfy your curiosity. If you want to actually apply any of the hard work you put in, you need a degree. I think that is the most interesting part of learning anything, applyin…
“ But to do anything interesting physics, astronomy, philosophy too you need to be in school.” Why would you say that? I am curious. Imagine you are into a specific physics subject and knows what to do with some of contemporary problems that are puzzling people, work on it to provide your solution, etc., and publish your findings. I would think no one could prevent you. Right?
Re: So you want to learn physics (2021)
#95Earlier quoted context omitted.
A physics undergraduate degree is different than a lot of degrees in that it's 100% incomplete for the purpose of training towards a real profession. Nobody hires physics bachelors. It's just the four year mark of your studies to be a 8+ year trained physicist. And for that purpose of being an intermediate degree to becoming a physics PhD, Navier-Stokes isn't relevant. You don't use it in most fields that are generat…
> You don't use [Navier-Stokes] in most fields that are generating physics PhDs in the 2000s and beyond. That's because physics degrees don't include much on fluid dynamics. If someone wants to get a PhD in fluid dynamics, they probably get a PhD in some variety of engineering. This goes back to what I said about the physics curriculum seeming weird to me, as it it's not about "physics" in itself. It's more a random…
The physics curriculum prepares people to do research on stuff that is published in "physics journals". You may not think that should be the goal but it is. Doing work on Navier-Stokes lands you in a math journal on PDEs.
On a more important note, the actual topics are completely irrelevant. What's important is learning to "think like a physicist". That's what has value even for those who don't go on to do academic research, which is most students. For any given physics topic that is relevant to real-life applications, there are engineers who actually know how to use it, something that would be ridiculous to expect from the superficial treatment a physics degree has to give any one topic.
Re: So you want to learn physics (2021)
#96A point that's rightfully emphasized by the author: > Solving problems is the only way to understand physics. There's no way around it. This generalizes well to other fields. I don't want to discourage anybody from trying to educate themselves in a difficult field (be it physics or something else), but that's a very common and immediately visible problem with autodidacts. If you haven't worked through enough hard pro…
That’s a POV I’ve grown to adopt as I got older (like many, perhaps). I used to heavily privilege theory, believing that everything could (and maybe should) be derived from first principles. Now I place the concrete over everything else; theory is nice when it can illuminate why the practice works. Otherwise, it’s just words. The most frustrating is when I have friends who have derived their entire understanding of a…
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Re: So you want to learn physics (2021)
#97Earlier quoted context omitted.
I only became reasonably proficient in physics when I took the summer off between undergrad and graduate school and spent three months, six days a week, ten hours a day, doing nothing but working through four years of undergraduate physics curriculum by solving problems from my textbooks. There is no substitute for solving problems.
Like another commenter, I'm curious what drove you to this. Seems like clearly A Good Idea I Could Have Benefited From, but my attitude was always: I finished the class, whatever I need to learn through application, life will point me toward. Yet I wish I had done something similar to what you did. What gave you the impetus?
We were required (by the state I believe) to take a comprehensive test assessing our competency at physics. I struggled with test and was disheartened that four years of strenuous effort would be all for naught. I knew I needed to do something to shore up my understanding of physics if I was going to retain the knowledge decades onwards. The other reason was a simple love for the beauty and underlying simplicity of the subject.
Re: So you want to learn physics (2021)
#98Rather than 27 (or however many) books, an ambitious student may be able to use just one big-ish book: Ian D. Lawrie's "A Unified Grand Tour Of Theoretical Physics". This even has a little 18 page "Snapshots of the Tour" which might be a trip down memory lane for those who studied physics long ago. Of course, it might also be impenetrable if you haven't had prior exposure to most of the material.. I have zero experie…
It will be impossible to learn physics from this book, even in the unlikely event that you already have all the requisite mathematical background (partial differential equations, vector calculus, tensors, etc.). Degree of “ambition” doesn’t come into it; you just can’t start out with special and general relativity and spacetime and quantum fields; you need to solve a lot of problems in newtonian mechanics and electro…
It was mostly just a recommendation to check out. I did not actually do it myself, but I tend to think I could have right after lin.alg./multivar calc freshman year and would have preferred it. Can't prove that, of course, since I didn't do it, but a year later I was loving Landau's Classical Theory of Fields which has a very similar relativity-first approach, and I did know a lot of relativity in high school. Wolfram went right from high school to grad school in physics at Caltech. The only very recently deceased late great Ed Fredkin got to be head of the MIT CS department with naught but a high school degree due to various life interventions and had some interesting "digital physics" ideas.
There are lots of pathways to learn & do. That is especially true of people coming to topics later in life, as I might expect is more common for HN comment thread readers. I know someone who learned to program in x86 assembly before they learned C (in fact one of the best programmers I know). If you talk to such people, I think you will find that their more varied backgrounds / ages in life when they approach things make anyone's dogmas more suspect. A great numerical relativist didn't study physics until his 30s. No idea what order he did things in, but I heard it was very non-standard.
So, I would encourage you to have more imagination of what might be possible / be less dismissive / jumping to conclusions. That is needlessly discouraging to many here were bemoaning "soooo many books/years/etc". "Ambition" might be "first learn diffgeo, then learn physics". I've been recommending that lately to a friend with extreme mathematical sophistication (a professor even) but no physics exposure, actually, but already some diffgeo exposure.
And, of course, "to learn physics" is maybe not to be a "produced physicist" any more than "to learn networks" means to "build a hardware router". It all depends. IMO, there are too many levels (& even directions/dimensions) of "having learned" to really even make "just can't", "only way" statements like you did. Elsethread, the diversity of even what "physicists" wind up having learned is shown to vary considerably (e.g. continuum mechanics). I find such absolutist statements needlessly discouraging to someone who might be hopeful to do it in "fewer steps". The way for most need not be the way for all or even the recommended way for any one person. People vary.
Re: So you want to learn physics (2021)
#99This has the same omission that my undergrad program had: continuum mechanics. Even just the very basics (pressure, velocity, etc in a moving, non-equilibrium system) and translating between the terminology used by different science and engineering fields (static pressure, total pressure, velocity pressure, stagnation pressure, hydrostatic pressure, dynamic pressure, plain old pressure, head, oh my!) is very useful.…
Idiot who transferred from physics to computer science after year 1 here, so please make allowances. But all of those phenomena are emergent. Shouldn’t physics focus much more on the underlying micro states and micro processes than the emergent phenomena?
Obviously there needs to be a transition, but at some point you go from physics to engineering. I suppose it depends what specialty in physics you go into. Nobody can specialise in everything.
Re: So you want to learn physics (2021)
#100Earlier quoted context omitted.
That’s a POV I’ve grown to adopt as I got older (like many, perhaps). I used to heavily privilege theory, believing that everything could (and maybe should) be derived from first principles. Now I place the concrete over everything else; theory is nice when it can illuminate why the practice works. Otherwise, it’s just words. The most frustrating is when I have friends who have derived their entire understanding of a…
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