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So you want to learn physics (2021)

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Re: So you want to learn physics (2021)

#101

Post by btrettel »

lanza wrote: post #93
btrettel wrote: post #84

Earlier quoted context omitted.

> 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…

You are missing my main point. Physics education tends to exclude fluid dynamics, so of course you wouldn't hear much about it or do research in it if you only have physics degrees. If a physics degree were about physics as defined in the dictionary, fluid dynamics would be more prominent. But "physics" as studied in a "physics" department is much more narrow than the dictionary definition.

Fluid phenomena is ubiquitous. You live in a fluid. You probably drive a car through a fluid and may occasionally take a plane through a fluid at higher speed. You surely use plumbing. I don't see how you can claim that fluid dynamics is not valuable given that. It's a lot more relevant to most people than quantum mechanics.

Re: So you want to learn physics (2021)

#102

Post by btrettel »

staunton wrote: post #95
btrettel wrote: post #84

Earlier quoted context omitted.

> 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 r…

Fluid dynamics is published in physics, engineering, and math journals, even if focused specifically on Navier-Stokes.

To do fluid dynamics research in a physics department, sometimes one has to spin it in some way that people with physics degrees care about. For example, saying that it's to understand chaos theory.

Re: So you want to learn physics (2021)

#103

Post by jagged-chisel »

simonh wrote: post #99
amluto wrote: post #65

This 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 c…

Physics: research, theorize

Engineering: practical implementation

That’s how it goes in my brain. It’s physics until we can build it reliably, then it’s engineering.

Re: So you want to learn physics (2021)

#104

Post by bmitc »

qsort wrote: post #3

A 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…

It's kind of a tautology though. Physics isn't remotely special in this regard at all, and it doesn't need generalizing from physics. One needs to work through anything to truly learn it: music, sports, gardening, life, writing, etc.

Re: So you want to learn physics (2021)

#105

Post by BeetleB »

simonh wrote: post #99
amluto wrote: post #65

This 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 c…

As GP said, continuum mechanics is often used for physics research. While not the Truth, the models can often be accurate. My own research involving transport in the quantum domain utilized some models from continuum mechanics.

(I didn't introduce it - it was already being used).

Re: So you want to learn physics (2021)

#106

Post by bmitc »

beltsazar wrote: post #79
qsort wrote: post #3

A 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…

>> Solving problems is the only way to understand physics. There's no way around it. The reason is that you think you understand what you read, but as Richard Feynman said: > The first principle is that you must not fool yourself, and you are the easiest person to fool. You think you understand 90% of what you read, but in reality it's probably only 20-30%. By doing the exercises, at the very least you'll know that y…

Although, I think what you're describing doesn't completely lie on the reader. Oftentimes, the author has plain just not explained things clearly or even remotely well, and the reader has to play a little bit of 20 questions to get to the meat of something. When a book is properly written, then the shared load between the reader and the writer is much more balanced.

Re: So you want to learn physics (2021)

#108

Post by BeetleB »

shanusmagnus wrote: post #85
BenFranklin100 wrote: post #26

Earlier 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?

> I finished the class, whatever I need to learn through application, life will point me toward.

In math/physics, it often won't. Solving lots of problems serves two particular purposes: To really solidify the concepts in your mind so you won't forget, and ensuring you learn the techniques and not just the knowledge.

For the former, you may find yourself in the position where you find yourself way over your head, and won't know where to start. You usually will not have a single gap, but many. You'll find yourself realizing you'll need to look up material from several textbooks to regain the knowledge you've lost. Once you begin that process, you'll pick up one of your old textbooks and while the physics knowledge may be absorbed, you'll realize you've forgotten much of the math needed to solve such problems. In the unlikely event you'll retain enough to follow the textbook, it is very unlikely you'll know the techniques well enough to solve the real world problem.

And your colleagues will. You'll be alone, and you'll drop out of that group. With physics/math, there often are hard boundaries in these groups. Those who meet the bar are in. Those who don't drop out, because it really sucks being the only person in the group who is struggling with what everyone else considers as basic.

SW engineering has a much more gradual change in skills amongst people, and usually the problems most people work on are fairly learnable in a short amount of time.

Re: So you want to learn physics (2021)

#109

Post by BeetleB »

gleenn wrote: post #51
projectileboy wrote: post #49

So happy to see the love for Griffith’s Intro to Electrodynamics. I know it gets dinged for not being sufficiently rigorous, but I’ve never read another math or science textbook that did as good a job of getting a beginner to truly understand the subject.

In what way is it not rigorous? I've never read it but it definitely seems interesting to have a "good" but non-rigorous science book. Does it just hand-wave over some things to get to other important topics?

It's pretty rigorous, and is perhaps the best EM book to get the intuition. I'm guessing the GP meant challenging in terms of the problem set.

Re: So you want to learn physics (2021)

#110

Post by BeetleB »

libraryofbabel wrote: post #38
bluish29 wrote: post #37

> Classical Electrodynamics by Jackson (essential). This is the bible of classical electrodynamics, and everyone who works through either loves it or hates it (I loved it). I agree that there is a division between who loves that book (like the author) and the majority of the graduate students who had nightmares (and sometimes still gets). I like this goodreads review of the book [1] > A soul crushing technical manual…

Well yes, but curious what book you would recommend instead for graduate electrodynamics? Note that she already recommends first studying Griffith's Introduction to Electrodynamics at the undergraduate level (and that one is a true pleasure to read imho).

From what I've heard, the value of Jackson is not the EM you'll learn, but the mathematical techniques you'll learn, which are widely applicable beyond EM.
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