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So you want to learn physics (second edition, 2021)

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Re: So you want to learn physics (second edition, 2021)

#41

Post by bilegeek »

raincole wrote: post #40
potbelly83 wrote: post #7

I have no idea why these sorts of posts are popular. Past college you're not going to learn physics by trying to self-study an entire university course. The best way to learn is just to pick a small part of physics you'd like to learn (preferably related to your job), i.e. how GPS work or some fluid mechanics etc... Then learn the physics you need for that. Knowledge accumulation can't be organized in a straight line…

> Past college you're not going to learn physics by trying to self-study an entire university course And why not? Because humans' brains stop working after they graduate from colleges? Most college students don't work that hard .

IMO: It's not learning that's the problem. It's learning and verifying you actually learned. I'm not saying "unless you can solve homework problems you haven't learned", but... kinda? With a complex generally-theory subject like Physics, the amount of effort you need to put into verification grows exponentially faster than the "learning" part; it's tough for many to get a "feel" like you could for chemistry or programming or electronics or mechanical stuff, difficult as those definitely can be.

Re: So you want to learn physics (second edition, 2021)

#42

Post by musgravepeter »

atkrista wrote: post #27

Saving this until after I retire and decide to invent my own crackpot Theory of Everything

Perhaps start with https://arxiv.org/abs/2605.21660

"It is certainly true that there are aspects of relativity that are counterintuitive, not only to retired engineers but also to many physicists."

Re: So you want to learn physics (second edition, 2021)

#43

Post by embedding-shape »

bilegeek wrote: post #41
raincole wrote: post #40

Earlier quoted context omitted.

> Past college you're not going to learn physics by trying to self-study an entire university course And why not? Because humans' brains stop working after they graduate from colleges? Most college students don't work that hard .

IMO: It's not learning that's the problem. It's learning and verifying you actually learned. I'm not saying "unless you can solve homework problems you haven't learned", but... kinda? With a complex generally-theory subject like Physics, the amount of effort you need to put into verification grows exponentially faster than the "learning" part; it's tough for many to get a "feel" like you could for chemistry or progra…

Most of us who learn (and always learned) outside of schools and academia, do so for some purpose and with some intention beyond the learned thing. I didn't learn programming to learn programming, I learned it because that's how you built websites. I didn't learn woodworking just to learn woodworking, but in order to build my own furniture, and so on.

Same can be applied here I'd say, and probably must (at least for me) be applied that way, for the learning to even be engaging. So don't learn physics just to learn physics, but learn it in order to be able to execute on something else, then learn the related parts to that.

Then the verification becomes part of what you're doing, and fun as well, as you're progressing on other stuff :)

Of course, YMMV and all that.

Re: So you want to learn physics (second edition, 2021)

#44

Post by gmueckl »

not-a-llm wrote: post #37
gmueckl wrote: post #29

Earlier quoted context omitted.

Conservation of energy is simply the invariance of a system to translation in time: the system shows the same time evolution from a well defined starting state regardless of whether that state exists at a time t or a time t+t' with an arbitrary t'. This is one application of Noether's theorem. This is an example of a topic that unstructured self study would likely skip. But it is included in every properly structured…

Noeter theorem and energy get complicated in General Relativity, because there is no global time translation symmetry https://curtjaimungal.substack.com/p/what-is-energy-actually Ignoring that, saying "energy must exist because of Noether and time-translation" doesn't really tell what energy actually is, not a very satisfactory response

On the contrary, this is best description of what conservation of energy means: all externally generated forces acting on the system do vary with time. Im other words, this is a closed system as defined in thermodynamics.

The nature of energy is really just a result of this property.

The difficulties with energy in GR are related to the fact that those equations alone allow for space-times that are truly bizarre. Some that are technically solutions to the field equations are clearly nonphysical (e.g. Goedel's solutions). There is also a priori no reason why e.g. expanding metrics should actually yield proper conservation of energy.

Re: So you want to learn physics (second edition, 2021)

#45

Post by mr_mitm »

raincole wrote: post #40
potbelly83 wrote: post #7

I have no idea why these sorts of posts are popular. Past college you're not going to learn physics by trying to self-study an entire university course. The best way to learn is just to pick a small part of physics you'd like to learn (preferably related to your job), i.e. how GPS work or some fluid mechanics etc... Then learn the physics you need for that. Knowledge accumulation can't be organized in a straight line…

> Past college you're not going to learn physics by trying to self-study an entire university course And why not? Because humans' brains stop working after they graduate from colleges? Most college students don't work that hard .

[dead]

Re: So you want to learn physics (second edition, 2021)

#46

Post by birdsongs »

embedding-shape wrote: post #43
bilegeek wrote: post #41

Earlier quoted context omitted.

IMO: It's not learning that's the problem. It's learning and verifying you actually learned. I'm not saying "unless you can solve homework problems you haven't learned", but... kinda? With a complex generally-theory subject like Physics, the amount of effort you need to put into verification grows exponentially faster than the "learning" part; it's tough for many to get a "feel" like you could for chemistry or progra…

Most of us who learn (and always learned) outside of schools and academia, do so for some purpose and with some intention beyond the learned thing. I didn't learn programming to learn programming, I learned it because that's how you built websites. I didn't learn woodworking just to learn woodworking, but in order to build my own furniture, and so on. Same can be applied here I'd say, and probably must (at least for…

I think you're possibly generalising your own experience to the masses. That's absolutely not the case for me.

I love learning to learn. I learned programming because I found a quick basic compiler / IDE on my dad's computer, along with some shipped examples, and it was actually magic to me.

I read our encyclopedias as a kid because it was just really cool. Likewise, I did physics in university not for a job (the jobs are shit), but because it gives me that feeling of expansive possibility and wonder that Carl Sagan gave me when I watched Cosmos growing up.

Most of my most passionate self learnings came about because of that feeling of magic, not because I was chasing an end goal.

Re: So you want to learn physics (second edition, 2021)

#47

Post by embedding-shape »

birdsongs wrote: post #46
embedding-shape wrote: post #43

Earlier quoted context omitted.

Most of us who learn (and always learned) outside of schools and academia, do so for some purpose and with some intention beyond the learned thing. I didn't learn programming to learn programming, I learned it because that's how you built websites. I didn't learn woodworking just to learn woodworking, but in order to build my own furniture, and so on. Same can be applied here I'd say, and probably must (at least for…

I think you're possibly generalising your own experience to the masses. That's absolutely not the case for me. I love learning to learn. I learned programming because I found a quick basic compiler / IDE on my dad's computer, along with some shipped examples, and it was actually magic to me. I read our encyclopedias as a kid because it was just really cool. Likewise, I did physics in university not for a job (the job…

> I think you're possibly generalising your own experience to the masses

Yeah, that's fair and probably true, it's limited to my own experience and the experiences of the people around me, not gonna claim it's universal so you're right.

> I did physics in university [...]

My comment is also explicitly not about you and your type ;)

> Most of my most passionate self learnings came about because of that feeling of magic, not because I was chasing an end goal

One could argue that the end goal you were chasing was feeling that magic again :) Jest aside, I do understand what you mean.

Re: So you want to learn physics (second edition, 2021)

#48

Post by ck2 »

if you really, really want to understand physics and are not afraid of hard math I highly recommend this youtube channel in particular

* https://www.youtube.com/@PhysicsExplainedVideos/videos

"Physics Explained"

But I am not kidding about hard math

He starts off slow and gentle but most of the videos 10 minutes in my brain is screaming and cannot keep up

Which is probably why textbooks are superior for some kinds of learning

But his videos are very well done

Re: So you want to learn physics (second edition, 2021)

#49

Post by Beijinger »

raincole wrote: post #40
potbelly83 wrote: post #7

I have no idea why these sorts of posts are popular. Past college you're not going to learn physics by trying to self-study an entire university course. The best way to learn is just to pick a small part of physics you'd like to learn (preferably related to your job), i.e. how GPS work or some fluid mechanics etc... Then learn the physics you need for that. Knowledge accumulation can't be organized in a straight line…

> Past college you're not going to learn physics by trying to self-study an entire university course And why not? Because humans' brains stop working after they graduate from colleges? Most college students don't work that hard .

My brain only started working after college.

Re: So you want to learn physics (second edition, 2021)

#50

Post by ndriscoll »

gmueckl wrote: post #29
somenameforme wrote: post #19

Earlier quoted context omitted.

I'd disagree and have done exactly that. I started with a reasonable basis in physics, but self studying through an entire course dramatically expanded my understanding. For an example of what I mean this [1] is Feynman's lecture on conservation of energy. It's something every schoolkid learns -- I'm fairly sure I saw my first pendulum from the nose demo in middle school, yet Feynman will take this and make you compl…

Conservation of energy is simply the invariance of a system to translation in time: the system shows the same time evolution from a well defined starting state regardless of whether that state exists at a time t or a time t+t' with an arbitrary t'. This is one application of Noether's theorem. This is an example of a topic that unstructured self study would likely skip. But it is included in every properly structured…

I suppose it depends on what you mean by unstructured (vs. the original claim of self-study). e.g. my method of self-study was generally to find course requirements for a degree program, find corresponding course descriptions and syllabi, find the relevant books, course notes, and/or video lectures and proceed through those.

e.g. I did formal study of basic physics in an engineering program, but Noether's theorem was never mentioned. I came to that through self-study, and can't really imagine how anyone would miss it unless "self-study" means "read random blogs and watch random youtube videos." I expect even browsing Stack Exchange and Wikipedia would expose you to most core topics fairly quickly.

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