
So You Want to Learn Physics - bootload
http://www.susanjfowler.com/blog/2016/8/13/so-you-want-to-learn-physics
======
Koshkin
This may seem somewhat unorthodox, but what I would strongly recommend is to
start _not_ by reading books on physics or math but read some books on
_history_ of physics (and math) first. This will give you some intangible
basic knowledge, or a sense, of what scientific research is all about, so that
many things that otherwise may end up being puzzling to you when you come to
learn the "hard science", won't. One recommendation I can make is Rhodes' _The
Making of the Atomic Bomb_.

~~~
j2kun
As a mathematician, I disagree, but this is probably because I already
understand the math pretty well. I'd much rather have a clear picture of the
most useful mathematical models for the various areas of physics (and where
they fail) than slog through the centuries of failed experiments and feuds.
Every time I ask a physicist for a clear picture of what light is
(mathematically, what the model says it is), I get a mix of "it's a wave but
also a particle" and random things that dead physicists have said about light.

I honestly don't care if Einstein thought God doesn't play dice, or if someone
way back when thought an atom was like plum pudding. I do want physical
intuition, but I want it through clear and well-explained mathematics.

That is, when I'm in the mindset to actually learn physics. Hearing about the
history is fine and dandy if I want entertaining stories.

~~~
S4M
As someone who as a student was good at math and bad at physics, I'd rather
disagree. Take for example the gravity formula F_{A->B} = G * M_A *
M_B/d(A,B)^3. It's very easy to interpret that, but where does that come from?
I can see why the gravity gets lower when the distance between A and B is
higher, but why does it depend of the inverse of the cube of the distance? The
formula is very easy to read, but since I didn't know where it came from, I
would forget easily.

On the other hand, it would have been intellectually pleasing(at least for me)
to know how Physicists came with it, what's the motivation behind 1/d(A,B)^3,
how did people come up with G, how it was measured, etc.

~~~
4ad
> F_{A->B} = G * M_A * M_B/d(A,B)^3

Your formula is wrong. It's either:

    
    
        F_{a} = F_{b} = G * m_a * m_b/r^2
    

or

    
    
        \vec{F} = G * m_a * m_b/|r|^3 * {\vec{r}}
    

> but where does that come from?

You find that by studying physics, not _history of physics_.

> it would have been intellectually pleasing(at least for me) to know how
> Physicists came with it, what's the motivation behind 1/d(A,B)^3, how did
> people come up with G, how it was measured, etc.

Yes, understanding a specific change in the state of physics at time T is most
certainly helped by understanding it at time T-1. But make no mistake here,
this is still physics and not _history of physics_ (whatever that means).

~~~
S4M
Thanks for correcting me. The fact that I remembered the formula wrong proves
that I didn't understand that formula well enough to remember it. It was been
about 13 years since I didn't do any physics, and I forgot most of it,
however, I remember well the math I learnt because I understood them much
better.

------
amelius
See also Leonard Susskind's series, [1].

> The Theoretical Minimum is a series of Stanford Continuing Studies courses
> taught by world renowned physicist Leonard Susskind. These courses
> collectively teach everything required to gain a basic understanding of each
> area of modern physics including all of the fundamental mathematics.

[1] [http://theoreticalminimum.com/about](http://theoreticalminimum.com/about)

~~~
andy_ppp
I have been wanting this course for years! Thanks!

------
ivan_ah
That's a great list. The only thing that's missing would be a linear algebra
course. The OP mentions it in passing, but a good understanding of LA goes a
long way. I did UGRAD in engineering, and when I switched to physics
everything was over my head, but my knowledge of LA still managed to keep me
afloat. Also, _matrix quantum mechanics_ is essentially straight up linear
algebra (vectors, unitaries, projections, etc.)

Now switching to a shameless plug mode, I'll mention my math+mech+calc book,
which would be a good addition to the section _1\. Introduction to Mechanics_.
Chapter2 of the book (on topic) is part of the preview:
[https://minireference.com/static/excerpts/noBSguide_v5_previ...](https://minireference.com/static/excerpts/noBSguide_v5_preview.pdf)

~~~
godelski
Linear is a must, especially if you are going to get into QM. I haven't read
your book, but the one by David Lay is a great text.

~~~
sn9
Strang's text is also great, and you can take the course via MIT OCW Scholar
from the man himself.

For those wanting a more mathematical perspective (versus engineering/applied
science), there's Axler's _Linear Algebra Done Right_.

For the programmers in the audience, another fun and illuminating (and cheap!)
text is Klein's _Coding the Matrix_.

------
racl101
I've always loved physics but I don't think it loves me back.

That is, I've always found it fascinating since high school but once you need
calculus to understand some of the more advanced stuff I feel that I get lost
in the math (which, admittedly, I suck at) and lose the intuition for what's
really going on. Then it just becomes a giant math problem that prevents me
from seeing the bigger picture.

It's just this problem I've had that I always sweat the small things and
sometimes miss the bigger picture or the main concept when I get frustrated
that I can't understand the details.

~~~
joeberon
There is a point early in your education as a physicist (Quantum Mechanics)
where it becomes impossible to have an intuitive understanding. For Quantum
Mechanics you can just do the calculation, there is no way you can get an
intuitive understanding, other than by becoming comfortable with the
mathematics.

I used the feel the same as you, but then I _gave up_. One day I was like
"screw it, I'm just going to take it for granted". I stopped caring about
getting a feel for _why_ things happen, just that they do and I know how to
calculate them. When that changed I was suddenly free, I didn't have to worry
about why things made sense or not anymore.

You still should understand what the problem is though. Physics isn't just
about understanding the mathematics, it's also about understanding the
physical arguments that goes along with it. Like how can we come up with the
problem to solve in the first place?

One problem I have often had is that in a long derivation my brain will be so
fried on the mathematics that I eventually forget what the terms in the
equations actually represent. I'm like "what is q again? oh yeah it's a
generalised coordinate".

It's cliche but the important part is not giving up. My favourite lecturer,
who is a theorist, says that the main issue that students have is fluency.
They _can do_ the mathematics, but they aren't _fluent_ at it. They aren't
quick, they're slow, it takes them time to work it out, etc. That is what
makes you forget, but eventually after seeing the mathematics so many times it
will becomes ingrained in your brain, and it will just feel obvious, and you
don't have to think about it. Eventually you will become fluent in the
mathematics and it will disintegrate as a boundary, and all you'll have to
think about is the physics. It's just practise.

~~~
tnecniv
> I used the feel the same as you, but then I gave up. One day I was like
> "screw it, I'm just going to take it for granted". I stopped caring about
> getting a feel for why things happen, just that they do and I know how to
> calculate them. When that changed I was suddenly free, I didn't have to
> worry about why things made sense or not anymore.

A very important development in my understanding of mathematics was developing
an intuition of when something is worth visualizing. Sometimes visualization
is extremely helpful. Sometimes it just makes understanding the problem more
difficult (looking at you quaternions).

> One problem I have often had is that in a long derivation my brain will be
> so fried on the mathematics that I eventually forget what the terms in the
> equations actually represent. I'm like "what is q again? oh yeah it's a
> generalised coordinate".

I had a professor who said something along the lines of "a good notation
liberates the mind while a poor one clutters it." I suspect he was quoting a
famous mathematician (as he was wont to do), but I cannot remember who
(Whitehead?).

------
lisper
Physics is made much harder than it needs to be by the fact that physics
pedagogy is generally terrible. Physics texts start by just throwing equations
at you, telling you "This is how it is" with no background or foundation about
_how we know_ that this is the way it is, or _what it means_ that this is the
way it is. There are some very good popularizations out there (like David
Mermin's "Boojums all the way through") but very little that bridges the gap
between these and "real" physics books. One of the things on my to-do list is
to write a book to try to fill this void, at least for quantum mechanics.

~~~
trevortheblack
I would on the whole agree that physics pedagogy is generally terrible. But
there are a handful of textbooks that do an excellent job on explaining the
WHY before the math. Griffith, as mentioned 3 times in the article is famous
for his excellent books.

I'm not sure if you have read the Griffith's textbook on Quantum, but I would
agree it does a reasonable job of introducing the topics before going too math
heavy. The first 2 chapters are devoted to introducing concepts before the
"boojums" of chapter 3.

But I wholly disagree with your assertion that QM should be taught _how we
know_ before what it means. QM tends to need to get across 3 things to the
introductory student, broadly, it's what the tools are (e.g. Schroedinger's,
uncertainty principle), how they depart from the classical understanding, and
what the mathematical foundations are (e.g. commutators and linear algebra). I
think that just teaching the tools, then the math, then the departure is by
far the best means of teaching QM. It's just too weird to contrast to
classical. Contrasting to classical at all would lend the student to an
understanding of QM in terms of classical, that is absolutely the wrong
mindset to be.

I'm an EE and Phy MS at UCLA.

~~~
lisper
> But I wholly disagree with your assertion that QM should be taught _how we
> know_ before what it means.

I didn't assert that, so you can't disagree with it :-) I think the how-we-
know and the what-it-means should both precede the math, but I don't have a
strong opinion on which of those should come first.

I have not read Griffiths, but I took a quick look at:

[http://www.fisica.net/quantica/Griffiths%20-%20Introduction%...](http://www.fisica.net/quantica/Griffiths%20-%20Introduction%20to%20quantum%20mechanics.pdf)

and I was not impressed. It seems like a completely traditional presentation,
and like all traditional presentations it completely misses the absolutely
central role that _entanglement_ plays in the conceptual foundations of QM.
(In fact, the word "entanglement" does not even appear in the table of
contents! Alas, the on-line text I found at the above link is not searchable
so I can't tell you if he doesn't address it at all.)

[EDIT] I've now read more of Griffiths and I would like to revise and extend
my above remarks :-) My original criticism still stands, but aside from that
the book is actually quite good.

------
westoncb
I've been thinking about reading _The Feynman Lectures on Physics_ recently,
but I always thought they were essentially textbooks; I was surprised to see
them described as 'popular' here. I remember reading something about their
origin, that some universities tried adopting them with the result being that
students found them too difficult (and many professors considered the material
to be a sort of fresh take on classical subjects).

~~~
kwhitefoot
How on earth can they be regarded as too difficult? The Feynman lectures were
set books at Exeter Uni. for my applied physics degree '74-'77, I don't
remember anyone complaining that they were too difficult, challenging of
course.

~~~
wodenokoto
Popular science books and coursework for applied physics degree are generally
not expected to have the same level of difficulty.

~~~
kwhitefoot
The title is 'So you want to learn physics'. If you aren't trying anything
challenging you aren't really learning physics, you are just getting a few of
the highlights.

~~~
wodenokoto
No. The site clearly places those lectures under the category "popular".

Also, "do you want to learn physics" might as well refer to high school level
physics.

I know plenty of + 30 who don't have a "high school" level understanding of
physics (despite their high school diploma) who might see that headline and
think "hmm, maybe I ought too" and they would be barking up the wrong tree.

The level of math and physics required to follow a first semester college
course in physics is beyond most highschoolers.

------
M_Grey
I can't recommend the book, 'Prime Obsession' by John Derbyshire enough.
'Gravity' by Hartle is invaluable and quite accessible. If you have a strong
background in calculus, you can also check out 'Gravitation' by Misner,
Thorne, and Wheeler.

~~~
joeberon
Hartle is nice. My GR course I'm doing right now uses that. If you have done a
bit of calculus of variations it's nice.

------
taktoa
I haven't fully worked through it yet, but I've been really enjoying reading
John Baez's Gauge Fields, Knots, and Gravity [1].

[1]:
[http://www.worldscientific.com/worldscibooks/10.1142/2324](http://www.worldscientific.com/worldscibooks/10.1142/2324)

------
danharaj
Also relevant
[https://www.staff.science.uu.nl/~gadda001/goodtheorist/](https://www.staff.science.uu.nl/~gadda001/goodtheorist/)

~~~
amai
This list from physics nobel prize winner Gerard 't Hooft "How to become a
GOOD Theoretical Physicist" is quite amazing.

But in case you are interested in the dark side you should read Gerard 't
Hooft`s article on "How to become a BAD Theoretical Physicist"
[https://www.staff.science.uu.nl/~hooft101/theoristbad.html](https://www.staff.science.uu.nl/~hooft101/theoristbad.html)

------
vortico
't Hooft's guide is really fantastic as a complement to an undergraduate
curriculum.

[http://www.staff.science.uu.nl/~001/goodtheorist/index.html](http://www.staff.science.uu.nl/~001/goodtheorist/index.html)

Edit: Looks like this has already been posted. But it's so good it needs
another bump.

------
shamino
I think this is a great list, and I'm so glad Susan took the time to lay all
of this out!

I have to add these two books to the list. I was surprised to see they didn't
make it, even though she nailed some of the other "bibles". The following were
my favorite books as an undergraduate physics major:

    
    
      - Introduction to Mechanics by Kleppner and Kolenkow 
      - Electricity and Magnetism by Edward Purcell
    

No true physics education would be complete without reading and going through
the problems in those books. I knew physics was my passion before, but these
books helped me fall in love with physics even more.

------
tim_sw
I really like Prof. Shankar's lectures and books.
[https://m.youtube.com/playlist?list=PLFE3074A4CB751B2B](https://m.youtube.com/playlist?list=PLFE3074A4CB751B2B)

[https://www.amazon.com/Fundamentals-Physics-Mechanics-
Relati...](https://www.amazon.com/Fundamentals-Physics-Mechanics-Relativity-
Thermodynamics/dp/0300192207)

[http://oyc.yale.edu/physics/phys-200](http://oyc.yale.edu/physics/phys-200)

~~~
tim_sw
He also has a book called "Basic Training in Mathematics: A Fitness Program
for Science Students"

[https://www.amazon.com/Basic-Training-Mathematics-Fitness-
St...](https://www.amazon.com/Basic-Training-Mathematics-Fitness-
Students/dp/0306450364)

------
sizzzzlerz
Learning physics requires more than simply reading text books. A significant
portion of actually understanding the concepts laid out in the book is
performing demonstrations and experiments in the lab. In college, we had a 3
hour lab each week to go with 3 1-hour classes and each was critical to
learning. I certainly admire anyone who wants to learn physics on their own,
especially without already having a strong mathematical education, but to
really grasp the meaning of the words in a book requires practical exposure in
a lab.

~~~
racl101
Depends what you are trying to achieve. If you are trying to gain an
appreciation for it (as a layperson) then I think you can forgo many of the
complicated experiments. On the other hand, if you are trying to prime
yourself for a career in it then you definitely must perform the experiments.

~~~
sizzzzlerz
I don't disagree that a lab isn't necessary if all you want is a cursory
overview of the various topics but I'm assuming that the person wanting to
learn physics wants a deeper understanding of the concepts. Really know what
those equations mean. That takes practical experiences in my opinion.

------
sp527
Wondering if anyone here has run into the same issue as me: I've wanted to
learn Physics properly (post college) but can't find time to balance it with a
job/having a social life. I've had a few false starts where I try for a week
or two and give up because the whole enterprise feels insurmountable. Anyone
else experience this/figure out a good strategy?

------
godelski
There is a classical mechanics missing in the grad school section. One of the
primary books used is by Goldstein.

I also recommend Classical Dynamics of Particles and Systems by Marion and
Thornton.

As was mentioned in another post Linear Algebra is a must, and I think David
Lay's book is a great one to start with.

As the author mentions, to learn physics you MUST DO PROBLEMS.

On another note I can't seem to find anyone that has mnemonic techniques for
learning equations. So if anyone comes across a good method I'd like to hear
it. And I'm not just talking about something like "low d high minus high d
low, square the bottom and away we go". But to more complex equations, like
memorize "memorize Einstein's field equation." A method that could potentially
work for any arbitrary equation.

~~~
antognini
I think the only way to consistently memorize an equation is to deeply
understand it. Not just how to apply it, but essentially how to derive it.
What motivates it. Why it _must_ take the form that it does.

With fundamental physical equations you have to be a little hand-wavy, because
they are, well, fundamental, so they can't be derived from anything else. But
you can motivate the form of the Schrodinger equation from the classical wave
equation. (I should note that Feynman disagrees with this claim, but you can
find a nice motivation for the form in Penrose's Road to Reality.) Regardless,
going through these motions will serve to embed the form of the equation in
your mind.

It also helps to write the form of the equation in a number of different ways.
Some may be easier to remember than others. Maxwell's equations, for instance,
are pretty easy to remember if you write them in terms of the EM stress-energy
tensor.

~~~
godelski
This is always how I have memorized them, really through repetition (back to
doing problems). The thing is that except for the basic ones and ones I use
excessively, I forget; I think this is common. In comparison I can remember
mnemonic lists of random items created years ago. I can't help but think there
is a way to store math information similarly. Because that would suggest that
it is a problem with the storage of the information.

I've always looked for more effective ways to study. And to counter your
suggestion you can definitely fully understand the principles of an equation
without being able to remember the equation itself. A simple example of this
would be the Laplacian in spherical coordinates. It is easy to understand what
is being done and the Cartesian form is trivial (most people have this
memorized even) and the spherical can be derived from it simply. Problem is
this takes way too much time. I don't think an example like this you could
argue that there isn't an understanding of what is going on, just a
familiarity issue. And thus how the information was stored. I'd argue that
most of those that know this off the top of their head do so from repetition
and not because of a better understanding than their Cartesian only
counterparts.

~~~
sn9
Mark Eichenlaub's Quora answer to this question [0] should give you much to
think about.

[0] [https://www.quora.com/Do-grad-school-students-remember-
every...](https://www.quora.com/Do-grad-school-students-remember-everything-
they-were-taught-in-college-all-the-time)

------
kapilkaisare
I would love to see similar lists for Chemistry, Biology, Architecture, Urban
planning...

The world of autodidactism needs a list of list of textbooks, providing
learning paths for all sorts of subjects.

~~~
sn9
These lists basically exist, though not conveniently in one place.

Just look at the required and elective courses at a few decent undergraduate
programs for your field of interest, form a DAG from the list of prerequisites
(which is sometimes conveniently shown as a flowchart by the program), and
track down the required textbooks.

If your field of interest exists as a well-studied undergraduate major, then
this list can be compiled in an hour or two.

------
Hydraulix989
For GR, I really liked Bernard Schutz's "A First Course in General Relativity"
\-- I read it from cover to cover.

Extremely lucid explanations of some very complex topics, and reading it for
the first time blew my mind.

This book "teaches" you well (compared to other books where I feel like I
really am putting in a ton of mental effort just to learn what the book is
trying to say, much like reading mathematics articles on Wikipedia), and it
still manages to move fast.

------
edtechdev
Start by playing with the physics simulations at
[http://phet.colorado.edu](http://phet.colorado.edu)

------
aidenn0
I didn't see any optics textbooks listed, so I'll propose two:

Fundamentals of Optics, Jenkins & White

Nonlinear Optics, Boyd

------
camikazeg
I understand the appeal of self learning physics for the sake of knowledge,
but is there a market for self taught physicists in the same way that there is
for self taught web devs?

I feel like you'd have to go through the university system. If not, what would
that pathway look like?

------
yati
Another good resource (compiled by Nobel Laureate Gerard 't Hooft):
[http://www.staff.science.uu.nl/~gadda001/goodtheorist/](http://www.staff.science.uu.nl/~gadda001/goodtheorist/)

------
Szel
Is there something similar for math?

~~~
ipnon
There's something here for everybody:
[https://hbpms.blogspot.com/](https://hbpms.blogspot.com/)

------
melling
HN post about the best way to learn physics:

[https://news.ycombinator.com/item?id=11216668](https://news.ycombinator.com/item?id=11216668)

------
mathattack
The post made me wish I majored in Physics!

------
arcanus
> If you work through the all of the textbooks in the Undergraduate Physics
> list of this post, and master each of the topics, you'll have gained the
> knowledge equivalent of a Bachelor's Degree in Physics (and will be able to
> score well on the Physics GRE).

I am not so confident: the physics GRE is a notoriously difficult test, and is
a significant barrier to acceptance to any Ph.d. program.

~~~
Steuard
Each fall I teach a mini-course for our physics majors who want to take the
Physics GRE. The trouble is that you can't do well on the test if you just go
in and try to solve as many questions as you can: it's 100 questions in 170
minutes, and many (most?) of the questions look like full fledged homework
questions (that would take even a pretty good student 5-10 minutes to solve,
or sometimes much longer). Instead, you need to learn all of the common tricks
and shortcuts that the test writers expect you to know and use (including
things like checking the units on all of the multiple choice answers to
eliminate some choices, or testing that the choices have the right limits like
time->0 or mass->infinity).

It's a pretty obnoxious test, to be honest. Once you've learned the types of
strategies to use, the GRE is testing _something_ meaningful about physics
knowledge and intuition, but I don't know how well that something correlates
with either "successful in classes" or "successful in research".

------
LHxB
Is someone aware of a similiar post replacing "Physics" with "Computer
Science"?

------
FarhadG
Congrats, Susan! I remember having a philosophy class with you (many) years
ago

