Reddit reviews: The best applied physics books

We found 72 Reddit comments discussing the best applied physics books. We ran sentiment analysis on each of these comments to determine how redditors feel about different products. We found 17 products and ranked them based on the amount of positive reactions they received. Here are the top 20.

Top Reddit comments about Applied Physics:

u/dargscisyhp · 7 pointsr/AskScienceDiscussion

I'd like to give you my two cents as well on how to proceed here. If nothing else, this will be a second opinion. If I could redo my physics education, this is how I'd want it done.

If you are truly wanting to learn these fields in depth I cannot stress how important it is to actually work problems out of these books, not just read them. There is a certain understanding that comes from struggling with problems that you just can't get by reading the material. On that note, I would recommend getting the Schaum's outline to whatever subject you are studying if you can find one. They are great books with hundreds of solved problems and sample problems for you to try with the answers in the back. When you get to the point you can't find Schaums anymore, I would recommend getting as many solutions manuals as possible. The problems will get very tough, and it's nice to verify that you did the problem correctly or are on the right track, or even just look over solutions to problems you decide not to try.


I second Stewart's Calculus cover to cover (except the final chapter on differential equations) and Halliday, Resnick and Walker's Fundamentals of Physics. Not all sections from HRW are necessary, but be sure you have the fundamentals of mechanics, electromagnetism, optics, and thermal physics down at the level of HRW.

Once you're done with this move on to studying differential equations. Many physics theorems are stated in terms of differential equations so really getting the hang of these is key to moving on. Differential equations are often taught as two separate classes, one covering ordinary differential equations and one covering partial differential equations. In my opinion, a good introductory textbook to ODEs is one by Morris Tenenbaum and Harry Pollard. That said, there is another book by V. I. Arnold that I would recommend you get as well. The Arnold book may be a bit more mathematical than you are looking for, but it was written as an introductory text to ODEs and you will have a deeper understanding of ODEs after reading it than your typical introductory textbook. This deeper understanding will be useful if you delve into the nitty-gritty parts of classical mechanics. For partial differential equations I recommend the book by Haberman. It will give you a good understanding of different methods you can use to solve PDEs, and is very much geared towards problem-solving.

From there, I would get a decent book on Linear Algebra. I used the one by Leon. I can't guarantee that it's the best book out there, but I think it will get the job done.

This should cover most of the mathematical training you need to move onto the intermediate level physics textbooks. There will be some things that are missing, but those are usually covered explicitly in the intermediate texts that use them (i.e. the Delta function). Still, if you're looking for a good mathematical reference, my recommendation is Lua. It may be a good idea to go over some basic complex analysis from this book, though it is not necessary to move on.


At this stage you need to do intermediate level classical mechanics, electromagnetism, quantum mechanics, and thermal physics at the very least. For electromagnetism, Griffiths hands down. In my opinion, the best pedagogical book for intermediate classical mechanics is Fowles and Cassidy. Once you've read these two books you will have a much deeper understanding of the stuff you learned in HRW. When you're going through the mechanics book pay particular attention to generalized coordinates and Lagrangians. Those become pretty central later on. There is also a very old book by Robert Becker that I think is great. It's problems are tough, and it goes into concepts that aren't typically covered much in depth in other intermediate mechanics books such as statics. I don't think you'll find a torrent for this, but it is 5 bucks on Amazon. That said, I don't think Becker is necessary. For quantum, I cannot recommend Zettili highly enough. Get this book. Tons of worked out examples. In my opinion, Zettili is the best quantum book out there at this level. Finally for thermal physics I would use Mandl. This book is merely sufficient, but I don't know of a book that I liked better.

This is the bare minimum. However, if you find a particular subject interesting, delve into it at this point. If you want to learn Solid State physics there's Kittel. Want to do more Optics? How about Hecht. General relativity? Even that should be accessible with Schutz. Play around here before moving on. A lot of very fascinating things should be accessible to you, at least to a degree, at this point.


Before moving on to physics, it is once again time to take up the mathematics. Pick up Arfken and Weber. It covers a great many topics. However, at times it is not the best pedagogical book so you may need some supplemental material on whatever it is you are studying. I would at least read the sections on coordinate transformations, vector analysis, tensors, complex analysis, Green's functions, and the various special functions. Some of this may be a bit of a review, but there are some things Arfken and Weber go into that I didn't see during my undergraduate education even with the topics that I was reviewing. Hell, it may be a good idea to go through the differential equations material in there as well. Again, you may need some supplemental material while doing this. For special functions, a great little book to go along with this is Lebedev.

Beyond this, I think every physicist at the bare minimum needs to take graduate level quantum mechanics, classical mechanics, electromagnetism, and statistical mechanics. For quantum, I recommend Cohen-Tannoudji. This is a great book. It's easy to understand, has many supplemental sections to help further your understanding, is pretty comprehensive, and has more worked examples than a vast majority of graduate text-books. That said, the problems in this book are LONG. Not horrendously hard, mind you, but they do take a long time.

Unfortunately, Cohen-Tannoudji is the only great graduate-level text I can think of. The textbooks in other subjects just don't measure up in my opinion. When you take Classical mechanics I would get Goldstein as a reference but a better book in my opinion is Jose/Saletan as it takes a geometrical approach to the subject from the very beginning. At some point I also think it's worth going through Arnold's treatise on Classical. It's very mathematical and very difficult, but I think once you make it through you will have as deep an understanding as you could hope for in the subject.

u/oro_boris · 3 pointsr/Physics

> Why is a photon massless and still has momentum?

Because momentum isn’t actually p = mv, as in Newtonian mechanics, but it’s really

p = ( E/c^2 ) v

For objects with a non-zero mass m, moving non-relativistically, E is approximately equal to mc^2 and then p is approximately equal to mv, the Newtonian value.

However, photons are intrinsically relativistic. They have energy even though they don’t have mass (their energy is proportional to their frequency, E = hf, where h is Planck’s constant) and, so, they also carry momentum. In fact, since their speed (in vacuum) is always c, the magnitude of their momentum, using the above results, is always p = E/c = h f/c = h/wavelength.

> Why can't anything go beyond the speed of light? (Cliché but I never really understood why despite of many videos floating on YouTube)

Please take a read at this post I wrote here some time ago, where I address that question. Please ignore the first two paragraphs as those were part of a rant.

> How does a magnetic field originate?

A magnetic field is created by electric charges in motion. Since, however, motion is relative (you’re not moving with respect to your chair but you are moving with respect to, say, the Sun), so is a magnetic field. In a reference frame where an electric charge is at rest, you’ll only measure the electric field generated by the charge. In a reference frame where the charge is in motion, you’ll observe both an electric field and a magnetic field.

Excellent introductory books on special relativity, in my opinion, are (in increasing order of difficulty):

Special Relativity: For the Enthusiastic Beginner


Special Relativity (Mit Introductory Physics Series)



Spacetime Physics: Introduction to Special Relativity


Einstein’s own books are pretty great too, and are now in the public domain. Search the Gutenberg project for them.

u/phaseoptics · 1 pointr/askscience

Perhaps a lot will be clearer if you get the quantum nature of the measurement of light's polarization. Classically, light is a transverse electromagnetic wave. When one measures a photon's polarization it assumes a definite value, i.e. some orientation. To say that light is unpolarized means that all electric field directions of every photon in a beam will have equal probability to be measured. If the light is polarized then it can be measured in one of only two states. "Circular polarization" means each possible state is described by a plane waves of equal amplitude but differing in phase by 90°. If the light is "elliptically polarized" then it's unmeasured state is described by two simultaneous plane waves of differing amplitude related in phase by 90°. It can also be called elliptically polarized if the amplitudes of the two states are equal but the relative phase is other than 90°. So an unpolarized beam of photons say, or a single photon with a polarization at some angle relative to your measuring polarizer say, is not split into two when sent through a polarizer, rather each photon takes one path or another according to probability.

Concerning your next group of questions about how light propagates through dielectric solids like glass... There is only free propagation, absorption, and scattering. Scattering can be either elastic or inelastic. Scattering theory is a rich subject because materials are so diverse in composition. The most common form of scattering in isotropic media like the atmosphere and dielectric solids composed of small molecules is an elastic form of scattering called Rayleigh scattering. Rayleigh scattering occurs when a photon penetrates into a medium composed of particles whose sizes are much smaller than the wavelength of the incident photon. In this scattering process, the energy (and therefore the wavelength) of the incident photon is conserved and only its direction is changed. Rayleigh scattering has a simple classical origin: the electrons in the atoms, molecules or small particles radiate like dipole antennas when they are forced to oscillate by an applied electromagnetic field. This is not an absorption and re-emission. If the scattering sources are stationary, then this secondary radiation is phase locked to the driving electromagnetic field. So perhaps this is what you mean by "coherent transmission". But even for a truly coherent source of photons, from a laser say, the coherence length is shorted by the presence of the dielectric.

Lastly, your bonus question... You need to read Richard Feynman's, QED: The Strange Theory of Light and Matter. Light propagates as a wave, even single photons. It therefore takes all possible paths, not just the path of least time! It's just that only those paths which arrive at the detector in phase will result in a non-zero amplitude. And for a single ray of light passing from one isotropic medium to another of different index of refraction, there is only one path that satisfies that condition, the path of least time. Anyway, you will love the book and will come away understanding light much better.

u/[deleted] · 3 pointsr/askscience

Disclaimer: I am an engineer, not a physicist, biologist, etc.

I've always been partial to Feynman's writings when it comes to non-technical discussions of physics. Six Easy Pieces is a great place to start, and if you enjoy it, you can try out Six Not So Easy Pieces. QED is a very accessible book on quantum electrodynamics. Don't let the complex-sounding title fool you--Feynman makes this subject very easy to understand for the layperson.

I really enjoyed reading Relativity for the Million by Martin Gardner, although it's been quite a while since I read it. Gardner is a great author, and this book is perfect for the interested layperson. If you enjoy puzzles, check out his other books. If you want to get a little more technical, Relativity: The Special and the General Theory by Einstein is a good choice.

If you're up for a challenge and willing to commit to a bit of study, I recommend The Road to Reality: A Complete Guide to the Laws of the Universe by Roger Penrose.

As far as magazines go, I've found that Science News keeps me up-to-date on the latest developments in science without getting mired in the details of subjects that I may not be familiar with.

u/QuentinDave · 3 pointsr/Astronomy
  1. I found this article trying to answer the same question. I was looking at the stars the other night, and wondering if I was seeing photons directly from the star, or if I was really seeing photons emitted from the atoms in the air directly above my eyes. Maybe they pass between the atoms in the air, because atoms in gasses are distant compared to massless photons, I thought.

    I have been googling for the past hour and I think they are absorbed, but they are emitted with more-or-less the same wavelength, resulting in more-or-less the same image.

    Photons travel at c between the atoms, but the absorption and emission causes an average slower speed, and thus a bend in its path. From the linked article:

    > By "absorption" I mean that the energy of the photon causes an electron of
    the atom to be kicked to a higher energy level, and the photon ceases to
    exist. Then, after a very small time delay, the electron goes back to its
    original (usually ground state) energy and "emits" a photon of the same
    energy (and thus same frequency and thus same wavelength) as the original
    "absorbed" photon.

    So to answer your question, yes, refraction is absorption->emission. The article in OP sorta glosses over this, ("This is not due to gravity, but refraction as the lens of our air slants its path before its final plummet to the nighttime country-side below.") perhaps to keep the theme of following one photon on its journey. From what I've read online, a good resource for more info on this is QED: The Strange Theory of Light and Matter by Richard Feynman.

    I think my original question is more of philosophical identity (is it really the "same" photon?) than of physics.

  2. The author used "burn" in the less literal definition: use (a type of fuel) as a source of heat or energy.

  3. The video in this article shows what an observer might see while traveling at near the speed of light. So basically, nothing--your whole field of view collapses into a single point. Also, this game made with/by MIT shows how you might experience the world as you artificially lower c. And it's actually pretty fun. This doesn't answer the frozen in time bit, however...

  4. This r/askscience post's answers generally seem to say that no time passes for a photon. However, they also stress that a "photon's reference frame" isn't a valid concept. I wanted to know why and I think the answer is in this wikipedia article about time dilation. It shows the formula for calculating the time elapsed for an observer moving at very high speed relative to a "stationary" observer. Basically, you divide the stationary time by the square root of 1-(velocity^2 / speedoflight^2 ).However if v=c, then v^2 / c^2 = 1, 1-1=0, the square root of 0=0, and you're now dividing by 0... which is probably why it's said that photons have no reference frame.

    Thanks for asking these questions, because I learned a lot in researching the answers lol. All this info made the original article seem even less science-based, but I still think it illustrates the awesome forces at work in this stellar hobby.
u/CrimsonCowboy · 1 pointr/scifi

Yes. From "The High Frontier", a book on making space colonies, you could deflect meteors - even nonmetallic - from a colony with an electric field. It required a charge of about two gigavolts to be maintained across the whole of it.

This is costly. And any visiting craft would have to be neutralized relative to whatever charge the colony holds.

Just coating a colony in slag is pretty good; sure, spin up will be harder, but... well, reasons previously listed.

I'm reminded of a conversation a friend had with me; a force field is basically something that would repel an object from contact with the field, right? And you'd need some sort of stabilizing element, right? Something spread across the whole field, probable uniformly?

Something like atoms?

What with the nucleus holding it together and the electrons around it providing the desired electric field?

Yeah. A sheet of strong plastic is essentially a force field.

BUT, that's not nearly as cool.

So you could make an electric field strong enough to repel something moving like a meteor, but... well, here's food for thought. Cathode ray TV's and monitors operate at 35Kv or lower. And they are designed to fail if they over voltage, because they shoot beams of electrons through/at a metal screen, and would deliver X-rays to the viewer if they didn't have such circuits.

Why did you think they were made of lead/strontium glass? Rhetorical question, it's to not irradiate the user.

So, having metal buttons on your person may well enough end up giving you cancer. Not so bad if it's your only choice, or you have a short time to live anyway.

Now, maybe if you could entrap differently charged ions in two fields layered over each other, you'd just need like, a mesh to generate and hold the fields, and then when an object passes through the fields, it'd explosively short it. Sorta like ablative armor but... This may still end badly for the user. Layer it, perhaps?

We do have a very good understanding of electricity on the atomic level; Quantum Electro Dynamics. Feynman wrote a really great introduction to it - he was a great teacher, and was one of the inventors of the theory. It's called "QED: The Strange Theory of Light and Matter".

Gravity is also pretty solid; Laplace fixed our understanding of orbital mechanics in the Napoleonic age. Whooole lot of differential equations there.

u/djimbob · 8 pointsr/askscience

Eh, first you have to read up on quantum mechanics and get a decent understanding of quantum mechanical spin and quantum numbers in general. Something like Shankar - Principles of Quantum Mechanics, though there are tons of textbooks on it. You won't really get into particle physics, but should read at least to the point of understanding addition of angular momentum and spin (typically in context of hydrogen atom).

Then a text on particle physics like Griffiths' Intro To Elementary Particle Physics. (You could also start Griffiths' Intro to QM).

You could also consult free resources like the particle data group, but their reviews will be largely gibberish if you don't understand the basics of QM / particle physics / group theory. (Articles like Quark Model, or Naming Scheme for Hadrons).

If you are looking at hobby-level interest without getting into any math/textbooks, the best I can suggest is Feynman's QED but it won't talk about isospin or hadrons or particle naming conventions but is a great layman introduction to quantum electrodynamics.

u/Kaputaffe · 11 pointsr/askscience

The answer to this is much, much deeper than any of the comments so far. The answer to "How does" is not "4%". The answer is in Quantum Electrodynamics.

I have to run to work, and Richard Feynman is much better at explaining things than me, so I'll point you to his book QED which is dedicated to answering this question as a way to explain QED.

Sorry to have to run because this is fascinating, but to give an accurate answer that really hits on the principles behind it, takes about 20 pages from one of the smartest men who ever lived. I couldn't recommend the book more - it is accessible to anyone of reasonable intelligence willing to read it carefully, and unlocks one of the great mysteries of nature in an entertaining and exciting way.

u/agate_ · 3 pointsr/askscience

I think the best answer is: since photons don't come with nametags, there's no way to tell, but in most cases, the light behaves as if it's the same photon. There are however some properties of light (diffraction, for instance) where thinking of each point in space as a source of new photons is useful.

For extra credit: the same is true of matter.

Not 100% related, but for more on this sort of thing check out Richard Feynman's short book "QED: The Strange Theory of Light and Matter". It's intended for ordinary laypeople, which says a lot about Feynman's confidence in laypeople, but it's great for the dedicated reader.

u/JimmyBob15 · 2 pointsr/askscience

Looking on their website it seems as if they do not let outside people borrow from their library, sorry :(.

I know many libraries have "partnerships" for the lack of a better word, where if you try to borrow a book from the library, and they don't have it, they will request it from somewhere else they are partnered with and get it for you.

Some ideas of books:

For my undergraduate astrophysics class I used - Foundations of Astrophysics by Ryden and Peterson, ISBN13: 978-0-321-59558-4

I have also used (more advanced, graduate level) - An Introduction to Modern Astrophysics by Carroll and Ostlie, ISBN13: 978-0-805-30402-2

There are plenty of other undergraduate text books for astrophysics, but those are the only two I have experience with.

Some other books that may be just fun reads and aren't text books:

A Brief History of Time - Hawking

QED: The Strange Theory of Light and Matter - Feynman

Random popular science books:

Parallel Worlds - Kaku (or anything else by him Michio Kaku)

Cosmos - Sagan

Dark Cosmos - Hooper

or anything by Green, Krauss, Tyson, etc.

Videos to watch:

I would also suggest, if you have an hour to burn, watching this video by Lawrence Krauss. I watched it early on in my physics career and loved it, check it out:

Lawrence Krauss - A Universe From Nothing

Also this video is some what related:

Sean Carroll - Origin of the Universe and the Arrow of Time

Hope you enjoy!

Edit: Formatting.

u/bebeschtroumph · 1 pointr/science

While I like the open courseware, I personally benefit from having a physical text to work through. If you're looking for a good, basic physics text book, that has a good overview of most topics, something like Giancoli works well. You can find used copies, or get the five separate sections in paperback. I still go back to that book when I've forgotten something basic.

The open courseware is really great to work through, but with any university level course, it's going to assume some basic physics knowledge. Giancoli explains things from first principles pretty well and is a good basic place to get an overview of topics.

Edit: I personally have the third edition, which you can pick up quite cheap, and you can also get the study guide and solutions manual, nice to have when working through problems.

u/ajslater · 3 pointsr/askscience

Indeed yes, there isn't so much absorbtion and reemission of quanta as i understand it as does the substance act like a matrix or diffraction grating. Then within the substance you have lots of little broken up waves all interacting with each other, canceling each other out in parts and bolstering each other in others. The 'super wave' made up of all these interactions propagates at slower than light speed, and potentially at an angle. Come out the other side (into a vaccum again) and there's no diffraction, no 'super wave' but back to light propagating at 'light speed again'.

There's probably a good quantum analogy too, but I don't recall it.

The thing to always remember is that these forces aren't quantum particles or idealized waves, those are just the best models we have for something we don't fully understand.

Read Feynman's QED, its short, written for the layman and completely awesome. It will also blow your freaking mind.

u/nobodyspecial · 1 pointr/books

QED - Richard Feynman QED is a small book that's an excellent introduction into Quantum Mechanics by one of the pre-eminent physicists of the 20th century. If you want to understand the double slit experiment, this is the book to read.

Time, Love, Memory - Jonathan Weiner A biography of Seymour Benzer, a physicist turned biologist whose lab demonstrated the existence of some fundamental genes. One of the more interesting series of experiments demonstrated how the brains of homosexual fruit flies were wired differently than heterosexual fruit flies.

I second scottkarr's "Misquoting Jesus." recommondation. It's a very interesting read on how the bible morphed over time. Read it after reading Time, Love, Memory and the analogies Benzer uses to describe gene mutation will really resonate.

u/palish · 2 pointsr/pics

I think any ELI5 will be oversimplified. You'll come away feeling like you've gained an insight, but the explanation won't match what nature really does.

If you want an understanding of how nature behaves, then you'll need to spend time reading a book called QED. It's actually very readable, even for dummies like me who have no math or physics training whatsoever.

There's a quote floating around that goes like, "According to Feynman, to learn QED you have two choices: you can go through seven years of physics education or read this book". And it's quite true.

You can find the book here or you can watch the videos here.

EDIT: For the truly curious, you can read part of the book here.

u/greysky7 · 1 pointr/timetravel

I just subscribed to this sub, and I'm so sad you didn't get any answers here. I came here after reading a few books that deal with the actual science behind the physics of time travel.

Here are a few to get you started.

How to Build a Time Machine

Time Travel and Warp Drives

I really recommend From Eternity to Here, it's just raw science on time, though there is an interesting chapter that really explains what it would take for travelling through time backwards. Overall, a very important read if you want to know what time actually is, compared to how we perceive it.

Also, I'll recommend the first book I started with, which I got into because I was writing a short story for a college class that involved time travel. It explains time travel and how to use it in fiction, so it's much less technical but gives a solid understanding as to how we would typically perceive the effects of them. it deals with getting paradoxes right etc. Here it is.

EDIT: Just realized all my links were to Canadian amazon, I'm sure they'll be on the US amazon if that's where you happen to live. Have fun!

u/krypton86 · 2 pointsr/Physics

I recommend Hewitt's classic Conceptual Physics or Giancoli's algebra-based text Physics: Principles with Applications (if you want to get into the swing of things, mathematically speaking).

If you really enjoy the material, calculus-based physics can come later. You run the very real risk of getting bogged down in one subject instead of making it through the major lessons of the other.

That being said, taking a course in calculus invariably introduces you to physics anyway since that's why it was created in the first place. You may be better off learning some calculus and leaving the physics for later. Even just a book on precalc could be helpful for you. There are tons of options out there — they're mostly the same in all honesty — but this one is very popular among universities in the states.

Go to a library and find some of these books and see what excites you. That will guide your decision.

u/Axi_om · 5 pointsr/Physics

Textbooks (calculus): Fundamentals of Physics: http://www.amazon.com/Fundamentals-Physics-Extended-David-Halliday/dp/0470469080/ref=sr_1_4?ie=UTF8&qid=1398087387&sr=8-4&keywords=fundamentals+of+physics ,

Textbooks (calculus): University Physics with Modern Physics; http://www.amazon.com/University-Physics-Modern-12th-Edition/dp/0321501217/ref=sr_1_2?ie=UTF8&qid=1398087411&sr=8-2&keywords=university+physics+with+modern+physics

Textbook (algebra): [This is a great one if you don't know anything and want a book to self study from, after you finish this you can begin a calculus physics book like those listed above]: http://www.amazon.com/Physics-Principles-Applications-7th-Edition/dp/0321625927/ref=sr_1_1?ie=UTF8&qid=1398087498&sr=8-1&keywords=physics+giancoli

If you want to be competitive at the international level, you definitely need calculus, at least the basics of it.
Here is a good book: http://www.amazon.com/Calculus-Intuitive-Physical-Approach-Mathematics/dp/0486404536/ref=sr_1_1?ie=UTF8&qid=1398087834&sr=8-1&keywords=calculus+kline
It is quite cheap and easy to understand if you want to self teach yourself calculus.

Another option would be this book:http://www.amazon.com/Calculus-4th-Michael-Spivak/dp/0914098918/ref=sr_1_1?ie=UTF8&qid=1398087878&sr=8-1&keywords=spivak
If you can finish self teaching that to yourself, you will be ready for anything that could face you in mathematics in university or the IPhO. (However it is a difficult book)

Problem books: Irodov; http://www.amazon.com/Problems-General-Physics-I-E-Irodov/dp/8183552153/ref=sr_1_1?ie=UTF8&qid=1398087565&sr=8-1&keywords=irodov ,

Problem Books: Krotov; http://www.amazon.com/Science-Everyone-Aptitude-Problems-Physics/dp/8123904886/ref=sr_1_1?ie=UTF8&qid=1398087579&sr=8-1&keywords=krotov

You should look for problem sets online after you have finished your textbook, those are the best recourses. You can get past contests from the physics olympiad websites.

u/misplaced_my_pants · 1 pointr/Physics

Theory and experiment are usually two divergent tracks in research. Basic science research asks questions for which the answers may never have an application.

The question of experimental propulsion seems to be much more in line with applied physics.

It doesn't really make sense to study string theory or quantum field theory if your interest is in propulsion.

This is the kind of stuff theory deals with and I don't think anyone would predict any of them would result in a novel approach to practical propulsion.

That said, if you want to devote your life to studying these topics in your free time, feel free to have at it. This is the kind of thing a graduate student might know.

u/lanzaio · 1 pointr/AskPhysics

Hmm... it seems like you're trying to learn the meanings of technical terminology that doesn't really lend itself well to non-technical understanding. What I mean by that is the understanding of what a tensor is is completely opaque if you don't use it thoroughly in the mathematics. Likewise for a manifold.

There's no non-mathematical description I'd find satisfactory to tell you what a tensor is.

Luckily I found this book when I was an undergrad. This book is hands down the best I've ever seen for summarizing what a tensor is. I forget if he goes into manifolds, but I'm pretty sure he touches on them.

u/kryptovox · 2 pointsr/AskPhysics

I saw this in the /r/physics thread and it appears that /u/Techercizer already gave you some sage advice. I'd like to add a point about your math, however...

>Algebraically, we could bring the speed of light to the opposite end of the equation... Square root of 186,282 miles per second is equal to something?

Where are you getting √c from? Drawing the m term away from c^2 and taking the square root of the other side leaves you with √(E/m) = c. By all means take more roots to your heart's content, but remember the first rule of solving equations: Whatever you do to one side of the equation you must do to the other. Come back when you understand the physical implications of taking √(√(E/m).

If I only possess vague, abstract conceptions of engineering concepts, can I really aid in the design of a suspension bridge? Can I do it without understanding calculus? I agree with Techercizer that your enthusiasm and curiosity are commendable, but when I hear you say things such as

>I don't feel that they are ignorant ramblings, rather concise logical statements

... from the other thread, you come off as not only ignorant, but arrogant as well.

Also, some reading! Check out this, this, and this. Enthusiasm and curiosity such as yours is rare, and deserves to be cultivated.

u/dnew · 2 pointsr/gaming

> You are, I believe, talking about indirect and subjective observation

Um, no. Photons are what you see. If you say you can't see photons directly, then you are blind.

> a photon is a rather unique particle.

This is factually incorrect. It behaves with substantially the same behaviors as all the other subatomic particles.

> It behaves as if it was both!

Also factually incorrect. It always behaves as a particle. Again, Einstein got a Nobel prize for his paper explaining this. Indeed, the very name "quantum mechanics" is based on the fact that photons are particles.

They sometimes behave in a manner consistent with the same mathematical formulas that waves obey. That doesn't make them waves, any more than a pedestrian obeying a traffic signal is a driver.

> incorporates probabilities, which is a way of saying "we don't really know".

Also incorrect. The probabilities are inherent in the reality, and it's very provably not anything to do with whether we can measure them. The probabilistic values (the choice of "heads" or "tails") quite literally is not there until you look, any more than it's there before the coin lands.

> Now I believe that we live in a deterministic universe

Physicists world-wide disagree.

> we can say with certainty if one throw or another will produce tails.

This is factually incorrect.

> Then again, my understanding of such things is laymanish.

No, your understanding of such things is mistaken. If you care to be less ignorant of this topic, may I suggest the lectures the greatest teacher of physics wrote for his wife?


You can also watch them online if you like. Just google youtube. Someone found them on an old film recording and uploaded them.

If you'd also like to understand relativity at slightly-less-than-layman level, I can also suggest


Neither one requires math above the level of the Pythagorean theorem (you know, the one about the size of the sides of a right triangle), or science past about sixth grade level.

Also note that when I say "ignorance", I do not mean anything pejorative. You just never learned this tremendously unintuitive field of study. :-) But I think it's really cool, so I highly recommend sitting back for a couple of evenings if you have time and inclination.

u/leoboiko · 3 pointsr/science

> If you want to involve photons in this picture, you can, but it won't help you very much.

I beg to differ. I only really understood what “electricity” is, including said guitar-amp phenomenon, when I got photons in the picture , thus creating a very different model than the one presented by most textbooks on transistor electronics. The stuff that moves at the speed of light when you turn a switch on? Photons. The stuff that actually transfers electromagnetic energy, including wire “electricity”, from a battery/source to charge? Photons. Stuff that binds electrons to protons? Photons. Stuff that get stored in capacitors? Photons. Hell the photon↔electron interaction goes well beyond “light” or “electricity” and do most things in the universe! (except gravity and nuclear phenomena). I don’t feel qualified to explain it all in quantum terms but I got the better picture from Richard Feynman’s QED, which I heartily recommend to any curious layman. (Also, this page).

u/Dimpl3s · 1 pointr/askscience

Recommended reading on the subject. Here's my explanation, though this is outside my expertises, and a physics major should offer a more comprehensive answer. But here we go.

When a photon strikes an atom, it causes an electron to jump to its next energy level. The photon is absorbed in the process, and its energy is conserved by an increase in the electron energy level. The atom won't like the configuration, so the electron will soon drop back down to the lower energy level, releasing a photon. This is called reflection.

Now, when you get enough atoms lined up in the right orientation, the image will be conserved. The book I provided offers an awesome explanation of the phenomena. Simply, the light can be considered to be reflected off the front surface and back surface. You know how light is sometimes thought of a wave? It is useful to think of it in this way for this explanation. The reflections from the back and front surface will interfere (two waves taking up the same space). If a peak meets with a valley, the two cancel. If a peak meets with another peak, it will interfere 'constructively', and the light will be preserved.

Now, if the surface is nice and smooth, a clear reflection will be seen as a result of this interaction between the two lights. reflections off glass windows works in this manner. When you are in a bright room at night, the light reflecting off from the room is brighter than the light coming in from outside. This is why you have a hard time seeing through your windows at night, and it helps to shield the glass from the light with your hands. BUT I DIGRESS

Now, you are correct in thinking that the absorption/emission event sends the photon in a random direction. But the waves associated with these random reflections cancel each other out in most cases. The only photon that survives the mass extinction are the ones that reflected with an angle of reflection equal to the angle of incidence.

But really, read the book I linked. It explains this all much better than I can.

u/PhysicsVanAwesome · 4 pointsr/learnmath

This may not be what you are looking for, but Feynman was a master of explanations. He wrote a wonderful book on quantum electrodynamics that you should absolutely check out called QED: The Strange Theory of Light and Matter. It will give you a pretty intuitive look at some of the ideas in QED.

u/Funksolo · 1 pointr/Physics

Try to find some of the old MIT text books (http://www.amazon.co.uk/Special-Relativity-MIT-Introductory-Physics/dp/0748764224) They're out of print but really very helpful. Also Young's and Freedmann is the core text of most of my courses =]

u/lectrick · 3 pointsr/AskReddit

Ah, nice work then.

After graduating high school with the physics lab named after me (not kidding- the head of the science department promised that to the first student who got both a 5 on the AP and 100 on the New York State Regents... it kept the name for 10 years apparently), I bombed out on physics at Cornell due to the stringent math requirement coupled with my total lack of math discipline. Asked Cornell if I could leave, they gave me 5 years without having to reapply, I joined the USAF, "found discipline" (and many other good things), came back, and kicked ass as a psych major with a lot of CS and other electives (I had unfortunately locked out both Physics and CS as Majoring options due to bombing out on the engineering calc). But it all worked out in the end.

I now do web development for an edgy startup and am fairly happy, but I still do things like read QED for fun, and wonder how I might better harness my science interests.

I have horrible memories of prelims, though. (At Cornell, a "prelim" is basically any big test.) Typically, on a calc or physics prelim, I would get all the bonus questions right (which actually tested understanding of the material) and get most of the rest of the test wrong due to running out of time (which essentially tested how many times you had seen that problem before).

u/Redspringer · 2 pointsr/baseball

Even though hector is a Yankees fan he knows what he is talking about. ;-)

It's all about pitcher vs. batter. Ask, what pitches can the pitcher throw effectively and how does this particular batter handle each one. You need to pay attention to the Pitch Count (i.e. 2 and 1) and how it pressures the both players into changing their approach.

This book is very good but can drag a bit (just like real baseball). http://www.amazon.com/Pure-Baseball-Keith-Hernandez/dp/0060925914

This is also interesting although a little wonky

u/Aardshark · 1 pointr/AskReddit

Try reading some of Feynman's lectures - he explains these difficult concepts very well.

Maybe The Strange Theory of Light and Matter would help.

I'm sure you can find a source on the internet pretty easily if you don't want to buy a printed copy.

u/airshowfan · 1 pointr/askscience

Oh good! It's even more BS-ey than I had realized!

My knowledge of quantum physics is limited to what one can learn from popular books (1, 2, 3 ). Could you try to explain the differences between the underlying models/assumptions on which Orch-OR is based, and the models/assumptions in established/standard physics? I would appreciate it.

u/SquirrelBoy · 2 pointsr/baseball

If you want more like this, The Physics of Baseball is a fantastic book.

u/sturg1dj · 3 pointsr/baseball

I can't find any original work, best I can do is a 15 year old article about the subject.


still an interesting read

plus this book

u/stewartr · 5 pointsr/science

QED: The Strange Theory of Light and Matter, Richard P. Feynman (Princeton Science Library)
To start, you need to you learn that eveything is made from complex waves of probability and that is the only way the math works. This short and inexpensive book is a work of art, accessible by the "intelligent layman". Then google the amazing Feynman!

u/TurkishSquirrel · 1 pointr/AskReddit

I would recommend reading, Feynman explains modern physics beautifully and tailors his writing to someone with very little math knowledge
Amazon Link

u/Ralath0n · 3 pointsr/outside

(OOC: Learning quantum mechanics is rather difficult if you actually want to understand it. You need to know vector calculus to even begin on anything but the simplest problems. If you are serious about learning and you don't know much about math, start with Physics by Giancoli. That should take you from basic algebra to introductory quantum mechanics. From there (Or if you are math savvy) go with Quantum Mechanics: Concepts and applications. Once you finish those you'll have a good basic knowledge on quantum mechanics.

If that sounds like a lot of work and you're just looking for a 'laymans explanation' I can recommend the old Feynman lectures on QED. He explains this stuff pretty understandably without going heavy on the math.)

u/LValance · 4 pointsr/Physics

What about poor Walker? It's Halliday, Resnick and Walker. Poor, poor forgotten Walker.

I agree that it is a great textbook and was the one I used in first year university nearly 20 years ago.

If you are interested in a couple other textbooks, consider Conceptual Physics by Paul G. Hewitt. It is a non-mathematical look at the basic concepts of physics and contains lots of fun questions with seemingly counterintuitive answers if you don't fully understand the concepts. I also really like Physics: Principles with Applications by Douglas Giancoli. It is mathematical (but doesn't involve calculus) and gives lots of different examples and explanations for different concepts (maybe too many sometimes) and lots of good problems (some of them are a little challenging for an intro textbook, but that's not a bad thing).

u/Morophin3 · 2 pointsr/askscience

Also, someone else mentioned Feynman's book, called QED. It's a great read.

u/5HLsBaby · 7 pointsr/IBO

I don't really have much advice. I procrastinate much less than I use to because I can't afford to procrastinate. There's a great quote in House MD: "You want people to drive safer, take out the airbags and attach a machete pointing at their neck. No one will drive over three miles per hour." It's really the same thing for me. If I procrastinate, for even a day, I'll be crushed the day after. After a month or so, I lost the ability to procrastinate.

For physics, I first start by reading the study guide. I see if everything seems familiar to me. If anything, even to the slightest bit, seems unfamiliar; I read the course companion. When I fully feel like I understood everything, I start solving past papers and the questions in the book. After I finish all of those, I move onto college(ish) level books. For example, I used THIS book a lot. I try to solve the juiciest questions I can find. After I feel confident on those questions, I go pack to past papers and try to solve everything mentally. If it was really easy, I'd know I'm good for a test. If I'm slow and inaccurate, I'll do everything again.

Well, not really. They respect me more because they see me study more but not as much as I expected. They were even pissed off at me for spending a lot on books.

Edit: Grammar.

u/Threetakes · 3 pointsr/baseball

The Physics of Baseball

If you're into science even a tiny bit, and if you're into baseball, this is an excellent book.

u/Sleestaks · 1 pointr/science

You must realize you are the box and the box is you. With the same instance that you understand your box, your box understands you. This means quantum mechanics may substitute for a cozier box?

On a sidenote however, I understood quatum mechanics at least a little better after reading QED The Strange Theory of Light and Matter I recommend it.

u/creaothceann · 5 pointsr/science

Recently I've read Feynman's The Strange Theory of Light and Matter. It's a nice "introduction" to the world of quantum physics. ((Also available online on certain sites.))

u/RamBamBooey · 1 pointr/AskReddit

QED: The Strange Theory of Light and Matter
It's short (less that 200 pages), it's written so a high school student can understand it and for many years I have gained new incite by thinking back on this book.


(I have many others - I just wanted to make certain this book appeared.)

u/bobotheking · 62 pointsr/IAmA

Three minor corrections:

  1. Measuring the position of an electron does not cause the path to be determined. The interference of all the paths is crucial for the observations we make.
  2. The electron (or any particle) has an equal probability amplitude to take all paths, not an equal probability. You had it backward. It is the complex phase of the probability amplitude that leads to interference patterns and the large-scale cancellation that gives rise to the appearance of classical behavior.
  3. You mostly have the right idea about the electron taking paths to the moon or Andromeda, but I think you glossed over the essential point. It does have a probability amplitude of equal magnitude to take one of those ridiculous paths, but those probability amplitudes will almost completely cancel with its nearest neighbors. That means we need to consider the path where the electron takes several days to reach the moon and then goes back in time to return to the detector! We also need to consider paths where it first goes back in time, then to the moon, paths where it goes to the moon and back faster than c, and paths where it circles the Andromeda galaxy three times and returns. What is important about each of these paths is not the specific path followed, but rather the endpoints. It must have left the source at the same time and reached the detector at the same time.

    If anyone is interested in an accessible introduction to this material, read Richard Feynman's QED.
u/SEMW · 1 pointr/science

If you want to understand how reflection behaves in a "true" way, read Feynman's QED. Transcripts of popular science lectures. They're not exactly simple to understand, but they were designed to be at least somewhat accessible.

u/gmarceau · 1 pointr/AskReddit

The man that said "if you think you understand when to mechanics, you do not understand quantum mechanics" is Richard Feynman. He also wrote a book that explains quantum mechanics, called QED.

u/relax_its_fine · 8 pointsr/AskPhysics

Read the QED lectures by Feynman, you won't get a better, more accessible explanation than that

u/mofo69extreme · 5 pointsr/askscience

The original work is apparantly in Volume 4 of Laplace's Treatise on Celestial Mechanics, but I couldn't find it online. Laplace shows that the speed of gravity would need to be at least 10^6 times the speed of light (this was in the 1830s, we probably have better bounds now). An excellent discussion of how GR deals with this issue with all the relevant references can be found in this paper by Carlip. He cites this paper (which I do not have access to) and a problem in this textbook for how the Newtonian calculation fails.

It's not so hard to see how the calculation goes. If gravity pointed to where the sun used to be, it would be off from where the sun is by an angle of about v/c radians. So the force would be F(total) = F(central) + F(c) where F(central) = F(newton)(1-v/c) is almost exactly the Newton term and F(c) points along the direction of Earth's motion with magnitude GMm(v/c)/r^(2). Unlike a central force, this second term should generate a calculable violation of angular momentum conservation from which you can compute how fast the radius of Earth's orbit varies, and you can show the for c = the speed of light, the orbit varies way too quickly.