# Feynman Lectures on Physics

1. Aug 13, 2008

### xavier_r

Well, I have got hold of Feynman's Lectures Volume 1,2,3...
I am trying to understand UnderGrad physics through self-study at home...

Are those 3 books enough to understand (at least conceptually) UnderGrad level physics???

2. Aug 13, 2008

### Andy Resnick

Those books present a comprehensive view of concepts used in Physics, at mid-level to advanced undergraduate sophistication. Understanding the material is a totally different question.

3. Aug 14, 2008

### codelieb

Reading the Feynman Lectures on Physics, or any physics book, is not sufficient to really understand physics. It is also necessary to practice, by doing exercises, and the Feynman Lectures, Vols I - III do not include exercises. So, you should also find a collection of exercises to practice with. Please see my posts:

https://www.physicsforums.com/showpost.php?p=1829100&postcount=5
https://www.physicsforums.com/showpost.php?p=1829132&postcount=7

Michael A. Gottlieb
mg@feynmanlectures.info

4. Aug 20, 2008

### mal4mac

What do you mean by 'really understand'? If someone reads that 'energy is conserved' they have understood some physics without doing any sums. And the understanding seems real enough to me. OK to actually *do* physics you probably need to do some exercises. To deny possibility of understanding, real or not, to the everyday reader seems to be an attempt to perpetuate a priesthood. And if 'understanding worthy of the name' only comes from number crunching then why did Feynman expend so much effort on popular books and lectures?

Last edited: Aug 20, 2008
5. Aug 20, 2008

### codelieb

By "really understand" I mean this: that given some well-defined physical situation, you can apply such concepts as conservation of energy to predict what will happen, with some precision.

Solving physics problems is not "number-crunching," unless you solve them numerically. It is, more generally, an intellectual process that (usually, but not always) requires some knowledge of (not necessarily advanced) mathematics, but even moreso, solving physics problems requires physical insight, an understanding of how to apply the concepts you have read about to real situations - that is what lies at the heart of a "real understanding" of physics. Unfortunately such insight is not gained by reading or listening to lectures alone - it can not be taught in any direct way, only by example, and it requires practice in applying the concepts you read (or hear) about to physical situations - that is why we make students do homework problems and take quizzes and tests, at Caltech.

You do not have to be a "priest" to work on physics exercises, as is well-demonstrated, for example in the solutions to physics problems posted at The Feynman Lectures website, by people from all over the world, from all walks of life and of all ages - people who are willing to do the work necessary to gain a real understanding of physics.

I do not think what I am saying is in any way unique to physics - it is true of many activities. For example, you can read all you want about chess, but unless you actually play the game, you can not understand it very deeply. You might know all the rules by heart, but that is only a superficial kind of understanding. As they say (with regard to weight-lifting) "No pain. No gain."

6. Aug 20, 2008

### mal4mac

Okay. How do you get politicians to understand physics "well enough" to realise the importance of providing funding for a supercollider? What if politicians said "you can only 'really understand' politics by standing for office?" They would get voted out, sharpish.

But I see what you are getting at, and I think you are largely right, but I think you should use less value loaded words. For instance, you might say to "really practice" physics you need to do the work. And I apologise for the "number crunching" crack :-)

And remember, Einstein said you should be able to explain any physics concept to a barmaid, and thereby give them an understanding of any aspect of physics. Maybe you could even do that with politicians.

7. Aug 20, 2008

### codelieb

"And remember, Einstein said you should be able to explain any physics concept to a barmaid, and thereby give them an understanding of any aspect of physics."

Einstein never said this, nor would he.

The original expression, 'an alleged scientific discovery has no merit unless it can be explained to a barmaid' is attributed to Rutherford. [See, for example: "Some Recollections and Reflections on Rutherford" by W. Bennett Lewis, Notes and Records of the Royal Society of London, Vol. 27, No. 1 (Aug., 1972), pp. 61, par. 1, and "Einstein: The Man and His Achievement" by G. J. Whitrow, pp. 42, par 2]

This quotation, which is very commonly misattributed to Einstein, serves as a good example of the necessity to carefully distinguish facts from popular beliefs (especially on the Internet).

8. Aug 20, 2008

### will.c

What, specifically is meant by "conserved?" Where does conservation of energy come from? Is it a special case of a more general phenomenon? Does "energy" manifest itself in other physical ways, or is it merely an interesting mathematical quantity? In fact, the most important question here is what the hell is energy, anyway?

If someone read that "energy is conserved," I submit that they have in fact understood absolutely nothing. By itself, it is a vacuous statement.

Physicists are not a priestly class; physics is not a religious vocation. "Real" understanding of physics is always available to people who aren't yet formally trained in it... It's just that a component of that understanding is "real" hard work, and merely reading someone else's words without trying your own hand is never going to cut it.

9. Aug 21, 2008

### mal4mac

Thanks for the correction. Clark's biography backs you up (p.418). He says it was Rutherford who made the barmaid quip. But he quotes Einstein as making the same point with "child" replacing "barmaid".