Richard Feynman on education in Brazil

In India, usually people who could not land a plum corporate job would resort to teaching (UG level) and they are entrusted with the job of shaping the next batch of engineers/artists. Also, teaching as a job is not greatly rewarding financially, hence it is not a popular choice. One could only imagine the outcome.

To state the facts, a school teacher teaching 4/5th grade kids would hardly be given a $150 salary. In second tier cities, it's even lesser.

I would say, not just this, but there is also a huge difference in the line of thought and a tendency to resign oneself to fate, among Indians. That is almost always part of the upbringing. The ones landing up as teachers would resign to their fates and stop (and resist vehemently) any attempt to keep oneself up-to-date or develop their skills.

And the sad part is, even the interested ones are forcibly turned into indifferent ones, due to various socio-cultural changes presently seen in the economically shining nation.

A relevant article: http://www.hindu.com/op/2011/04/24/stories/2011042453622000....

It's also a matter of opportunity. People in the US consider opportunity a given. It's not so in most of the world, people may choose to educate themselves, even forcibly via repetition, because there may not even be other things to do, and it's better to have some kind of education than no education. The exceptional kids of course do not follow that rule, they'll make it no matter what.

Allow me to clear up one tiny misconception—the professors and the way the syllabus is taught at IITs (at least D) is not that much better either—a large of my part of my syllabus in solid mechanics, etc. (just to name a specific example) was simply glossed over as facts to ingest without even touching the mathematical foundation. I've had to spend a really large part of my final year project revisiting maths, solid mechanics to get that foundation and then build upon it to make a good project.

There have also been particularly memorable incidents where a professor teaching surveying got confused about what sin\theta was.

There is a big difference between knowing something is true and understanding why it's true. A criteria one of the top preparatory schools in Dallas looks for when evaluating candidates for admittance is, does the student ask "Why?".

When you understand why something is true -- the reasons behind it -- you are relating it/connecting it to what you already know and understand. You're creating a Web of associations -- a mental framework you can build on -- you're not learning it in isolation. The most important question anyone can ask is "Why?".

It's soul-crushing to read this, isn't it?

Every day I am confronted with former students who have been taught like this. I took fluid dynamics 3 times, until I found a teacher willing to teach it instead of just letting us memorize the whole thing. When you really understand a subject, it's like hitting the light switch and realizing you were in a dark room.

I feel for those who live their professional lives in dark rooms.

OTOH, I am sure Mr. Feynman was no ordinary teacher himself. His students were very, very lucky. His bar was unusually high, impossibly high for many teachers.

Total digression, but I was kind of mystified by some of the phrases he used. For instance-

I said, “That’s how it looks to me, when I see you teaching the kids ‘science’ here in Brazil.” (Big blast, right?)

Not only does that sound really conversational, it sounds like modern slang.

Very informative, thank you!

Something I've been mulling over for awhile now is... what does it mean to represent a color with numbers?

That is, every pixel on our monitor is RGB 0 through 255. But what about in physics? Well, "color" is a photon whose wavelength falls between 400nm (short wavelength; intense energy; "ultra"-violet; and violet = blueish; therefore 400nm = "the blue side" of the EM spectrum; this is how I remember that) and 700nm (red).

So on one hand, we have three numbers, R, G, and B; on the other hand, we have a single number, wavelength.

Obviously, the answer is that R, G, and B have some significance to the human eye. But wait a minute; every human eye is different. Some people are color blind, for example. So these RGB values can't really claim to have a physical basis.

Now, what is the meaning of a combination of colors? Let's say, RGB(50,50,0) + RGB(0,50,50). Is the result RGB(50,100,50), like you'd expect?

I think not.

RGB is not a linear space. In the same way you can't add two points on the Richter scale, you can't add two RGB values and get a meaningful result, I think.

So then we have something called "sRGB", which claims to be a linear space. But really, sRGB is merely RGB space "warped" to conform to the gamma curves of standard monitors. It still has no physical meaning, as far as I can see.

I believe perhaps the correct answer is...

When a light source emits light (for example an incandescent light bulb), it's really emitting many different wavelengths along the EM spectrum. The final color is the result of our eyes combining those wavelengths.

So, to add two colors A and B, we must first convert them both from RGB back into the EM spectrum (think of it like a histogram, where the X axis is wavelength from 400nm to 700nm, and the Y axis is the intensity of each wavelength); then add the two spectrums; then finally convert the resulting spectrum back to RGB.

Will this produce the same results as (A + B)? I don't think so, but I haven't tried it.

Food for thought...

Personally I think the whole wave-particle business shouldn't be touched upon until the student understands that in reality those things are just complex vectors in a configuration space, not a little ball bouncing around. Equivalently you can think of them as outlined in Feynman's QED (which anyone interested in physics should read), as arrows. The word "wave" shouldn't ever be mentioned in introductory quantum mechanics.

Then once that's over, you explain to the students this: http://www.youtube.com/watch?v=_7OEzyEfzgg it's a duality of interpretation, not reality, we use wave mathematics for simplified calculations. Plus if you interpret it as a wave (as Feynman shows) you run into problems with experimental results not coming out as expected that a particle interpretation doesn't have problems with. (And for some reason I can't think of color in terms of waves, it makes much more sense if I think of it in terms of the energy of a photon with the brightness as a function of how many photons there are, which then ties back to a probability point of view where it's obvious that it's brighter where there's probabilistically more photons.)

http://lesswrong.com/lw/r5/the_quantum_physics_sequence/ remains for me the best introduction to thinking sanely about the subject without becoming confused from the get-go as you start talking about waves vs. particles.

First off, thank you for pointing this out. I occasionally teach introductory physics and I had never realized that people could interpret the graph in that manner. I'll try to make nip this in the bud when I present this material in the future.

Your alternate graph, however, shows another common misconception that is matched in your text. Specifically, the amplitude of the wave varies, but the intensity does NOT. The amplitude being graphed can be though of as the strength of the electric field pointing.... how about to the north? Then, when the amplitude is negative, all that's happening is that the field is point to the south, instead of the north. The intensity of the light is the energy contained within the electromagnetic field, which is independent of which direction the field is point. Thus, where you have dark spots in the graph where the amplitude goes negative, the intensity of the light is just as strong as it was at the peaks.

The obvious next question is what happens when the amplitude is zero? Well, the changing electric field produces a magnetic field. This magnetic field reaches its maximum value where the electric field goes to zero and goes to zero itself at the minima and maxima of the electric field's amplitude. Thus, the total energy electromagnetic energy, and, therefore, the intensity of the light, is constant across the whole graph.

That's why I'm cautious about using your proposed diagram. I've known many students with the misconception that light alternates between bright and dark as it travels and that lines up exactly with what you've drawn.

Well, I lived in Brazil for 7 years, and only recently (like, a couple weeks ago) moved back to the US. What I could never understand is how you could trust a programmer that doesn't speak (and read) fluent English. Not being facetious here, but the fact is most good documentation is in English. I was the lucky exception while back in Argentina, but I feel that's still a widespread problem in Brazil.

A pity though, because I know for a fact there's plenty of great talent there.

Now you'll probably be downvoted for not being politically correct, but I agree with you. At least in my experience, most Indian-educated graduates I have worked with, were very willing to use a slew of acronyms to somehow trying to convince others that if they know the acronym, then they "understand" the concept. It is hard to describe it. You'll notice it when you encounter it.

> working with Indians

Few Indians, you mean. (Though a majority of them would end up in that 'few' category)

Well, in the US at least its kind of impossible to pass math/engineering exams without having some sort of deeper understanding of the problem. It sounds like the exams in Brazil at the time didn't expand upon anything past memorized definitions - I think you'd be hard pressed to find a serious physics course in the US that would let you get away with that.

I remember sitting in a class at Columbia and wondering why students were asking so many pointless questions, designed to show how much they knew rather than establish anything useful.

In my university (Oxford, Modern History) you feared looking stupid by asking questions at lectures, and instead asked your friends afterwards and read up yourself.

Different cultures, none are perfect, I guess.

I imagine Feynman's lectures would have made me feel "too stupid to ask". Probably says more about me than him :)

Another brazilian CS undergrad here. Sadly, I can vouch for what olh said.. In some worst cases, teachers at public universities decide not to show up at classes.

Most of us don't :-(

But don't feel too good about it. Science teaching is, for all I can gather, going down the drain just about everywhere.

They have Andressa Vieira. That's beauty enough for any man.

Then this will be the most interesting book you've read this year: http://www.amazon.com/Surely-Feynman-Adventures-Curious-Char...

I don't know if it's too much offtopic, because it's about elementary school, but hey, let's go: I went to first 2 classes of a private school in Sao Paulo in '89-'90. I was a smart kid and had 9.5-10.0 average (0-10.0 scale) despite I had to learn the language at first. One day in class, the teacher of biology (or sth like that) started talking about fish and stated that a dolphin is a fish. I argued with her saying it's a mammal, she said I was wrong, I didn't give up, but for the moment it was case closed. After a few days on the next lesson with her, she raised the topic once again to say that I was partly correct, because a dolphin is a "mammal-fish". We've had a laugh with my parents to this day, and I was always wondering how high school and college education works around there if a science teacher in elementary school can be so dumb. Our education system in Poland is far from perfect, not to say completely broken, but I must say that at least teachers in elementary have the basic knowledge not to miseducate kids.