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Richard Feynman on education in Brazil

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Re: Richard Feynman on education in Brazil

#61

Post by jacobolus »

palish wrote: post #35
ignifero wrote: post #34

Earlier quoted context omitted.

RGB values can be added to create other colors, just like painters mix colors (just divide the sum by 2 to avoid saturation), because the R, G and B colors were arbitrarily selected from the beginning to match what the artists were familiar with. In the case of combining beams, what changes is the intensity of the beam, the frequency spectrum does not change at all (there is two photon excitation, but that's a comple…

You are missing my point. From a physical standpoint , it makes no sense to add two RGB colors. It makes sense to add two lengths. (1 inch) + (1 inch) = (2 inches). It does not make sense to add two RGB colors. The result is not a meaningful physical quantity. In the same spirit, (7.8 earthquake) + (8.3 earthquake) != (16.1 earthequake). This is a big problem for those of us who are trying to reproduce how nature loo…

That's not true. It makes perfectly reasonable sense to add two RGB numbers, but you have to translate them into a linear space first (see http://en.wikipedia.org/wiki/Gamma_correction). Indeed, our whole scientific framework for understanding color is based on the ability to meaningfully add such numbers. Look up “Grassman’s Law”. (The wikipedia article is kind of spare, unfortunately.)

Re: Richard Feynman on education in Brazil

#62

Post by pckhoi »

zwischenzug wrote: post #42
microarchitect wrote: post #21

Earlier quoted context omitted.

I'm not sure why you think it's question of culture. There are plenty of people of Indian origin in the US who have fairly strong ties to Indian culture, but I've never heard any complaints about them being unable to understand stuff.

They were raised in the US?

rather they conform to the US way, more likely. Local custom matters.

Re: Richard Feynman on education in Brazil

#63

Post by glhaynes »

palish wrote: post #40
ignifero wrote: post #37

Earlier quoted context omitted.

Sorry if i am being dense but you got me confused. It makes sense to add 2 rgb vectors from a perceptional standpoint: you add a red color on a green color you get a yellow. It also makes sense from a physical standpoint: the resulting frequency spectrum will have peaks near both red and green, thus what we perceive as yellow. If instead you mean that "red" is not a physical quantity, i totally agree, it's just a nam…

What I'm saying is that RGB(128,128,128) is not halfway between RGB(0,0,0) and RGB(255,255,255), in the same way that a 4.0 earthquake is not halfway between a 0.0 earthquake and an 8.0 earthquake. The scale is non-linear. As far as I can see, the only true linear space is frequency space --- aka "EM spectrum" space.

I believe this is why a gamma transform is made at presentation time. But maybe what you're interested in is adding RGB tuples before presentation?

Re: Richard Feynman on education in Brazil

#64

Post by gcb »

zalew wrote: post #14
gcb wrote: post #12

so precise it's scary. Dropped out of the prestigious, public, academia in brazil. and after my second (failed) company got my degree from one of the smaller, less prestigious ones. Had lots of experimentation though

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…

haha i can relate to that too.

on 3rd grade i argued with my science teacher when she 'taught' us that the Moon was bigger than Earth. or something as bad as that.

She kept her point and i mine until she sent me to the principal for disrupting her class. Principal lost words when i explained her the reason I was there

Re: Richard Feynman on education in Brazil

#65

Post by dguaraglia »

thiagofm wrote: post #15

First of all, I'm brazilian. I study computer science and things are bad here. I'm very lucky to be able to understand english well enough to have studied most of courses MIT OCW have that are interesting to me. Teachers here "teach" in a different way, it's sad. Currently, there's much potential being lost. People here are educated to get a job and work to buy a car, house and consume a lot, which is actually perfec…

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.

Re: Richard Feynman on education in Brazil

#66

Post by simpleTruth »

palish wrote: post #35
ignifero wrote: post #34

Earlier quoted context omitted.

RGB values can be added to create other colors, just like painters mix colors (just divide the sum by 2 to avoid saturation), because the R, G and B colors were arbitrarily selected from the beginning to match what the artists were familiar with. In the case of combining beams, what changes is the intensity of the beam, the frequency spectrum does not change at all (there is two photon excitation, but that's a comple…

You are missing my point. From a physical standpoint , it makes no sense to add two RGB colors. It makes sense to add two lengths. (1 inch) + (1 inch) = (2 inches). It does not make sense to add two RGB colors. The result is not a meaningful physical quantity. In the same spirit, (7.8 earthquake) + (8.3 earthquake) != (16.1 earthequake). This is a big problem for those of us who are trying to reproduce how nature loo…

What your missing is the concept that RGB colors are based not around the physical property's of light but the eyes ability to detect light using Rods and cones. In the real world there is a difference between 390 nm light and 390.00001nm light all the way up to749.9999 nm. However all of that is abstracted away and the eye only really cares about the relative intensity of RGB when there is enough light or just B and W in really low light conditions.

So, to fool a machine you might need to exactly match all the individual wavelengths relative intensity but with a human you get to ignore most of that and just look at 3 numbers per pixel.

PS: A small number of people can detect 4 colors but the net effect of this is almost meaningless for various reasons.

Re: Richard Feynman on education in Brazil

#68

Post by Apocryphon »

ojosilva wrote: post #17

Just for clarification: Richard Feynman, Nobel physicist wrote this piece about his experiences teaching in Brazil in... 1950. So I don't think this is a very precise account of education in Brazil nowadays, but it sure does sound like education there (and almost anywhere else) in the 50s -- my mom tells me she would read out loud to herself until dawn the day before an exam, as she was taught auditory learning. This…

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.

Re: Richard Feynman on education in Brazil

#69

Post by neild »

palish wrote: post #40
ignifero wrote: post #37

Earlier quoted context omitted.

Sorry if i am being dense but you got me confused. It makes sense to add 2 rgb vectors from a perceptional standpoint: you add a red color on a green color you get a yellow. It also makes sense from a physical standpoint: the resulting frequency spectrum will have peaks near both red and green, thus what we perceive as yellow. If instead you mean that "red" is not a physical quantity, i totally agree, it's just a nam…

What I'm saying is that RGB(128,128,128) is not halfway between RGB(0,0,0) and RGB(255,255,255), in the same way that a 4.0 earthquake is not halfway between a 0.0 earthquake and an 8.0 earthquake. The scale is non-linear. As far as I can see, the only true linear space is frequency space --- aka "EM spectrum" space.

I believe what you are looking for is the alpha channel--the fourth color component which specifies how to blend two values. It doesn't make sense to add RGB(0,0,0) and RGB(0.5,0.5,0.5). It does make sense to add RGBA(0,0,0,0) and RGBA(0.5,0.5,0.5,0.5).

Re: Richard Feynman on education in Brazil

#70

Post by TheSOB88 »

microarchitect wrote: post #54
raghava wrote: post #53

Earlier quoted context omitted.

Culture does matter. In India, boasting about ranks/marks of one's kids is pretty much a cultural thing, everyone does that, with an enormous pride. This breeds a batch of kids who want marks and not the knowledge or understanding of things. Almost everything is a darned 1/2/5/10 marks question. Even the interested ones are forced to conform and be one in the herd. Indian social framework by large kills creativity an…

Culture does matter. In India, boasting about ranks/marks of one's kids is pretty much a cultural thing, everyone does that, with an enormous pride. This breeds a batch of kids who want marks and not the knowledge or understanding of things. Fair enough. I agree with this. Almost everything is a darned 1/2/5/10 marks question. Even the interested ones are forced to conform and be one in the herd. This maybe true, but…

I really, really doubt there is some genetic limit that prevents people from thinking. It's just a case of mindset. People who are coerced into rote memorization and 'surface learning' have just lost their curiosity and do not realize that thought is something you can do. I mean, we live in a post-industrial age. All throughout history most people 'did what they were told'.

People don't question because they don't think authority will like it.

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