Why is orange juice yellow?

[pianorama]

This question has been bugging me for the last few days, but I finally decided ask since my dad just made some homemade orange juice, which, like I was expecting, was orange. So when I open the store bought orange juice in the morning, why is it yellow? WHY!? It doesn't list colouring as one of the ingredients.

[semme]

probably because the constellation of the electrons in the molecules produce that kind of color. why? i dont know. a cobalt and chlorine molecule ( CoCl4) has the most beautiful blue you can imagine. i think it has to do with electrons jumping around, reflecting or producing wavelengths that we see as color. im not a 100% sure, so if someone knows better, lemme know

[steve jones]

I surpose its better than calling it 'purple juice' though? 

Or maybe its down to our dodgy GM oranges!

[mikey6]

Possibly coz it's made from oranges!!! and therefore referring to the friut not the colour.
I guess the question should be why is the juice of oranges yellow? In that case, an ornage is called an orange because the outside is orange, not becuase of the colour of the juice.

[timothy42b]

And you know that the primary colors you were taught in grade school were (and are) wrong, right?

Completely and demonstratably wrong, yet still taught.  (and one of several reasons my kids no longer let me talk to their science teachers.  another being that nonsense about glass being a liquid, and another being the misleading descriptions of air flow over an airplane wing.  No, it doesn't go faster on top.) 

[henrah]

And you know that the primary colors you were taught in grade school were (and are) wrong, right?

Completely and demonstratably wrong, yet still taught. (and one of several reasons my kids no longer let me talk to their science teachers. another being that nonsense about glass being a liquid, and another being the misleading descriptions of air flow over an airplane wing. No, it doesn't go faster on top.)

How/why are they wrong? What are the correct ones? And I thought glass was a liquid, a very very viscous liquid, cos if you look at really old windows they are kind of wavy at the bottom and slightly thinner at the top. Or is this from the glass melting slightly to a liquid during the summer, then cooling back into a solid in the winter? And what is the correct flow of air over a wing?

Please explain these, I'm intrigued ^_^
Henrah

[cosine]

And you know that the primary colors you were taught in grade school were (and are) wrong, right?

Completely and demonstratably wrong, yet still taught.  (and one of several reasons my kids no longer let me talk to their science teachers.  another being that nonsense about glass being a liquid, and another being the misleading descriptions of air flow over an airplane wing.  No, it doesn't go faster on top.) 

I'm curious too. When people make big assertations I fond of seeing data and facts to support the assertations.

[timothy42b]

How/why are they wrong? What are the correct ones? And I thought glass was a liquid, a very very viscous liquid, cos if you look at really old windows they are kind of wavy at the bottom and slightly thinner at the top. Or is this from the glass melting slightly to a liquid during the summer, then cooling back into a solid in the winter? And what is the correct flow of air over a wing?

Please explain these, I'm intrigued ^_^
Henrah

Okay, the colors one is tricky so I'll save it for a separate answer.  Besides, I still get confused myself.

But glass is easy.  It may or may not be a liquid depending on your definition.  I am an engineer and by our definition (supports shear stress) it is clearly solid.  The physicists definition I think relies on order, but since at room temperature common silica glass is below T-sub-g, glass transition temperature, it is also a solid to them.  I will not rule out that somebody might have a definition that calls glass a liquid.  However I can absolutely prove that it does not flow.  We have glass goblets found in Egyptian tombs thousands of years old - their shape has not changed.  We have microscope and telescope lenses hundreds of years old.  They are still optically correct, they have not detectably flowed at all.  So what about windows?  Well, they didn't flow either.  They were made that way.  The older process for making plate glass always produced a thin and thick edge.  Window installers would put the thick edge down.  Common sense would tell you if windows flowed enough to get wavy and thick at the bottom, the older ones would be showing a gap at the top by now. 

Okay, scratch one urban legend.

Now, airplane wings.  We've all seen the picture in the high school science book that shows air above the wing traveling further, so it must go faster, and faster air is supposedly lower pressure.  But what accelerates that air to go faster?  It is matter and it must obey F=ma.  Well, it doesn't.  It actually lags.  But here's what really happens, simplified.  Air is sticky, it follows the profile of the wing and is thrown downward at the back edge of the wing.  Throwing the air down pushes the wing up.  The math gets tricky but I think you can see the common sense of it. 

Okay, scratch two.  I promise to answer color in a way you will probably believe shortly. 

[pianorama]

Possibly coz it's made from oranges!!! and therefore referring to the friut not the colour.
I guess the question should be why is the juice of oranges yellow? In that case, an ornage is called an orange because the outside is orange, not becuase of the colour of the juice.

The juice is orange. What my question is, why is commercial orange juice yellow when the juice is clearly orange, as in home squeezed orange juice?

[Tash]

wow what orange juice are you drinking?? i can tell you that here in sydney the orange juice is in fact orange, both the homemade and generally manufactured brands. thus if you want your orange juice orange buy aussie juice!!

[henrah]

The juice is orange. What my question is, why is commercial orange juice yellow when the juice is clearly orange, as in home squeezed orange juice?

Because it's not real orange juice! It is most likely from concentrate, and/or had tons upon tons of preservatives and additives added on top.


Btw, has anyone here (from the UK) tried Innocent smoothies? They are the don of all fruit juice drinks. [advertising ramble]No preservatives, no additives, and not from concentrate. And they taste great! Just fruit, squashed and put in a carton.[/advertising ramble] It's so blindingly simple, I can't believe no company has ever done it before. If you can, you should definately check out Fruit Towers, their offices, it's so classy! They have an open window with 'Burglars this way' written on an arrow leading to it: class!
Henrah

[lau]

Because it's not real orange juice! It is most likely from concentrate, and/or had tons upon tons of preservatives and additives added on top.


Btw, has anyone here (from the UK) tried Innocent smoothies? They are the don of all fruit juice drinks. [advertising ramble]No preservatives, no additives, and not from concentrate. And they taste great! Just fruit, squashed and put in a carton.[/advertising ramble] It's so blindingly simple, I can't believe no company has ever done it before. If you can, you should definately check out Fruit Towers, their offices, it's so classy! They have an open window with 'Burglars this way' written on an arrow leading to it: class!
Henrah

i think it is real orange juice, the only thing they do to it is pasterize it to kill the sick germs. Sometimes they may add extra vitamins or citric acid to provid tartness or sometimes extra sugar. I think it is very rare to find preservatives in orange juice, I am looking at the ingredients at this very moment. The natural sugar and the fact that the concentrate is frozen is a good enough preservative. But unconcentrated orange juice may be different. ........yes.

[rimv2]

Orange juice is orange.

Yellow doesnt exist

[mycrabface]

Ok sorry i havent read the entire thread and i might be repeating what sme said before me....
It might be yellow because the concentration of orange is much lesser.. Wow.. sounds lame..

[pianolearner]

This question has been bugging me for the last few days, but I finally decided ask since my dad just made some homemade orange juice, which, like I was expecting, was orange. So when I open the store bought orange juice in the morning, why is it yellow? WHY!? It doesn't list colouring as one of the ingredients.

I just poured myself a glass of orange juice and I must admit it does look yellow (depending on your definition of orange). It says on the carton "100% pure squeezed Orange Juice. Not made from concentrate".

[mutedstring]

curious georges...

[henrah]

Yeah my brother is pretty curious....


>_<

[pianistimo]

mycrabface is probably correct - orange juice is supposed to be orange so maybe it IS dilluted with something.  you know i bought a bag of oranges the other day and i was sure that they were hybrids with grapefruit.  the color inside was a mixed color (not orange and not grapefruitish - but inbetween).  no seeds.  and a completely BLAND taste.  maybe when not enough oranges are grown - they get desperate and think no one will notice if they either squeeze a few grapefruits in or grow these GIANT oranges that taste terrible.

start saving organic seeds!  it's like losing your mother's locket to find a fruit with no seed in it.  am thinking of organizing a seed campaign.  you know organic flowers (that are basically wild flowers) bloom more prolifically and hardily.  there are wild roses, too.  am thinking of growing some.  not everything has to be hybrid to be good - and some of the wild ones smell beautifully. 

back to orange juice.  what if you took the juice back to the store and complained about the color and taste?  they probably never have anyone with energy to go back and complain.  if everyone revolted they'd have to go back to putting the orange in orange juice. 

[pianorama]

The orange juice I drink is Tropicana. It says not from concentrate. It has added calcium because my family doesn't drink milk very often, except in our cereal.

NEWS FLASH! NEWS FLASH! NEWS FLASH! NEWSFLASH!

I just went upstairs and asked my family (including 2 of my aunts) why our orange juice is yellow. My dad replied, "The orange juice is not yellow, it's orange!", which is rediculous, because it's completley yellow, like the sun on a cloudless summer day at noon. (Hmmm... Though the sun does look sort of white. Not that I spend hours looking at the sun, I just happen to catch glances when I look in it's direction) Then I asked the other 5 people in the room what colour it is, and all 5 of them replied, "pale orange". So that makes it 1 to 6, against me. arrrgghhh! They're playing mind games on me again!
I'll try to get a pic posted and have a poll asking whether the orange juice is yellow, pale orange, or completley orange.

                                                                   Lowell

  Bah, mind games.

[timothy42b]

Perhaps it is possible people see orange juice differently.  Though most people are trichromats, wikipedia says there may be some women who are tetrachromats, with the addition of yellow.  I had thought the tetrachromat theory rested primarily one British woman, who had a second level of red.

Anyway, blue yellow and red aren't primary colors, and mixing yellow and blue will not give you green.  Try it and see - if you have pure enough colors it really won't.  If your blue has enough cyan it might.

Your eyes have three and only three types of cone:  blue, red, green.  Those are the primary colors.  Stimulating those three receptors in various proportions gives you the perception you see the rest. 

That makes it completely obvious what happens when colored light shines on your eyes.  When light reflects off pigment it gets confusing.  Now you are subtracting light - but it only matters in that it doesn't stimulate your only three receptors. 

[pianolearner]

Perhaps it is possible people see orange juice differently.  Though most people are trichromats, wikipedia says there may be some women who are tetrachromats, with the addition of yellow.  I had thought the tetrachromat theory rested primarily one British woman, who had a second level of red.

Anyway, blue yellow and red aren't primary colors, and mixing yellow and blue will not give you green.  Try it and see - if you have pure enough colors it really won't.  If your blue has enough cyan it might.

Your eyes have three and only three types of cone:  blue, red, green.  Those are the primary colors.  Stimulating those three receptors in various proportions gives you the perception you see the rest. 

That makes it completely obvious what happens when colored light shines on your eyes.  When light reflects off pigment it gets confusing.  Now you are subtracting light - but it only matters in that it doesn't stimulate your only three receptors. 

Tim,

Completely correct. Anyone who works in the broadcast industry knows that RED,GREEN,BLUE are the real primary colours, not those other pretend primary colours that "arty" people talk about 

[pianistimo]

yet, homemade orange juice really is orange.  i say, put them side by side and decide which you really want to drink.  orange tastes better.

[pianorama]

Here we go, the pic: (sorry it's so small)
https://www.pianostreet.com/smf/index.php?topic=16792.msg179814

[fencingfellow]

Tim,

Completely correct. Anyone who works in the broadcast industry knows that RED,GREEN,BLUE are the real primary colours, not those other pretend primary colours that "arty" people talk about 

Almost correct.
Truth is, there are TWO sets of primary colors, and they are different if you are talking about light or pigment.

Red, Yellow, Blue are the primary pigment colors...and yes, if you mix pure paint, they will create proper secondary colors (cyan, as someone posted before, is a mix of blue and green that has more blue than green).

The primary colors of light are green, yellow, red, as can be demonstrated (for example) with flashlights with colored light bulbs.  Note that these CANNOT merely be painted regular light bulbs, since then the pigment color rules are applied.

[emmdoubleew]

Now, airplane wings.  We've all seen the picture in the high school science book that shows air above the wing traveling further, so it must go faster, and faster air is supposedly lower pressure.  But what accelerates that air to go faster?  It is matter and it must obey F=ma.  Well, it doesn't.  It actually lags.  But here's what really happens, simplified.  Air is sticky, it follows the profile of the wing and is thrown downward at the back edge of the wing.  Throwing the air down pushes the wing up.  The math gets tricky but I think you can see the common sense of it. 

Okay, scratch two.  I promise to answer color in a way you will probably believe shortly. 

Holy crap, are you sure enough about this that I can ask my physics teacher?

EDIT: Wait, what are you talking about, nothing accelerate the air, it just has to cover the larger distance of the top of the wing without slowing down. I don't get what you're saying.

[timothy42b]

Holy crap, are you sure enough about this that I can ask my physics teacher?

EDIT: Wait, what are you talking about, nothing accelerate the air, it just has to cover the larger distance of the top of the wing without slowing down. I don't get what you're saying.

I am sure of part of it.  Air flow over the wing is complex and some areas are still debated.

But about the larger distance of the wing, I am 100% sure.  Your elementary science books all say the air has to cover a larger distance over the wing in the same time, therefore it must go faster, therefore it must be lower pressure.  Why does it have to cover a larger distance?  Well, that isn't explained.  And in fact, wind tunnel studies show it doesn't happen.  So the whole "larger distance in same time equals faster airspeed" turns out to be bogus. 

[pianistimo]

then why do birds have the similar wing design?  last night i watched something about the tiger beetle being the fastest insect.  suppose that design will be the next race car?  i don't really know.  legs might slow a car down.  but they're lightweight legs.  also, the beetles mostly sprint and stop when they eat their prey.  but, they are fast.  probably a combination (birds, insect/design) of materials (lightweight),shape, and energy expended vs. physics of how the universe affects our speed (water, air, heat, whatever). 

[timothy42b]

You might well ask why whales, bats, and chimpanzees all have five fingers like humans.

I could answer that for you, but I'm not going to be much help on the birds and beetles.

[pianolearner]

Almost correct.
Truth is, there are TWO sets of primary colors, and they are different if you are talking about light or pigment.

Technically you are talking about additive mixing primaries (light) or subtractive mixing primaries (paints). Television is the best and most well known example of additive mixing. If you look closely at your picture tube, you will see RED, GREEN & BLUE dots. Each group of 3 makes a pixel (picture element). If you are a reall geek, you would be interested in knowing the Trichromatic ratio. 1 T lumen of White = 0.59 T Green + 0.3 T Red + 0.11 T Blue. The human eye is most sensitive to green.

[pianolearner]

then why do birds have the similar wing design?  last night i watched something about the tiger beetle being the fastest insect.  suppose that design will be the next race car?  i don't really know.  legs might slow a car down.  but they're lightweight legs.  also, the beetles mostly sprint and stop when they eat their prey.  but, they are fast.  probably a combination (birds, insect/design) of materials (lightweight),shape, and energy expended vs. physics of how the universe affects our speed (water, air, heat, whatever). 

Nobody is disputing that the shape of the wings will result in flight. It's the explanation of why it does that people are debating. Everybody explains flight with the Bernoulli Equation, but it isn't enough. You need to consider Newtons laws as well. Both Bernoulli and Newton's theories are needed to explain the way a wing produces lift.

https://www.f1-country.com/f1-engineer/aeorodynamics/bernoulli.html

[timothy42b]

Technically you are talking about additive mixing primaries (light) or subtractive mixing primaries (paints). Television is the best and most well known example of additive mixing. If you look closely at your picture tube, you will see RED, GREEN & BLUE dots. Each group of 3 makes a pixel (picture element). If you are a reall geek, you would be interested in knowing the Trichromatic ratio. 1 T lumen of White = 0.59 T Green + 0.3 T Red + 0.11 T Blue. The human eye is most sensitive to green.

You can mix light, or you can mix pigments, which absorb light.  So there are two ways to approach the problem.

What you cannot get around is the fact that the normal human retina has three and only three color receptors, and they are red, green, and blue.  No yellow. 

[prometheus]

More puzzling; why can we call the juice 'orange juice' without frowning?


Actually in my first language the word orange isn't used for either the fruit or it's juice, so I really have no clue.

[fencingfellow]

More puzzling; why can we call the juice 'orange juice' without frowning?


Actually in my first language the word orange isn't used for either the fruit or it's juice, so I really have no clue.

We call it orange juice because the name of the fruit is "orange".  It really has nothing to do with the specific color of the juice (though presumably the name was chosen because the skin of the fruit is orange).

As for your first language not be the word "orange", this shouldn't be surprising.  It is comparitively uncommon for words in different language to have the same origin.  The words that do (we all know some) are the rare case.

[prometheus]

Yeah, duh.
I meant how can you call something orange juice while looking at it and seeing it is yellow. You would imagine that the brain world protest, but it doesn't.

It just proves Orwell was a right.

[timothy42b]

We call it orange juice because the name of the fruit is "orange".  It really has nothing to do with the specific color of the juice (though presumably the name was chosen because the skin of the fruit is orange).

As for your first language not be the word "orange", this shouldn't be surprising.  It is comparitively uncommon for words in different language to have the same origin.  The words that do (we all know some) are the rare case.

Good point.  Along these lines it shows a higher level of abstraction to call it orange juice whatever the color. 

There are probably many more examples.  The Yalu river in China is brown but we don't call it the brown river.  When I have a sun tan, I'm still not really the color tan.  Etc., etc.  But don't "call me mellow yellow!" 

[jehangircama]

1.the airflow thing is due to bernoulli's theorem. The aerofoil is shaped so as to provide an upward vertical force when it moves horizontally through air. This force makes the plane fly. (the cross section of the wings of a plane are shaped like an aerofoil). the air rushing past gains a higher speed on the topside than on the bottom. From Bernoulli's principle, this causes an upward force on the wings which balances the weight of the plane. Bernoulli's principle is that "as we move along a streamline the sum of pressure, kinetic energy per unit volume and the potential energy per unit volume remains a constant.

2.glass is said to be a supercooled liquid.

3. colours are formed due to the excitation of electrons from one energy level to another. when the electron drops back to its original (ground) energy state, the excess energy is lost in the form of a radiation. this radiation is the colour we observe.
 hope this helps.
ps of course Newton's laws will apply everywhere with motion , ie, in the calculations we use. 

[pianolearner]

3. colours are formed due to the excitation of electrons from one energy level to another. when the electron drops back to its original (ground) energy state, the excess energy is lost in the form of a radiation. this radiation is the colour we observe.
 hope this helps.

Not very clear. Electromagnetic radiation is a mixture of radiation of different wavelengths and intensities. When this radiation has a wavelength inside the human visibility range (approximately from 380 nm to 740 nm), it is called light. We perceive the different wavelengths or (frequencies) as colour.


colour ~wavelength
red ~ 625-740 nm 
orange ~ 590-625 nm
yellow ~ 565-590 nm
green ~ 500-565 nm
cyan ~ 485-500 nm 
blue ~ 440-485 nm 
violet ~ 380-440 nm

[jehangircama]

yes, naturally as

E=hv where v is the frequency, E is energy and h is planck's constant. if the frequency of the radiation of energy E lies in the visible range, we see the corresponding colour.
normally when we deal with normal electrons the radiation is in the visible range.
high speed electrons when stopped by a metallic plate cause UV  or X rays whereas nuclear transitions of nuclei between nuclear energy levels produce gamma rays.
frequency is inversely proportional to wavelength so we can talk in terms of wavelength as well, obviously

[bernhard]

   Orange juice is not yellow.
   
   Yellow is the label we apply to the inner (visual) feeling we experience when we look at the orange juice in the photo. Therefore, yellow is not a property of the orange juice (and therefore looking for explanations in the electrons, molecules, etc.) is not going to be much help.
   
   It could also be argued that the orange juice in the photo is all colours, but yellow (since it absorbs all wave lengths ,except yellow which it reflects).
   
   Read more about the consequences (philosophical and otherwise) of the above statements in this thread:
   
   https://www.pianostreet.com/smf/index.php/topic,16738.0.html
   (Is grass green? Use of adjectives)
   
   https://www.pianostreet.com/smf/index.php/topic,11704.msg122476.html#msg122476
   (Is grass green? Interesting discussion follows on posts by xvimbi and Ted)
   
   https://www.pianostreet.com/smf/index.php/topic,4550.msg44040.html#msg44040
   (Is grass green? Linguistic consequences – long discussion about eternity)
   
   Best wishes,
   Bernhard.

[pianolearner]

   Orange juice is not yellow.
   
   Yellow is the label we apply to the inner (visual) feeling we experience when we look at the orange juice in the photo. Therefore, yellow is not a property of the orange juice (and therefore looking for explanations in the electrons, molecules, etc.) is not going to be much help.
   
   It could also be argued that the orange juice in the photo is all colours, but yellow (since it absorbs all wave lengths ,except yellow which it reflects).
   
   Read more about the consequences (philosophical and otherwise) of the above statements in this thread:
   
   https://www.pianostreet.com/smf/index.php/topic,16738.0.html
   (Is grass green? Use of adjectives)
   
   https://www.pianostreet.com/smf/index.php/topic,11704.msg122476.html#msg122476
   (Is grass green? Interesting discussion follows on posts by xvimbi and Ted)
   
   https://www.pianostreet.com/smf/index.php/topic,4550.msg44040.html#msg44040
   (Is grass green? Linguistic consequences – long discussion about eternity)
   
   Best wishes,
   Bernhard.

I agree. I suppose it would be more appropriate to ask, “Do you think that the juice of the fruit called orange is different to the colour of it's skin?” Or “Do you think "Orange Juice" is the same colour as the skin of a ripe banana?”

N.B: The skin colour of a ripe banana is yellow.

[timothy42b]

1.the airflow thing is due to bernoulli's theorem. The aerofoil is shaped so as to provide an upward vertical force when it moves horizontally through air. This force makes the plane fly. (the cross section of the wings of a plane are shaped like an aerofoil). the air rushing past gains a higher speed on the topside than on the bottom. From Bernoulli's principle, this causes an upward force on the wings which balances the weight of the plane. Bernoulli's principle is that "as we move along a streamline the sum of pressure, kinetic energy per unit volume and the potential energy per unit volume remains a constant.

2.glass is said to be a supercooled liquid.

3. colours are formed due to the excitation of electrons from one energy level to another. when the electron drops back to its original (ground) energy state, the excess energy is lost in the form of a radiation. this radiation is the colour we observe.
 hope this helps.
ps of course Newton's laws will apply everywhere with motion , ie, in the calculations we use. 

Well, I disagree on all three points.  Though not so badly on point 3. 

1.  Sorry, but you're wrong.  The air doesn't go faster on top of the wing.  Wind tunnel experiments prove it.  You are regurgitating urban myth taught in elementary school science classes.  If you think the air goes faster support your theory with some evidence. 

2.  Glass is "said to be?"  I don't care if YOU say glass is a supercooled liquid.  You have not defined either term.  I say it is a solid and the science supports me.  We can argue semantics, the one thing I can absolutely prove is that glass does not flow at room temperature.  Those windows that look wavy were that way the day they were made. 

3.  You are talking about light, not color.  Light exists at various frequencies.  We see color because we have color receptors in our retinas and our brain interprets frequencies as color.  Normal people have three and only three types of cones:  red, green, blue.  I have somewhat less than the normal number of red cones therefore I am a bad judge of dull colors though not truly color blind.  Primary colors must be based in some fashion on the three color receptors and these don't include yellow. 

[pianistimo]

ok.  so what i deduce from all this is that florida oranges get somekindof gamma rays, whilst california oranges get natural light in just the right orange frequency and wavelength to produce a real orange color.  or maybe in both states there are orange oranges and yellow oranges. the yellow oranges are mutants from the orchard.  they have been dancing with grapefruits and have a sort of sour/seedless/lots of juice quality - saving time and money growing  simply oranges.  (ok.  it's not proven - but why do some oranges taste bland?).

where does the glass fit in?  i'm confused.  oh, yes, i see.  the glass you  put the orange juice into.  duh.  i always drink mine out of a plastic glass.  does this affect taste or simply coldness?  also, they are green.  suppose that would affect the color slightly.

[pianolearner]

ok.  so what i deduce from all this is that florida oranges get somekindof gamma rays, whilst california oranges get natural light in just the right orange frequency and wavelength to produce a real orange color.  or maybe in both states there are orange oranges and yellow oranges. the yellow oranges are mutants from the orchard.  they have been dancing with grapefruits and have a sort of sour/seedless/lots of juice quality - saving time and money growing  simply oranges.  (ok.  it's not proven - but why do some oranges taste bland?).

where does the glass fit in?  i'm confused.  oh, yes, i see.  the glass you  put the orange juice into.  duh.

You forgot one very important thing! The cones in YOUR eyes might be different , let's not complicate things by adding taste.

[pianistimo]

are you implying that i am not a good judge of orange?

[pianolearner]

are you implying that i am not a good judge of orange?

I'm saying that we may not be on the same wavelength

[pianistimo]

that's because you're a conehead.  (just kidding, of course) 

[jehangircama]

timothy42b, for a discussion on the properties of glass see
https://math.ucr.edu/home/baez/physics/General/Glass/glass.html

and obviously i would talk about the different wavelengths of light. it is the different wavelengths of light which causes the different colours, after all

as to the airflow thing, its true that that's what i learnt in school. so i have to check that one up.

[pianolearner]

and obviously i would talk about the different wavelengths of light. it is the different wavelengths of light which causes the different colours, after all

as to the airflow thing, its true that that's what i learnt in school. so i have to check that one up.

I think tim was being more specific. The universe is filled with electromagnetic radiation of different wavelengths but it is colourless. Radio waves, visible light, X-rays, and all the other parts of the electromagnetic spectrum are fundamentally the same thing, electromagnetic radiation. The receptors in our eyes are sensitive to a narrow band of this electromagnetic spectrum and the brain interprets these wavelengths as colour. We would see everything differently if our eyes were only sensitive to the infrared or ultraviolet wavelength and if our eyes had a much wider bandwidth we would "see" TV, Radio and Satellite signals. You could argue the colour only exists in our imagination.

[jehangircama]

fair enough

btw are any of you physics majors or are you'll engineering students