Anyting to do with red being the color of blood? But blood only turns red when exposed to oxygen when a person is bleeding. ????????????
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Anyting to do with red being the color of blood? But blood only turns red when exposed to oxygen when a person is bleeding. ????????????
Not really. I have to leave shortly, I will post the answer tomorrow, if nobody has come up with it by then.
The primary colors of light are red - blue and green.
Red is also more visble at a distance than other colors.
Yes, you got it. Red has the longest wavelength of all colors. As a result it can be seen from afar, it can also penetrate fog better than other colors, which all have lower wavelengths.
I am sure our ancestors must have observed that red is visible over longer distance than any other color, so it made sense to make red the color of danger. That way danger may be detected sooner.
As to why green is the color of go ahead, green is the most pleasant color to human eye. Here the answer lies in evolution; human eye was evolved to see green all around. It makes sense to make the most pleasant color the color of go ahead.
That's a different question, the original was specifically about the colour of traffic lights, and talloola's right, the most visible colour is yellow. That's why fog lamps have a yellow cast, and why so many cabs are yellow, research showed that its higher visibility led to fewer collisions.
One would think that Red and Violet being at both end of the visible spectrum would be harder to see than yellow and green in the center of the spectrum...
One would be correct. :smile: The human eye is most sensitive to the middle of the visible spectrum, the yellow-green part.
Correction
What was deemed to be the greatest invention from 0001 - 2000 AD
Why?
Hint 1 - Last name - 9 letters - also a hint
A link to check out and please comment on.
The point of the thread is fun + thinking = OK to me.
The Scattering of Light and the Importance of Color in Daily Life | Scienceray
Interesting and well written, with good pictures, though the nerd in me found the explanation of what I would have explicitly identified as Rayleigh scattering a little weak. If my memory is correct--and gawd only knows where I picked up this bit of trivia--in the middle of the visible spectrum, wavelengths around 500-600 nanometers which we perceive as the yellow-green zone, the human eye can detect colour differences of as little as 1 nanometer, while out toward the blue and red ends, around 400 and 700 nanometers respectively, we need about 10 nanometers difference in wavelength to perceive a change in hue. This has something to do with the differing sensitivities of the several types of rod and cone cells in the retina, which makes sense: we see most clearly in the wavelengths at which the atmosphere is most transparent.
Well you are more knowledgeable than I regarding this - I googled -Red - Danger - Physics - lots of chaff came up but this did seem to be closest to what could be a reasonable answer.
Here is some discussion as to why red represents danger (incidentally Goober, I found this by Googling for 'red danger physics', same as you).
Red light
This clever puzzle was told to me by one of my Indian friends.
In ancient India, a wealthy merchant died and left his estate to his three sons. The oldest son got half, middle son 1/4th and youngest son, 1/5th.
They divided all the estate accordingly, until they came to horses. The merchant had 19 horses and they couldn’t figure out how to split them (they didn’t want to sell the horses). They had the horses in the front yard and were debating what to do.
A man was passing by on his own horse; he stopped to see what was going on. The brothers explained the problem to him. The stranger offered to tell them how to split the horses, for a small fee.
So the question is, how did he split the horses? I could not come up with the answer until my friend gave me a hint. So here is the hint.
Hint: Why is the question asked in such a roundabout, convoluted manner? Why not simply ask, how to split 19 horses in the proportion ½, ¼ and 1/5?
Red light
This clever puzzle was told to me by one of my Indian friends.
In ancient India, a wealthy merchant died and left his estate to his three sons. The oldest son got half, middle son 1/4th and youngest son, 1/5th.
They divided all the estate accordingly, until they came to horses. The merchant had 19 horses and they couldn’t figure out how to split them (they didn’t want to sell the horses). They had the horses in the front yard and were debating what to do.
A man was passing by on his own horse; he stopped to see what was going on. The brothers explained the problem to him. The stranger offered to tell them how to split the horses, for a small fee.
So the question is, how did he split the horses? I could not come up with the answer until my friend gave me a hint. So here is the hint.
Hint: Why is the question asked in such a roundabout, convoluted manner? Why not simply ask, how to split 19 horses in the proportion ½, ¼ and 1/5?
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The sons borrowed an extra horse to make the total number of horses 20.
Then the oldest son got 1 / 2 of 20 is is 10 horses
Tthe middle son got 1 / 4 of 20 is 5 horses.
The youngest son got 1 / 5 of 20 is 4 horses
Since 10+5+4 = 19, the horses could be divided among the three brothers in such a way that the borrowed horse was left over, and could be returned to its owner.
An old one with similar logic
Old because of the price of a hotel room and because I first heard of it when I was a kid:smile:
Three men rent a hotel room.
Each pays $10 for a total of $30 spent on the room.
The next day the hotel owner tells the three men that they over paid for the room as it only costs $25.
The three men tell the owner to give them each a dollar back and he can keep two dollars.
If you do the math, each man paid $9 a piece for the room for a total of $27. plus the $2 they gave the owner which brings the total out of pocket to $29.
The question is where did the other dollar go?
Old because of the price of a hotel room and because I first heard of it when I was a kid:smile:
Three men rent a hotel room.
Each pays $10 for a total of $30 spent on the room.
The next day the hotel owner tells the three men that they over paid for the room as it only costs $25.
The three men tell the owner to give them each a dollar back and he can keep two dollars.
If you do the math, each man paid $9 a piece for the room for a total of $27. plus the $2 they gave the owner which brings the total out of pocket to $29.
The question is where did the other dollar go?
Gutenberg - Printing Press..
A question for you Judge Goober.
How much wood could a woodchuck chuck if a woodchuck could chuck wood?
Quite so. Once he gave me the hint, I also didn't have any problem with it. Only thing is that you have to regards the man riding the horse as relevant information, or it doesn't make sense.
That would be another way of tackling the problem, Spade. Once you have numbers 19 and 20 together, the rest is easy.
This is an old one indeed, I have heard it several times. The two dollars they gave the owner came out of the 27 they paid. They paid 25 for the room and 2 to the owner. The number 30 is irrelevant here, since they did not pay 30$, they paid only 27.
Our tour guide in Jordan told us a couple of puzzles once in the bus (one of them was the one DaSleeper mentioned, it is a well known puzzle). He seemed to be fond of puzzles, so I told him the one from India, about three sons. He liked it so much that he told me he will tell it to the tourists from now on.
Long time no see, Captain. Welcome back.
There is one tiny problem here- What about the 19/20 of a horse that was to be kept by the merchant? :smile: (I know I'm an a&&hole) :lol::lol:
Here is one from Iraq (that is the advantage of having international friends, one learn so much about other countries).
Two friends from Basra once started on a journey. They made camp for night and they spotted a stranger. They invited him to share a meal with them. Friend A had five loaves of bread, friend B had 3. They divided each loaf into three parts and each partook of one.
At the end of the meal, the stranger thanked them, gave them 8 dinars and left. Now the two friends had an argument. Friend A said that he should get 5 dinars and B should get 3, since he contributed five loaves his friend contributed only 3. Friend B said that since they are friends, it is only fair that they split it evenly four each.
So, what is the fairest way of splitting the eight dinars? Hint: they are both wrong.
Two friends from Basra once started on a journey. They made camp for night and they spotted a stranger. They invited him to share a meal with them. Friend A had five loaves of bread, friend B had 3. They divided each loaf into three parts and each partook of one.
At the end of the meal, the stranger thanked them, gave them 8 dinars and left. Now the two friends had an argument. Friend A said that he should get 5 dinars and B should get 3, since he contributed five loaves his friend contributed only 3. Friend B said that since they are friends, it is only fair that they split it evenly four each.
So, what is the fairest way of splitting the eight dinars? Hint: they are both wrong.