Question about color/light

This is a discussion on Question about color/light within the A Brief History of Cprogramming.com forums, part of the Community Boards category; We recently had a fairly long discussion about the color spectrum, light, and pigments about a month ago. I was ...

  1. #1
    l'Anziano DavidP's Avatar
    Join Date
    Aug 2001
    Location
    Plano, Texas, United States
    Posts
    2,738

    Question about color/light

    We recently had a fairly long discussion about the color spectrum, light, and pigments about a month ago. I was thinking about that today as I was driving my car.

    As I was driving my car home today I passed an intersection with flashing yellow lights. It was dusk, and as I approached these flashing yellow lights, I looked right at them. To my surprise, for a split second they looked red. I was surprised by this, and decided to look again at the next set of flashing yellow lights. Again: for a split second they looked red as I approached them in my car and looked directly at them. (I was going approximately 80 miles per hour on a highway).

    Can anyone provide an explanation for this? All light travels at the same speed, and so I see know reason why the light with red wavelength would reach my eyes at a noticeably sooner time than any of the other wavelengths. Is there any kind of optical illusion going on here?
    My Website

    "Circular logic is good because it is."

  2. #2
    Devil's Advocate SlyMaelstrom's Avatar
    Join Date
    May 2004
    Location
    Out of scope
    Posts
    4,077
    I think it mentioned something about yellow lights looking red as you approach them in my driver's education manual. Stop running red lights before you kill someone.
    Sent from my iPadŽ

  3. #3
    Ethernal Noob
    Join Date
    Nov 2001
    Posts
    1,901
    You're a Cylon.

  4. #4
    & the hat of GPL slaying Thantos's Avatar
    Join Date
    Sep 2001
    Posts
    5,681
    Quote Originally Posted by DavidP View Post
    We recently had a fairly long discussion about the color spectrum, light, and pigments about a month ago. I was thinking about that today as I was driving my car.

    As I was driving my car home today I passed an intersection with flashing yellow lights. It was dusk, and as I approached these flashing yellow lights, I looked right at them. To my surprise, for a split second they looked red. I was surprised by this, and decided to look again at the next set of flashing yellow lights. Again: for a split second they looked red as I approached them in my car and looked directly at them. (I was going approximately 80 miles per hour on a highway).

    Can anyone provide an explanation for this? All light travels at the same speed, and so I see know reason why the light with red wavelength would reach my eyes at a noticeably sooner time than any of the other wavelengths. Is there any kind of optical illusion going on here?
    Perhaps it has to do with the method being used to generate the light. It could be that the red part is generated first prior to the green part. /shrug

  5. #5
    Devil's Advocate SlyMaelstrom's Avatar
    Join Date
    May 2004
    Location
    Out of scope
    Posts
    4,077
    Quote Originally Posted by Thantos View Post
    Perhaps it has to do with the method being used to generate the light. It could be that the red part is generated first prior to the green part. /shrug
    Or perhaps at a specific angle there was something obstructing the green light completely. Though, I'm pretty sure all of those traffic lights are just white light with colored covers in front of them. I could be wrong, though.
    Sent from my iPadŽ

  6. #6
    Woof, woof! zacs7's Avatar
    Join Date
    Mar 2007
    Location
    Australia
    Posts
    3,459
    Or the windshield of your car bent the light

    Try hang your head out the window and see if it still happens

  7. #7
    Registered User hk_mp5kpdw's Avatar
    Join Date
    Jan 2002
    Location
    Northern Virginia/Washington DC Metropolitan Area
    Posts
    3,806
    If you were moving away from the light at about .215c then a yellow light (~510THz) would appear red (~420THz). Come on, you can tell us, were you speeding away? ....really fast?
    "Owners of dogs will have noticed that, if you provide them with food and water and shelter and affection, they will think you are god. Whereas owners of cats are compelled to realize that, if you provide them with food and water and shelter and affection, they draw the conclusion that they are gods."
    -Christopher Hitchens

  8. #8
    Registered User
    Join Date
    Nov 2004
    Location
    India
    Posts
    515
    why the light with red wavelength would reach my eyes at a noticeably sooner time than any of the other wavelengths.
    Considering speeds of 80 mph, i don't think you would have any problems with red light traveling faster or yellow traveling slower . Also, color you perceive is because of the difference in wavelengths. Lower the wavelength, higher the frequency, so the speed of all kinds of lights remains constant.
    Last edited by PING; 05-27-2008 at 07:23 AM. Reason: typo
    Code:
    >+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.[-]>++++++++[<++++>-] <.>+++++++++++[<++++++++>-]<-.--------.+++.------.--------.[-]>++++++++[<++++>- ]<+.[-]++++++++++.

  9. #9
    The superhaterodyne twomers's Avatar
    Join Date
    Dec 2005
    Location
    Ireland
    Posts
    2,262
    You ever take acid? Maybe you were tripping...

  10. #10
    Cat without Hat CornedBee's Avatar
    Join Date
    Apr 2003
    Posts
    8,893
    I think searching the physical side of things is the wrong approach. It's got to be an optical illusion.
    All the buzzt!
    CornedBee

    "There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code."
    - Flon's Law

  11. #11
    Malum in se abachler's Avatar
    Join Date
    Apr 2007
    Posts
    3,189
    Until you can build a working general purpose reprogrammable computer out of basic components from radio shack, you are not fit to call yourself a programmer in my presence. This is cwhizard, signing off.

  12. #12
    Frequently Quite Prolix dwks's Avatar
    Join Date
    Apr 2005
    Location
    Canada
    Posts
    8,048
    I'd be inclined to think that you were looking at lots of green-coloured objects just before you looked at the light, so in contrast the yellow light looked red. Kind of like sticking your hand into cold water, and then into room temperature water. (It feels hot.)

    Your speed almost certainly had nothing to do with it.
    dwk

    Seek and ye shall find. quaere et invenies.

    "Simplicity does not precede complexity, but follows it." -- Alan Perlis
    "Testing can only prove the presence of bugs, not their absence." -- Edsger Dijkstra
    "The only real mistake is the one from which we learn nothing." -- John Powell


    Other boards: DaniWeb, TPS
    Unofficial Wiki FAQ: cpwiki.sf.net

    My website: http://dwks.theprogrammingsite.com/
    Projects: codeform, xuni, atlantis, nort, etc.

  13. #13
    & the hat of GPL slaying Thantos's Avatar
    Join Date
    Sep 2001
    Posts
    5,681
    That pound of reefer he had right beforehand probably didn't help either

  14. #14
    Devil's Advocate SlyMaelstrom's Avatar
    Join Date
    May 2004
    Location
    Out of scope
    Posts
    4,077
    Quote Originally Posted by Thantos View Post
    That pound of reefer he had right beforehand probably didn't help either
    Littering and...
    Sent from my iPadŽ

  15. #15
    Unregistered User Yarin's Avatar
    Join Date
    Jul 2007
    Posts
    1,691
    I bet it had to do with the lighting method. You said it was flashing, meaning it was on a capacitor, and it was most likely led lights, so I'm guessing what's happening is when the capacitor initially lets out the electricity, it's frequency is off a little, causing the led to mimic the effect.
    A class that doesn't overload all operators just isn't finished yet. -- SmugCeePlusPlusWeenie
    A year spent in artificial intelligence is enough to make one believe in God. -- Alan J. Perlis

Page 1 of 2 12 LastLast
Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Alice....
    By Lurker in forum A Brief History of Cprogramming.com
    Replies: 16
    Last Post: 06-20-2005, 03:51 PM
  2. Debugging question
    By o_0 in forum C Programming
    Replies: 9
    Last Post: 10-10-2004, 06:51 PM
  3. Question about pointers #2
    By maxhavoc in forum C++ Programming
    Replies: 28
    Last Post: 06-21-2004, 01:52 PM
  4. Question...
    By TechWins in forum A Brief History of Cprogramming.com
    Replies: 16
    Last Post: 07-28-2003, 10:47 PM
  5. Question, question!
    By oskilian in forum A Brief History of Cprogramming.com
    Replies: 5
    Last Post: 12-24-2001, 01:47 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21