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Speed of light

  1. Feb 18, 2004 #1
    If you are in a spaceship traveling the speed of light and you turned on your headlights what would happen?
  2. jcsd
  3. Feb 18, 2004 #2


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    It would be paradoxical, that's one reason why you can't travel at the speed of light. Einstein had a thought like this (of course he lived before cars with headlights), and remembered it afterward as one of the threads leading him to relativity.
  4. Feb 25, 2004 #3
    Actually it is possible to go faster

    It is possible to go faster than the speed of light in a medium, such is the case with cherenkov radiation near nuclear reactors. It also gives a sweet blue glow.
  5. Feb 26, 2004 #4


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    Yes indeed. Usually when someone raises questions like that about the speed of light, they mean the speed of light in a vacuum, the constant c.
  6. Mar 26, 2004 #5
    Kyle, when you are travelling at the speed of light, I hope you don't need to see where you are going.

    Whats the point of being able to see in the direction you are traveling if by the time you see where your going you are already there - therefore no head lights required provided you do not have mass.........
  7. Mar 31, 2004 #6
    bend your mind on this one

    ? why is the speed of light constant ?
    ? why no matter how fast we go does light stay constant from our frame ?

    first you have to know how fast you are moving, calculate the speed of your molecules, then add the speed of the earths rotation, then add the speed of the earths orbit, then add the speed of our sun throug its galactic orbit, then add the speed of our galaxy through space, then add the speed of the universe's expansion, and the relative speed of the universe's center.

    you will be able to add some of thses speeds up, and come up with a number somewhere in the neighborhood of 20k m/s
    and there are some hypothesis on the speed of the few we cant negotiate, bringing our relative speed to somewhere around 31-32 thousand miles per second, or roughly 1/6 th the speed of light.

    now, concider that all the data we have of other galaxies and distances and speed is based on light. give light a speed of zero and see how our calculations change, and become something altogether different and i might add, more believable..
  8. Mar 31, 2004 #7
    another quick note,
    photons by definition travel faster than the speed of light, if you consider that the light we measure is made up of a photon traveling along a wave...
    Last edited: Mar 31, 2004
  9. Mar 31, 2004 #8
    ok, im new so im on a roll
    ask yourself how many times the number 3 occurs in nature (terrestrial and extraterrestrial)

    here are some examples
    3 fundemental races of human
    3 basic rules of relativity
    3 is the basis of all navigation (triagulation)
    3 noticable dimensions
    there are about 2000 more give or take, if you include our history as sentient beings
    why do i ask this?
    3 will be the clue to unraveling space travel, (via folding space/warp )
  10. Mar 31, 2004 #9


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    Umm, Cavalli-Shorza identifies 5 "genetic groupings" not 3 races. Relativity (special) is based on 2 postulates, not 3. Triangulation isn't the basis of celestial navigation (crossing position lines from 2 stars is). And if you accept relativity, we have 4 noticible dimensions, not 3.

    Could all these 3's be in the eye of the believer?
  11. Mar 31, 2004 #10

    Well your post definetly got me thinking about relative speeds and frames of reference.
    1) You can't always just add up all the speeds, (i.e. depending on where you're at on the planet you may be going in the opposite direction that the sun is propelling you so you would have to subtract.) Harmonic motion has instananeous velocity but average over time is zero.
    If you could stand directly above the sun (without burning you're feet) with the solar system zipping by you. It becomes apparent that the average rotational velocity due to the spin of the planet of any point on the planet is zero. I'm not sure if this is same at the galaxy level.

    2)The expansion of the universe. Yikes ? Is this going in one direction? If so it would have an average velocity. However, some scientists? Sorry Physicists? believe the Universe is expanding and contracting obviously very slowly from our perspective. But if this is true then from a far enough perspective ,it could be very fast and thus have an average velocity of zero. Simply because they could maybe live long enough to take enough data to get an average velocity.


    Anyway thanks for making me think?

  12. Mar 31, 2004 #11
    anglo, asian, african ( all other races fall into one of these catagories at some point in our short history)

    to travel through space you need to know 6 points, otherwise you would run into stars or end up somewhere you would not want to be. yes you need to know the posistion of 2 stars, but you fail to add yourself into the equation. triangulation of your relative posistion is just a step, to actually travel you need to know what quadrant you are in and have a destination, so add 3 more. for a total of 6.

    to see something, then move towards it would be utterly foolish, concidering that most heavenly bodies we see are moveing, and we can only see where there "were" and not where they "are"
    Last edited: Mar 31, 2004
  13. Mar 31, 2004 #12
    we often confuse aspects of speed that "are" pertinent.
    ? how fast is electricity ?
    if your said electricity travels at or near the speed of light, you would of course be incorrect. in fact a baby crawling for the first time could quite possibly outrun electricity. (i belive most estimats put it at about 4.7 CM/ per hour) it appears to move so fast becouse the "hose is already full of water"
    ? what does this have to do with light ?
    concider that the universe is already packed solid with photon, and "light" is just the result of some interaction with it. kinda like the "hose" effect on a larger scale and without boundries.
    ? what does the difference in definition mean ?
    if light is a result or a universal photonic mass, then we need only learn to manipulate phtonic "bouyancy" and we could travel anywhere in the universe instantly 8)
    Last edited: Mar 31, 2004
  14. Mar 31, 2004 #13
    1. geomotry of space time
    2. frames of referance
    3. light speed is constant

    looks like 3 to me 8)
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