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Thread: Light from Lightspeed?

  1. #1 Light from Lightspeed? 
    Forum Senior Booms's Avatar
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    Lightspeed is perceived as a constant, we assume you cannot conventionally travel faster than lightspeed (actually if someone could explain that thinking that would be great)

    So if, hypothetically, I was going at lightspeed, and I shone a torch what would happen? in both ways, If I shone it forward would it go at double lightspeed? or would the light appear to stop? and if I shone the torch behind would the light actually stop?


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  3. #2  
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    First off, a material object cannot travel at light speed, but only at speeds less than that.

    So let's change it so that you are traveling at 99.999999% of the speed of light as measured by some observer.

    From your perspective, you see both beams traveling away from you at the speed of light as measured relative to yourself.

    The other observer however, measures the light as traveling at the speed of light relative to himself. And thus sees the beam fired forward by you as increasing its distance from you at a rate of only 0.0000001% of the speed of light, and the one you fired backwards as increasing its distance from you at just under twice the speed of light.


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    From my understanding the reason why you still see light traveling at c is because of time dilation causing everything outside of your spaceship to appear to move faster as you go faster in your spaceship. So when you are traveling at 99.999999% c, everything appears to move 99.999999% faster, hence giving the speed of light its original c velocity as you see it.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

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  5. #4 Re: Light from Lightspeed? 
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    Quote Originally Posted by Booms
    Lightspeed is perceived as a constant, we assume you cannot conventionally travel faster than lightspeed (actually if someone could explain that thinking that would be great)

    So if, hypothetically, I was going at lightspeed, and I shone a torch what would happen? in both ways, If I shone it forward would it go at double lightspeed? or would the light appear to stop? and if I shone the torch behind would the light actually stop?

    It works like it normally would.


    Sincerely,


    William McCormick
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  6. #5  
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    Quote Originally Posted by Cold Fusion
    From my understanding the reason why you still see light traveling at c is because of time dilation causing everything outside of your spaceship to appear to move faster as you go faster in your spaceship. So when you are traveling at 99.999999% c, everything appears to move 99.999999% faster, hence giving the speed of light its original c velocity as you see it.
    This is not correct. Time dilation is completely reciprocal; If you are moving at a high speed with respect to me, I see your clocks running slow, and you see my clocks running slow, not fast.
    "Men are apt to mistake the strength of their feelings for the strength of their argument.
    The heated mind resents the chill touch & relentless scrutiny of logic"-W.E. Gladstone


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    Then what is the mechanism that allows for you to still see light traveling at c from the reference frame of the guy in the spaceship?

    I know we have experimentally tested a number of relativity ideas, but have we actually measured the speed of a clock outside the craft while traveling at a given speed as apposed to another given speed?

    To me it seems completely natural to see everything going by proportionally faster as you time dilate further, its a natural innate mental consequence.....don't they think that upon being sucked into a black hole, you will see the universe die almost instantly? Doesn't this follow my idea that everything appears to speed up as you go faster?



    By the way....remember when I said a while ago that relativity is enough to cause someone to commit suicide? Guess what, someone did commit suicide while reading through Einsteins work.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

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  8. #7  
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    I think the trick is that it's only completely reciprocal when there's no acceleration involved, only relative velocities. Thus the twin paradox. The acceleration required to send one twin away is what makes their ages different in the end.
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  9. #8  
    Forum Senior Booms's Avatar
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    Thanks everyone plenty of stuff to think on now :?



    Oh and just a final clearup, can anyone explain exactly why nothing can go faster than light? I remeber it has something to do with F=ma and going faster makes you more massive requiring more energy to continue at a constant speed, I don't understand so any help?
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  10. #9 Re: Light from Lightspeed? 
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    Quote Originally Posted by Booms
    Lightspeed is perceived as a constant, we assume you cannot conventionally travel faster than lightspeed (actually if someone could explain that thinking that would be great)

    So if, hypothetically, I was going at lightspeed, and I shone a torch what would happen? in both ways, If I shone it forward would it go at double lightspeed? or would the light appear to stop? and if I shone the torch behind would the light actually stop?
    Einstein's special theory of relativity can be derived from the assumption of just two basic principles:
    1) The speed of light is the same in all inertial reference frames.
    2) The laws of physics take the same form in all inertial reference frames.

    From these two assumptions one can derive the Lorentz transformation that relates phenomena in one interial reference frame to phenomena in another inertial reference that is moving relative to the first one. It is the Lorentz transformation that shows that it is impossible for anything, matter or information, to travel faster than the speed of light.

    In fact, if you assume that ANY phenomena propagates at a fixed speed X in all inertial reference frames then the result is the Lorentz transformation with X playing the role of c. It just so happens that it is the speed of light, c, that has been experimentally verified to be the same in all reference frames.

    So, if you shine a flashlight, the light emanating from it will be seen to travel at c, in each and every inertial reference frame. It will not appear to be stopped to any observer. It will not appear to travel at twice the normal speed to any observer. ALL observers will see it traveling at the usual speed of light, c.

    This WIKI article gives a pretty good overview of the derivation of the Lorentz transformation. It may not be intuitively clear to you that the Lorentz transformation is how things should work, but only because you are used to Newtonian mechanics and the Galilean transformation. But the Lorentz transformation has been shown experimentally to be correct, and at the speeds that you encounter in everyday life, it is so close to the Galilean transformation that you do not detect the difference.
    http://en.wikipedia.org/wiki/Special_relativity
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  11. #10  
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    Quote Originally Posted by Booms
    Thanks everyone plenty of stuff to think on now :?



    Oh and just a final clearup, can anyone explain exactly why nothing can go faster than light? I remeber it has something to do with F=ma and going faster makes you more massive requiring more energy to continue at a constant speed, I don't understand so any help?

    Here is where the English language and a very old test, adopted by the government, may play into a confusion.

    Perhaps light creating rays, are just about as fast as anything can go. But it was never proven how fast those rays are by multi subatomic particle scientists.

    Some tests clearly showed that, they had the ability to make effects instantly across great distances. Especially when something blocks a light ray. The effect that should not have been seen for over 1.5 seconds, took place instantly. From the moon.

    So although it may be so, that nothing is faster then the rays that create light. Light might be a whole lot faster then the governments adopted light speed standard from the early nineteen hundreds claims it is.

    Sincerely,


    William McCormick
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  12. #11  
    Forum Radioactive Isotope MagiMaster's Avatar
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    The speed of light was measured as early as 1676. Well before the advent of "multi-sub-atomic-particle physics".
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  13. #12  
    Forum Senior Booms's Avatar
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    somehow Drrocket made more sense than you mccormak
    It's not how many questions you ask, but the answers you get - Booms

    This is the Acadamy of Science! we don't need to 'prove' anything!
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