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Thread: Electromagnetic waves (Light, Radio, etc)

  1. #1 Electromagnetic waves (Light, Radio, etc) 
    Forum Isotope (In)Sanity's Avatar
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    Perhaps someone can help explain this,

    http://www.afrlhorizons.com/Briefs/Jun02/OSR0201.html

    So light can't travel any faster but it can be slowed down and stopped? I could see this if light was a particle, but not if it is a wave like so many have theorized.

    The idea of the wave was much like tossing a stone in a still pond, the ripple effect of energy emanates from the point of impact.

    So the light energy would ripple across matter as a wave. This is fine until we get experiments that show it can be slowed down or even stopped. If it were a true wave one would think this couldn't happen.

    Also, what exactly does it ripple across in the vacuum of space? If light is a particle again I could see this happening.

    Why does light travel at a speed no faster then aprx 186,000 miles per second? It would be funny to find out it has mass that we just can't measure and Einsteins E=mc^2 somehow plays into it's speed limit.

    I'm not saying it's not a wave, I'm just trying to figure out how it can be slowed down (or stopped) as a wave.


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  3. #2  
    Forum Sophomore buffstuff's Avatar
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    You know, I'm stuck. But can't light be sped up past the speed of light?


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  4. #3  
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    Light sometimes acts as a particle, and sometimes as a wave. Fact is, it's something different. Scientists have been working on the 'Complete Unifying Theory' for some time, to combine (general and special) Relativity and Quantum Physics, but as far as I know, they have not yet succeeded.

    The answer to your question might take a long to get here, (In)sanity...

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  5. #4  
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    I actually believe that electromagnetic waves do not exist!
    What exist are photons.

    Take a look on this page for a full explanation:
    http://www.geocities.com/anewlightin...th_photons.htm

    A new theory can rise...
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  6. #5  
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    Quote Originally Posted by martillo
    I actually believe that electromagnetic waves do not exist!
    What exist are photons.

    Take a look on this page for a full explanation:
    http://www.geocities.com/anewlightin...th_photons.htm

    A new theory can rise...
    So how is the speed difference explained? Light travels faster then radio waves if I'm not mistaken.
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  7. #6  
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    You wrote:
    So light can't travel any faster but it can be slowed down and stopped? I could see this if light was a particle, but not if it is a wave like so many have theorized.
    I mean I agree with that.
    When photons pass trough a dense medium they collides with atoms in a small interval of time and they are braked momentaneously. After that they recover their "light speed" again. This process is repeated innumerable times. What is slowed down is the average velocity of the photons.

    The problem is how to explain the interference and diffraction behaviours of light with the particle model of photons. This is what I present in the site: www.geocities.com/anewlightinphysics

    Special structures are proposed for the photon, neutrino, electron so that the interference and diffraction patterns are predicted theoretically.

    Finally I must say that light, heat, radio waves, microwaves, etc are all radiations of photons and have the same emission speed. I defend the old Emission Theory where the final velocity is affected by the speed of the source: if the source have a speed u the velocity of the emitted photons is ç = c+u where c is the famous constant.
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  8. #7 Re: Electromagnetic waves (Light, Radio, etc) 
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    Quote Originally Posted by (In)Sanity
    Perhaps someone can help explain this,

    http://www.afrlhorizons.com/Briefs/Jun02/OSR0201.html

    So light can't travel any faster but it can be slowed down and stopped? I could see this if light was a particle, but not if it is a wave like so many have theorized.
    In the classical view a light wave is made up of an electric field and a magnetic field that oscillate at right angles to each other.

    Since the light wave has an electric and a magnetic component, the speed at which the light wave can travel through a material depends on the material’s resistance to changes in electric and magnetic fields; if the resistance to either one is high, it will cause the light to travel more slowly. In fact, the speed of light in any material can be calculated if you know the electric permittivity and magnetic permeability (which is physics jargon for resistance to change in electric and magnetic fields) of the material.
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  9. #8  
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    Pseudoscience nutters, go home. This discussion is not for you.

    Moving on.


    Light is both a particle and a wave. This has been experimentally confirmed.

    Anything with mass that moves is both a particle and a wave. Toss a baseball and it's got a wavelength, just too obscenely small. An electron is better; you can see it behave like a wave when it spreads out in the slit experiment.

    Also, light and radio waves are all a part of the "electromagnetic wave spectrum" ranging from UV light to infrared light to radio waves and further, all traveling at approximately 3 x 10^8 m/s in a vacuum. Everyone should know the speed of light can be derived from the Maxwell equations; the material the light travels in changes constants in the equations so that the speed works out to be slower. This is common knowledge, really. It's AP Physics C. High school physics.

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  10. #9  
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    Look, nothing (as far as we know) can travel faster than the speed of light in a vacuum, ok? Nothing. Light can't travel faster because in a vacuum is the only place where there is nothing to slow light down. Outside a vacuum, even if it's travelling through air, light is slowed down from hitting air particles. Inside a vacuum, nothing is there to slow it down, so it travels the fastest it can travel, which is the fastest anything can travel (as far as we know). Now, the point that article is trying to make is that this professor has managed to slow light down to a standstill, which has never been done before (she got $500,000 over 5 years for it).

    Of course, some argue with her and say that you can't stop light completely and all she did was slow it down so much that we can't register it's movement through the particle cloud she created, but that's besides the point.

    So anyway, this professor got light to stop and that's cool and there's not much more to discuss about it so follow Zero's advice, this discussion is all about fact, not philosophy.
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  11. #10  
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    Of course light passing light is the fastest thing of all
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  12. #11  
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    Zero,
    This was for me:
    Pseudoscience nutters, go home. This discussion is not for you.

    Moving on.
    I think that Pseudo.Science is to not be able to explain how light and electrons can be particles and have a "wave-like" behaviour and then invent that they are both, that things are "dual"!
    Also Pseudo-Science is to invent theories full of contradictions and paradoxes.

    Pseudo-Science nutter don't need to enter the internet, they believe that all in Science have already been done and that there will be nothing new in the future. For them all is in scholar books and nothing on them can have a mistake. They are perfect enough for their minds which do not ask too much questions...

    I think that is you that don't need to enter this forum. There are many other forums where any discrepancy with today's established theory is automatically deleted, those are places right for you!
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  13. #12  
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    We are currently in the process of setting up an experimental PseudoSci section for the all the "nutters" ( :wink: ). So hopefully that will be up soon and we will see how that goes. PM me if you have any suggestions.
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  14. #13  
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    martillo, you are clearly emptyheaded, and you know it yourself. Knee-jerk response to the offhand reference to pseudoscience nutters, mm? Feeling guilty? It's funny to see.

    I will not bother correcting your misguided view of physics, because you're probably one of those nutters who claim pi is a rational number, and because those people are just so much of a lost cause.
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  15. #14  
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    Zero,

    As I can see you are a specialist in personnal attacks, really good eh?
    I wonder if you are so good in Physics...

    For example I would like to discuss my arguments against Relativity that I expose in: http://www.geocities.com/anewlightin...Relativity.htm

    There I present that Relativity do not support some very important laws of Physics like the De Broglie: lambda=h/mv which is not invariant under a change of coordinates.

    I also suggest that the Davisson-Germer can be an experimental proof that Relativity is wrong because it works only with the constant ("rest value") mass for the electrons. Of course it can be argued that only small velocities are present but I think that for science a 10% of C is considerable enough to detect "relativistic mass variations. Also I don't understand why the same experiment with higher velocities is not citated as a proof towards Relativity! If some mass variation could be detected the experiment would be an excellent proof.

    May be this subject is not directly related to the topic we are posting so I opened a new topic: "De Broglie against Relativity" (It's in the new Pseudo Science forum).

    Well, I will wait for your "expert" answer...
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  16. #15 subject 
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    martillo, you are absolutely right. Think what is the main constituent of any substance? empty space, between the particles there is more space than anything, just like a vaccum. So light actually does travel at its usual 3x10^8 ms^-1 atleast between atoms. But when we have an atom in the path of a photon what happens is that it absorbs the energy that a colliding photon posseses. An electrons orbiting the atom is allowed to then move up to a higher energy state to acomodate this energy. Usually only for a rotation or less before reemitting it but this is still a lengthy proccess in comparison to travel without interference.

    In the case at hand so much stored energy has been removed from the system by super cooling that all electrons are set to ground state, so that they are extremely eager to retain energy. A large amount of energy can then be acomadated by the cloud for a relatively long period of time. Energy absorbtion/emission is discrete and can be controlled by using specific frequencies of light such that the stored energy can be displaced again.
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  17. #16  
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    AdmiralFloyd,

    That's exactly what I think about.

    The problem is that the wave concept of the light cannot explain this.
    This experiment can be an excellent argument towards the particle concept of light.
    The concept of light as an electromagnetic wave is so established that confuses it all.

    I have developed a text where all kind of transmission of signals can be interpreted with photons as carriers. The waves are not necessary at all in signal communications theories!
    I think you can be interested. Please visit:
    http://www.geocities.com/anewlightin...th_photons.htm

    Even the Hertz experiment that seemed to prove the existence of electromagnetic waves can have another interpretation with photons!
    See: http://www.geocities.com/anewlightin...xperiments.htm
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  18. #17 Why 
    Forum Freshman AdmiralFloyd's Avatar
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    why can a wave model of light not explain this? why would a particle view more adequatly describe the absorbtion of photon energy? please explain so that others and myself can have a go at addressing this issue also.
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  19. #18 Re: subject 
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    Quote Originally Posted by AdmiralFloyd
    So light actually does travel at its usual 3x10^8 ms^-1 atleast between atoms. But when we have an atom in the path of a photon what happens is that it absorbs the energy that a colliding photon posseses. An electrons orbiting the atom is allowed to then move up to a higher energy state to acomodate this energy.
    This is not true. When atoms absorb light and promote an electron up to a new energy level it takes around 10^-6 seconds for them to re-emit the light. That’s a LOT longer than the minor changes in speed caused by the refractive index of a material. Also, when the photon is reemitted it can travel in any direction. This should make it impossible for a focused beam of light to travel through a material, since the photons would be constantly getting deflected off in different directions.
    Usually only for a rotation or less before reemitting it but this is still a lengthy proccess in comparison to travel without interference.
    Electrons do not orbit around atoms like planets around the sun.
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  20. #19 re: comments 
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    This is not true. When atoms absorb light and promote an electron up to a new energy level it takes around 10^-6 seconds for them to re-emit the light. That’s a LOT longer than the minor changes in speed caused by the refractive index of a material.
    This is what i was trying to explain. In the time it takes a photon to be re-emitted from an electron, by your figure, it could have traveled another 300 meters (in a vaccum). So as we both said; light travels at constant speed, but appears to be slowed as it takes these many intervals along its path.

    Also, when the photon is reemitted it can travel in any direction. This should make it impossible for a focused beam of light to travel through a material, since the photons would be constantly getting deflected off in different directions.
    In the case of glass and visible light, the photons are not scattered. UV light cannot penetrate glass, and infra-red is somewhat scattered by it. But waves in the visible spectrum have a frequency such that the ressonant frequency of electrons in glass allow them to be remitted cleanly in the same direction (not completely, but largely).

    Electrons do not orbit around atoms like planets around the sun.
    I know this, what really occurs is not something we can think of, this is a model that works.
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  21. #20  
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    AdmiralFloyd wrote:
    why can a wave model of light not explain this? why would a particle view more adequatly describe the absorbtion of photon energy? please explain so that others and myself can have a go at addressing this issue also.
    (In)Sanity wrote at the start of this topic:
    So light can't travel any faster but it can be slowed down and stopped? I could see this if light was a particle, but not if it is a wave like so many have theorized.

    The idea of the wave was much like tossing a stone in a still pond, the ripple effect of energy emanates from the point of impact.

    So the light energy would ripple across matter as a wave. This is fine until we get experiments that show it can be slowed down or even stopped. If it were a true wave one would think this couldn't happen.
    How do you apply the wave model of light to photoelectric effects?

    How the wave is absorbed by the electrons?

    [/quote]
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  22. #21 re: 
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    I just painstakingly made this diagram in paint to help you visualise how the electric and magnetic components are absorbed whilst retaining their perpendicular mutual propogation both in wave and atomic form.

    http://www.digitalaudience.net/blueg...absorbtion.jpg
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  23. #22  
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    AdmiralFloyd,

    I saw the image and if I well understand your point of view you show an incident ray colliding with an electron. But this is closer to a particle model of light than the wave model where a spherical wave is generated by a source and at some distance it becomes a plane wave affecting a big region of space. The problem is then how a "big" plane wave can affect only one electron particle delivering the precise energy: E=hf.

    In your image I see a travelling point with some electric and magnetic component.
    This is more similar to the model of photon I present in www.geocities.com/anewlightinphysics where an electromagnetic structure is proposed for the photon. The photon is presented there as a particle with a special elctromagnetic structure. The photon can be seen as an "electromagnetic particle" in opposition to the "electromagnetic wave" model of light.
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  24. #23 Re: re: comments 
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    Quote Originally Posted by AdmiralFloyd
    This is what i was trying to explain. In the time it takes a photon to be re-emitted from an electron, by your figure, it could have traveled another 300 meters (in a vaccum). So as we both said; light travels at constant speed, but appears to be slowed as it takes these many intervals along its path.
    Then how do you explain the fact that even radio waves and gamma rays will slow down in an material, even though those can’t be absorbed by the electron around an atom? Radio waves are too low in energy to promote and electron to a higher energy level, and gamma rays have too much energy (they knock the electron completely off, leaving an ion behind).
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  25. #24  
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    if light isnt waves martillo, how come they can experience interferens and have wave propeties?
    light is both particles and waves
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

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  26. #25  
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    Scifor Refugee and AdmiralFoyd,

    Photons are not absorbed and re-emitted by atoms in a dense medium. Photons are just braked progressively as the photon reaches an atom, then it passes by its side and is re-accelerated while it leaves the atom by an electric and magnetic ("electromagnetic") interaction.
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  27. #26  
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    Zelos,
    This is very well explained in Chapter Four at the site. Please take a look.
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  28. #27  
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    explain it here
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

    On the eighth day Zelos said: 'Let there be darkness,' and the light was never again seen.

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  29. #28  
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    Zelos,
    Sorry but I can't. You must understand the proposed structure for the photon, how light travels in trains of them and how the Hugens reasoning is well applied to the trains with graphics. Too extense for a post!

    Please take a look there.
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  30. #29  
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    done
    silly, many negative words following in along train here.
    I am zelos. Destroyer of planets, exterminator of life, conquerer of worlds. I have come to rule this uiniverse. And there is nothing u pathetic biengs can do to stop me

    On the eighth day Zelos said: 'Let there be darkness,' and the light was never again seen.

    The king of posting
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  31. #30 Re: Electromagnetic waves (Light, Radio, etc) 
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    Quote Originally Posted by (In)Sanity
    Perhaps someone can help explain this,

    http://www.afrlhorizons.com/Briefs/Jun02/OSR0201.html

    So light can't travel any faster but it can be slowed down and stopped? I could see this if light was a particle, but not if it is a wave like so many have theorized.

    .
    Big head answer :
    Nothing known can travel faster than light only hypothetical tachyons. Light howevertravels at a constent - Einsteins constent(the correct definition of C). Light cant slow down or stop because if it does for all intents and purposes it ceases to exist. It becomes massless and energyless so is no longer detectable. Anything with a rest mass of above 0 cannot travel the speed of light because the energy needed to get it there becomes infinate. Light has to travel at C to have an energy greater than 0 so therefor cannot travel bellow C. For those who understand the lorentz factor: if you take E=γMoC^2 - einsteins equation in terms of rest mass. Gamma(γ) cannot be infinate if M>0 and gamma has to be infinate if M=0 for the equation to square. Im pretty surethat light being a particle-wave has no bearing on this whatsoever.
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  32. #31  
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    Sorry for my misspelling of constant, can't the mods add an edit to this engine?
    "A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." Albert Einstein
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  33. #32  
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    look again, you may find it next to the quote and delete buttons to the top right hand corner of the post.
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  34. #33  
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    Quote Originally Posted by wallaby
    look again, you may find it next to the quote and delete buttons to the top right hand corner of the post.
    Ah thanks it's not there at the moment but you've put me on the track to finding the problem. I'll go check see if it's a check box in the profile.
    "A man's ethical behavior should be based effectually on sympathy, education, and social ties; no religious basis is necessary. Man would indeeded be in a poor way if he had to be restrained by fear of punishment and hope of reward after death." Albert Einstein
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