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a few questions about light.

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thespeculator

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How does light get up to those high speeds? <br />Why does it always travel at that one speed?<br />Is it possible for light to go faster than the proclaimed speed of light when it is being sucked into a black hole?<br />Is it possible to slow light down?<br />What is light made out of?<br /><br />Thank you.<br />
 
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nexium

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Traditional answers may be wrong. Light behaves as if it is a wave in some experiments, but more like a particle in other experiments. The particle is called photon. Light "travels" slowly in transparent materials possibly because it is absorbed by molecules and a new photon is emmitted a few fentoseconds later, on the opposite side of the molecule. Neil
 
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alkalin

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Neil,<br />Interesting idea, but there is the problem as to why the release of another photon would be in the exact same direction.<br /><br />So here is another idea, but I cannot promise it is better. That a substance such as glass has various degrees of density, implying that the atomic structure might be closer together, or that the glass is made up of atoms that are larger and higher in atomic weight. One thing that is certain is that the higher the density, the more refraction will occur at the glass surfaces. This implies to me how a light photon might be interacting with the atoms in the glass. An atom is nearly empty, but it has many waves within from various sources such as the electrons. When a large atom is encountered by a photon, it is traveling through many waves that directly affect its own single wave. Can this slow the photon? It seems likely to me for various reasons which I do not have the expertise or time to elaborate on. But the simple explanation is that the photon is slowed until it reaches the farthest wave in the atom that can influence its exit speed from the atom, and that wave gives it the speed c minus the effect of other nearby atoms, which it will maintain until it encounters another atom. <br /><br />Can I tie this to refraction? Certainly, and to diffraction as well, but I’ll save diffraction for later. Traveling side by side are various photons of different wavelengths. The glass surface has an unbalancing effect from a photon entering that surface at an angle to it which will change its direction. If you draw a sketch of an atom laden surface, and a photon coming near to it, where does the photon first encounter waves of another atom before it reaches the one that is its destiny? On the side it begins to come nearer to. I hope I made these thoughts somewhat clear, but it doesn’t mean I am right. So let’s look at the different energies of the photons ‘color’ or waves. The longer waves have less energy than the shorter
 
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Saiph

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Light attains such speeds because it is a wave....and waves need not "accelerate" as they are only a transfer of energy.<br /><br />Or...if you go with the photon picture, the cheap arguement is it accelerates according to f=ma. mass of a photon is zero, so that for any force, the acceleration can be any value....inlcuidng infinite.<br /><br />Light travels at the speed "c" because of the way the electromagnetic fields in the light interact. The electric field can only change the magnetic field so fast (and vice versa).<br /><br />It can go slower through mediums, just as neil says.<br /><br />Alkalin: The reason the idea of the absorption and re-emission picture work is you have two types: a scattering and refractive system.<br /><br />In a scattering system, the material s "opaque" to that wavelength of light. The photons are absorbed, then re-emitted in a random direction. This diminishes the light in the line of sight, for that wavelength.<br /><br />If the material is not opaque to that wavelength, the light is not truly absorbed. It is however, expended in oscillating the electrons in thier orbits by modifying the orbital energy (but not causing a true transition). In this case the wavefront actually affects many, many atoms. <br /><br />This oscillation causes each electron to emit their own spherical wavefronts of the same frequency. It is by interference that the lines of propagation are created. I.e. you only get light reflected in one direction, transimitted in another because interference "kills" the light going in any other direction.<br /><br />Glass falls into this second category for visible light. The lght oscillates most of the photons on the surface, causing a reflection wave, and a transmitted wave at the appropriate angles (having a specific set of atoms on one side, and not the other, is what causes the angles to be different). <br /><br />The reason for the slower transmission speed is it takes time to oscillate the electrons (they've got inertia af <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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thespeculator

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Thanks for the responses!<br /><br />I don't understand how light could be a wave because then how would it move through outer space? Don't waves need a medium to travel through?<br /><br />Some other questions that come to mind are, Could a stray electron become a photon? And, are some photons bigger than others (trying to figure out how only one type of photon could be such a variety of colors)?<br /><br />Maybe the energy of whatever reaction that creates the photon deturmines how fast they are produced and/or the energy of the photon, and thus the color?<br /><br />
 
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alkalin

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Think of the wave as having properties that generate each wave from magnetic and electric moments or forces at right angles to each other. Each generation takes a moment to create the next right angle component ahead of the last generation. When that component is generated, it begins again to generate the next right angle component, etc. Each generation progresses the photon only so fast in space, which is the value of c, unless being influenced by nearby matter. These are properties known in physics yet exactly why these forces exist or behave this way we do not know. But they can be described mathematically. (Correct me if I am wrong, Saiph)<br /><br />Electric motors use a similar principle of a moving charge to generate a magnetic field, which then pulls the armature forward.<br />
 
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Saiph

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alkalin's got it right,<br /><br />and you've asked some classic questions. Light does behave like a wave, the fact that it refracts into a rainbow, and can create interference patterns is proof of that. And because all other waves require a medium, physicists believe light had a medium it traveled in as well, the aether (or ether). All attempts to find this aether have failed and attempts to show that some required properties/observations don't exist...have succeeded. So aether doesn't/didn't work out.<br /><br />Magnetic and electric fields can exist in a vacuum, without any medium. Light is these two fields messing with eachother, and those alterations propagating out from the source.<br /><br />One way to think of it, is the universe has electrical and magnetic fields everywhere already. Imagine them as untouched, so completely calm. Then, an electron moves, causing a disturbance. This disturbance, this change, takes time to communicate itself to the field everywhere else, and you get a ripple, like in a pond. A water wave is made of water, and EM wave is made of EM fields. In that sense, it is a wave, in a medium.<br /><br />The complication arises with the observed fact that you can isolate small "packets" of light (photons)...and thus rises the concept of a self-propagating wave (with no medium).<br /><br />Each photon has a size about equal to it's observed classical wavelength IIRC. So each color has at least a single seperate photon. The more photons of that color/energy, the brighter the observed light of that color. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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thespeculator

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The variety of answers is really interesting. Nobody seems positive about their answer though. lol<br /><br /><br /><font color="orange">"Think of the wave as having properties that generate each wave from magnetic and electric moments or forces at right angles to each other."</font><br /><br />So would the photon be generating these magnetic and electric feilds or would it be relying on the feilds of bodies of mass around it?<br /><br />In what experiment(s) does light act like waves? I am having a hard time thinking of them as a wave. Is it to do with the doppler effect? (Never mind. Thank you Saiph.) <br /><br />I still see gaps in the thought of it being a wave though because I could explain it all as a particle... I'll try to explain my thoughts later as I am out of time right now: got to go to class.<br />
 
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Saiph

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Well...I don't think you can explain refraction as a particle, and I'm certain you can't explain the young double slit experiment (with the interference patterns) strickly as a particle. <div class="Discussion_UserSignature"> <p align="center"><font color="#c0c0c0"><br /></font></p><p align="center"><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">--------</font></em></font><font color="#999999"><em><font size="1">----</font></em></font><font color="#666699">SaiphMOD@gmail.com </font><font color="#999999"><em><font size="1">-------------------</font></em></font></p><p><font color="#999999"><em><font size="1">"This is my Timey Wimey Detector.  Goes "bing" when there's stuff.  It also fries eggs at 30 paces, wether you want it to or not actually.  I've learned to stay away from hens: It's not pretty when they blow" -- </font></em></font><font size="1" color="#999999">The Tenth Doctor, "Blink"</font></p> </div>
 
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thespeculator

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Refraction would be easier to explain as particles than Young's experiment... But I'm beginning to doubt the validity of what my explanation would be.<br /><br />So then if light is traveling through a magnetic sort of medium in space does that mean it would not be able to travel past a certain point away from the matter in the known universe?
 
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siarad

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Interesting point, is light piling up at the edge of the Universe where permeability & permittivity may cease or does it continue into the abyss at infinite speed.<br />c<sup>2</sup> = 1/u<sub>0</sub> e<sub>0</sub> <br />where u<sub>0</sub> and e<sub>0</sub> are the permeability and permittivity of the vacuum. <br />Not mathematically the accurate formula as I don't know how to make square root signs but the answer's the same.
 
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