alpha2cen Posted December 26, 2010 Share Posted December 26, 2010 (edited) There were many discussions about traveling of the light through the vacuum before. It's important. How to travel the light in the vacuum? There is no medium to transfer the light wave. Edited December 26, 2010 by alpha2cen Link to comment Share on other sites More sharing options...
swansont Posted December 26, 2010 Share Posted December 26, 2010 Light does not need a medium. Electric and magnetic fields can exist in a vacuum. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 26, 2010 Author Share Posted December 26, 2010 (edited) Light does not need a medium. Electric and magnetic fields can exist in a vacuum. Light is a transverse wave, so it need medium to move. For example, water wave needs water and air boundary face to move. So vacuum has that kind of property, doesn't it? Edited December 27, 2010 by alpha2cen Link to comment Share on other sites More sharing options...
Nexium Tao Posted December 26, 2010 Share Posted December 26, 2010 (edited) Light can indeed propagate through a vacuum because it is electromagnetic in nature. It isn't actually a wave it just behaves similar to a wave. It is actually part of the electromagnetic spectrum and it has different properties It consists of electric and magnetic fields oscillating perpendicular to each other.. Hence it is a transverse wave. A transverse wave is a moving wave that consists of oscillations occurring perpendicular (or right angled) to the direction of energy transfer. These phenomena of simultaneous motion in two directions go beyond the kinds of waves you can create on the surface of water. Edited December 26, 2010 by Nexium Tao Link to comment Share on other sites More sharing options...
swansont Posted December 26, 2010 Share Posted December 26, 2010 Light is a transverse wave, so it need medium to move. That's an assumption/assertion on your part. People have looked for a medium in which EM waves propagate, but predicted properties are not found. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 27, 2010 Author Share Posted December 27, 2010 (edited) When we give energy to the vacuum, we can make particles. Vacuum + energy --------------> matter + antimatter Similarly light traveling is that when we gave a small energy to the vacuum, +- fluctuated phenomena is occurring, isn't it? I do not say Ether. I'd like to say is the unknown property of the vacuum. Vacuum is general property of the Universe. Electron, proton, neutron, neutrino and photon are special property of the Universe. The things we most using are electron, proton and neutron combined particles. But the most particles comes from the vacuum. Edited December 27, 2010 by alpha2cen Link to comment Share on other sites More sharing options...
lemur Posted December 27, 2010 Share Posted December 27, 2010 (edited) Imo, vacuum is the product of multiple gravity wells pulling matter away from each other. I don't think that light propagates through empty space but through gravitational field-force by contracting/expanding field-force. Given the absence of empirical data from outside any gravitational-field, what makes anyone even think that space exists except as gravitation? Is it even possible to theorize the existence of EM force outside of gravitational fields? Edited December 27, 2010 by lemur Link to comment Share on other sites More sharing options...
alpha2cen Posted December 27, 2010 Author Share Posted December 27, 2010 Why light speed in the vacuum is constant? It's not dependent on photon itself. If light traveled through the empty space, it would dependent on photon concentration - Fick's Law. When photon intensity is high, the light speed is fast, and when photon intensity is low, light speed is slow. The light speed constancy is related to vacuum medium constancy. Same case is the sound. The speed of the sound in the air is dependent on air density. Link to comment Share on other sites More sharing options...
swansont Posted December 27, 2010 Share Posted December 27, 2010 Why light speed in the vacuum is constant? It's not dependent on photon itself. If light traveled through the empty space, it would dependent on photon concentration - Fick's Law. When photon intensity is high, the light speed is fast, and when photon intensity is low, light speed is slow. The light speed constancy is related to vacuum medium constancy. Same case is the sound. The speed of the sound in the air is dependent on air density. I think that at least one of the assumptions in Fick's law does not apply to photons, but to the extent the concept applies it would refer to the speed at which the intensity variations would move, not the individual photons. Fick's law refers to concentration diffusion and flux, not individual particle speed. There is actual experimental evidence which indicates that light speed is constant in any inertial frame, and not measured relative to some medium. There is no preferred frame. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 28, 2010 Author Share Posted December 28, 2010 There is actual experimental evidence which indicates that light speed is constant in any inertial frame, and not measured relative to some medium. There is no preferred frame. Till now we try to find Higgs Boson but we can not find it. I think, there may be something in the vacuum but we can not find it. How about this experiment? First we make long vacuum path for light travel. Next we vary light intensity and wave length(from radio wave to gamma ray). And then, we measure light intensity at the beginning point and the finish point. Vacuum path length has to be long. If there is any variation, we can consider vacuum as a medium. Link to comment Share on other sites More sharing options...
swansont Posted December 28, 2010 Share Posted December 28, 2010 Basically that's been done. GPS works at dawn or dusk, when the light intensity level is high at the satellite but low on the ground. GPS relies on c being a constant. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 30, 2010 Author Share Posted December 30, 2010 Can we divide the light into electric waves and magnetic waves? Link to comment Share on other sites More sharing options...
swansont Posted December 30, 2010 Share Posted December 30, 2010 Can we divide the light into electric waves and magnetic waves? No. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 31, 2010 Author Share Posted December 31, 2010 If visible light is electromagnetic wave, can we control it by magnetic force? Magnetic wave concept comes from Maxwell's equation. How do we find it is correct in the vacuum? Most important evidence? Link to comment Share on other sites More sharing options...
swansont Posted December 31, 2010 Share Posted December 31, 2010 If visible light is electromagnetic wave, can we control it by magnetic force? No. Link to comment Share on other sites More sharing options...
alpha2cen Posted December 31, 2010 Author Share Posted December 31, 2010 Then, why light speed is reduced when it 's moving through the glass? The related parameters are density. And, transparentability is related to the distance between crystals. There is no factor to reduce the light speed except electric or magnetic force. Electric force can be removed here, because electron excess material, metal, never have light transparentability. Link to comment Share on other sites More sharing options...
swansont Posted December 31, 2010 Share Posted December 31, 2010 Light slows down in a medium because the light interacts with the medium (i.e. atoms or molecules), but this is not true if there is merely a field present. Link to comment Share on other sites More sharing options...
Janus Posted December 31, 2010 Share Posted December 31, 2010 Then, why light speed is reduced when it 's moving through the glass? The related parameters are density. And, transparentability is related to the distance between crystals. There is no factor to reduce the light speed except electric or magnetic force. Electric force can be removed here, because electron excess material, metal, never have light transparentability. The light's speed is not reduced, only it's apparent speed. As photons travel through the glass, They encounters molecules. These absorb the photons, increasing their own energy. After a slight delay, a new photon is released in the direction of the first and the molecule returns to its rest state. It is these repeated delays between absorption and emission that account for the increased time that it takes light to pass through the glass and the reduction in its apparent speed. While the light travels from molecule to molecule it still travels at c. Link to comment Share on other sites More sharing options...
swansont Posted December 31, 2010 Share Posted December 31, 2010 I think it's OK to say the light's speed is reduced; it's the speed of the photon that remains the same. Link to comment Share on other sites More sharing options...
lemur Posted December 31, 2010 Share Posted December 31, 2010 If light is not affected by a magnetic field, what causes aurora borealis (northern lights)? I've always heard it's due to the magnetic pole. Link to comment Share on other sites More sharing options...
swansont Posted January 1, 2011 Share Posted January 1, 2011 If light is not affected by a magnetic field, what causes aurora borealis (northern lights)? I've always heard it's due to the magnetic pole. Charged particles, not light, funneled to the poles by the magnetic field. They collide with oxygen or nitrogen, and recombination/de-excitation is the source of the light. Link to comment Share on other sites More sharing options...
alpha2cen Posted January 1, 2011 Author Share Posted January 1, 2011 (edited) If light is not affected by a magnetic field, what causes aurora borealis (northern lights)? I've always heard it's due to the magnetic pole. Aurora is different from Sun light. Sun light is the electromagnetic wave which is directly emitted from the sum. But, Aurora is different. When Solar wind blowing from the sum the ions(most of proton) which is contained in it hits the magnetic field in the Earth. At that time, most of ions pass by without trouble, but some of ions come down to the high altitude atmosphere of the North pole, and collide with atomic molecules around, at this process light is emitted, we call it Aurora. So Aurora is generated from the collision between high energy charged particle and atom. Edited January 1, 2011 by alpha2cen Link to comment Share on other sites More sharing options...
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