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Bilal Saad

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"Light on Light" is that true or "Light in Light" is that true?

my issue here is about light by physical photons, what I mean is can light interfere with another light or they are keep separated with out interfere. but our eyes can't distinguish it. what i ask the photons have wight? if it has wight so that means they are can Collision, i need someone explain that.

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    Oct 13 2011: That is a very interesting question, Bilal.

    We see "light", as in a very particular region of the electromagnetic spectrum. There is much more "light" around us than we realise in everyday life - you've got the radiowaves, microwaves, cosmic rays, IR, UV, etc ... and it's all behaving just like the "light" we see with our eyes. It really is just an enourmous mess of stuff coming and going in every direction, bouncing off everything around us ... and somehow our brains are able to sort it all out, by registering "light" of very particular wavelengths, and painting a picture in our minds (a picture nothing like the true reality of what is actually around us, but something we can deal better with in our everyday marcoscopic world).

    'They' say light acts like a particle sometimes and like a wave other times, but that's not quite right - it does not quite behave exactly like either in these situations. We really don't know that much about light.

    Now is there actually some form of interference going on .. hmm. Sure, we can "drown out" the light we receive from distant stars by making things bright enough locally, but that does not suggest we're interferring with the light from those distant stars, just that we're taking ourselves past the limits of what our brains can register - we're interferring with our light detecting tools.

    I cannot off the top of my head think of anything that would suggest that light interferes with itself. We know that gravity (something else we know very little about) is capable of interfering with light, "gravitational lensing", something predicted by Einstein and recently proved. I guess we need more brains to bounce this off, sorry! Very interesting question, though.
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      Oct 14 2011: Hi Ashley, Thanks to your comment, my point view about that if light can scene the gravity then the light photons has wight, if light have wight so the light can Friction with any thing, if the friction can light make it then we can make Engine working by light. what you say about that, please help me.
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        Oct 20 2011: Ah you see Bilal, Einstein came up with his famous e=mc^2 law, and a consequence of it is that for anything with mass to travel at the speed of light would require infinite energy. Not only does time slow down when you move faster, but you also gain mass when you move faster, and when moving at the speed of light not only is there no direction of time, but your mass is also infinite. Therefore light itself cannot have "real" mass.

        Gravity does not interfere directly with light. What it does is warp the very fabric of space itself through which light travels. An analogy would be to draw a straight line on a sheet of paper and then picking up the paper and bending it. The straight line now appears bent. There are all sorts of other ways to interfere with light in this sense - putting a glass prism in front of it and getting a rainbow of colour - but this is just interfering with the medium through which the light travels.

        Now moving from Relativity into the other room, Quantum Physics, I cannot remember ever seeing photons interacting with each other in Feynman diagrams.

        Would be nice if we could have someone more informed help maybe clarify things for us.
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          Oct 20 2011: Hi Ashley, I've been searching for someone helping me about that and i found this remarkable website http://www.science.ca/ there is a scientist who help me about that. i can't think how we can explain the light and we can't able explain the atom itself when i asked them what the space between electrons layers, it is empty space or not empty space he don't know? and another question how the first layer have 2 Electrons and the second layer have 8 Electrons isn't the second layer far than first layer should the gravity will be less in the second layer how it hold on 8 electrons, 8 electrons should be nearest to the core of atom to equal the force of gravity of core, and a lot of Q's with out A's, if you know any place can handle those questions i will be grateful to you.