This one mainly goes out to those of you who heard about the fairly recent experiment with a laser and some sort of "cosmic molasses." Some physiscist was actually able to slow down a laser ray to, oh, I think it was 32 mph. But wouldn't that mean that light 's speed was dependent upon it's surroundings(be they of certain special make-ups). So wouldn't that also prove that if you can slow down the speed of light, you can just as surely speed it up. That would also prove that light is a particle because the substance would have to stick with the light to work continuously. A wave would just pass through it.


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I'm really not a shorty.


[This message has been edited by Shorty (edited September 19, 1999).]

Speed of light is constant only in pure vacuum. In presence of matter, light slows down. But nothing can speed it up. Also, light is both particles and waves, not just one or the other.

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I am; therefore I think.

Boris, you cannot positively say that light is both a particle and a wave, or either of them alone. We can't even look at atoms, let alone the fundamental entity of light. But most of what you say proves my point quite well. If it is possible to slow something down, then why isn't there a possibility that you can speed it up. Besides, say that it was possible to go faster than light. Untill we have the capability to do so, there will always be sceptics. but then again, if it is not possible, there will always be people that think it is.

Shorty,

Actually we can not only image atoms, but now the actual electron orbitals as well (and they turn out to look exactly as predicted by quantum electrodynamics). Also, you cannot image light because it cannot stand still. Moreover, we use the electro-magnetic field to image everything else; using the electromagnetic field to image light (which is a disturbance within electromagnetic field) is a bit futile, wouldn't you agree?

Light travels because the electromagnetic field restores itself when disturbed. Much as water waves travel at the same speed on a water surface (provided gravity remains constant) -- so will light travel at a constant speed within the electromagnetic field, unless the very properties of the field are altered (in which case, all the matter we know and love would likely disintegrate.)

Matter interferes with light propagation, therefore slowing it down. That's why we are able to design refractive optics; that's why your iris is able to focus objects on your retina. Similarly, you can slow down water waves by placing shallow sandbars in their way. However, when nothing obstructs the wave's passage it goes at a constant, maximum speed. Ditto for light.

Now, matter and energy are fundamentally equivalent, therefore using the same underlying principles of propagation (whatever they may be), not to mention that atoms and molecules use that very same electromagnetic field to hang together -- all of which means that matter itself cannot propagate through space faster than light. It can't even go <u>at</u> the speed of light.

Thus, our only hope to travel faster than light is to cheat and take shortcuts (like distorting spacetime or some such thing.) Whether tricks like that are even possible remains to be seen.

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I am; therefore I think.

There are some attributes of light that we can explain only if we take the light as particels, and there are some that we can explain with wawe theory. Tahts a dual theory of light.
As for speed of light, I agree with Boris, it is const. in vacuum. But Ive seen somewhere that there are particels that travel faster than light ( for a very, very short time), but thats only a theory,...

schredinger,

Those faster-than-light particles you have likely heard about are tachyons. They are a by-product of an outdated interpretation of relativity, which noone takes seriously any more. Tachyons are supposed to be somewhat opposite of normal matter -- they can travel arbitrarily fast, but they cannot slow down to the speed of light. The tachyon with infinite speed is the lowest-energy tachyon; tachyons approaching the speed of light approach infinite energy. Anyway, it's all science fiction...

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I am; therefore I think.

A long time ago, I went to the Detroit Main Library. I went with a friend so I had nothing to do and I asked for information on antimatter. The lady came back with folders full of clips from magazines and papers. While reading this material I came across an interesting tidbit: when matter and antimatter destroy each other, some particles travel away faster than the speed of light. Sorry, I don't remember any details. This long winded explanation is because I can't give an exact source. Interesting if true.