>>Well at least spell possibilities right before you put it in your signature.
LOL! I didnt notice that (obviously). And i'm usually so careful with my speling.
>>Well at least spell possibilities right before you put it in your signature.
LOL! I didnt notice that (obviously). And i'm usually so careful with my speling.
"There's always another way"
-lightatdawn (lightatdawn.cprogramming.com)
one thing puzzling me recently,
light goes at light speed in a vacuum, but slows down in other media. so light travels at light speed, goes thru the medium at sub-light speed, then on exiting is at light speed again. why's that ?? whats holding it back in the media and what makes it speed up again ??
Steve
"light goes at light speed in a vacuum, but slows down in other media goes thru the medium at sub-light speed, then on exiting is at light speed again. why's that ?? whats holding it back in the media and what makes it speed up again ??"
Well all waves display this property, the speed at which they are propogated is dependant on their medium.
Light, is an oscilating magnetic and electrical field at 90 degrees to each other, the reason it "slows down" can be thought of as due to interactions with electrical and magnetic fields present in the medium.
Think of it like this, the magnetic field causes the propogation of an electric field which causes the propogation of another magnetic field... when in a medium other electrical and magnetic fields can slow this process down (simplification), when back in free space the process returns to its former rate.
Last edited by Clyde; 06-04-2002 at 03:57 PM.
Yeah...um...flux capacitor.
the laws of physics exist because of humans.
the reality behind the laws of physics exists regardless of human existance.
THis is what should be said.
"the reality behind the laws of physics exists regardless of human existance. "
There is no distinction, the laws of physics are laws of "reality". We just don't have all the laws 100% nailed down at the moment, though it would seem we are pretty close with some of them.
is an individual light photon the same one prior to entering a medium as the one exiting the medium. or not ????? has it caused propagation in the medium, so its not the same photon ?? or has an individual photon passed thru the medium??Originally posted by Clyde
"light goes at light speed in a vacuum, but slows down in other media goes thru the medium at sub-light speed, then on exiting is at light speed again. why's that ?? whats holding it back in the media and what makes it speed up again ??"
Well all waves display this property, the speed at which they are propogated is dependant on their medium.
Light, is an oscilating magnetic and electrical field at 90 degrees to each other, the reason it "slows down" can be thought of as due to interactions with electrical and magnetic fields present in the medium.
Think of it like this, the magnetic field causes the propogation of an electric field which causes the propogation of another magnetic field... when in a medium other electrical and magnetic fields can slow this process down (simplification), when back in free space the process returns to its former rate.
Steve
Thats a good question, but its not that one photon propagates another photon, the photon it's self is made up of an electrical and magnetic field, propagating each other.
Like a wave "packet", i'm not sure whether the photon exiting a medium is the "same" as the one entering, it may be (though i'm not sure applying individuality to photons is completely valid), or it may be that transmission through a medium means that photons are absorbed them re-emited.
mmmm
something else i was just wondering, can you emit a single photon from some device ?? would it behave like a wave ??
Steve
This bit about reaching the speed of light Clyde.
Clyde:
"Ah but it's not possible to push infinitely hard, to reach the speed of light, you would need to do an infinite amount of work, which would require an infinite amount of energy, and since the amount of energy in the universe is finite, it's impossible (assuming here that the object you are trying to accelerate has rest-mass)."
But if I am in a rocket using mass as fuel. Then as I get closer to the speed of light the mass of my fuel increases in proportion, allowing me to burn extra and keep accelerating as if I have infinte fuel. Thus again increasing both my fuel and speed until I reach light speed.
Last edited by novacain; 06-04-2002 at 11:00 PM.
"Man alone suffers so excruciatingly in the world that he was compelled to invent laughter."
Friedrich Nietzsche
"I spent a lot of my money on booze, birds and fast cars......the rest I squandered."
George Best
"If you are going through hell....keep going."
Winston Churchill
"But if I am in a rocket using mass as fuel. Then as I get closer to the speed of light the mass of my fuel increases in proportion, allowing me to burn extra and keep accelerating as if I have infinte fuel. Thus again increasing both my fuel and speed until I reach light speed."
It doesn't increase in proportion, the closer you get to 'c' the larger the increase in mass becomes.
"something else i was just wondering, can you emit a single photon from some device ?? would it behave like a wave ??"
Yes you can, and yes it does, though it acts like a particle as well. If you emit a single photon and pass it through a series of slits it appears to "split" in two and interfere with itself resulting in a classic interference pattern.
Last edited by Clyde; 06-05-2002 at 04:29 AM.
"But if I am in a rocket using mass as fuel. Then as I get closer to the speed of light the mass of my fuel increases in proportion, allowing me to burn extra and keep accelerating as if I have infinte fuel. Thus again increasing both my fuel and speed until I reach light speed."
Nope, because relative to the mass you are accelerating, the mass of the fuel stays the same.
Light has dual nature. In certain phenomenon it's behaviour is better explained using wave-nature (interference, diffraction etc.), yet in others using particle-nature (photo-electric effect, compton's effect etc.) makes things a whole lot easier. (a/c to de-Broglie's hypothesis)
The fore-mentioned phenomenon is, IMO, better understood using particle-nature of light.
Light particles (photons) experience resistance in their path in the presence of material medium and hence tend to slow down, whereas in vacuum they face no hindrance and move at maximum velocity.
>> But if I am in a rocket using mass as fuel. Then as I get closer to the speed of light the mass of my fuel increases in proportion, allowing me to burn extra and keep accelerating as if I have infinte fuel. Thus again increasing both my fuel and speed until I reach light speed.
The mass of the fuel does increase, but why do you forget that the mass of your rocket also increases with it, hence, more fuel is required for it's acceleration.
Overall, the relative proportion remains the same.
Last edited by Zeeshan; 06-05-2002 at 10:22 AM.
"The fore-mentioned phenomenon is, IMO, better understood using particle-nature of light.
Light particles (photons) experience resistance in their path in the presence of material medium and hence tend to slow down, whereas in vacuum they face no hindrance and move at maximum velocity. "
If light was acting as a particle is would slow down in the medium but it would not speed up again after it left it.
>If light was acting as a particle is would slow down in the medium but it would not speed up again after it left it.<
Which is when the particle/wave properties both come out, right? Anyway, isn't the slowing down of light through a medium caused by the refraction of the wave? If so, light slowing down in a medium would be attributed to the wave properties of light.
Or not.
