Speed of light

littlegreenmanfrommars
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RE: RE: I don't know if

Message 45843 in response to message 45839

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I don't know if this helps, it's way over my head.
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Slow light is the propagation of an optical pulse or other modulation of an optical carrier at a very low group velocity. The term is usually only applied when the velocity is at least hundreds of times slower than the speed of light in a vacuum. There are many mechanisms which can generate slow light, all of which create narrow spectral regions with high dispersion, i.e. peaks in the dispersion relation. Schemes are generally grouped into two categories: material dispersion and waveguide dispersion. Material dispersion mechanisms such as Electromagnetically Induced Transparency (EIT), Coherent Population Oscillation (CPO), and various Four Wave Mixing (FWM) schemes produce a rapid change in refractive index as a function of optical frequency, i.e. they modify the temporal component of a propagating wave. This is done by using a nonlinear effect to modify the dipole response of a medium to a signal or "probe" field. Waveguide dispersion mechanisms such as photonic crystals, Coupled Resonator Optical Waveguides (CROW), and other micro-resonator structures modify the spatial component (k-vector) of a propagating wave.

I THINK what this means is that light travels more slowly in a dense medium, and that scientists have developed media that, while still transparent to light, have the effect of slowing it down by previously unheard of amounts. I THINK!! lol

A predominant figure of merit of slow light schemes is the Delay-Bandwidth Product (DBP). Most slow light schemes can actually offer an arbitrarily long delay for a given device length (length/delay = signal velocity) at the expense of bandwidth. The product of the two is roughly constant. A related figure of merit is the fractional delay, the time a pulse is delayed divided by the total time of the pulse.


Thanks Kinhull..I'm not sure that is the same thing that Tullio is talking about... and it's making my brain try to remember things I haven't seen or thought about in years.

Ouch.


debugas
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The speed of light is the

The speed of light is the maximum speed of propogation of information.

ultimately we define this speed as the distance a photon manages to travel during some oscilations of a cetain micro-world structure (some transitions between the two hyperfine levels of the ground state of the caesium-133 atom).

for me the fact the speed of light is finate means that information propogation is
done "locally" that is from one point to near points and not some arbitrary distant points that are far away.

if you've heard of Conway's Life game the analogy would mean - the value of a given cell in (n)-th generation will in (n+1)th generation only influence the 8 nearby (neighbouring) cells and not other distant cells. That means the information in the given cells (e.g. of a flyer) will shift itself N cells only after some M generations. N/M defines the speed of the flyer. the simplest flyer in Life game repeats its shape in 4 generations (M=4) and manages to shift itself 1 cell (N=1) during that 4 ticks, so its speed is 1/4 and the maximum speed in life game is 1 (it is the "speed of light" )

ML1
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RE: The speed of light is

Message 45845 in response to message 45844

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The speed of light is the maximum speed of propogation of information.

[...]
for me the fact the speed of light is finate means that information propogation is done "locally" that is from one point to near points and not some arbitrary distant points that are far away.

if you've heard of Conway's Life game the analogy would mean - the value of a given cell in (n)-th generation will in (n+1)th generation only influence the 8 nearby (neighbouring) cells and not other distant cells. That means the information in the given cells (e.g. of a flyer) will shift itself N cells only after some M generations. N/M defines the speed of the flyer. the simplest flyer in Life game repeats its shape in 4 generations (M=4) and manages to shift itself 1 cell (N=1) during that 4 ticks, so its speed is 1/4 and the maximum speed in life game is 1 (it is the "speed of light" )


I like your life analogy.

From my shallow knowledge, I agree with your view. All the fun with entanglement and "spooky resolving of state at a distance" can only be due to internal hidden ('entangled') states... Unless that is we find something really spooky!

So how would our physics alter if "c" or the fine constant were greater or smaller?

Regards,
Martin

See new freedom: Mageia Linux
Take a look for yourself: Linux Format
The Future is what We all make IT [url=http://www.gnu.org/copyleft/gpl.html](GPLv3)[/u

Dr. C.E.T.I.
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RE: I know this is where

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I know this is where the hardcore physicists hang out so I'm sure one of you can point me in the right direction.

Someone over on seti has asked me 'why' the speed of light is what it is. I don't recall ever coming across an explanation for this and any derivation of anything I've seen just states that what it is.

It's set me wondering.

Is it something along the lines that if it were different we wouldn't be here (like the fine structure constant?).

'ello Es - good ta c u doin' good over 'ere. i just recently started w / Einstein - thought i's drop ya a line. . .

. . . the Truth is Out There

debugas
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RE: the fun with

Message 45847 in response to message 45845

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the fun with entanglement and "spooky resolving of state at a distance" can only be due to internal hidden ('entangled') states

Unfortunately these hidden variables possibility so far had been rejected by the experiments on EINSTEIN-PODOLSKY-ROSEN paradox
I find myself uncomfortable with the results but i have no ground to disbelieve it

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