Man, I knew I should've gotten in on the ground floor in
any effort to speed up light -- someone's going to be
rich beyond their wildest dreams.
(Thanks to a post over at Slashdot) the Science Blog
reports that:
[snip]
A team of researchers from the Ecole Polytechnique F�d�rale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light � both slowing it down and speeding it up � in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions. Their results, to be published in the August 22 issue of Applied Physics Letters, could have implications that range from optical computing to the fiber-optic telecommunications industry.
I doubt they are exceeding the speed of light. Propogation delay inside
fiber is about 2/3 the speed of light so perhaps they have succeeded to
increase the speed to 3/4?
I doubt they are exceeding the speed of light. Propogation delay inside
fiber is about 2/3 the speed of light so perhaps they have succeeded to
increase the speed to 3/4?
-Hank
I have seen experiments with antennas and Oscilloscopes, done by Hewlett and
Packard in the 1920s I believe. They have shown the left wing of a dipole
antenna knows things in advance that you do to the right wing. The little
spike they photographed on their scope did prove it. I have seen a repetition
of that experiment at Darmstadt University studying computerscience and
having lessons in electricity. I am a hamradio operator. Those guyes are
always curious. But sorry I did not comprehend what that experiment was all
about.
The experiment has shown that really the left wing of the dipole antenna
"knows things before you do them". But for you to see them you have to
get that information throug a coax cable. That information will reach you
the moment you do it. Here we go
On the other hand I have read again and again about those Lausanne people
sending information through tunnels at speeds faster than light and they
could proove it. Using normal fiber under normal environment conditions
gives things an interesting twist. Now everybody can touch it.
Perhaps they are referring to being able to vary the speed while it is below the speed of light. That is, slowing it down to 1/10th the speed of light, and then speeding it up to 1/5th the speed of light.
Perhaps they are referring to being able to vary the speed while it is below the speed of light. That is, slowing it down to 1/10th the speed of light, and then speeding it up to 1/5th the speed of light.
Steve Brown
I have had a look into one of my microwave books. I have seen in coax
cables the speed of lite drop to 90% or 80% depending on the insulator,
the dielectric. In waveguides, you might say in a coax cable without the
wire in the midle and without the insulator the speed goes up.
Seeing antennas made of coax always smaller than actual wavelenght and
antennas made of waveguides always bigger than wavelenght suggests
inside that waveguide the speed must be higher than the speed of light.
Those people experimented with tunnels first. You might say waveguides.
But now they are playing around with fibre. That allows us to verify
wether you really can send information faster than lite in it. I hope
we can make the cable long enough. Hopefully across the atlantic.
No, they were actually over the speed of light for a "portion of the
signal":
"They were also able to create extreme conditions in which the light
signal travelled faster than 300 million meters a second. And even though
this seems to violate all sorts of cherished physical assumptions,
Einstein needn't move over relativity isn't called into question, because
only a portion of the signal is affected."
I asked about this article to someone who works on optical properties
of materials. Here's what he says (I don't pretend to understand
everything though):
" This is called superluminal propagation, and many groups have shown
it in different media; this one is in fiber. However, this does not
violate anything apparently because it is only the leading edge of a
pulse, and information still cannot go faster than c.
I have been trying to understand what Einstein actually said.
Apparently he said that "information" cannot be transmitted faster
than c. Now light has a phase velocity which exceeds c all the time.
The textbooks then say that it is the group velocity that cannot
exceed c. But I found out while writing my book that even that is
possible near resonances. Then I saw somewhere that "energy velocity"
cannot exceed c. Well, I tried deriving that in a general medium and
cannot see why it is fundamentally impossible. I asked around, and
one of my colleagues says that it is far more subtle than even
Einstein may have realized..it is the leading edge of a pulse (or
something like that) that can exceed c, but the whole pulse itself
cannot. I really don't understand that part, and haven't found any
text describing it. (Need to find one)."
Not the speed of light; the speed at which the electromagnetic
wavefront travels through *that* conductor. Yep; this is velocity
factor. It can go down surprisingly far.
