[Turtle]

Saw this today and thought you all would find it intersting. >>

Future fibre networks to exceed light speed? - ZDNet UK

Originally Posted by zdnet.co.uk

...Exceeding the speed of light, approximately 300,000km per second, is supposed to be completely impossible. According to Einstein's special theory of relativity, it would take an infinite amount of energy to accelerate an object through the light barrier.

But two German physicists claim to have forced light to overcome its own speed limit using the strange phenomenon known as "quantum tunnelling". ...

[CraigD]

Originally Posted by Turtle

Saw this today and thought you all would find it intersting. >>

Future fibre networks to exceed light speed? - ZDNet UK

C1ay posted this news in brief thread on the same story yesterday afternoon. The ZD article Turtle links is, IMHO, better than the telegraph.co.uk article in the news thread.

At first glance, I’m surprised that knowledgeable professional scientists would claim that the effect described is “the only violation of special relativity that I know of”, or believe that it could be used for a faster-than-light communication device. Quantum physics contains may examples of “superluminal effect at a distance”, but none that can be exploited to practically send a signal (or a physical object) to a distant point at greater than the speed of light in vacuum. At second glance, the cynic in me suggests that this is most likely a publicity stunt to draw attention – and, hopefully, additional research funding – to these scientists. In the practical world of limited-funding science, I can’t fault them for that.

[alexander]

Two German scientists (Gunter Nimitz and Alfons Stahlhofen) just proved that through photon tunneling, you can accelerate photons to move faster then the speed of light. Actually they just demonstrated this with 2 prisms about a meter apart shining light on the same detector, now even though they are not equidistant from the surface, the photons from both lenses were shown to hit the surface at the same time.

I may be wrong ofcourse, since i dont have time to find more evidence, all i have to go by is a Russian newspaper article dated Aug 17th and a wiki article titled Faster-than-light

[Jay-qu]

Originally Posted by alexander

Two German scientists (Gunter Nimitz and Alfons Stahlhofen) just proved that through photon tunneling, you can accelerate photons to move faster then the speed of light. Actually they just demonstrated this with 2 prisms about a meter apart shining light on the same detector, now even though they are not equidistant from the surface, the photons from both lenses were shown to hit the surface at the same time.

I may be wrong ofcourse, since i dont have time to find more evidence, all i have to go by is a Russian newspaper article dated Aug 17th and a wiki article titled Faster-than-light

Its to this that I was referring, but if this experiment turns out to be correct we have to be careful how we define speed and acceleration in these situations. ie is the photon actually moving FTL or is it just 'transported' across the gap FTL - is there a difference, I would say yes, as there is no possibility of detecting the photon in the intervening gap.

[freeztar]

Originally Posted by Jay-qu

Its to this that I was referring, but if this experiment turns out to be correct we have to be careful how we define speed and acceleration in these situations. ie is the photon actually moving FTL or is it just 'transported' across the gap FTL - is there a difference, I would say yes, as there is no possibility of detecting the photon in the intervening gap.

I agree with your thoughts Jay.

If it is quantum tunneling based upon quantum uncertainty, then it is safe, imho, to call this effect 'teleportation' rather than FTL travel. Of course, teleportation is not an accurate description as it is more of a probability (from what I gather from the reading material available).

Nonetheless, if we measure from our reference frame, some information appearing in a location faster than light speed, then we must agree that FTL travel has transpired, from our frame of reference. This is not in disobeyence of SR as Jay-qu has pointed out, but it speaks volumes for quantum dynamics. It's implications are potentially enormous.

[alexander]

Originally Posted by jay

Its to this that I was referring, but if this experiment turns out to be correct we have to be careful how we define speed and acceleration in these situations. ie is the photon actually moving FTL or is it just 'transported' across the gap FTL - is there a difference, I would say yes, as there is no possibility of detecting the photon in the intervening gap.

Right, it seems to change position FTL, but does it actually travel the distance. I see where you are going with this, sort of. Say I'm driving a car at 60 miles an hour (yeah ok), and all of a sudden I instantaneously transport a mile down the road (and according to quantum theory it may very well happen, hence why i am reading and watching more into the string theory). But without having any equipment that detected the car on the road while i was instantaneously traveling that mile there are questions to ask: does this mean that i traveled at infinite speed for that moment, or did i continue to travel at 60mph bu happened to instantaneously relocate to a different coordinate in a space/time fabric, say via something like a worm whole.
Am I on the right track of thinking here? (and i am not a math person, more of a philosophical physics person)
If i am, then we may have to redefine speed to include the concept of body positioning over the distance...

[Jay-qu]

yes alex thats just it, how are we to redefine velocity when things can appear to instantaneously relocate. If is was using a wormhole as the mechanism for relocation I would still think it would take some time, possibly shorter but also possibly longer, because the idea of a wormhole is your still occupying space, just twisted up non-flat regions of it. Which would mean they could also serve as detours, not just short-cuts.

[LaurieAG]

Originally Posted by Jay-qu

Its to this that I was referring, but if this experiment turns out to be correct we have to be careful how we define speed and acceleration in these situations. ie is the photon actually moving FTL or is it just 'transported' across the gap FTL - is there a difference, I would say yes, as there is no possibility of detecting the photon in the intervening gap.

Hello Jay-qu,

Has anybody come across an accurate image on how the experiment was setup/undertaken?

I had a look at the New Scientist article and their image of the light paths didn't seem right. Their image showed the control beam travelled along the back edge of the first prism for a distance before 'reflecting' off the inside of the first prism, at the mirror of the angle it came in (i.e. was the control photon tunelling as well, because it certainly wasn't reflecting normally).

Surely, if the 'tunnelling' photon was going through the prism(s) at the same angle as the control photon and it went across the gap to the second prism, you would expect the control photon to reflect off the front face of the second prism, leaving the actual distances travelled by both photons being much the same.

[Jay-qu]

No, I havent, at the moment Im just enjoying speculating on this slight possibility but I would love to see a published article or experimental setup.

[LaurieAG]

Hi Jay-qu,

Originally Posted by Jay-qu

No, I havent, at the moment Im just enjoying speculating on this slight possibility but I would love to see a published article or experimental setup.

I just dug up the following article, they refer to the setup and have some good images/diagrams.

Popular Science - Feature

Purely imaginary solutions of the wave equation seem to imply a zero shift in the phase of the wave – which would mean that the wave spent zero time in the barrier, crossing it instantaneously (or perhaps more accurately getting from one side of the barrier to the other without crossing the intervening space). With the electromagnetic analogies available, it was tempting to test tunneling time for real using photonic experiments.

First microwave [3] and later optical experiments [4,5]were carried out to measure the total tunneling time of the photons.(In Fig.2: the tunneling time is tv+th) This strange, two part timing is due to the nature of frustrated total internal reflection. The photon is not a point, but extends out into the gap, so the reflection appears to take place behind the surface of the first prism, resulting in a shift down the surface before reflection, D in the diagram, called the Goos-Hänchen shift. This shift was conjectured by Newton 300 years ago, but only measured in 1947 by Goos and Hänchen.

The small value of the tunneling time results in velocities faster than light – photons crossing the barrier take less time than they should at light speed. In the actual experiment, using microwaves, it was found that both reflected and transmitted beams left their respective prisms at exactly the same time. With the distance d set at 60mm, the microwaves should have taken 20 picoseconds to cross the gap. However this time was not detected. The experiment was accurate to ±5 picoseconds, so something should have shown up. It seems that tunneling inside the barrier is nonlocal, proceeding in zero time. (Details of the experimental set-up are given in [6])

It might seem possible that the tunneling photon actually heads straight across the gap and doesn’t first undergo the shift – but the time taken is independent of the gap size and as near as can be identified identical with the time to cover the distance D.

Another interesting aspect of the tunneling process is that the predicted energy of the tunneling particles is negative. This fact, often overlooked in photonics, is noted in solid state physics [7], in quantum mechanics [8], and some textbooks on near-field optics. Are tunneling photons detectable? Theory says no, they should only be in evidence outside the barrier – see, for instance [8 and 9]. We have carried out a standard experiment with an undersized waveguide as shown in Fig.1a.