Saturday, August 18, 2007

Yes, but the real issue here is whether the effect can be used for practical superluminal communications AKA signal nonlocality. Note that virtual quanta do have a direct gravity effect. They do not have a direct electrodynamic effect in the case of photons, i.e. a virtual photon does not make a counter click, though it does shift sharp atomic spectra. A Valentini has shown how quantum theory must be changed to allow signal nonlocality.
On Aug 17, 2007, at 2:39 PM, art wagner wrote:

On Aug 17, 2007, at 8:49 AM, Jack Sarfatti wrote:

OK I looked at the 2002 paper on the Hartman effect below which is certainly correct. The author at end seems to say you cannot use the stored energy in non-propagating evanescent standing waves to effectively transmit a bit faster than light using the "group delay" eq (13), but, while that may be true, he does not prove or explain why it is that way.

On Aug 17, 2007, at 8:22 AM, Jack Sarfatti wrote:

Again issue is whether they can show useful FTL signaling to move data around computers for example. Probably not.
On Aug 17, 2007, at 5:22 AM, wrote:

Boffins issue speeding ticket for FTL photons

Photons will appeal, citing Hartman

By Lucy Sherriff ? More by this author
Published Friday 17th August 2007
Two German scientists claim to have broken the speed of light with a tunneling photon, a pair of prisms and a gap of about three feet. According to New Scientist, G√ľnter Nimtz and Alfons Stahlhofen from the University of Koblenz claim to have made the photon jump "instantaneously" across a barrier ranging from a few millimeters to three feet.
They started with a pair of prisms sandwiched together to make a 40cm cube. Then, they shone microwaves with a wavelength of 33cm through the prism. As they gradually moved the prisms apart, the microwaves, which had passed straight through, began to be refracted. Some of the microwave photons, however, tunneled across the gap. So far, so good. All in line with our expectations. But Nimtz and Stahlhofen say the refracted photons and the tunneling photons arrived at their respective detectors at the same time, regardless of the size of the gap. This, they claim, suggests that the tunneling photons have jumped the gap much faster than the speed of light. Nimtz told the magazine that the results were a violation of Einstein's theory of special relativity. But not everyone is convinced the pair have interpreted their results correctly. Some argue that what the scientists have observed can be explained by the so-called Hartman Effect. This predicts that "the tunneling (sic) time becomes independent of barrier length for thick enough barriers, ultimately resulting in unbounded tunneling (sic) velocities." What this means is that single photons can appear to travel faster than the speed of light. But researchers suggest that tunneling time should not be considered as a transit time, but rather as a "cavity lifetime." Herbert G Winful from the University of Michigan explains in this paper that anomalously short delays in barrier tunneling "should not be linked to a velocity since evanescent waves do not propagate." So, Einstein is off the hook, and thus restored to his rightful place as top boffin. ®

No comments: