Hi Horace. I wanted to address you points with the article text, but the link has gone sour...
Anyway, I think your differentiation is moot. I can build a radio circuit that displays behavior EXACTLY as shown in the graph. The link I posted to Nimtz illustrates how this can be done ( my own work is unpublished or I'd link you to it instead). The key issue remains, how do we define velocity? As the authors point out, the older notions of group and phase velocity need be extended to include a third velocity, what they call the "signal velocity" or what I call the transistion or shock velocity. Horace writes: >I think it is fairly well known in QM that all photons >do not travel at c, but rather have a distribution of travel times. Really? Are you saying that photons in a vacuum can travel faster or slower than c according to QM? That doesn't seem right to me. Or are you trying to describe the fact that photons tend to take all possible paths from the source to the receiver and therefore arrival times can vary. I seem to remember this from Feynmans QED, and I've seen the exact same thing with free space antennae. K. -----Original Message----- From: Horace Heffner [mailto:[EMAIL PROTECTED] Sent: Tuesday, December 07, 2004 3:54 PM To: [EMAIL PROTECTED] Subject: RE: Superluminal cavity resonances was RE: Fast-food for thought At 2:08 PM 12/7/4, Keith Nagel wrote: >Let's look at that graph again. > >http://physicsweb.org/articles/news/8/11/10/1/041110 > >Notice how the light speed delayed pulse is larger than the slow or >fast wave? Let's imagine two machines as you describe, the only >difference being that one is implemented using the fast wave and the >other with the light speed delayed signal ( the large one ). > >If I set the detector to trigger at the peak ( roughly the "center of mass" >of the energy of the pulse ) the fast wave will be faster than >the delayed wave. If I set the trigger at the 50% point on the >risetime, now my light speed delayed system is going to be >faster than my fast wave system. It appears you are misinterpreting the subject graphic (or I am.) I take it as in incident count graph. It is a tabulation of photons by arrival times. Some photons arrive early, some late. It is not a pulse trace, but could be if all the photon's detection pulses were summed (pulse time averaged) together. I think it is fairly well known in QM that all photons do not travel at c, but rather have a distribution of travel times. My point is that it pays to go way out on the tip of the trace as far as possible. In this case that would be at the single photon detection level. Now, the problem is that on average, the first photon may arrive early or late. On average we don't do better than c with a single fiber. My suggestion is to simultaneously transmit a given bit on lots of fibers at once. Then, *with any desired degree of but not perfect reliability*, based on the number of fibers used in a bundle, an early photon will be sensed within a time window that provides communication at greater than c velocity. We can do reliable communications way out on the front of the distribution. By sending multiple bits at a time in parallel, along with a timing pulse, we can use error detection and correction techniques to greatly increase reliability. By sending photons on two bundles, one bundle having photons sent if the data bit is 1, the other having photons sent if the data is 0, we can reliably do error correction at the bit level way out on the tip of the pulse, before any photons even arrive at velocity c. A more simple test of concept might be to use two bundles from Alice to Bob, with Bob having a repeater to send the data back to Alice on two return bundles. Alice could then measure the error rate as well as turn-around time. Regards, Horace Heffner
