quote: To create their cable, the Canadian researchers joined together five-metre sections of coaxial cable with alternating electrical impedences. Radiation in the frequency range 9 - 11 MHz is partially reflected at the boundaries of these segments, which gives the cable its absorption band. Haché and Poirier sent electromagnetic pulses with frequencies between 5 and 15 MHz through the cable, and found that the group velocity reached three times the speed of light for frequencies in the absorption band.
Haché and Poirier emphasize that their experiment does not break any laws of physics. Although the group velocity exceeds the speed of light - an effect permitted by relativity - each component of the pulse travels slower than light. It would be impossible to transmit information faster than light because it would be encoded onto a single frequency component.
How, or why, does relativity permit the 'group velocity' to exceed the speed of light?
Posts: 13123 | Registered: Feb 2002
| IP: Logged |
posted
Well...that's ONE possible explanation. The other possible explanation is the so called "rumor effect." It has been known for many years that nothing travels faster than rumors. Especially in scientific establishments. And, of course, no good rumor mill can operate in a vacuum. Or with just one conduit.
But, get a group of scientists together. Mix in grad students and a few admin types. And voila! Faster than light communication is not only possible, but one might say "inevitable."
Oddly, since this speed is much faster than that of sound, often people know things before they've been said. In a model of modern efficiency, some researchers have found that they can actually confirm and deny a rumor in advance of anyone even having uttered it near any other person.
The Bush Administration has funneled all of next year's NSC budget into this "mission critical" work. Or so I heard. I think.
Posts: 22497 | Registered: Sep 2000
| IP: Logged |
posted
Another mechanism for FTL information transfer is implied by Bell's theorem. Please don't ask me to explain it as I don't really understand it.
It involves Borh's hidden variables system to explain contradictions between quantum theory and relativity. It is debatable whether hidden variables can be used to transfer information. No one has come up with a mechanism to do so, but some physicists think it may provide a loophole in relativity that allows supraluminal information transfer. Mastery of hidden variables would also lead to other really astounding technologies. Here's what I posted on the Post-einsteinian physics thread : Check out Greg Bear's "Moving Mars" about a future Mars (24 or 25th Cent) that learns how to access Bell theorem non-local particle descriptors. This allows instant teleporting ignoring light speed, destruction/creation of matter/energy anywhere in the universe and other seemingly miraculous stuff. Now that's a HACK! You could hack the universe on your laptop on the beach (probably go thru batteries pretty quick)
Posts: 6316 | Registered: Jun 2003
| IP: Logged |
Printer-friendly view of this topic
![[Big Grin]](biggrin.gif)
