Faster-than-light electric currents could explain pulsars

[n2doc]

By George Musser


Claiming that something can move faster than light is a good conversation-stopper in physics. People edge away from you in cocktail parties; friends never return phone calls. You just don't mess with Albert Einstein. So when I saw a press conference at the American Astronomical meeting this past January on faster-than-light phenomena in the cosmos, my first reaction was to say, Terribly sorry, but I really have to go now. Astrophysicists have been speaking of FTL motion for years, but it was always just a trick of the light that lent the impression of warp speed, a technicality of wave motion, or an exotic consequence of the expansion of the universe. These researchers were claiming a very different sort of trick. Dubious though I was, I put their press release in my "needs more thought" folder and today finally got around to taking a closer look. And what I've found is utterly fascinating.

The researchers, John Singleton and Andrea Schmidt of Los Alamos and their colleagues, have built a sort of wire in which an electric pulse can outpace light. They get away with it because the pulse is not a causal process. It does not ripple down the line because charged particles are bumping into each other, a process that is subject to Einstein's speed limit. Instead, an external controller drives the particles and can synchronize them to make a pulse pass through the wire at whatever speed you want. The particles are like dominos in a row. A causal process is the usual domino effect in which each domino knocks down the next; the dominos move at their own speed, determined by their size and spacing. An acausal process is if you knocked down all the dominos with your hand; the dominos move however fast you can make them. The photo above shows an early version of the contraption; the wire is the white arc on the right, and the controllers are the circuit boards on the left.

This method of breaching the speed barrier might seem like cheating -- after all, no material object is breaching the barrier. But electromagnetically it doesn't matter. Whatever the origin of the pulse in a wire, it involves the motion of electric charge and emits electromagnetic radiation. The radiation propagates outward at the speed of light, but is forever shaped by the speed of whatever generated it. When Singleton, Schmidt, and the rest of their team generate slower-than-light pulses using their technique, the resulting radiation looks just like the radiation created by ordinary causal pulses. For faster-than-light pulses, the radiation looks just like the radiation that would be created if charged particles really could exceed the speed of light.

Which is to say, it looks pretty weird. Not only is the radiation tightly focused in space, it is tightly focused in time -- a pulse that originally takes, say, 10 seconds to generate might be squeezed into 1 millisecond as all the electromagnetic wavefronts get jammed together. The temporal focusing causes the radiation to spread out over a wide swath of the electromagnetic spectrum. In addition, the focusing provides a degree of amplification, causing the intensity of the radiation to diminish not with the inverse square of the distance but with the inverse distance.

more

http://www.scientificamerican.com/blog/post.cfm?id=faster-than-light-electric-currents-2010-06-18

[jgraz]

1. Very cool, thanks for posting.

[Vinnie From Indy]

2. I'm sticking with Al

[j420norcal]

3. Isn't Quantum Entanglement faster than light?

I remember reading somewhere that it was estimated QE transmits information at a speed of AT LEAST 10,000 times the speed of light.

[mindwalker_i]

4. Quantum entanglement should be an instantaneous effect

Actually, it may be more than instantaneous. The basic deal is this: you set up a situation where you don't know the actual values of two things, but you know they add up to a certain value. For example, momentums of two objects add up to zero or the spins of two photons are opposite. When you actually measure the quantity on one object, the other object then has a known value.

Dr. John Cramer of the university of Washington is putting together an experiment that should first, send a signal with this and second, send a signal backwards in time. The core principle is to use entangled beams of photons created from parametric downshifting of a laser, and send one beam into a classic double-slit experiment. The other beam goes into a measurement apparatus that either is capable of determining the momentum of each photon (in principle), or is set not to record this infortmation. That will destroy the interference pattern on the initial beam, or not, depending on the setting of the measurement. This experiment was done by Birgit Dopfer in 1998.

Next, Cramer wants to delay the measurement by 50uS with fiber-optics. If that works, and there's no good reason it won't, then a signal will effectively be sent back in time. I cornered Dr. Cramer at Norwescon in April, bought him a beer and pretty much picked his brain. He's my hero!

[laconicsax]

6. That is and isn't instantaneous.

Once the measurement is done, the observed effects will be instantaneous, but because the signal is technically sent back in time, it isn't instantaneous--it's always been like that.

Fun with time paradoxes.

[qazplm]

7. I dont believe it's actually information

that is transmitted.

Maybe multiple states collapse into one simultaneously and instantaneously, but I don't the one entangled particle tells the other particle what to do once you observe it.

[j420norcal]

8. I agree

but I really have no other words to explain it and my understanding of this principal is quite limited.

[Kip Humphrey]

5. c squared