Speed of light broken with basic lab kit

New Scientist.com ^ | 16 September 02 | Charles Choi

[Hessian]

Except in Afghanistan, (which is 30 minutes off from the rest of the world) where it would be 43 past the hour...

[Physicist]

Anybody got a clue here?

There have been three or four spates of articles over the past few years in the popular press about FTL signals, but this is the first time I recall the difference between group velocity and phase velocity being mentioned in the article itself, so I count that as progress. Let me see if I can illustrate it more clearly.

Suppose I have a train that's four miles long. It passes through Hicksville on the way to Podunk, which is four miles away. It is travelling at thirty miles per hour, which is the speed limit on the line. Any faster, and the conductor gets reprimanded.

Officially, the location of the train is counted as the center of the train, no matter how long the train is. By the time the train officially leaves Hicksville, the train's engine is halfway to Podunk. At that point, unbeknownst to the engineer, who is preoccupied with the train's speedometer, the engine and the first few cars of the train get decoupled from the rest of the train. Four minutes later, the train--now consisting of the engine and a few cars--arrives at Podunk.

The official speed of the train is 60 miles per hour, which is twice the speed limit. The engineer is duly reprimanded, and customers line up to buy tickets for the new high-speed rail service.

[Solson]

Faster processing speeds will first come from nano-tech rather than fater than speed of light transmission of data...

[scouse]

Sheesh! These kids today; They break everything they touch.

[AdamSelene235]

Another reason not to fixate on "prestige" universities.

You mean the ones that teach the difference between phase and group velocity?

[maximus@Nashville]

I am pleased to see this at my alma mater, the second largest university in the state of Tennessee as well as being a state school. Amazing what they can do when concentrating on non-PC issues.

[Free the USA]

Index Bump

[2oakes]

I like the explanation of the "Kingon" particle, as provided by Terry Pratchett.

When a king dies, his next in line becomes king instantly, whatever their place in the Universe, therefore making the "Kingon" the fastest particle.

Experiments on kings using near-death torture is undergoing in further research.

[Cachelot]

You throw 200 GB in one second at your computer and see what happens.

I do that all the time, and it just glows slightly. Quite pleasant, really. Should I worry?

[apochromat]

If it's twelve seconds past the minute here, then it's twelve seconds past the minute everywhere, except where they can't afford a good clock.

[matrix]

Schrodinger's cat

Schrodinger's cat is a famous illustration of the principle in quantum theory of superposition, proposed by Erwin Schrodinger in 1935. Schrodinger's cat serves to demonstrate the apparent conflict between what quantum theory tells us is true about the nature and behavior of matter on the microscopic level and what we observe to be true about the nature and behavior of matter on the macroscopic level.

First, we have a living cat and place it in a thick lead box. At this stage, there is no question that the cat is alive. We then throw in a vial of cyanide and seal the box. We do not know if the cat is alive or if it has broken the cyanide capsule and died. Since we do not know, the cat is both dead and alive, according to quantum law, in a superposition of states. It is only when we break open the box and learn the condition of the cat that the superposition is lost, and the cat becomes one or the other (dead or alive).

We know that superposition actually occurs at the subatomic level, because there are observable effects of interference, in which a single particle is demonstrated to be in multiple locations simultaneously. What that fact implies about the nature of reality on the observable level (cats, for example, as opposed to electrons) is one of the stickiest areas of quantum physics. Schrodinger himself said, later in life, that he wished he had never met that cat.

Read more about it at:

>	The Measurement in Quantum Mechanics FAQ provides more about Schrodinger's cat.
>	For a lighter look, see "Schrodinger's Cat: Fun Quantum Physics Experiments You Can Do In Your Spare Time!"

[kcar]

Did anything interesting happen temporally?

[jwh_Denver]

"You throw 200 GB in one second at your computer and see what happens."

Good point. Since this light thing is still in it's infancy and we know that they've been working on a light speed computer it may be a merge of technology that makes for a bazillion speed chip to handle processing.

[balrog666]

The official speed of the train is 60 miles per hour, which is twice the speed limit. The engineer is duly reprimanded, and customers line up to buy tickets for the new high-speed rail service.

That's a good one.

[apochromat]

The neat thing about a relativistic time frame is that if the reference source is one light-second away, it sets your "instantaneous" time at one light-second relative difference. So if a c-velocity beam leaves the reference source at time H 00:00, it arrives here at H 00:01. If the beam had traversed the same distance 60 times faster than light, it would have arrived at H 00:00:01. This is easily disproven, of course.

[balrog666]

By using the oscilloscope to trace the pulse's strength and speed, the researchers confirmed they sent the signal's peak tunnelling through the cable at more than four billion kilometres per hour.

Now how about this part? How does an oscilloscope trace (operating far, far below the speed of light) measure (or confirm a meaurement of) anything at, or above, the speed of light without combining measurements of multiple pulses or simply tracking some phase shift of the combination signal? It still seems to be very sloppy writing and/or very sloppy lab work to me.

[apochromat]

Same thing works in both directions, even if a UFO flies by my window at 0.5 c and commands me to say cheese when the beam arrives here. This boring fact has befuddled physicists for decades.

[Physicist]

It sounds as if they are using an oscilloscope to measure the pulse shape and timing at the end of the cable. They know the starting pulse and they measure the ending pulse. I don't see why that wouldn't work.

[FormerLurker]

Electrons usually travel at about two-thirds of light speed in wires, slowed down as they bump into atoms. Hache says it may be possible to send usable electrical signals to near light speed.

Electrons travel MUCH slower than 2/3s light speed in wires. In fact, it is actually ELECTRIC FIELD that produces what we know as electromotive force, electromagetic waves, and various other phenomenon...

Electrons actually "drift" through a conductor at VERY slow speeds. Accordingly, this phenomenon is known as Electron Drift.

Given a copper conductor with a diameter of 2mm, and a DC current of 1 Amp, it would take 12 hours for an electron to travel 1 meter..

[FormerLurker]

Might this be related to Longitudinal EM Waves?