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Speed Of Light Broken With Off Shelf Components
jukal writes "An interesting article at NewScientist.com: " Now physicists at Middle Tennessee State University have broken that speed limit over distances of nearly 120 metres, using off-the-shelf equipment costing just $500.", " it may be possible to use this reflection technique to boost electrical signal speeds in computers and telecommunications grids by more than 50 per cent. 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. ""
anyone selling a bridge?
Cretin - a powerful and flexible CD reencoder
it's not just a good idea, it's the law!
sulli
RTFJ.
Ack! I bet by the time I hit submit, some other guy using electrons travelling faster than light will have beaten me to first post!
Damn you technology!
Using onion skins, sixty-four removed coke labels and an ampersand.
----
"Those who quote others are more likely to one day be quoted" -Tom Planter
Speed Of Light Broken With Off Shelf Components
Careful here, guys. Breaking the speed of light would be a truly wondrous, nobel-prize winning acheivment. Building transmission eqipment which boosts signal speed is really good and worthwhile, but nowhere near as important an advanced as superluminal transmission.
Please check your headlines!
The next Slashdot story will be ready soon, but subscribers can beat the rush and slashdot the links early!
http://scienceworld.wolfram.com/physics/Superlumin al.html
http://www.weburbia.com/physics/FTL.html
http://physicsweb.org/article/world/13/9/3
The thing that really seems interesting about this is that they're doing this with cheap equipment, which will make experimenting with this a lot easier.
Can anyone explain how this would be used to increase subluminal transmission of electrical signals, as mentioned in the article? This whole group velocity thing has always seemed like a bit of an illusion to me, and none of the explanations I've seen has really clarified how it's anything more than that.
Imagine a rotating laser light source. If you had a laser beam that was rotating at only 2rpm, the beam would move across the surface of the moon at approx 1.7 times the speed of light, but you are not really moving anything (not even light) at more than c. You can't use this to transmit any information or power.
JET Program: see Japan, meet intere
Ye gods, I hate these types of stories. The real physics is always more subtle and interesting than the press makes them out to be.
The vast majority of the experiments I've seen like this (I've really only looked at photon tunneling, but this sounds *very* similar from the write-up) are explained by wave-shaping, and the side-effects of that, and are not actually FTL at all. But of course, that's hard to explain to people, so the New Scientist, et al, just go for the "Speed of light broken!" headline, which mis-leads everyone.
Grrr.
If you want to see a "thing" travelling faster than light, sweep a searchlight across a cloudy sky. That lit-up patch can, in principle, travel faster than light -- but it's not matter or energy, only an appearance.
And the last paragraph: "electrons usually travel at two thirds the speed of light". Wow, who needs particle accelerators?
What is a writer who can't distinguish the speed of electrons from the speed of the electrical signal doing writing for New Scientist? What is New Scientist doing publishing such crap?
What the group has attained is a transmission line with a phase velocity greater than the speed of light. This is actually not too hard to do with a resonant line (which they have), but they have constructed a cute, cheap way to demonstrate it. The group velocity, which is the speed at which information moves, is still less than c, and they explicitly say so.
The best use for a setup like this is to bring a good demonstration of the difference between the two to an undergraduate laboratory setting, to hammer into students forever the importance of the difference.
This is known because researchers observed the results of the experiment a month before it was actually attempted.
At first, they were confused by their output terminal spewing phrases like "Hello world!", "Is this thing on?", "How can we tell if it's working??", "What's WRONG with this FSCKING THING??", "FSCK IT! I'm going home!!!" late last month. Earlier this week, one researcher was sending keyed kignals into the system, and becoming frustrated at the lack of output, until he and a colleague accidentally picked up a stack of printed logs from 4 weeks ago and discovered the system had worked before it had been turned on.
Neither researcher could be reached for comment, as they both suddenly became multi-quadrillionaires and are living on private islands in the South Pacific.
bytesmythe
Hypocrisy is the resin that holds the plywood of society together.
-- Scott Meyer
Did you see the related stories associated with this article?
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15 August 2001
So which is it light is speeding up or slowing down???
Just to get some things straight:
Although it is possible to define and even measure speeds faster than the speed of light in vacuum, you cannot transmit signals with a speed faster than light.
You can have electrons faster than the speed of light in a certain medium, that's when you get Cherenkov radiation.
You may think tunneling can give you speeds faster than light, but that's only possible for a part of the particles that tunnel and on average you won't be faster. Since you don't know which particle is going to be faster, no increase in signal speed.
You may even see that the peak of a signal arrives faster, but that is only because the whole shape of your signal is changed and amplitude of your signal is reduced, so that the peak moves forward during the tunneling process. There is no way that
the signal front is faster than light.
The experiment is interesting in so far that it gets you closer to the speed of light which is your limit.
***Quis custodiet ipsos custodes***
Shine a laser at a mountain a hundred miles away and rotate at modest speed--the spot of light will move faster than light. From the fluffy description in the New Scientist, it sounds as if they roughly did an electrical version of that--what moves is something you construct in your mind, not anything tangible or anything you could use to "send signals faster than light". And, unlike the "complicated setups" they are referring to, their effect is purely classical.
I hope you arent scolding the /. editors for this, because if you look at the article it has an almost identical headline.
Speed of light broken with basic lab kit
Im not here now... Im out KILLING pepperoni
Uh Oh - this whole Victor Ninov thing is going to result in his name becoming a verb
"Jeez, you really Ninov'd those results!"
I hate it when that happens
Robots are everywhere, and they eat old people's medicine for fuel.
Not quite.. the thing is not that it was falling down but that the guy thought he was buying Tower Bridge.
no sig.
Regarding phase velocity vs. group velocity, both phase velocity and group velocity can exceed c - see Superluminal, second paragraph. Group velocities exceeding c have been done for decades - for a bit of a history, see No thing goes faster than light.
The innovation in this case seems to be that it's doable with cheap equipment, and over fairly long distances.
c ~ 1802617528320.3 furlongs/fortnight
Sandurz: Prepare for light speed.
Helmet: No, no, light speed is too slow.
Sandurz: Light speed too slow?
Helmet: Yes, we'll have to go right to...Ludicrous speed!
Sandurz:Ludicrous speed! Sir, we've never gone that fast before. I
don't think the ship can take it.
Helmet: What's the matter, Colonel Sandurz...CHICKEN?!
NO! NO! Please don't mod me, I'm too young to die a troll. *click* Oh the pain, the pain...
"Slashdot! We don't suck any worse than the traditional media!"
The cake is a pie
You know, non-physical object can travel faster than the speed of light. You can do these experiments very cheaply. Take a laser, point it at the moon, and shake it around. The image you make with it traverses the surface faster than the speed of light. That doesn't mean anything is actually moving faster than c. The experiment described is of the same sort. Interesting, but packaged in a terribly misleading way.
I have already proven that you can break the speed of light barrier, in 5 years. I was visited today by myself. I guess in 4 years I am going to fall while hanging a picture in the bathroom, and hit my head on the sink. I'll be knocked unconscious and have a vision of something called the flux capacitor. It will take a year to develop, and I will be able to travel faster than the speed of light. Oh wait, or was it travel in time? Crap, I can't remember what I told me.
My beliefs do not require that you agree with them.
I'm going to munge this pretty righteously, but it's for a good cause (explaining how the speed of light wasn't violated).
:-)
Take a bunch of cars in traffic -- stop 'em, say there's an accident. Cops go ahead, clear the accident. Open road, right? Clear to go 65.
Does the entire traffic jam disappear immediately? Nope. Each *car* may be able to go 65 now, but they have to wait for the car in front of them to go away. That takes time -- two to five seconds. There's a bit of a blurring, as people see cars three or four cars ahead start to speed up -- but just because the cars *could* go sixty five, doesn't mean they *are*.
If you were sitting above the traffic in a copter, you'd look down and see a "pulse" travel slowly back through the crowd, as slowly everyone saw the car in front speed up. Eventually the entire group would speed up to some maximum speed.
The speed of the cars forward is the group velocity (more or less).
The speed that "all clear" pulse went backwards, that's the phase velocity.
Imagine everyone was drunk -- that pulse would go back really, really slow. Imagine everybody's car had a computer, linking 'em together. The *moment* the guy in front of them moved, they'd speed up too. That pulse would go quite fast, and traffic would be rather more bearable.
Same speed limit -- same group velocity -- but phase velocity ranges from near zero to past the speed of light, depending on whether drunk drivers or synchronized computers are behind the wheel.
At no point does any care break the speed of light, though
--Dan
From the post: "Electrons usually travel at two-thirds of light speed in wires".
Now that would be truly remarkable and fairly dangerous, what would happen if you cut the cable and pointed the end at someone?
In reality, electrons move abysmally slow, something along 2cm/hour if I remember my high-school physics classes correctly. What moves at 2/3 the speed of light in wires is the signal.
Think of it this way: when you turn your kitchen hotwater tap, water starts flowing from your tap immediatly and water starts flowing within the pipes very quickly as the sudden _change in water pressure_ (signal) propagates through your pipes.
The water itself however, is not really moving this fast. It is not the same water going in that is coming out.
Someone please sign Hemos up for physics 101? I would do it but I live in Norway and I doubt he would be able to concentrate on anything else than our fjords if he bothered coming here.
"There is no substitute for thinking" - Bjarne Stroustrup
I think the best analogy I've ever seen is the one using ping pong balls.
Imagine you have a long tube filled with pingpong balls all the way to each end. Then, when you push another ball in one end, what happens? Another ball immediately pops out the other end, at exactly the same speed that you pushed in the first one, but potentially miles away from your end of the tube. But still, none of the pingpong balls ever went faster than you pushed in the first one.
Even if it is/were possible (has anyone actually gone to the trouble to email the scientist who supposedly did the experiments?), there would be some severe expected problems.
They're talking about interfering waves. That means pulsating DC, if not straight AC. Get this up to a frequency to even be useful (ala GHz to compete with CPU or networking technology), and suddenly you're broadcasting your signal. (Though coax's construction does cause some muting of this, IIRC) And putting it on silicon is a thing for Intel to do.
And just for proof that it's not possible: "superposition."
It says that waves will pass through each other and come out the same on the other side. Easiest to see in a ripple tank, or maybe in a physlet.
What's this Submit thingy do?
The group velocity is the speed at which the information travels. Obviously that's the thing that we'd dearly love to increase.
-h-
Now if you were standing at the end where the laser (or bullet, in another poster's machine gun analogy) impacts are coming to, what would it look like to you (assuming it stops just short of hitting you)? The answer is, you'd see the closer impacts first, and the more distant impacts later. It would appear that they are going away from you. So from this perspective, time would appear to be going backwards.
The thing is, we might actually see such things happen out in space. Stars that are emitting energy in a specific direction, other than their poles, and are rotating, can illuminate dust clouds at some distance off to the side. On the side where the rotation is coming towards us, and at a distance sufficient to make the effect traverse faster than light, we'll actually see (if we can see that level of resolution) the effect go backwards. Combining the effect with an accurate rotation rate measurement, a very accurate distance from the star to the dust cloud can be measured. Then from there you can work back to an accurate mesure of the distance. In reality the distances will be rather small for quickly rotating stars, so it can't be observed directly. But surely it's effects can be predicted from other determinations of that distance and rotation rate, and then used to confirm those measurements.
now we need to go OSS in diesel cars
Prof. Farnsworths Clone: Thats impossible, you cant go faster than the speed of light. Prof. Farnsworth: Of course not, thats why scientists incresed the speed of light in 2208.
"Sic Semper Tyrannosaurus Rex."
Whew! Imagine how many points that speeding ticket will add to your driver's license!
Remember "Bring 'em on"? *sigh