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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
i didn't realize we were overdue for yet another "speed of like broken" article submission.
guess taco's gotta meet his quota...
https://www.accountkiller.com/removal-requested
That explains why I've been getting sunburned lately.
Best Windows Freeware
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!
While the instantaneous speed of electrons in copper at room temperature is about 1.6 x 10^8 cm/sec (and in random directions), the drift velocity of the electrons which determines the measured macroscopic circuit current is much smaller.
Since an electron carries a charge of 1.6 x 10-19 Coulombs, and one Ampere is a current of one Coulomb per second, the number of electrons passing any cross-section of the wire is 1/(1.6x10-19) or about 6.3x10^18 electrons per second. This must equal the drift velocity Vd of the electrons times the number of mobile electrons Nl per unit length. Since copper has a valence of one, and fundamental experiments have shown that these valence electrons behave just like free electrons, Nl is just the density of copper atoms (8.45x10^22 / cm^3) times the cross sectional area A of the wire. Therefore,
Vd = 6.3x10^18 / (NlxA)
or Vd = 0.0024 cm/sec
The time for an electron to traverse the one meter length of the wire is therefore about 12 hours. The drift velocity of electrons is very small due to the carrier scattering with the atomic vibrations ("phonons") at room temperature. In fact, it is just this scattering behavior that is responsible for the linear relation between electric field and current density in a conductor, or in more familiar terms, Ohm's Law. Note that the electromagnetic field, and hence any voltage changes, associated with the electrical current propagates down the wire at a speed close to the speed of light (3x10^10 cm/sec).
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.
Wasn't there just an article on frauds in physics?
"Live Free or Die." Don't like it? Then keep out of the USA
Can anyone explain to a non-physicist the implications of this sort of thing to Lorentz-Transformations, etc. I mean photons have energy and therefore mass and once accelerated past the speed of light wouldn't the mass and energy of said photon be several different shades of infinite?
Also, I can't help but mention a partially relevant comic: Prof Jack's Fun with Relativity
lysergically yours
What everyone wants, of course, is to send real information around at that speed. As is repeated ad nauseum every time we have a FTL dicussion on /., that isn't what is going on here. You can't move real information faster than light by any method we know. So you cannot use this to reduce the latency between your chip and RAM. Because the receiving end doesn't know ahead of time what it is supposed to receive.
But this could be useful for the clock. Unlike bits moving to and from various places, there is no element of unpredictability and surprise in the clock. You just want to get a nice predictable thud seen everywhere on the chip in sync. This effect can be used to keep distant parts of a chip in closer sync. The pulse of the clock isn't real information, it is just staying in step.
From the article: Signals also get weaker and more distorted the faster they go, so in theory no useful information can get transmitted at faster-than-light speeds, though Robertson hopes his students and others can now rigorously and cheaply test those ideas.
Obviously FM transmission would not be useful by this method. After the speed of light you would loose frequency integrity. But it maybe useful as an Amplitude Modulation(AM) medium where the frequency only has to be approximated.
You say things that offend me and I can deal with it. Can you?
Does this mean that I have to remove my e=mc^2 tatoo? Really?!?
Not as fast as me. I'm the speed-master. Just watch me get out of this seat [stands up], and RUN! [trips on shoelaces].......... [shoot]
Jonahweb.com has stuff.
ACM Technews (for those of us who get it) also has an article about this here. Hrm... Wonders idly whether that spinning noise is Einstein in his grave...
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.
it looks to me like they're using a trick of electron waveform properties by using the collisions between two opposing wavs to propogate signals faster than the electrons themselves are traveling.
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?
fp!
Just a quick reminder that ``c'' and "the speed of light" aren't exactly the same.
``c'' is the speed of light in a vacuum at a temperature of absolute 0, and it is a constant. Guess what? Alter the temperature or remove the vacuum, and it's not ``c'' any more.
Bill Nye the Science guy is rolling in his grave over CmdrTaco's stupidity.
When I went through all my college Physics classes I thought I understood the speed of light. Not that Stephen Hawking had anything to worry about, but I felt I had enough of a handle on what it meant to not sound a complete sod in a conversation.
So now 10+ years have crawled by, and I realize I must not have had any sort of inkling about the damned thing. They've gone faster than light, stopped it, and turned it into tapioca. If anyone tries to talk to me about this topic anymore, I'll just nod quietly and change the topic to something less elusive... like religion.
Bah.
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
If I recall correctly from 6.313 (Tom Knight's Contemporary Computer Design Course), signals can appear to travel faster than the speed of light, but leading edges of frequency changes cannot, so information still obeys the speed limit (well, leaving aside quantum partical physics games).
...according to Einstein's laws. This is actually stated later in the article, but it deserves a more prominent position.
What these people have done is (at best) to spread information at sub-light speeds that are faster than they were before.
Certain types of waves can seem to go faster than light, but this is not really information that is being spread. For example, if two long beams are crossing at a small angle, then the intersection can move faster than light - but information can't.
Tor
Information transfer is essentially energy transfer. It is possible to make something change in response to something at the other end of the coax faster than the speed of light, but at the end of the day no information can be transfered.
So, in my opinion, this isn't going to make those electrons in your computers and comms links move any faster.... oh well.
Imagine an enormous pair of scissors, many light-years on a side. Now imagine opening and closing the blades. The spot where the two blades come together might well travel faster than light, since it is not a physical object...it's simply a point in space. It also doesn't bear any information, since its location at any instant is just a matter of computation. IANAP, but I take it that the story here is the same kind of thing. What's traveling fast here is the peak of the pulse, not the electrons in the pulse itself. Because this pulse will bear information (unlike the intersection point of the scissors), it is limited to the speed of light.
YEeh, a wire in open air is pretty close to c, but most wires are in circuits with lots of copper around, and usually the speed is at .6 to .8 c.
What is Off Self Components?
Is this a new section at Radio Shack I don't know about?
See any basic electromagnetic field theory for a better explanation.
then lets say that we send information as intersections.. duh!
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.
Yeah but I'll be an old man by the time they reach me to power my computer!!!
Satanists get good grades too...suspiciously good grades
Did you see the related stories associated with this article?
Related Stories
Black hole theory suggests light is slowing
8 August 2002
Light may have speeded up
15 August 2001
So which is it light is speeding up or slowing down???
With a headline like "Speed Of Light Broken With Off Shelf Components" I can see why.
For shame!
Robots are everywhere, and they eat old people's medicine for fuel.
From what I understand, the electrical signals interfere with each other, causing a peak in the signal ahead of where the signal itself is? Or something like that? But isn't that interference radio waves, and don't radio waves travel at the speed of light? So how does it end up going faster? I'm confused... And where do you get an oscilloscope (sp?) that can measure into the billions km/hr for less than $500?
If I can get 50 per cent, imagine how many I can get for a dollar
*rimshot*
Where 2 billion=arbitrarily large
On re-reading the article and a couple of links posted by a thoughtful reader, I now understand why there is no problem with infinite mass. It's worth noting that NO MATTER OR INFORMATION actually exceeds the speed of light in these experiments. Therefore it is thoroughly impossible to use these methods for faster than light communication.
I still recommend checking out the comic.
lysergically yours
Here's my take on the story:
Only the peak of the signal was propagated faster than the speed of light. Actual information cannot travel faster than the speed of light. For example, imagine that a bicycle is an atomic piece of information (that is, it is only useful when completely assembled). If you dissasemble the bicycle into several parts, then the front wheel (or any individual part) may travel over a distance faster than the speed of light so long as the average speed of all the components is less than the speed of light. Obtaining the transmitted information is equivalent to re-assembling all of the separate parts into a complete bicycle.
but that's not a surprise.
Today I found this 'selling a bridge' twice, and I can't understand what it means. Is it an idiom?
I use dictionary.com as my main online dictionary, but up to now, I haven't found a good idiom reference online. Any suggestions?
light speed in various materials.
here.
You know light speed varies depending on materials and wavelength, and it's possible for a particle to exceed LOCAL light speed. This gives off Cerenkov radiation, like nuclear reactors in water, the particles that hit the water exceed local c, and give off a blue glow.
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***
I'll believe it when I see it and not a second sooner. Unless I can travel back in time and see it a second earlier! If it's true its great but their are to many bs artists in the world and especially in academia. Just because you have a phd it doesnt mean that you arent a liar or a crook, or a bolshevik, but I digress.
Keep in mind that no single electron is moving faster than light. That would conflict with Einsten's theory of relativity since an electron has mass and accelerating any mass to the speed of light requires infinite (not a lot, infinite--hence impossible) energy. It is the signal itself (the wave) that is moving at speeds faster than light. Compare (Actually equate) this to the movement of electrons in any cable. While the signal may get from your soundcard to your headphones instantaneously the individual electrons require a long time (minutes, hours: depending on the current) to go from one end of the cable to the other.
Comcast Broadband Pricing: :)
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. . . that this is nothing new at all. As they say in the article, no energy gets sent faster than light. It's just a pattern of interfering waves. Nothing spectacular at all.
It's analogous to this:
A (strong) flashlight is pointing to a screen very far away.
When you put your hand in front of the flashlight, the shadow that your hands casts is thus hugely magnified - say 100 million times.
Thus, you can move your hand at a non-relativistic speed, like 4 meters per second, but the magnification causes the shadow to move *faster* than the speed of light - in this case, 4x10^8 meters per second.
This is OK, because the shadow doesn't carry any energy or information. Nothing here violates causality.
Admittedly, I don't know how the authors of this article expect to get taken seriously coming out quickly with claims of FASTER THAN THE SPEED OF LIGHT!
and...
Signals also get weaker and more distorted the faster they go, so in theory no useful information can get transmitted at faster-than-light speeds, though Robertson hopes his students and others can now rigorously and cheaply test those ideas.
Well, if you had this hooked up to some sort of computer network, all it really looks like you'll be able to do is smurf someone at 4 billion km/h.
--Chag
many years ago even though it was falling apart (which is why the brits were selling it).
Aren't they inviting a lawsuit from God by publishing this? The restrictions regarding the speed of light are there to protect God's IP. By sharing the knowledge of how to get around these restrictions allows anyone to create their own Universes, which clearly violates patent #000000000.
"People that quote themselves in their signatures bother me" - athakur999
Apple already does this stuff for their Faster Than Light(tm) G4 Processors.
Oh wait, take that back. They removed that line.
-- Len
This one may not stand the test of peer review. If you read the article, you'll note that the apparatus used was a maglite, a mirror and a stopwatch, with all results certified by Victor Ninov.
Do not taunt Happy Fun Ball(TM)
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.
While the peak moves faster than light speed, the total energy of the pulse does not. This means Einstein's relativity is preserved, so do not expect super-fast starships or time machines anytime soon.
Signals also get weaker and more distorted the faster they go, so in theory no useful information can get transmitted at faster-than-light speeds, though Robertson hopes his students and others can now rigorously and cheaply test those ideas.
So, 1) we still cant move faster than light and 2) Its not even usable to send real signals.
Way to go guys! Why dont we just have a big party with the grant money instead?
Scott.
Somebody pointed out that this may not be practical for electronics because of the overhead needed to sync the two signals. It seems like the most practical use would be in communicating over extremely long distances. Your overhead would be made up in the time you save transmitting the signal. If you could do this, somehow, without the cable, it could reduce lag time between, say, earth and mars.
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
This is a fraud - I just took some equipment off my shelf, and I can't duplicate these findings!
Seems trivial when compared to this other New Scientist story
feints within feints, wheels within wheels
...that brought you perpetual motion last week.
I can just see Roscoe P. Coltrane throwing his hat in the dirt and spitting, as the Duke boys go flying by on their faster-than-light car running on perpetual motion technology.
Beats all you never saw,
never followed natural law
Since the day they was born..
"While the instantaneous speed of electrons..."
Wow, didn't take you long to prove your ignorance.
Just as a minor bit of nit-picking, breaking the speed of light itself is something that is neither new nor difficult to do (and in fact, you don't need to spend 500 USD on equipment for this, either) - it just gets difficult when you actually want to transmit information.
quidquid latine dictum sit altum videtur.
What is Slashdot going to do next? Post an article titled "WIN FREE SEX"?
It is by the juice of the coffee bean that thoughts acquire speed, the teeth acquire stains. The stains become a warning
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.
You're using an assumption that always bugs me.
Let's say, for example, that I've got a 1 AU (about 8 light-minitue) long indistructable rod and I'm out in space. I push the rod. Common sense says that the far tip of the rod moves at the same time I move the near tip. But that'd break the speed of light; forgetting about inertia for a moment, it'd take at least 8 minutes for the rod to move after I push the near end.
If I have a powerful laser out in space that points out to 1 AU, and a spin it 180 degress, the "spot" of light doesn't move; light just starts moving out at c in the opposite direction.
Yeah, and that's probably not what you meant... but it's bugged me ever since High School.
That is incorrect. The group velocity *is* faster than light, but like you said, that is not the same as energy or information travelling faster than light.
BTW, does "rsidd" have anything to do with Repetitive Stress Injury?
...then how can they tell the test succeeded? Isn't PASS or FAIL useful information?
This really says two things:
1] This has been done from time to time and nobody probably ever noticed.
2] You can also break the speed of sound using off-the-shelf components. But it isn't much of a miracle if you are beating it in a different form (electricity, light, etc).
Why do these stories keep cropping up as freakin' news. I mean if Taco and company are going to keep putting them on the front page, why not all the stories from people who omit or add an extra minus sign and re-work all of Maxwell's equations coming up with goofy results. Any student with a good first year graduate e&m course or even a good qm course will realize this is just the whole issue summarized by answering the question, "What do you mean by the velocity of a propagating wave?" Start with defining packet velocity and go from there ....
...I just don't understand, sorry.
Sounds like to me we'll soon have Hyper-Pulse Generators, and we'll have to form a religious techno-cult to administer our FTL communications network. We'll just have to start building BattleMechs so we can defend the network from invaders.
OK, seriously, the whole "faster-than-light" aspect of this is just sloppy reporting. I guess this is the "New Science" covered in New Scientist now.
--Mythos
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
depending on the medium its traveling in.
Seriously. It loses time slamming into atoms and then being re-emitted. In dense objects its pretty slow.... Heck, even air can slow it down a little (Thats why we have Cherenkov radiation, which occurs whenever a particle moves faster than a photon does _in air_). The poster obviously wanted to make things seem more interesting by neglecting to mention the 'in a medium' part. While its a little dodgy to me how yer going to get an electron to flow faster than light normally would in a medium, and actually approach C (the _Absolute_ speed of light, as it travels in a vacuum), they arent talking about exceeding the speed of C.
So please chill out, O children of the sci-fi channel. theyre not talking about anythng _that_ off the wall.
"Electrons usually travel at about two-thirds of light speed in wires, slowed down as they bump into atoms."
I remember from physics class that speed of the electrons was very small in wires. But speed of signal might be 2/3*c.
you can't have a title that says speed of light broke, and then say that it may be one day possible to go near the speed of light.
fooyey
( i didn't read the article yet - because I suck )
People should be careful with their wording. They intentionally used poor wording to raise eyebrows and get attention and possible funding. Phase velocity is much different than group velocity. It's meaningless to even mention the speed of light when speaking of phase velocity. This really pisses me off as a physicist that some people are so irresponsible.
Maynord
Does this mean the Dolorean now only has to go 22MPH now?
I need to test the IE of this machine and this is the easiest way I know how.
But we all know that electrons have properties of particles as well as waves. So that makes me wonder if all electrons travel at the same speed, or are they traveling in a range of speeds, with the average electron going at the nominal speed for a given medium? In other words, are some going slower and some going faster? And if so, is it possible that some are actually going much closer to the speed of light than others?
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...
Those that are fluent in the german language at least may be interested in checking out the following explanatory file on tunneling:
http://theory.gsi.de/~vanhees/faq-pdf/nimtz.pdf
quidquid latine dictum sit altum videtur.
get so far across the room so quickly.
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...
Wait, i've got it!! How about...we use light to transmit information at the speed of light? WE WILL RULE THE EARTH...OR SOMETHING.
Anyway, since when does going down to a hardware store and buying a flashlight and a light sensor constitute newsworthiness?
Cheers,
Bowie J. Poag
With such bloated cost estimates, those scientists must be working for the Pentagon, because the last time I checked, those materials were much cheaper than $500.
Time machine: Here I come!
Next step: finding a deLorean on eBay...
You can't take the sky from me...
Well, I can't find 'selling a bridge' in any permutation there, but that's a well-beaten dead horse already... anyway, there's an idiom reference here that you might try out.
"The best argument against democracy is a five minute chat with the average voter."
--Winston Churchill
"Slashdot! We don't suck any worse than the traditional media!"
The cake is a pie
It's kinda hard to believe an article that gets basic physics wrong.
The actual speed of electrons in wire is very very slow - on the order of milimetres per minute.
The speed of electrical signals on the other hand is normally around 0.6c.
You'd think that the editors at New Scientist would have a clue. I studied this stuff at High School - age 15. It's not Rocket Science.
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.
Anyone have a mirror of the NewScientist web site? Their web programmer is clueless (and has been told about this a few times) and developing stuff that is incompatible with some proxy servers.
now we need to go OSS in diesel cars
yo this licks my nuts
was able to hurl a 100 kilo piece of rock through the castle wall.
Nothing to see here. Move along.
the new scientists are konfused.
Stop measuring sine waves. Measure something with information in it. You're reading harmonics or you've got Alpha-Phi's next door with an EMP-inducer fscking with your heads.
No electron goes beyong c in this experiment.
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.
Everyone who made some physics know that electrons are not moving at light speed in wires. Even not at 2/3 of light speed; but only at some centimeters / second. Or all our wires would be quite hot in our computers and phone lines :-)
:-)
Only the electric field (aka information) propagate at the light speed.
So this article does not look really serious.
Does slashdot start publishing fake stories ?
(btw, this is my first comment
One very simple question. Why does everyone think that FTL travel/communications suddenly breaks causality or more generally, allows time travel into the past/messages to arrive before they are sent, etc.?
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
...how about this:
"MAN USES OFF-THE-SHELF COMPONENTS TO TRAVEL BACK IN TIME"
Story: 34-year-old Miami resident tapes Thursday's Weakest Link for viewing on Saturday morning.
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.
"The different electrical resistances in the hybrid cable cause the waves in the pulse's rear to reflect off each other, accelerating the pulse's peak forward."
If the pulse's peak is being accelerated forward, isn't that basically saying that the group velocity is being accelerated? Am I correct that the group velocity is essentially the speed of the peak of the wavepacket?
Or are they saying that they are increasing the phase velocity to superluminal speeds but the group velocity, while increasing, is still staying below c?
The best way to predict the future is to invent it.
what if i took a solid object.. like a broomstick, and pushed and pulled it in a pattern.. like morse code. doesn't the data get to the destination.. like some guy's stomach, instantaneously, faster than light speed?
very impractical.. but wouldn't the data technically be transferred faster than light?
i've always wondered this.
On the other hand, increasing transmission speeds in computers, whose signals typicall travel at around
-h-
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-
Haven't these people watched "Event Horizon"?
This is magnitudes worse than human cloning or nuclear fission!
Doing this kind of research (FTL travel) can have world-ending implications and cause tremendous time-warping and severe gravimetric distortions.
BAN THIS RESEARCH!
"Signals also get weaker and more distorted the faster they go, so in theory no useful information can get transmitted at faster-than-light speeds"
While the peak moves faster than light speed, the total energy of the pulse does not
So not only are laws NOT being broken here, it's of little real use. I can't see how they can even claim the wave peaks are traveling faster than light, as it would be rather impossible to measure such a figure.
I would like to see the math behind such a claim.
Half the people on /. are idioms, and the other half don't know it.
More shame on /. for uncritical repetition.
Okay someone had to do it...
There was a young lady named Bright
whos speed was much greater than light.
She set out one day,
in a relative way,
and returned the previous night.
Not....
Unlike water, etc., that travels down the interior cavity of a pipe, electricity travels over the surface, exterior of a wire....what a dope.
Also on from the article: "Speed of light broken with basic lab kit" This always happens where some title says light speed has been broken then all ppl get their hopes up and spread rumours and pseudo science sites pop-up and then everyone points to the part where it says relativity has been preserved and that there is really nothing useful. So don't tell us light speed has been broken until it has! Geez
It's right between the two sections: "Heisenburg Compensation" and "Energy Producers"
"Lisa, in this house we obey the laws of Thermodynamics!"
-Homer J.
Karma: Non-Heinous
Something about this is driving me totally crazy: those knowledgable about physics say its "only the phase velocity" blah blah blah "only the peak of the wave" and so on. What I can't understand is, If you can't detect this peak until after enough time has elapsed, then how do you know it really got there faster. And if you *can* detect it when it actually arrives, the how come you can't transfer information with it? (like an on off on off code or something?)
Play Command HQ online
Just a heads up for all you armchair physics experts, I'm sending this message on May 15, 2048 ...so don't laugh!
Now, I've gotta send an email to 1999 warning myself not to buy that VA stock. "Yeah, I know it's dropped all the way down to 50...don't buy it."
char *mySig;
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
My waves book from 61' clearly shows that the phase velocity can travel much much faster than the group velocity of waves... radio engineers have known this for about 70 years... I'm not exactly sure whats new. They're using the superposition of signals that dont degregate as much in cheap wire? (wow, they pick up that idea from 19th century physicists?) Thats worth publishing? I'm surprised this site doesnt have information about the /exciting/ developments in hydrinos (this is sarcasm). Measuring a signal whose wave peaks over the wavelength arive at 4 times the speed of light (note: The information or /energy/ of the wave still doesnt go faster than the speed of light) is about as exciting and mysterious as eating beans and getting gas from them...
Hell, I am on Mac OS X at the moment.
All the glory of UNIX, right? Well, UNIX without X. UNIX without a path listing in the file browser. UNIX without a standard c++ compiler. UNIX without, well UNIX.
Then again, it is UNIX with commercial software. A mixed blessing, but not so bad.
Back in my day, UNIX(Linux) was pure. I had no commercial software, aside from netscape. Back in my day, we(I) had my wyse dumb terminal and didn't care that the rest of the world(literally) had their cga and vga and svga monitors and their fancy mice.
I may only be 16, but I've used everything from the Timex Sinclair to the Altair to the VAX to, my favorite, unix. I run Linux and Mac OS X exclusively. This is my day, and unix is still going strong.
You can't judge a book by the way it wears its hair.
Scientists announced today that they have created a freezer that cools things below absolute zero made entirely from parts salvaged from a 1962 Ford Thunderbird. Following this amazing news, a group of graduate students announced their construction of an aparatus, built entirely from elmer's glue and tooth picks, which accelerates forever with no outside force. Not to be outdone, the Apache Software Organization announced a few hours later the availablity of mod_perl for Apache 2.0.
Poor Einstein, I thought. :)
Time is an illusion, lunchtime doubly so. --Ford Prefect
That would be the most ambivalent ceremony ever. Can you imagine the audience of physicists feeling good for the winner but so damn irritated at having to rewrite everything yet again?
The coolest voice ever.
Just for those who haven't really read these "speed of light broken" articles, the group velocity is greater than c, but none of the parts (photons or electrons) exceed c at any point.
Don't radio waves and microwaves travel faster than light.
I'm sure you could find an old radio or Microwave oven for under $500
-- If you try to fail and succeed, which have you done? - Uli's moose
A shadow is the absence of light. There's nothing there to move. You couldn't even say that any information travelled faster than light. The edge of the shadow didn't carry information from its old location to the new one.
I couldn't care less about whether energy got transferred faster than light or not. Can anyone claim that this 'system' transfers Information faster than light? I seriously doubt it. Sounds like a load of BS to me.
"it's not just a good idea, it's the law!"
Speed of light... Not just a good idea. It's the solution to the monetary cost of justice.
Wow that is a revolutionary concept. A law that simply can not be broken. No need to enforce it, because nobody will ever be breaking it, because that is impossible. No need to reserve space in the jails, no sherrifs, lawyers or courts. No system of enforcement? Hmm, then why have the law at all? I hereby declare the limit to the speed of light obsolete.
Btw, who is going to inform Washington? We need more laws of nature.
--- Hindsight is 20/20, but walking backwards is not the answer.
Yomegaman's post does not deserve a 0!
"c ~ 1802617528320.3 furlongs/fortnight"
That's it. That will be 50 years of force-feeding the metric system for you buddy.
--- Hindsight is 20/20, but walking backwards is not the answer.
Back in my day, UNIX(Linux) was pure.
I had no commercial software
You would then know that Linux != UNIX. Unix IS commercial software
Burma?
There are two different issues here.
1) I haven't yet understood how you can transmit a signal faster than light without transmitting information faster than light... That apparently is the claim of the scientists. Others have made this claim too, earlier this year, and I didn't understand it then either. Somehow you can measure the emerging wavefront but not the information it contains, before the electron actually "gets there".... Fascinating if possible, but why that wavefront (or whatever it is that travels faster than light in a vaccuum) doesn't contain information is something I'd like to understand.
2) There is a claim that electrons (in a non-vacuum) can be pushed closer to the speed of light (in a vacuum). Well maybe they can, and then, of course they would contain information, and could in theory be used for computing. That seems within the range of possibility.
But the first claim still makes not sense to this nonphysicist. I hope someone can explain.
Actually, electrons in wire travel about as fast as you can walk. Yes, it's true; look it up in an intro to electrical theory book.
The electric fields induced by the moving charges (electrons) move at a fraction of the speed of light depending on the the material inside the transmission line. Light propagates in materials with dielectric constants closer to air faster.
...apparently I missed most of the above discussion where multiple people try to explain... never mind.
You science types love to draw lines in the sand and say works like 'never' and 'can't'.
The world can't be round, right?
One day another Galileo will come along and make all of you eat your words.
The world is infinitely more complex and all of our understanding doesn't even scratch the surface.
Thank you Dave Raggett
I've written this like 4 times so far, and I can't make it sound convincing, only slight analogy I can come up with is moire patterns they appear to move faster than there components do it's the same in this case, the peak is made up of many component waves, each moves at a fraction like 1/2 or 2/3 the speed of light, the peak is formed as each of these waves passes over the other thing is these waves have to be in place before the peak can form, you could probably guess when the peak is going to arive at the other end just by looking at the setup signals coming down the wire.
Nope, not going to cause any revolution in telecoms, or data transfer, and for timing/signaling events there's other systems available.
The speed of light is broken all the time. It causes Cherenkov Radiation...
m l
http://rd11.web.cern.ch/RD11/rkb/PH14pp/node26.ht
And yes, I know people usually mean the speed of light in a vacuum
See that "Preview" button?
Well, I don't see why you wouldn't bet transmitting one bit of information, namely that the light has struck area X = true.
"Your superior intellect is no match for our puny weapons!"
I can't read the article because the server is crying, but there is a minor fact that many people on here are missing. Nothing can travel faster than the speed of light in a vacuum. There are other mediums through which objects can travel faster than light.
Ok, here's the way it was explained to me. Instead of ping-pong balls, imagine a really long rope, that you could pull back and forth to send messages or whatnot. When you pull on one end of the rope (or push in a ping-pong ball), you start a compression wave, and this wave must travel at a speed less than or equal to c. This applies no matter how hard the rope/ping-pong balls are. Like it or not, c is forever (damn laws of physics!)
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."
In the meantime, why don't you sit in the corner and think about what you've done...
I didn't give up my career to raise a light-breaker! Not in this house!
In the future, I would want to not be isolated from my friends in the Space Station.
1000 years from now, Gandahar was destroyed. 1000 years ago, Gandahar will be saved.
ceci n'est pas une sig.
Electrons don't travel at relativistic speeds in a wire, who travels this fast is the electric field. The electrons travel very slowly indeed (some centimeters/minute)...
Bill Nye is dead?
They never claimed to do that. Infact, this seems like nothing more than a variant of the 'group velocity' stuff in your average modern physics class. While this is interesting, please try not to mislead with the article title.
In a quantum sense, it seems that it is possible for particles to travel faster than the speed of light. Using tiny "tubes" through which microwaves have a small liklihood of traversing, studies have shown that while most waves stop dead, some "jump" through the tube instantaneously. Someone please explain why this does not collapse the laws of physics as we know them.
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.
The electrons don't carry information in wires. Electric fields carry information. The electrons happen to move about in the electric field. The electric fields propagate at about 2/3 the speed of light through metal, depending on conductance. Electrons move comparatively slowly (in part because they bump into things and heat up). It would take a heck of a lot of energy to accelerate an electron to 2/3 the speed of light inside a wire. I believe they move at speeds measured in single meters per second.
-m
From the article
"While the peak moves faster than light speed, the total energy of the pulse does not. This means Einstein's relativity is preserved, so do not expect super-fast starships or time machines anytime soon."
In my fire control "A" school I was taught about this phenom in our class on waveguide propagation theory... read the article people...no laws broken... and I learned this 15 years ago...
In other news, today I changed the light bulb in my Maglite(TM) when it burned out.
This sig no verb.
- Hilary Rosen, evil leader of the RIAA, is a lesbian! Does this make her more or less cool?
If she's twentysomething, hot, and an exhibitionist then she's more cool. Anything else, and I just don't care one way or another.
HTH
Finally I get the chance to try out this thoughtexperiment which has gone on in my mind these last few days. Please correct me if Im wrong.
:)
How to send a superluminal signal:
- get a stick at least 300.000.000 M long
- have a person in each end
- one person pushes the stick (something which can be done in under one second)
- the other person registers the signal
And you have a signal which travelled the distance light does.... in less than one second.
So Bonker, where do I collect the Nobel-prize?
-Kraft
Live and let live
Gossip does
Interesting how various people cling to Einsteins theories.
I wonder when they will be 'overhaulled' in the same way as the concept of a flat earth was.
Merely saying of something that it breaks one of these laws is not therefore proof of impossibility.
Just a thought.
AC
They certainly do not. An electron's mean speed down a wire is of the order of a few centimetres a second. It's the signal that moves much faster.
"The new wave is not value-added; it's garbage-subtracted" - Esther Dyson, Dec 1994
Finally! I can lower my ping by a whole 3ms!
:)
RAR!
"Electrons usually travel at about two-thirds of light speed in wires, slowed down as they bump into atoms".
Sorry - but that's utter rubbish. The electrons themselves do not travel at such speed, rather the charge itself. From high school physics I recall that electrons in wires travel at centimetres per minute - and not a significant fraction of the speed of light as this post suggests.
The kilogram is the base unit!
http://www.wikipedia.org/wiki/SI_base_unit
The concept that the phase velocity of a wave can travel faster than the speed of light is not new. There are plasmas residing in the upper atmosphere with indicies of refraction less than 1 which lead to phase velocities faster than the speed of light. However, the group velocity of a wave travels at (more like near) the speed of light. Since the information bearing signal is really contained in the group velocity portion of the wave and thereby bounded by Einstein's relativity principle, one cannot achieve superluminal communication with this technique.
t m
Those poor students are going to be wasting a lot of time. *sigh*
Here is a website explaining the mathematical principles stated above,
http://www.mathpages.com/home/kmath210/kmath210.h
Wasn't there a story a few months back about how a scientist slowed the speed of light down to 39mph by passing it though some medium. So, I have no problem exceeding the speed of light in my bmw. ;)
Drop a pebble in a pool of water, a pond, a lake, or a smooth ocean.
Observe. The packet of waves created by the pebble radiate out and as they do - they disperse. Dispersion means that they spread out and make a larger packet over time. This is because the phase velocity and the group velocity aren't the same. If you look closely at the wave packet, you'll notice that the crests of the waves move faster than the whole packet of waves.
This whole thing is a very well understood and old phenomenom. Its easy to get the phase speed to move at a different speed than the group speed. And how fast it is doesn't really mean much - its just an illusion of motion.
I think the same thing happens in microwave guides.
with infinite mass comes infinite gravity, so basically if you swung a long enough stick fast enough, you'd create a black hole :).
:)
Same kind of things as the argument - what if you took a step forward on a spaceship travelling at light speed? Of course the problem is that you'd have to have a chunk of normal space-time within the ship to do that, or be in some wormhole that breaks standard laws of physics (ala warp bubble?) or else you'd be torn apart by the black hole created by your own ship...
*shrug* food for thought...
This is your first, from back in April. Sorry. (:
Whoever stated that signature sizes should be limited to one hundred and twenty characters can just go ahead and kiss my
Now It's been modded to -1.. You moderators are total cocks.
Whew! Imagine how many points that speeding ticket will add to your driver's license!
Remember "Bring 'em on"? *sigh
If they get speeds that exceed the speed of light in a given medium (say, a wire), won't they have to deal with the energy dissipation caused by Cerenkov radiation?
Fascism starts when the efficiency of the government becomes more important than the rights of the people.