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Technology Science

Scientists Speed up Light 416

Posted by CowboyNeal from the breaking-the-law dept.
An anonymous reader writes "With off-the-shelf components, scientists have managed to speed up light beyond the 'universal' constant of c, or roughly 300 million meters/sec. This, and the previous ability to slow light down could shake up the telecom world, according to the story at Science Blog." Also, all those posters with 186,000 miles per second as a speed limit need to be amended. At least entropy is still around!
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Scientists Speed up Light More

Scientists Speed up Light

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  • Overhyped as always (Score:5, Informative)

    by trip11 ( 160832 ) * on Saturday August 20, 2005 @12:40PM (#13362222) Homepage
    Everyone say it together with me: "Phase velocity vs Group velocity" There are no photons in this experiment that are traveling faster than the speed of light. Only collections of them that 'appear' to be doing so. Think of this as an example: I space people out in a line, each of them two light minutes apart from the people next in line (all at rest with respect to each other). Now I go about talking to them and informing them of my plan. At 12:00 the first person waves, at 12:01 the second person waves, at 12:02 the third person waves, and so forth. My "wave" is propogating, therefore, at twice the speed of light. This is the same thing that this experiment is doing more or less. By spending extra time setting up the experiment, you can make it appear that a light pulse travels faster than c, but like my "wave" it is only an appearance.
    • The important question we all want to know is does this mean reduced ping times? Seriously though, it takes 100ms or more for a signal to reach half way around the globe. Anything that can speed that up would be much appreciated.

      I read somewhere that entangled photons don't allow faster than light information transfer either. Is there any hope for faster than light information transfer?

      • Re:Overhyped as always (Score:2, Informative)

        by Anonymous Coward
        Information transfer *is* what's limited by c. It then *follows* that a particle cannot travel faster than light, but that's a simple case. In general the limit applies to an experiment only if that experiment could be used to transfer information.
        • That gives us a very interesting insight on the computational infrastructure of the universe: Information is the first-order concept, particles and fields (arguably, the same thing) are higher-order constructs.

          Interesting, very interesting....

          • Re:Overhyped as always (Score:5, Interesting)

            by jc42 ( 318812 ) on Saturday August 20, 2005 @10:01PM (#13364549) Homepage Journal
            My favorite cosmology has long been the one in which every particle in this universe is a data structure inside a computer in the real universe. That computer is running the simulation that is our universe.

            In this model, the basic unit of our reality is a bit of memory in the real universe. Elementary particles are a second-order concept, a data structure made of a collection of bits. Time itself is quantized, and the quantum is the time it takes the real computer to calculate the "next" state of all the particles in our universe.

            It can be fun to argue this cosmology. But it has gotten somewhat less fun since the Matrix movies came out. It's no longer such a radical concept.

            In such a universe, miracles are easy to explain. Something has gone wrong, so the simulation is stopped and restored from backup. A bit of editing is done, and the simulation is restarted.

            Maybe this is what the Intelligent Design people are really talking about ...

        • I was doubtful about this because of entanglement so I quickly googled entanglement information [google.com] and the first result, from Stanford encyclopedia [stanford.edu] says this:

          Quantum Entanglement and Information [stanford.edu]
          Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Entanglement can be measured, transformed, and purified. A pair of quantum systems in an entangled state can be used as a quantum information chann

        • Re:Overhyped as always (Score:4, Insightful)

          by bunratty ( 545641 ) on Saturday August 20, 2005 @09:45PM (#13364494)
          Information transfer *is* what's limited by c.
          That may be what our most current theories say, but theories can always be wrong. We actually don't know if there's an absolute speed limit on information transfer. Remember, science can never absolutely prove any fact about the real world, only come up with models that attempt to describe the phenomena we've seen so far.

      • Re:Overhyped as always (Score:5, Funny)

        by MillionthMonkey ( 240664 ) on Saturday August 20, 2005 @02:52PM (#13362964)
        The important question we all want to know is does this mean reduced ping times?

        Sure. Just get together with your friends around the world and prearrange a ping to happen at exactly midnight GMT everywhere. You can get your ping to go infinitely fast if you do that (in terms of phase velocity) and CowboyNeal will write up a story about how you've shattered the speed of light and shaken up the telecom world.
    • Yes - of course - but does that have any bearing on the use of this technology in transmitting pornography?

    • Re:Overhyped as always (Score:5, Insightful)

      by justanyone ( 308934 ) on Saturday August 20, 2005 @12:52PM (#13362326) Homepage Journal
      Mod parent UP.

      Information flow (see: Steven Hawking's theories) cannot propogate at faster than the speed of light, or causality is violated and we have (dead virgins/future grandfathers) all over the place.

      All 4 basic forces: electromagnatism, gravity, strong nuclear, and weak nuclear (not Nukular; bite me, George) forces propogate at the speed of light in their reference frame. If we switch frames we're not fooling anyone; if we preposition information we're not watching causality violations.

      This kind of story is quite irritating, not due to the actual achievement involved (playing with light propogation is actually very cool geek-cred stuff), but the overhype and miscommunication to all the laypersons out there who just go, "Yup, that's an 'oops', they said it was a law and now it ain't. I guess evolution might not really be true, dad-gummit, I don't trust me none o' dem smarty pants anyway."

      • Oops, should have spell checked myself, Sorry, that's "electromagnetism". At least I know when I'm wrong, though. Mostly. If you don't listen to my wife. Mostly.

      • Re:Overhyped as always (Score:5, Funny)

        by Raul654 ( 453029 ) on Saturday August 20, 2005 @01:02PM (#13362396) Homepage
        ...or causality is violated and we have (dead virgins/future grandfathers) all over the place

        "And so the Trekkies were executed in the mannor most befitting virgins - thrown into volcanoes" - Futurama

        I never realized there might be a corollation!
        • ...or causality is violated and we have (dead virgins/future grandfathers) all over the place "And so the Trekkies were executed in the mannor most befitting virgins - thrown into volcanoes" - Futurama I never realized there might be a corollation! So, this involves throwing waving vigin trekkies waiting in line to be thrown into volcanoes to go faster than light?
        • Let's not also forget that Fry was, after all, his own grandfather.

      • Not quite (Score:5, Informative)

        by pauljlucas ( 529435 ) on Saturday August 20, 2005 @01:22PM (#13362518) Homepage Journal
        All 4 basic forces: electromagnitism, gravity, strong nuclear, and weak nuclear ... forces propogate at the speed of light in their reference frame.
        They propagate at the speed of light in all reference frames, i.e., the speed of light is the same to all observers.

        (However, including the nuclear forces is moot since they have no influence nor can they be observed outside the nucleus of an atom.)

        • Weak nuclear force involves transport of massive particles (W and Z) which can be observed travelling along timelike trajectories and had therefore darned well better not be travelling at the speed of light. Further they can be observed as real particles at extra-nuclear distances from a collision, so are not constrained to the nucleus. The strong force is indeed confined. Also, lose bonus points for not complaining about description of electromagnetism and weak force as separate fundamental forces - whe

        • Re:Not quite (Score:3, Informative)

          by ultranova ( 717540 )

          (However, including the nuclear forces is moot since they have no influence nor can they be observed outside the nucleus of an atom.)

          Really ? I can see the Sun shining just fine.

          Perhaps you meant that they can't be directly observed, only indirectly by the way of their consequences ? But surely you realize that this is true for all forces except electromagnetic - even with the proposed gravity sensors, you can't actually see the gravity waves, you can just see weights moving.

          Anyway, including nuclea

      • Re:Overhyped as always (Score:3, Funny)

        by Anonymous Coward
        (not Nukular; bite me, George)

        Rock on! Way to stick it to the man!

        You really showed that son of a bitch a thing or two.

        The only way we're ever going to fix this country is to randomly bring up a cliche point about the current president in the middle of scientiffic discussions.

      • Re:Overhyped as always (Score:3, Insightful)

        by cahiha ( 873942 )
        Information flow (see: Steven Hawking's theories) cannot propogate at faster than the speed of light, or causality is violated and we have (dead virgins/future grandfathers) all over the place.

        Hawking didn't come up with that idea; why are you giving him credit for it?

        All 4 basic forces: electromagnatism, gravity, strong nuclear, and weak nuclear (not Nukular; bite me, George) forces propogate at the speed of light in their reference frame.

        That has only been demonstrated for electromagnetism; for the other
      • dead virgins/future grandfathers


        Wow... that sounds like an awesome movie title. I'd by tickets for that shit in a heartbeat!

      • Nuclear vs. Nukular (Score:5, Insightful)

        by Anonymous Coward on Saturday August 20, 2005 @01:59PM (#13362740)

        Re:Overhyped as always (Score:5, Insightful)
        by justanyone (308934) on Saturday August 20, @12:52PM (#13362326)

        All 4 basic forces: electromagnatism, gravity, strong nuclear, and weak nuclear (not Nukular; bite me, George)

        Mixing politics with science; always a good idea (especially if you really really hate George Bush enough, which makes anything acceptable).

        But seriously, if "nukular" was an acceptable pronounciation by Jimmy Carter -- who was one of the first nuclear engineers in the Navy (Academy class of 1946) -- and tens of millions of other Americans -- including Dwight Eisenhower and Bill Clinton -- why single out George Bush?

        See

        http://volokh.com/2002_09_15_volokh_archive.html#8 5468441 [volokh.com]

        http://volokh.com/2002_09_15_volokh_archive.html#8 5473616 [volokh.com]

        http://volokh.com/2002_09_15_volokh_archive.html#8 5473709 [volokh.com]

        http://volokh.com/2002_09_15_volokh_archive.html#8 5473746 [volokh.com]

        [Eugene Volokh, 9:53 AM] September 19, 2002

        WHAT'S WRONG WITH "NUCULAR"? Today's Slate Explainer [msn.com] reminded me of this question, which I've thought about a bit in the past.

        One common answer is that saying "nucular" is wrong because "nuclear" is spelled, well, "nuclear," and not "nucular." But the standard rebuttal (mentioned in the Slate piece) is: How do you pronounce "iron"? I actually remember pronouncing it "iron" as a kid (as in "irony" without the "y"), and being told that this is not the usual pronunciation -- "iern" is probably the best way of representing how you're really supposed to pronounce it. If this phenomenon (called "metathesis") is OK in "iern," why isn't it OK in "nucular"?

        But this is just the tip of the objection -- the broader objection is that this is English we're talking about here. English, the language of "women," of "colonel," of "laughter" and "slaughter," of "get" and "gem." As reader Brian Dulisse points out, "forte" can be pronounced "fortay," "fort," or "fortee." "This pronunciation is wrong because it doesn't match the spelling" isn't much of an argument in English.

        It seems to me that the only sensible answer to "What is wrong with 'nucular'?" is "This is not the standard way that high-class people say it," coupled with "This term is a shibboleth that high-class people, and those influenced by them, use to sort those they'll call 'high-class' from those they'll call 'low-class.'" That's all the "wrong" there is here. Yes, I know this sounds like a leftist cultural critic position; but sometimes, as here, the leftist cultural critics are right. One day, "nucular" might be treated the same as "ah" for "I" or "crick" for "creek" -- a regional accent that's not wrong, but just different. It might even become the "correct" pronunciation, with "nuclear" sounding archaic or affected. It won't flow from a change to logic or morality, only a change of attitude by enough people in the influential classes, or by a change of who counts as the influential class.

        So what of it? Well, if you're teaching a child (or an adult) to speak, of course you should teach him to say "nuclear," simply as an instrumental matter -- sounding high-class is usually (not always, but usually) more profitable, especially where the shibboleths are concerned. If you're making a purely esthetic judgment, well of course you're free to say "'Nucular' sounds ugly to me," just like you can say "Picasso looks ugly to me" or "Broccoli tastes bad to me." And if you're tr

        • But seriously, if "nukular" was an acceptable pronounciation by Jimmy Carter -- who was one of the first nuclear engineers in the Navy (Academy class of 1946) -- and tens of millions of other Americans -- including Dwight Eisenhower and Bill Clinton -- why single out George Bush?

          Because before Bush was elected, "nucular" was used as a political tool to represent the argument that Bush is unintelligent. But now, it's used as a symbol of the anger the left feels over Bush being elected twice. When's the las
      • "or causality is violated"

        So far, the only thing saying that causality can't be violated is the apparent lack of tachyons. Other than that, causality can be wrong, it's just that means there's no such thing as free will.

        • So far, the only thing saying that causality can't be violated is the apparent lack of tachyons.

          So far the only thing saying that causality can't be violated is the apparent lack of any documented cases of causality being violated.

          Even if someone proves that there is no tachyons, it doesn't mean that causality suddenly becomes absolutely proven.

          Other than that, causality can be wrong, it's just that means there's no such thing as free will.

          Um, how does a causality violation force me to do anythi

      • when will people learn to spell "propagate" correctly?

        Parent and grandparent are quite good -- but "propogate" sounds like a Washington neologism for a scandal involving bee pollen.

        It's hard to sound authoritative if you can't even spell.

    • My "wave" is propogating, therefore, at twice the speed of light..... you can make it appear that a light pulse travels faster than c, but like my "wave" it is only an appearance.

      This is what happens when you let marketing into the physics department. As long as the customer believes it.... :-)
               
    • Or... correct me if I'm wrong! ...

      Being in a bank lineup, slowly progressing toward the front of the line during the lunch rush hour, you pass a bag of Mentos forward to share. While you (a photon) move slowly, the Mentos move (the information) moves quickly.

      Or like a wave on the ocean: individual water molecules drift in the currents at a slow speed, while the wave moves quite rapidly across the water. Photons versus waveforms.

    • Re:Overhyped as always (Score:5, Informative)

      by lgw ( 121541 ) on Saturday August 20, 2005 @01:06PM (#13362419) Journal
      There are some experiments in which photons are travelling faster than "the speed of light", because c is defined in a vacuum, and a vacuum is not the lowest impedance available.

      Even in a vacuum, light doesn't travel as photons for the entire journey (at least, if you believe in quantum). Light spends some of its time as electron-positron pairs which exist very briefly, before annihilating to product a new photon. As the electron-positron pair travels slower than the speed of light, light in a vacuum (which is how we've defined c) travels slighty slower that the speed of a photon.

      When you shine a light between very closely spaced conductive plates, that reduces the available "wavelengths" of the electron-positron pairs (I don't like that terminaology, but it makes the temporary electron-positron pairs less likely to occur), so the light spends more time as photons. Therefore light is travelling faster than "the speed of light".

      But not really, it's just that c is standardized on the wrong empirical constant. What you care about is the speed of photons, not the speed of light in a vacuum.
      • But the calculated value of c (which is far more useful than the measured one, as it's exact [if you use units which make all the other constants exact values, anyway]) is the speed of photons, rather than light in a vacuum, isn't it?

        Talking of quantum effects on light - i much prefer the fact that a sheet of lead speeds up light. It's because the only light reaching the detector is light that's tunneled through the lead (like electron tunnelling, but with photons), and therefore hasn't travelled as far.

    • Re:Overhyped as always (Score:5, Informative)

      by exp(pi*sqrt(163)) ( 613870 ) on Saturday August 20, 2005 @01:06PM (#13362425) Journal
      Don't explain it. Show [netspace.net.au] it!
    • Many thanks- as someone who doesn't know much about physics other than what I can get from books like In Search of Schroedinger's Cat, it's always really cool to see something explained clearly and cleverly.

      My main question the article didn't answer was "how does the process work?", and you've not only shed light on the Stimulated Brillouin Scattering, but done so in a way that accessible to me, a non-physics person.

      thanks!
    • To allow faster space travel, scientisis increased the speed of light in 2208. Duh;)
    • Everyone say it together with me: "Phase velocity vs Group velocity" There are no photons in this experiment that are traveling faster than the speed of light.

      That does seem like the most likley explanation, but if it is, why is this being hyped in the press? We have had experiments showing FTL phase velocity for decades, and they are useless for information transmission.
    • Just to be a smart ass:

      The first person waves at 12:02.
      The second at 12:04 :D

      Unless you have an observer next to every person with a stopwatch. And then you still have to wait a few years for them to return you the results.

      (BTW, the third person didn't wave. He was sick of waiting for the signal.)

    • Domino block analogy (Score:5, Informative)

      by Alwin Henseler ( 640539 ) on Saturday August 20, 2005 @02:20PM (#13362824)
      Set up say, 1000 domino blocks in a row. Then tip the first one over. Given constant size, weight, spacing of individual blocks, and a horizontal surface, you will observe blocks falling down at a constant rate/speed ('c'). Given that constant rate/speed, tipping over the first block will cause all blocks to fall down, tipping over the last block some time later. Time delay calculates as distance divided by 'c'.

      Now, create 'extreme conditions', where the first domino block is down, the last one is still standing, and halfway down the row, blocks are falling, but not quite down on the floor. Then, observe the 'wave front' of falling domino blocks. It will appear to move faster than the previously determined 'c'. How come?

      Look more closely: as each block falls down, there's a fixed delay before it hits the next block. But what happens under our 'extreme conditions'? At the exact time a previous block would have hit the next one (under normal circumstances), that next block is already falling down! The time it takes for the 1000 blocks to fall down, is less than what normally would be expected.

      Did this 'c' constant get violated? Nope, it still took the same amount of time for each block to fall down. Was the maximum 'c' speed exceeded? Nope. After tipping the first block, it still took the same amount of time before this 'information' was passed on to the next block. With a set of 1000 blocks all standing, the time needed for an initial 'disturbance' to be passed on to the last block, is still limited by 'c'.

      So these 'extreme conditions' are like pre-tipping each block, and let you observe something that appeared to move faster than 'c'.

      Nice for the lab folks, but other than that, sensationalist journalism. Wake me up when trans-atlantic ping times (sending actual packets with random data) dive below the time dictated by the speed of light.

  • warp speed (Score:4, Funny)

    by longdead ( 860403 ) on Saturday August 20, 2005 @12:40PM (#13362227) Homepage
    but can they achieve warp speed yet?
    • More importantly, can they achieve infinite probability drive, or generate an S.E.P (Somebody Else's Problem) Field.
      • In other words, Warp 10.
    • Warp speed's too slow. They need to achieve ludicrous speed!

  • repost? (Score:2, Informative)

    by rkruse ( 837943 )
    Hasn't this already been done before?
    • Hasn't this already been done before?

      Are you saying dups travel into the future by going faster than c? Hmmm, the new science of dupology. Let's see, if two dups leave two different keyboards at the same time, and one dup can reach /. before the first dup is finished being typed, then the first dup is published but the second dup is not yet, unless it then goes faster than light and beats the first dup to /. such that it gets published before the second dup, and now they are both published. This is why Or

  • Ludicrous Speed! (Score:5, Funny)

    by Anonymous Coward on Saturday August 20, 2005 @12:40PM (#13362233)
    Were they able to speed it up to ridiculous speed, or perhaps even plaid?

  • Comment removed (Score:5, Funny)

    by account_deleted ( 4530225 ) on Saturday August 20, 2005 @12:41PM (#13362241)
    Comment removed based on user account deletion

    • Re:Finally (Score:3, Funny)

      by cei ( 107343 )
      Dark is faster than light... when you open a drawer, you see the light going in, but you don't see the dark escaping.

      Dark is more dense than light. It settles to the bottom of large bodies of water, while light seems more boyant.

      There are no light bulbs, just dark suckers. You notice how a burned out lightbulb can be a dark grey? It's full.

      Candles were primative dark suckers.

  • Bet you any money... (Score:2, Informative)

    by gowen ( 141411 )
    ... it's "only" the phase velocity. This has been done before, and, since information is carried at the group velocity, there aren't any serious "light-cone" repercussions for Einsteinian limits on causality.
  • "And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn't move over - relativity isn't called into question, because only a portion of the signal is affected."

    So no, this isn't the massive, century-defining, warp-drive-enabling experiment you all are dreaming for. Sorry. It's neat, and it'll probably have cool applications though. And that should be enough.

  • Nothing too new... (Score:5, Informative)

    by Space cowboy ( 13680 ) * on Saturday August 20, 2005 @12:42PM (#13362252) Journal

    There's more than one measure of the speed of light - the phase velocity and the group velocity. It's the group velocity that can't travel faster than c, the phase velocity is free to travel faster assuming dispersion is allowed. In any event, information travels at the speed of the group velocity, which is why the write-up mentions that Einstein ain't wrong just yet ("only a portion of the signal is affected").

    If you look at this treatment of wave velocity [mathpages.com], it's reasonably clear ([grin] - at least if you've done undergrad physics, but then in that case you'd know all about it anyway :-)

    A good quote from the above link:

    Unfortunately we frequently read in the newspapers about how someone has succeeded in transmitting a wave with a group velocity exceeding c, and we are asked to regard this as an astounding discovery, overturning the principles of relativity, etc. The problem with these stories is that the group velocity corresponds to the actual signal velocity only under conditions of normal dispersion, or, more generally, under conditions when the group velocity is less than the phase velocity. In other circumstances, the group velocity does not necessarily represent the actual propagation speed of any information or energy. For example, in a regime of anomalous dispersion, which means the refractive index decreases with increasing wave number, the preceding formula shows that what we called the group velocity exceeds what we called the phase velocity. In such circumstances the group velocity no longer represents the speed at which information or energy propagates.

    The phenomena is also discussed in Feynman's Lectures on Physics ( vol 1, Chapter 48-6) in a bit more rigor - these books ought to be required reading of any physics undergrads :-)

    Simon

    • here's an example... (Score:5, Interesting)

      by jxyama ( 821091 ) on Saturday August 20, 2005 @12:50PM (#13362312)
      Not sure if it's 100% relevant, the example I remember from school is: Take a powerful spotlight and place an object in front of it. Now go, really, really far away and watch the shadow cast by the object on the wall. Further you go, more "magnified" its movement will be, i.e., since the spotlight will be bigger further away, waving an object across the face of the spotlight will move the shadow on the wall across greater distance. If the spotlight is powerful enough, you can extend the wall as far as you want and the shadow will move as fast as you want, even faster than the speed of light.

      Note that no information is being transmitted faster than the speed of light in such a case. Shadow may traverse across the spotlight faster than the speed of light, but the actual information that creates the shadow is still transmitted at the epeed of light from the spotlight to the wall.

      • I don't think the shadow would move faster than the speed of light in that case, the time it takes for the light "update" to show up on the wall is just going to take longer when you're really really far away. So if you move something across the spotlight, it will just take longer to show up on the wall. Like how if the sun went out, we'd just know 7 minutes or so later rather than the shadow hitting us instantly...
      • Actually, I don't think that's technically correct. I may be wrong, but if you did this in a very dusty (big) room, you'd see sort of a wave of light (like on a rope if you pull up on one end and see a wave travel down the rope) going down towards the far wall.

        Have an object and a spotlight. Rotate the spotlight around the object (always pointed at it) and after a certain distance, the shadow will be moving very fast. But not faster than light. After that point, you'd be seeing the shadow that was cast in t
    • Good post. I recall a lecture I had from a PhD from Los Alamos when I was doing my undergraduate degree about the group velocity exceeding c, but they could still not transmit information at that velocity. The information velocity isn't the phase velocity, but it isn't necessarily the group velocity either.
    • There's more than one measure of the speed of light - the phase velocity and the group velocity. It's the group velocity that can't travel faster than c

      No, both phase velocity and group velocity can exceed c. (The quote you give makes that point.) Signal velocity cannot, however. If it could, you'd have immediate time travel, according to special relativity.

  • Don't have to change the constant (Score:4, Informative)

    by Azarael ( 896715 ) on Saturday August 20, 2005 @12:42PM (#13362253) Homepage
    When people have 'c' recorded, it's assumed that it's referring light in a vacuum and it's not messed around with. So the values can stay the same.
  • a coffee-can exhaust and a NOSx kit
  • Does this story count as an obligatory Futurama reference?

  • Cesium Chamber Experiment from Before (Score:5, Informative)

    by vectorian798 ( 792613 ) on Saturday August 20, 2005 @12:45PM (#13362276)
    Is this really that new? This has happened before. Read here: CNN: Light can break its own speed limit [cnn.com]

    And before we all start yapping, I quote from the (CNN) article:

    This effect cannot be used to send information back in time," said Lijun Wang, a researcher with the private NEC Institute. "However, our experiment does show that the generally held misconception that `nothing can travel faster than the speed of light' is wrong.

  • They were also able to create extreme conditions in which the light signal travelled faster than 300 million meters a second. And even though this seems to violate all sorts of cherished physical assumptions, Einstein needn't move over - relativity isn't called into question, because only a portion of the signal is affected.

    Can someone explain to me how it could be that just because only "a portion" of the signal is affected, this does not violate what has been previously understood to be an absolute law

    • Re:Something's amiss here... (Score:5, Interesting)

      by PDAllen ( 709106 ) on Saturday August 20, 2005 @01:05PM (#13362416)
      Suppose you had a chain of people 3,000,000km long, and you had them do a Mexican wave. It'd take (a lot) more than 10 seconds to go from one end of the chain to the other because people don't react that fast.

      Now suppose you gave each person a Bleepy Thing (tm) which you have sychronised beforehand so they go off at staggered intervals, the last one at the far end of the line 2 seconds after the first. You have the chain of people do its Mexican wave by standing as soon as their Bleepy Thing goes off. Wave velocity will be approximately 5c. There's no problem synchronising the bleepy things, just set them to go off at the right time intervals when they're all together in one place and then move them fairly slowly (like 100km/s is fine) to the right places in the chain.

      So why doesn't that break relativity? Answer: the wave does not carry information that fast. In fact the only information you get from the far end of the wave is the time the bleepy things were set to go off at - which reached you much slower than light speed when the bleepy things were sent down the chain beforehand.

      This is much the same trick just done with a light wave not a Mexican wave.
    • No information and no energy is transmitted faster than c. No physics book has to be rewritten.

      Actually, they should be rewritten, to point out once and for all that there are three relevant velocities of light: phase velocity (the speed with which the waves of monochromatic light move), group velocity (the speed with which a particular shape of mixed light moves), and signal velocity (the speed with which the information-carrying signal moves). With clever experimental setups, you can speed up or slow do

  • I have read this article everywhere I turn, on every news show I've watched today. Most of them are *NOT* portraying the "discovery" in its proper context.

    Jerry
    http://www.cyvin.org/ [cyvin.org]
  • Is this really making the light waves go faster, or is it just anomalous dispersion? I heard in one of my Physics lectures that you can make something happen that looks like superluminal motion, and it caused a bit of controversy when someone did it, but it's not actually the wave that's moving faster than c - it's actually the wave envelope, which is related to the amplitude of the wave. I could try and explain, but I'd only make things confusing (if I haven't already!), so I have found some animations you

  • Obligatory Futurama Reference (Score:3, Funny)

    by forkazoo ( 138186 ) <<wrosecrans> <at> <gmail.com>> on Saturday August 20, 2005 @12:58PM (#13362371) Homepage
    This isn't supposed to happen until 2208

    http://www.gotfuturama.com/Information/ListsRefere nces/timeline2.dhtml [gotfuturama.com]
  • What kind of horse shit is this?! We all know that they don't increase the speed of light until 2208.
  • mmm, some would disagree
    http://www.cheniere.org/techpapers/GiantNegentropy .pdf [cheniere.org]

    Before the flack comes. Yes, as we currently define "energy", there is no way to reverse entropy. It's all based on assumptions, and they may not always be correct.

    Check it out, see what you think.

  • "A team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light - both slowing it down and speeding it up - in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions.

    "The US Defense Advanced Research Projects Agency (DARPA) considers it so important that it has been funnelling millions of dollars into projects such as "Applications of Slow Light

  • As was evidenced by the new FTL(faster than light) optical data processing center at the core of Slashdot, This article was accidentally Posted INTO the PAST!!!!

    Thus, making the first post read a DUPE, and not this one. This is the original! /my head asplodes.

    iceberg
  • In other news, these scientists appear to have some sort of contract with ASUS...
  • What with this workaday world, I'm too busy to read the articles anymore. So I'll just make up the story in my head. Scientists sped up light. Experiments -- launched a flashlight from a rocket, spun fiber optic lines really fast around their heads?
  • I'm not sure if anyone already posted the actual paper. ScienceBlog only links to itself and references a future printed publication. Well, here it is:

    http://www.opticsexpress.org/abstract.cfm?URI=OPEX -13-1-82 [opticsexpress.org]

  • You know, come to think about it, I have noticed a billionth of a second delay on my phone calls to china... Is the speed of light really a limiting factor in telecom?
  • two objects moving in opposite directions at just over half the speed of light. relative to each other, they are traveling faster then the speed of light. That's why they can't see each other.
    • Actually, they can see each other. The light from each object will travel at C regardless of the reference frame. It's that weird funkyness that comes up with relativity.

      Basically, if you are travelling at -.5C and you emit a photon, the photon doesnt end up traveling at 1C-.5C= .5C It just travels at C, always.
  • They're using fibre optic cable and have slown down light so much the web page is not perceptable for 100 years on standard webbrowsers.
  • This post really ticks me off. Why? because i submitted the same story yesterday and it was rejected. Make up your minds, you evil moderators from the cubicles in the basement. RAWR!!!
  • Quoth the poster:

    At least entropy is still around!

    For now ....

  • Is it a co - incidence that this appears next to a story about how people not invited to the foo camp set up a salon des refuses ?

    Perhaps there should be bizzaro /., where the real stupid stories can appear, like, perpetual motion machine patent squelched, the plutocrates are sitting on anti gravity, razor blade that lasts forever, 100 mpg carburetor,.etc.

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