German Scientists Declare Speed of Light Broken

SpaceKiwi · Aug 17, 2007

Apologies if this subject has already been covered previously, but this story has been on the radio news here most of the day. I'm very interested to hear what you physicist-types make of it all, and whether it's just a gross exaggeration/media beat-up of what's happened. One thought I had when reading a couple of press reports on the 'discovery' ... it is said that the photons which experienced quantum tunnelling would arrive simultaneously with those ones deflected? This is supposedly quicker than would conventionally be expected to be the case? My thought/question is this; if they were travelling FTL, shouldn't they actually arrive earlier than even those photons being deflected? Anyway, here's one of the many articles that seem to be circulating on the Internet today ... <blockquote>In reply to:<hr />German Scientists Declare Speed of Light Broken August 16, 2007 10:15 PM A "Macroscopic Violation" of Special Relativity According to modern physics, the speed of light is a fundamental, unbreakable limit. Yet two physicists are now claiming they have done just that, and propelled a stream of photons faster than the speed of light. GÃ¼nter Nimtz and Alfons Stahlhofen of the University of Koblenz, Germany, have been researching a phenomenon known as quantum tunnelling. Two prisms are placed together. When a light is shown through the prisms, a detector picks up the light and records information about the photon. However, when the two prisms are separated, Nimtz and Stahlhofen discovered that photons would occasionally "tunnel" between the prisms -- arriving at the detector sooner than should theoretically be possible. The two scientists say they have now tunneled photons "instantaneously" across a distance of up to one meter. Their conclusion, stated in a recent paper, is that the speed limit of special relativity has been vio</blockquote> <div class="Discussion_UserSignature"> Who is this superhero? Henry, the mild-mannered janitor ... could be!-------------------------------------------------------------------------------------------Bring Back The Black! </div>

Smersh · Aug 17, 2007

Hi SpaceKiwi, Someone did start a thread in FS, but I just posted advising of the thread here and put a link. If the threads could be merged here somehow would be handy. (Or maybe move the other one here.) This is a fascinating subject imo. <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea." Churchill: "Nancy, if you were my wife, I'd drink it."Website / forums </div>

3488 · Aug 17, 2007

There is a thread on this in Phenomena. Superluminal Speeds? Perhaps that is more appropriate a place than a forum supposedly devoted to 'real' science. Andrew Brown. <div class="Discussion_UserSignature"> "I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before". Linda Morabito on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.http://www.launchphotography.com/ http://anthmartian.googlepages.com/thisislandearthhttp://web.me.com/meridianijournal </div>

Smersh · Aug 17, 2007

Thanks Andrew I just noticed the Phenonema one as well and made a post about a guy disputing this theory. Maybe Phenonema would be the best place, not sure. <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea." Churchill: "Nancy, if you were my wife, I'd drink it."Website / forums </div>

robnissen · Aug 17, 2007

I don't agree that this thread belongs in phenomena. I have little interest in discussions with the woo-woo crowd who believe that "If I can imagine it, it must be possible." Just because you can imagine a temperature of -1000 F, or imagine a speed of 500Km/sec, does not make either possible. This, however, is different. This appears to be perhaps legitimate research that is most likely being interpreted incorrectly, or otherwise not violating c, but it seems to me that it is a subject of legitimate scientific discussion. Many discoveries in science often come from apparently "impossible" experiments, that ended up not being impossible either because the result was misunderstood, or there was a hole in the science.

Smersh · Aug 17, 2007

Well I thought I'd copy/paste my post in the Phenonema thread here. Not sure where this topic will end up but I guess we should be posting about that in "Suggestions & Announcements" anyway (but I'm as much to blame as anyone else... ) ========================================== There is a guy here who says this claim by the scientists is not correct ... Latest "faster than the speed of light" claims wrong (again) By Chris Lee | Published: August 16, 2007 - 07:38PM CT A paper submitted to the physics arXiv has been picked up by a number of major news outlets (e.g., the Daily Mail) because the paper suggests that its authors have measured something traveling faster than the speed of light. Unfortunately, the claim is worse than weak; it is silly. I'll talk about why that is after briefly discussing their research. The paper in question has no data at all so; although it asserts that it has measured superluminal velocities, it offers nothing to back that up. It also has very little in the way of experimental detail, so we can't determine with certainty what they are measuring, making it very difficult to evaluate their claims. We'll take as close a look as we can, given these limitations. Rest of article in above link. <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea." Churchill: "Nancy, if you were my wife, I'd drink it."Website / forums </div>

emperor_of_localgroup · Aug 17, 2007

I think our science is primarily limited only to the things that can be observed by or derived from our senses That is a comment by a poster in the Link given in the origial post. Anytime I read of FTL discussion they always say 'If you travel at FTL speed, you'll arrive at your destination before you leave'. Where does this come from? If things can travel faster than light and we can see things faster than light, then this statement is 100% wrong. That's why the quote above is significant. Though I'm not sure the researchers in this case saw 'group velocity' or real velocity. Group velocity, it has been proved before, can exceed speed of light. <div class="Discussion_UserSignature"> Earth is Boring </div>

yevaud · Aug 17, 2007

As this is a tunnelling event, neither would apply. It would be a "pseudo-velocity," since no real space was traversed in the experiment. <div class="Discussion_UserSignature"> Differential Diagnosis: "I am both amused and annoyed that you think I should be less stubborn than you are." </div>

a_lost_packet_ · Aug 17, 2007

I think the title of the news article is unintentionally misleading. Thou shalt not allow mass bearing particles to travel through 4d space faster than light.... I think there is a translation problem from technobabble to mediaspin here. Still, interesting article but not the classic "faster than light" phenomenon described in the title/text. <div class="Discussion_UserSignature"> I put on my robe and wizard hat... </div>

Smersh · Aug 17, 2007

Anytime I read of FTL discussion they always say 'If you travel at FTL speed, you'll arrive at your destination before you leave'. Where does this come from? I believe it comes from one of Einstein's relativity theories doesn't it? Effectively it would be a form of time travel, although I'm not sure if Einstein actually carried the theory that far (or believed that FTL was possible.) It just seems a logical progression of his theory which I believe was taken to a point of speed slightly slower than light speed. (Need equations here and I have trouble with my 9 x table ... ) <div class="Discussion_UserSignature"> <h1 style="margin:0pt;font-size:12px">----------------------------------------------------- </h1>Lady Nancy Astor: "Winston, if you were my husband, I'd poison your tea." Churchill: "Nancy, if you were my wife, I'd drink it."Website / forums </div>

jaxtraw · Aug 18, 2007

It's intrinsic to Special Relativity, at least from the geometric interpretation of it. In a Minkowsi spacetime, as you travel faster you travel through time slower, until at c you wouldn't be moving through time at all. Faster than c you'd be going "backwards" through time. But the whole point is, if SR and Minkowski spacetime are correct, it's intrinsically impossible to do so by any normal means. A hypothetical (and currently entirely imaginary) warp drive might allow you to travel faster than c, but only by not moving in a normal sense, instead you cheat by making space smaller. Heh. In that case, you're not moving in a normal sense and so the relativistic effects don't apply anyway. But so far that can only be done with movie special effects. Seriously, either SR is incorrect, or it can't be done. Discussing what would happen if you travel faster than light is like discussing what would happen if you gained the power to control fate with your mind. Fun in a fictional sense, but impossible in reality.

kelvinzero · Aug 18, 2007

Here is my attempt of explaining how an instantaneous communicator would create a time paradox. Ill have to break it into different posts (1/3) Suppose we have two spacemen on two space ships that are stationary wrt to each other, and one light year apart. We place a third spaceship exactly halfway between them, so that a radio pulse sent out from the middle spaceship arrives at the other two simultaneously, from their point of view. If an instantaneous message is sent by one spaceman as they receive this timing pulse, it will be received by the other as they also receive the same timing pulse. The diagram below shows the signal radiating out from the middle ship like a ripple on a pond that is stationary wrt to the ships.

kelvinzero · Aug 18, 2007

Now consider an earthman on earth as the fleet passes by. Because the speed of light is the same for all observers, the pulse from the middle ship radiates like a ripple on a pond that is stationary wrt to the earthman.. From the earthmans point of view, the pulse hits the back ship before it hits the front ship. Its not just the arrival of the pulse which happens earlier. Any event synchronized with the arrival of that pulse must appear to happen earlier at the rear ship for the earthman, in order to remain synchronized for all observers.

kelvinzero · Aug 18, 2007

(3/3) Now assume all three have instantaneous communicators. Suppose the earthman sends a message to the lead spaceman, timed to coincide with the arrival of the radio timing pulse to the lead spaceman. The lead spaceman immediately passes the message onto the rear spaceman. Because it is instantaneous, its arrival coincides with the arrival of the timing pulse at the rear ship. The rear spaceman immediately passes on the message to the earthman. However, because the earth man sent the message when the pulse arrived at the lead spaceman, and receives the message as the pulse arrives at the rear spaceman, they must receive their own message back before they sent it.

emperor_of_localgroup · Aug 18, 2007

I understand your math. My argument is Einstein's SR is based on the idea that c is the ultimate speed, the highest speed we can have, nothing else after that. When v=c, time t=0, time vanishes, so close the SR chapter, end of SR chapter and start a new chapter. In other words, we should NOT use SR equations to find out what happens when speed is higher than c (if possible) because those equations are based on or lead to one very strict property of speed. There is a discontinuity. Its like asking 'what do like to eat for dinner after you die?'. There are two sets of rules before and after death. Faster than light transmission and 'instantaneous' transmission are two different things. If there is a speed and there is a distance, there will always be a finite time of travel. As a result, there is no 'arrival at destination before departure'. <div class="Discussion_UserSignature"> Earth is Boring </div>

Kalstang · Aug 18, 2007

One other thing that you should ask is "How do we know that "c" is the fastest that anything can go?" After all we barely know whats going on in our own solar system...much less whats going on in the entire universe. Which is much much much much much much much much much much much much much much much much much much much much much much much much bigger. (add a few more "muchs to that please....<img src="/images/icons/wink.gif" />") <div class="Discussion_UserSignature"> I have an answer for everything...you may not like the answer or it may not satisfy your curiosity..but it will still be an answer. "Imagination is more important then Knowledge" ~Albert Einstien~ Guns dont kill people. People kill people.Solar System </div>

alokmohan · Aug 18, 2007

Topis is superluminal.It should not go to phenomena.

derekmcd · Aug 18, 2007

I don't believe Einstein ever postulated that nothing can go faster than the speed of light. General relativity states that something with mass can not be accelerated to the speed of light or beyond. I know it is a bit of nit picking, but there is a difference. <div class="Discussion_UserSignature"> <div> </div> <div>"If something's hard to do, then it's not worth doing." - Homer Simpson</div> </div>

jaxtraw · Aug 18, 2007

Well, because in terms of a relativistic universe the question is meaningless. Velocities are defined as a proportion of the speed of light and that's it. It only appears that that is not the case to us at low speeds, because at very low speeds it looks the same. We should really calibrate speedometers in units of proportion of the speed of light rather than with a linear scale <img src="/images/icons/smile.gif" /> That's just the way the universe works... To ask what happens faster than light is like asking what happens below absolute zero, or at a velocity less than zero. Treating velocity as scalar, there isn't any velocity below zero. You can't move less than not at all. Or consider a heap of bricks. You can talk about what happens when you remove a brick, but once you've removed the last brick, you can't remove any more, so a discussion of what happens when you remove a brick from a heap of zero size is without meaning. It can't be done. You can't have a heap of -1 brick or -10 bricks. When the heap hits zero size, that's it, end of discussion. No more heap to discuss <img src="/images/icons/smile.gif" /> What Einstein showed was that there's a maximum limit too, at least in terms of velocity. There is no "faster than light" to discuss. Really, I think the problem is partially semantic, in that c isn't as such "the speed of light", it's "the fastest speed anything can ever go" and light happens to travel at that speed. I prefer to think of it as the speed of information exchange in the universe, personally. One can then think, why can't a brick go faster than c from A to B? and the answer is, because the information that the brick has arrived at B can't get from A any faster than at a velocity of c. C isn't some kind of empirically measured max speed at all, as such. It's a basic property of the universe. If relativity is a correct theory <img src="/images/icons/smile.gif" /> Hope that makes some kind of se

emperor_of_localgroup · Aug 18, 2007

I think I saw this 'riddle' (I know you call it thought experiment) before. Interestingly some one left out the time when earth guy sent the message. This is my take. We'll call E (the earth guy), A (the lead spaceship guy), and C (rear spaceship guy). Now take a look at the attached pic. This is the time-line by which message will travel from person to person. Finally Alokmohon has come around. He used to recommend everything for Phenomena. Kalstang: You are right, it's only 21st century and many people have already made up their minds about the universe. It's laughable. <div class="Discussion_UserSignature"> Earth is Boring </div>

kelvinzero · Aug 18, 2007

I cant see your image yet. I added some text in bold to clarify that the the earthman sends the message to the lead spaceman to coincide with the arrival of the timing pulse to the lead spaceman. The earthman recieves the pulse back at the point in time where the timing pulse reaches the rear spaceman. In the earthman's frame of reference, the timing pulse reaches the rear spaceman before it reaches the lead spaceman.

emperor_of_localgroup · Aug 19, 2007

A few things about my diagram. 1) As long as you give a point in time for E to send the message, time discrepancies will go away. 2) In my diagram reception of message by C is not dependent on timing pulse. 3) The problem you described started between the second and third dot of my diagram. 4) Now, if you want to say, guy E sends message after C receives the timing pulse, then a simple geometry can tell you timing pulse will always arrive at A before the message. In other words, you can not synchronize message with timing pulse. Btw, anyone ever experimentally verified that c is independent of reference frame? Using SR equation it can be proved, but I haven't heard of any experiment. <div class="Discussion_UserSignature"> Earth is Boring </div>

kelvinzero · Aug 20, 2007

The most famous one is: http://en.wikipedia.org/wiki/Michelson-Morley_experiment (apparently done in 1887) But since then it has hugely tested. Now days it is something you pretty much cant survive without, like trying to navigate around the world without accepting it is a globe. Here are some tests of general relativity from wiki: http://en.wikipedia.org/wiki/Tests_of_general_relativity (Im not claiming to be able to prove it myself)

alokmohan · Aug 20, 2007

General theory of relativity does not rule out FTL.George Sudarshan may tell you more.

emperor_of_localgroup · Aug 20, 2007

Number (4) statement in my last post is definitely true when the spaceship fleet is moving away from the earth. But to prove the statement when the fleet approaches the earth will take a lot more works. That's the only way your argument of 'receive before transmit' may happen. Someday when I get enough idle time, I'll try to prove that will also be impossible to do. Michaelson-morley's famous experiment was to disprove existence of 'aether' (spell??), but it may indirectly points to independence of c of reference frame. To get an actual proof IMO, without a shadow of doubt, we need not only the earth but another reference frame outside the influence of earth. The problem with experimetnal verification of any part of relativity is it requires extremely high speed and/or light, which makes any result extremely small, so small it can fall within the margins of experimental errors. I guess experimental relativity got a partner - string theory. <div class="Discussion_UserSignature"> Earth is Boring </div>

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