Re: [silk] Speed of light broken?
On 23-Sep-11 6:16 AM, Udhay Shankar N wrote: > Erm. I don't have either details or theoretical background to say more > at this point, but does anyone else have any thoughts? > > Udhay > > http://www.bbc.co.uk/news/science-environment-15017484 Update: relativity may not be in danger after all. https://www.technologyreview.in/blog/arxiv/27260/ Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity The relativistic motion of clocks on board GPS satellites exactly accounts for the superluminal effect, says physicist. It's now been three weeks since the extraordinary news that neutrinos travelling between France and Italy had been clocked moving faster than light. The experiment, known as OPERA, found that the particles produced at CERN near Geneva arrived at the Gran Sasso Laboratory in Italy some 60 nanoseconds earlier than the speed of light allows. The result has sent a ripple of excitement through the physics community. Since then, more than 80 papers have appeared on the arXiv attempting to debunk or explain the effect. It's fair to say, however, that the general feeling is that the OPERA team must have overlooked something. Today, Ronald van Elburg at the University of Groningen in the Netherlands makes a convincing argument that he has found the error. First, let's review the experiment, which is simple in concept: a measurement of distance and time. The distance is straightforward. The location of neutrino production at CERN is fairly easy to measure using GPS. The position of the Gran Sasso Laboratory is harder to pin down because it sits under a kilometre-high mountain. Nevertheless, the OPERA team says it has nailed the distance of 730 km to within 20 cm or so. The time of neutrino flight is harder to measure. The OPERA team says it can accurately gauge the instant when the neutrinos are created and the instant they are detected using clocks at each end. But the tricky part is keeping the clocks at either end exactly synchronised. The team does this using GPS satellites, which each broadcast a highly accurate time signal from orbit some 20,000km overhead. That introduces a number of extra complications which the team has to take into account, such as the time of travel of the GPS signals to the ground. But van Elburg says there is one effect that the OPERA team seems to have overlooked: the relativistic motion of the GPS clocks. It's easy to think that the motion of the satellites is irrelevant. After all, the radio waves carrying the time signal must travel at the speed of light, regardless of the satellites' speed. But there is an additional subtlety. Although the speed of light is does not depend on the the frame of reference, the time of flight does. In this case, there are two frames of reference: the experiment on the ground and the clocks in orbit. If these are moving relative to each other, then this needs to be factored in. So what is the satellites' motion with respect to the OPERA experiment? These probes orbit from West to East in a plane inclined at 55 degrees to the equator. Significantly, that's roughly in line with the neutrino flight path. Their relative motion is then easy to calculate. So from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. "From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter," says van Elburg. By this he means shorter than the distance measured in the reference frame on the ground. The OPERA team overlooks this because it thinks of the clocks as on the ground not in orbit. How big is this effect? Van Elburg calculates that it should cause the neutrinos to arrive 32 nanoseconds early. But this must be doubled because the same error occurs at each end of the experiment. So the total correction is 64 nanoseconds, almost exactly what the OPERA team observes. That's impressive but it's not to say the problem is done and dusted. Peer review is an essential part of the scientific process and this argument must hold its own under scrutiny from the community at large and the OPERA team in particular. If it stands up, this episode will be laden with irony. Far from breaking Einstein's theory of relatively, the faster-than-light measurement will turn out to be another confirmation of it. Ref: arxiv.org/abs/1110.2685: Times Of Flight Between A Source And A Detector Observed From A GPS Satellite. -- ((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
Re: [silk] Speed of light broken?
On Fri, Sep 23, 2011 at 10:49:19AM -0700, Heather Madrone wrote: > I had an experience of the illusoriness of time when I was 18 that has > stuck with me. Whatever time might be, if it has any sort of existence You suggest that first-person experiences, especially vivid ones, are particularly convincing as a reliable source of knowledge. They are not; it is trivial to reliably reproduce personally very convincing experiences by way of hallucinogens. Including that time is illusory, the sense of identity of with the universe and similar advanced entertainment. Disney on steroids, nothing else. > outside of the human construction of it, it's not in the cardboard box > we label "Time." -- Eugen* Leitl http://leitl.org";>leitl http://leitl.org __ ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE
Re: [silk] Speed of light broken?
On Sat, Sep 24, 2011 at 22:56, Venky TV wrote: > Must have been quite terrible in the bad old days before these laws > were passed -- with brash young photons skipping mass and harassing > poor, defenseless, church-going neutrinos. (As someone once said, > "Neutrinos has mass? I didn't even know they were catholic.") > > How did the scientists at the Large Hard-on Collider ever find time > for this, by the way? I thought they had their hands full groping for > the elusive Higgs-Bosom. ROTFFL. +1.
Re: [silk] Speed of light broken?
On 23 September 2011 06:16, Udhay Shankar N wrote: > Erm. I don't have either details or theoretical background to say more > at this point, but does anyone else have any thoughts? Well, I was quite interested to discover, courtesy of Mint, that these laws of physics are a century-old. http://www.livemint.com/2011/09/23223513/8216Faster-than-light8217.html?atype=tp Must have been quite terrible in the bad old days before these laws were passed -- with brash young photons skipping mass and harassing poor, defenseless, church-going neutrinos. (As someone once said, "Neutrinos has mass? I didn't even know they were catholic.") How did the scientists at the Large Hard-on Collider ever find time for this, by the way? I thought they had their hands full groping for the elusive Higgs-Bosom. Venky (the Second).
Re: [silk] Speed of light broken?
On 24-Sep-11 6:43 PM, ss wrote: > How small can you slice time? What is the smallest unit of time. Would time > appear as a discrete particle if you sliced it small enough. This may be of interest [1] Udhay [1] http://arxiv.org/abs/1010.4354 -- ((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
Re: [silk] Speed of light broken?
On Saturday 24 Sep 2011 9:42:53 am Sirtaj Singh Kang wrote: > Dave Long is a model you have constructed in your head based on a > dataset gathered by your senses. In the second case the model is > somewhat less accurate, that's all. > Absolutely. But the point here is that if a "single moment in time" is a plane where light from the past converges and light going to the future diverges, it is physically immpossible for me to contruct a Dave Long from exactly that plane. Different parts of Dave Long are constructed from different planes of time and I put them all together in my mind and say. "This is Dave Long at this time". The "time" that my mind believes is a single point in time is not a single point in time at all. It is a construct of Dave Long's different parts from different points in time. Perhaps, if my mind did not create such a construct, I would "see" Dave Long as one might see a segment of a flickering TV screen in an old movie or seen through a stroboscope. The mind requires a certain minimum slice of time to process information and construct it as what we call reality. How small can you slice time? What is the smallest unit of time. Would time appear as a discrete particle if you sliced it small enough. shiv
Re: [silk] Speed of light broken?
On 24-Sep-11, at 5:46 AM, ss wrote: [snip] Well tell me your take on this. If I see you lying in bed from the foot end of the bed, I am technically not seeing you at any single moment in time. What I see of your feet comes to me a short time before what I see of your nose. My ability to see you as a whole is entirely conscructed by "fudging" and by the concatenation of several moments in time as being "one moment" and "you" are defined in my mind by that fudging. Imagine if the light from your feet reached me 50 years before light from your nose. What would "you" be? Dave Long is a model you have constructed in your head based on a dataset gathered by your senses. In the second case the model is somewhat less accurate, that's all. -Taj.
Re: [silk] Speed of light broken?
On Sat, Sep 24, 2011 at 3:24 AM, Thaths wrote: > On Thu, Sep 22, 2011 at 6:27 PM, Srini RamaKrishnan wrote: >> If future visitors can't really communicate ever or offer evidence of >> their existence then afaics time travel is kind of useless. > > As useless as going to a film? As useless as visiting a historical ruin? True, there are those possibilities. Look but don't touch. How unfair. Cheeni
Re: [silk] Speed of light broken?
Deepa Mohan wrote [2011-09-23 07:07]: > Just wish to point out that there are many concepts that are fact > today...and which were considered utterly impossible beforean airliner > weighing several tons, flying in the air; man reaching the moon; talking in > real time, with hardly an effort, to a person halfway across the world; > being able to see the smallest detail of someone's attire from a point in > spacethe list is endless. Sowhy not? I still cannot get over the > fact that sitting at home, I am able to read the book that my > grand-daughter is holding in her hands in St.Louis. The difference between the examples cited and this news is that the above are not physical impossibilities but practical impossibilities: no one could figure out how to do any of them well enough. This on the other hand, seemingly challenges a physical law: not just something that seems darned hard to do, but that should, by definition, be impossible. - Pranesh signature.asc Description: OpenPGP digital signature
Re: [silk] Speed of light broken?
On Thu, Sep 22, 2011 at 6:27 PM, Srini RamaKrishnan wrote: > If future visitors can't really communicate ever or offer evidence of > their existence then afaics time travel is kind of useless. As useless as going to a film? As useless as visiting a historical ruin? Thaths -- Marge: Quick, somebody perform CPR! Homer: Umm (singing) I see a bad moon rising. Marge: That's CCR! Homer: Looks like we're in for nasty weather. Sudhakar Chandra Slacker Without Borders
Re: [silk] Speed of light broken?
On Saturday 24 Sep 2011 4:52:16 am Dave Long wrote: > If one has already observed an event, it's definitely in the past. > (and our past light-cone intersects its future light-cone) > If another event observes our present, it's definitely in the future. > (and our future light-cone intersects its past light-cone) > If neither of these cases is true, the event isn't in the past or in > the future, so it could be happening "at the same time" (and for some > observers*, will be) > Well tell me your take on this. If I see you lying in bed from the foot end of the bed, I am technically not seeing you at any single moment in time. What I see of your feet comes to me a short time before what I see of your nose. My ability to see you as a whole is entirely conscructed by "fudging" and by the concatenation of several moments in time as being "one moment" and "you" are defined in my mind by that fudging. Imagine if the light from your feet reached me 50 years before light from your nose. What would "you" be? shiv
Re: [silk] Speed of light broken?
Somehow this brings to mind Minkowski's space time. All in all it consitutes gobbledygook to me. It's probably gobbledygook because you're attempting to let a philosopher (who apparently can't even manage simple calculations with complex numbers) explain it. Gobbledygook In, Gobbledygook Out. But in Minkowski space-time with real time the plane of simultaneity is entirely space-like separated from the observation point. If real time is accepted it would appear that we cannot have the space of phenomenal experience. Nonsense. If "time is what keeps everything from happening at once", then the plane of simultaneity is behaving exactly as one would expect. Stuff that happens "at the same time" takes a while to find out about, and the further away it is, the longer it takes. How is this counterintuitive? If one has already observed an event, it's definitely in the past. (and our past light-cone intersects its future light-cone) If another event observes our present, it's definitely in the future. (and our future light-cone intersects its past light-cone) If neither of these cases is true, the event isn't in the past or in the future, so it could be happening "at the same time" (and for some observers*, will be) -Dave * http://en.wikipedia.org/wiki/Relativity_of_simultaneity Foogilly bargilly / Albert the physicist's Mollusc of reference / Gives us our "space" Laws of dynamics hold / Relativisticly Such a constraint then yields / Gravity's face
Re: [silk] Speed of light broken?
On 9/23/11 8:42 AM September 23, 2011, Deepa Mohan wrote: I am quite sure that this view of time, along with the other views of time that we have good metaphors for, is quite wrong. How are you so sure that "this view of time...is quite wrong"? I feel it deeply. This might make me quite wrong and all the metaphorical views of time quite right, but I, naturally enough, don't think so. I had an experience of the illusoriness of time when I was 18 that has stuck with me. Whatever time might be, if it has any sort of existence outside of the human construction of it, it's not in the cardboard box we label "Time." If I were to say that time is inextricably linked to change and motion, that it cannot be separated from the dynamic properties of the universe, that there is no way in which it is static, am I saying anything at all? And yet all of our metaphors for time have a sense in which time will hold still so we can capture an instant of it. Time never hold still, and we can't catch it. We can't turn back the clocks or arbitrarily move to a different place in it because time doesn't work that way. Prior to the invention of the calculus, we had no good way of thinking about dynamic systems. We needed those deltas and epsilons and being able to ask the question "okay, so we can't divide by zero, (or take instantaneous velocity, etc.), *but if we could*, what would the answer be?" before we could properly think about systems that include change. This allows us to think of systems that include time, but it doesn't allow us to think of time itself. I think we haven't yet invented the mathematics that will let us truly make sense of time. We don't yet have a tool that makes time accessible to our minds. Relativity suggests strongly that time is weird stuff, and it gives us a starting place for thinking about time, but it doesn't really give us a map of time's territory. My suspicion is that time is an artifact of another deep property that we haven't yet identified and in order to understand time, we need to understand that deep property, whatever it is. I realize this is worth what you paid for it. :D -- Heather Madrone (heat...@madrone.com) http://www.sunsplinter.blogspot.com Power at its best is love implementing the demands of justice. Justice at its best is power correcting everything that stands against love. - Martin Luther King
Re: [silk] Speed of light broken?
> > > I am quite sure that this view of time, along with the other views of time > that we have good metaphors for, is quite wrong. How are you so sure that "this view of time...is quite wrong"?
Re: [silk] Speed of light broken?
On 9/22/11 8:28 PM September 22, 2011, Deepa Mohan wrote: I somehow have a sense of time as a kind of tapestry hanging on a wall; we move past; what is behind us at right in front of us is visible to us, but what is ahead is hidden. Suppose we find a way of approaching the tapestry from the other side, or a way of "unhiding" the hiddenwith time travel, one could go to other parts of the tapestryif I presuppose the outcomes (results) of certain actions to be fixed (no open-ended "if this, then that") events, and time, could be (theoretically) approached from the "other side" too. I am quite sure that this view of time, along with the other views of time that we have good metaphors for, is quite wrong. I have no clue what time is, or whether it has any sort of objective existence at all but is instead an artifact of some other, deeper structure. I'm fairly certain that we haven't even started asking the right questions about time. A question that occurred to me today is: how does time relate to space? Is it a sort of weird uncle that space keeps locked in the attic or is it some other species entirely? This sort of thinking also make me want to re-read Ursula Leguin's The Dispossessed. -- Heather Madrone (heat...@madrone.com) http://www.sunsplinter.blogspot.com Power at its best is love implementing the demands of justice. Justice at its best is power correcting everything that stands against love. - Martin Luther King
Re: [silk] Speed of light broken?
On 9/23/11 6:06 AM September 23, 2011, Sirtaj Singh Kang wrote: That said, the day they disprove the Laws of Thermodynamics is the day I move to the forest and learn Stone Age subsistence agriculture, because I would at that point be unfit to be anywhere near technology. -Taj. I am so looking forward to the day they repeal the 2nd law of thermodynamics. -- Heather Madrone (heat...@madrone.com) http://www.sunsplinter.blogspot.com Power at its best is love implementing the demands of justice. Justice at its best is power correcting everything that stands against love. - Martin Luther King
Re: [silk] Speed of light broken?
On Friday 23 Sep 2011 6:36:27 pm Sirtaj Singh Kang wrote: > Otherwise any opinion I have on any public policy that depends on > science would be "provably" correct one day and laughably wrong and > dangerous the next. > > That said, the day they disprove the Laws of Thermodynamics is the day > I move to the forest and learn Stone Age subsistence agriculture, > because I would at that point be unfit to be anywhere near technology. > I have come to believe that the frontiers of science follow a fractal pattern and will only lead to increased complexity and ambiguity the deeper one goes. Ultimately it really does boil down to Maya. IMO. shiv
Re: [silk] Speed of light broken?
On Fri, Sep 23, 2011 at 6:36 PM, Sirtaj Singh Kang wrote: > Yesterday: coffee/alcohol is bad for you! > Tomorrow: coffee/alcohol will save your family! Am currently reading this: http://www.flipkart.com/books/0007326769 which tends to address the food type news reports. Worth a read. -- b
Re: [silk] Speed of light broken?
On 23-Sep-11, at 6:16 AM, Udhay Shankar N wrote: [snip] Neutrinos sent through the ground from Cern toward the Gran Sasso laboratory 732km away seemed to show up a tiny fraction of a second early. You know, I'm convinced that the real victim here is not the Standard Model but us half-educated laypersons who care enough to be informed citizens. If I depended on up-to-date science news I would never know anything: 1990: Neutrinos have no mass! (high school teacher explaining conservation of mass in fission) Some years later: Neutrinos have non-zero mass! Yesterday: coffee/alcohol is bad for you! Tomorrow: coffee/alcohol will save your family! Last month: speed of light cannot be exceeded Today: CERN exceeds speed of light with massed particle! It's exhausting. I'd subscribe to a yearly science research omnibus that updated my school textbook with Stuff Every Adult Should Know. Otherwise any opinion I have on any public policy that depends on science would be "provably" correct one day and laughably wrong and dangerous the next. That said, the day they disprove the Laws of Thermodynamics is the day I move to the forest and learn Stone Age subsistence agriculture, because I would at that point be unfit to be anywhere near technology. -Taj.
Re: [silk] Speed of light broken?
On Friday 23 Sep 2011 6:16:30 am Udhay Shankar N wrote: > Erm. I don't have either details or theoretical background to say more > at this point, but does anyone else have any thoughts? > Well the only thing I can recall about a layman's view of the theory of relativity is that at the sped of light, time comes to a standstill - i.e zero and mass becomes infinite. Using a "logical" extrapolation of that anything that travels faster than light should have a mass heavier than infinity and time should become negative. Somehow this brings to mind Minkowski's space time. All in all it consitutes gobbledygook to me. Enjoy: http://en.wikibooks.org/wiki/Consciousness_Studies/The_Philosophical_Problem >The physical theory of relativity consists of four dimensional geometry plus > the assumption of causality and the assumption that physical laws are > invariant between observers. It should be noted that space-time could > contain preferred frames of reference and is not, by itself, a theory of > relativity. The assumption that physical laws are invariant between > observers leads to the postulate that nothing can travel faster than c > metres per second. This means that the constant c, which in Minkowski > space-time is the conversion factor from seconds to metres then has a new > significance as the maximum velocity. > >A result of c being a maximum velocity is that nothing can travel from > regions of the light cone that are spacelike separated to the observer at > coordinates (0,0,0,0). This is problematic for observers if time is real > because, as Stein (1968) wrote: > >“in Einstein-Minkowski space-time an event's present is constituted by > itself alone.” (Stein 1968). > >However, to each of us it seems that the present is characterised by many > things simultaneously. As will be discussed below, this simultaneity of > present things also results in the appearance of phenomenal space. But in > Minkowski space-time with real time the plane of simultaneity is entirely > space-like separated from the observation point. If real time is accepted > it would appear that we cannot have the space of phenomenal experience. shiv
Re: [silk] Speed of light broken?
On Fri, Sep 23, 2011 at 8:40 AM, Guillaume Marceau wrote: > >> I wish it is possible, it is kind of exciting to imagine... > > > > Just wish to point out that there are many concepts that are fact > > today...and which were considered utterly impossible before > > This one, it is really a mind bender to consider how it could be possible. > > Because of the relativistic phenomena of the "relativity of > simultaneity", if faster-than-light travel was possible, we would have > to throw away causality. I don't know about you, but I like causality. > It's rather hard to imagine what life would be without it. > That is precisely the exciting part...the un-imaginability of itwho could have foreseen that we could communicate with each other, in seconds, across the globethat I could share a scene I've just witnessedthat you can look at me, and I at youeven a couple of decades ago? > > From wikipedia: > >If the spatial distance between two events A and B is greater >than the time interval between them multiplied by c then >there are frames of reference in which A precedes B, others >in which B precedes A, and others in which they are >simultaneous. As a result, if something were travelling >faster than c relative to an inertial frame of reference, it >would be travelling backwards in time relative to another >frame, and causality would be violated. In such a >frame of reference, an "effect" could be observed before >its "cause". Such a violation of causality has never been >recorded, and would lead to paradoxes such as the >tachyonic antitelephone. > > http://en.wikipedia.org/wiki/Speed_of_light#Upper_limit_on_speeds Yabbbaaah, barely made sense of that jungle of words. I somehow have a sense of time as a kind of tapestry hanging on a wall; we move past; what is behind us at right in front of us is visible to us, but what is ahead is hidden. Suppose we find a way of approaching the tapestry from the other side, or a way of "unhiding" the hiddenwith time travel, one could go to other parts of the tapestryif I presuppose the outcomes (results) of certain actions to be fixed (no open-ended "if this, then that") events, and time, could be (theoretically) approached from the "other side" too. I think this would have to be one's consciousness moving through time, as one's physical body would be bound by the time frame of its existenceMy imagination fails at this pointand as you say, what is unimaginable gets exciting. I love the Calvin series on his meeting his past and future selves.made me think a lot. I realize this is an inarticulate post. But I can't express it better.
Re: [silk] Speed of light broken?
>> I wish it is possible, it is kind of exciting to imagine... > > Just wish to point out that there are many concepts that are fact > today...and which were considered utterly impossible before This one, it is really a mind bender to consider how it could be possible. Because of the relativistic phenomena of the "relativity of simultaneity", if faster-than-light travel was possible, we would have to throw away causality. I don't know about you, but I like causality. It's rather hard to imagine what life would be without it. >From wikipedia: If the spatial distance between two events A and B is greater than the time interval between them multiplied by c then there are frames of reference in which A precedes B, others in which B precedes A, and others in which they are simultaneous. As a result, if something were travelling faster than c relative to an inertial frame of reference, it would be travelling backwards in time relative to another frame, and causality would be violated. In such a frame of reference, an "effect" could be observed before its "cause". Such a violation of causality has never been recorded, and would lead to paradoxes such as the tachyonic antitelephone. http://en.wikipedia.org/wiki/Speed_of_light#Upper_limit_on_speeds Exciting times indeed.
Re: [silk] Speed of light broken?
On Fri, Sep 23, 2011 at 6:57 AM, Srini RamaKrishnan wrote: > On Fri, Sep 23, 2011 at 2:46 AM, Udhay Shankar N wrote: > > > > Erm. I don't have either details or theoretical background to say more > > at this point, but does anyone else have any thoughts? > > > I wish it is possible, it is kind of exciting to imagine... > Just wish to point out that there are many concepts that are fact today...and which were considered utterly impossible beforean airliner weighing several tons, flying in the air; man reaching the moon; talking in real time, with hardly an effort, to a person halfway across the world; being able to see the smallest detail of someone's attire from a point in spacethe list is endless. Sowhy not? I still cannot get over the fact that sitting at home, I am able to read the book that my grand-daughter is holding in her hands in St.Louis. The fact that the scientists are playing devil's advocate is the most heartening sign. I join Cheeni in hoping this is true, too...horizons will open up in unimagined directions.
Re: [silk] Speed of light broken?
On Fri, Sep 23, 2011 at 2:46 AM, Udhay Shankar N wrote: > > Erm. I don't have either details or theoretical background to say more > at this point, but does anyone else have any thoughts? > Let's just say the chances of an experimental error are staggeringly larger than the overturning of the theory of relativity. That said, no doubt the scientists at CERN have been doing their hardest to prove themselves wrong before publication, so it's going to be interesting. I've always thought that if conventional notions of time travel apply, that is to say you can head back in time to a historical period in your own time dimension, then by now we should have had a visitor from the future. If future visitors can't really communicate ever or offer evidence of their existence then afaics time travel is kind of useless. Lack of any proof from the future so far means that at no point in time in the future will there be an authorized or rogue time traveler who lets the past know of the future. That said, I wish it is possible, it is kind of exciting to imagine...
[silk] Speed of light broken?
Erm. I don't have either details or theoretical background to say more at this point, but does anyone else have any thoughts? Udhay http://www.bbc.co.uk/news/science-environment-15017484 22 September 2011 Last updated at 17:28 GMT Speed-of-light experiments give baffling result at Cern By Jason Palmer Science and technology reporter, BBC News Puzzling results from Cern, home of the LHC, have confounded physicists - because it appears subatomic particles have exceeded the speed of light. Neutrinos sent through the ground from Cern toward the Gran Sasso laboratory 732km away seemed to show up a tiny fraction of a second early. The result - which threatens to upend a century of physics - will be put online for scrutiny by other scientists. In the meantime, the group says it is being very cautious about its claims. "We tried to find all possible explanations for this," said report author Antonio Ereditato of the Opera collaboration. "We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't," he told BBC News. "When you don't find anything, then you say 'Well, now I'm forced to go out and ask the community to scrutinise this.'" Caught speeding? The speed of light is the Universe's ultimate speed limit, and much of modern physics - as laid out in part by Albert Einstein in his special theory of relativity - depends on the idea that nothing can exceed it. Albert Einstein in Pittsburgh on 28 December 1934 Much of modern physics depends on the idea that nothing can exceed the speed of light Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit. But Dr Ereditato and his colleagues have been carrying out an experiment for the last three years that seems to suggest neutrinos have done just that. Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another. The team prepares a beam of just one type, muon neutrinos, sending them from Cern to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos. In the course of doing the experiments, the researchers noticed that the particles showed up a few billionths of a second sooner than light would over the same distance. The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery. But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit, and that has motivated them to publish their measurements. "My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato said. But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy". "And of course the consequences can be very serious." -- ((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
