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Big story ....CERN scientists break the speed of light

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    #92
    TheMilkyPirate
    Registered Users Posts: 5,963 ✭✭✭TheMilkyPirate


    Morbert wrote: »
    Looks like the result has survived the modified experiment, ruling out a few important sources of systematic errors. While I am not holding my breath, I am getting a little excited.

    Is there many more possible errors?


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    #93
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Professor_Fink wrote: »
    That is for the GPS in a car. The GPS cards they used are far more accurate (go watch the CERN lecture, since they went through the GPS in excruciating detail), and use a multifrequency encoding the circumvent the usual limiting factor imposed by the state of the ionosphere.

    Could something be up with the Ionosphere?

    I might given the Cern lecture a look - I'm not so sure I'm up for excurciating at the minute. I don't want to look, but are they averaging the GPS result from the different frequencies. (one of the many things I've forgotten how to do, was the equations for GPS - the one used by cars is accurate to 1 square metre. But I don't remember any parts that took into account atmospheric effects )

    If there was solar flares were more active than usual, could it throw their GPS.

    The most likely explanation I have heard so far is that the fact that they only did the geodesy survey twice might fail to detect periodic changes in the earths shape (which do occur).

    The path is from Cern, Switzerland, to Gran Sasso, Italy- 450 miles (720km) apart. I wonder do things like the temperature of the crust, variations in tension (I think that's enough to cause anomalies in gravity), plus little shifts, would those things add up - or at least mess up the measurements.


    My understanding of relativity: if you took two synchronised clocks from Cern, and transported them to Gran Sasso. One by car, the other by train. The clock travelling by train would be slightly ahead of the clock that travelled by car, once they both reached Gran Sasso. (or do I have that back to front?).

    If you could hear each clock ticking from Gran Sasso, would the clock on the train sound like it was ticking faster?

    Or I have something wrong? This is confusing me. If instead of a clock tick - each clock emitted a sine wave ( say 60 Hz) - which is put through a speaker. I know this is wrong, but I don't understand why. But if, the person in Gran Sasso measured the difference in frequency - would the ratio of observed frequency over 60 Hz give the ratio of time dilation. I know that's wrong, if it was right clocks in aeroplanes, would be out of synch with ground all the time.


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    #94
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    krd wrote: »
    Professor_Fink wrote: »
    That is for the GPS in a car. The GPS cards they used are far more accurate (go watch the CERN lecture, since they went through the GPS in excruciating detail), and use a multifrequency encoding the circumvent the usual limiting factor imposed by the state of the ionosphere.

    Could something be up with the Ionosphere?

    I might given the Cern lecture a look - I'm not so sure I'm up for excurciating at the minute. I don't want to look, but are they averaging the GPS result from the different frequencies. (one of the many things I've forgotten how to do, was the equations for GPS - the one used by cars is accurate to 1 square metre. But I don't remember any parts that took into account atmospheric effects )

    If there was solar flares were more active than usual, could it throw their GPS.

    The most likely explanation I have heard so far is that the fact that they only did the geodesy survey twice might fail to detect periodic changes in the earths shape (which do occur).

    The path is from Cern, Switzerland, to Gran Sasso, Italy- 450 miles (720km) apart. I wonder do things like the temperature of the crust, variations in tension (I think that's enough to cause anomalies in gravity), plus little shifts, would those things add up - or at least mess up the measurements.


    My understanding of relativity: if you took two synchronised clocks from Cern, and transported them to Gran Sasso. One by car, the other by train. The clock travelling by train would be slightly ahead of the clock that travelled by car, once they both reached Gran Sasso. (or do I have that back to front?).

    If you could hear each clock ticking from Gran Sasso, would the clock on the train sound like it was ticking faster?

    Or I have something wrong? This is confusing me. If instead of a clock tick - each clock emitted a sine wave ( say 60 Hz) - which is put through a speaker. I know this is wrong, but I don't understand why. But if, the person in Gran Sasso measured the difference in frequency - would the ratio of observed frequency over 60 Hz give the ratio of time dilation. I know that's wrong, if it was right clocks in aeroplanes, would be out of synch with ground all the time.
    Only if the clock on the train was travelling faster than the one in the car. When side by side both clocks will tick at the same time though. The reason for this is that on the train it's not the clock that is slowing down, it is time itself. The same does happen on planes but the differences are unnoticeable to Humans (we're talking nanoseconds).


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    #95
    old_aussie
    Registered Users Posts: 3,410 ✭✭✭old_aussie


    A total of 15,000 beams of neutrinos - tiny particles that pervade the cosmos - were fired over a period of three years from CERN towards Gran Sasso 730 (500 miles) km away, where they were picked up by giant detectors.

    If their calculations are as accurate as the miles to kilometers conversion above then there is a small problem.


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    #96
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    old_aussie wrote: »
    A total of 15,000 beams of neutrinos - tiny particles that pervade the cosmos - were fired over a period of three years from CERN towards Gran Sasso 730 (500 miles) km away, where they were picked up by giant detectors.

    If their calculations are as accurate as the miles to kilometers conversion above then there is a small problem.

    I cut and pasted that figure from the Guardian (also known, pejoratively, as the Gaurnaid - for typos and errors)


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    #97
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    AlmightyCushion wrote: »
    Only if the clock on the train was travelling faster than the one in the car. When side by side both clocks will tick at the same time though.

    Yes. I was implying that - assuming a train will typically travel much faster than a car. Especially some of those high speed Euro ones. And I'm not sure - but maybe it still stands that Mussolini got the trains to run on time.

    A long time ago, I studied some science at an IT - I'm slowly working back to it. But can't even do some of the simple maths I used. I've been reading up on Einstein's relativity - but I haven't got that far with it. Like I don't understand, yet, why nothing can, or is supposed to, travel faster than light.
    The reason for this is that on the train it's not the clock that is slowing down, it is time itself.

    But time is relative. When it comes to sound. If there is a brass band on a train, and they all play the note D, if the train is going fast enough - people in front of the train, will hear the note E, because the frequency has been shifted up by the Doppler effect (or another way to put it, the wavelength has been shortened) However, on the train, the band still hear the note D - and this is where relativity gets weird - the space and time for the observer, is not the same space and time for the band on the train.


    Now. I know I'm wrong - but I'm not sure how I'm wrong.

    If on the train, there was a clock, with a very loud second tick - and the train was going very fast, but nowhere near the speed of light (don't want to calculate and estimate - I am that rusty) but lets say a few thousand miles an hour. To a stationary observer - within earshot of the clock tick, somewhere well in front of the train - the clock tick would sound like it was going a lot faster than one tick per second - or 1 Hz, if you want to be particular. let's say the train was going fast enough the Doppler effect made the tick 2 Hz. That would be a massive time dilation. You wouldn't be able to take a long car journey on a motorway, without having to reset your watch when you got to your destination.

    Now. I know, that time dilation caused by relativity, is related to light (I haven't worked the proof out myself - hopefully in a few months time - just for the sake of being able to say I've done it - and an irritating curiosity).

    If the train had a light bulb on the front - it was going fast enough - if the observer in front of the train saw a blue light - you could calculate the time dilation based on the observed shift in the wavelength.

    If the time dilation were to be calculated from the Doppler effect with sound (not light) - if would be a massive difference.
    The same does happen on planes but the differences are unnoticeable to Humans (we're talking nanoseconds).

    It's in nanoseconds, because the time dilation is related to light, and not sound. If you consider how I've used sound - the differences become very noticeable. With planes, the difference would be in full seconds, even minutes - I know I'm wrong, but I don't understand why I'm wrong.


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    #98
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    krd wrote: »
    AlmightyCushion wrote: »
    Only if the clock on the train was travelling faster than the one in the car. When side by side both clocks will tick at the same time though.

    Yes. I was implying that - assuming a train will typically travel much faster than a car. Especially some of those high speed Euro ones. And I'm not sure - but maybe it still stands that Mussolini got the trains to run on time.

    A long time ago, I studied some science at an IT - I'm slowly working back to it. But can't even do some of the simple maths I used. I've been reading up on Einstein's relativity - but I haven't got that far with it. Like I don't understand, yet, why nothing can, or is supposed to, travel faster than light.
    The reason for this is that on the train it's not the clock that is slowing down, it is time itself.

    But time is relative. When it comes to sound. If there is a brass band on a train, and they all play the note D, if the train is going fast enough - people in front of the train, will hear the note E, because the frequency has been shifted up by the Doppler effect (or another way to put it, the wavelength has been shortened) However, on the train, the band still hear the note D - and this is where relativity gets weird - the space and time for the observer, is not the same space and time for the band on the train.


    Now. I know I'm wrong - but I'm not sure how I'm wrong.

    If on the train, there was a clock, with a very loud second tick - and the train was going very fast, but nowhere near the speed of light (don't want to calculate and estimate - I am that rusty) but lets say a few thousand miles an hour. To a stationary observer - within earshot of the clock tick, somewhere well in front of the train - the clock tick would sound like it was going a lot faster than one tick per second - or 1 Hz, if you want to be particular. let's say the train was going fast enough the Doppler effect made the tick 2 Hz. That would be a massive time dilation. You wouldn't be able to take a long car journey on a motorway, without having to reset your watch when you got to your destination.

    Now. I know, that time dilation caused by relativity, is related to light (I haven't worked the proof out myself - hopefully in a few months time - just for the sake of being able to say I've done it - and an irritating curiosity).

    If the train had a light bulb on the front - it was going fast enough - if the observer in front of the train saw a blue light - you could calculate the time dilation based on the observed shift in the wavelength.

    If the time dilation were to be calculated from the Doppler effect with sound (not light) - if would be a massive difference.
    The same does happen on planes but the differences are unnoticeable to Humans (we're talking nanoseconds).

    It's in nanoseconds, because the time dilation is related to light, and not sound. If you consider how I've used sound - the differences become very noticeable. With planes, the difference would be in full seconds, even minutes - I know I'm wrong, but I don't understand why I'm wrong.
    I'm on my phone at the moment so I'll be brief and give a better explanation when I have a proper keyboard. Doppler shift is the phenomenon you are talking about and it is unrelated to relativity. The difference in tone is down to compression of the sound wave and not to do with the time dilation effect of relativity.

    On a plane the difference is nanoseconds, not seconds.


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    #99
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    AlmightyCushion wrote: »
    I'm on my phone at the moment so I'll be brief and give a better explanation when I have a proper keyboard. Doppler shift is the phenomenon you are talking about and it is unrelated to relativity.

    The Doppler effect is related to relativity.
    The difference in tone is down to compression of the sound wave and not to do with the time dilation effect of relativity.

    The tone appears compressed from the perspective of an inertial observer. In reality, there can be no such thing as an inertial observer - we're all moving in space. If you were truly inertial in space, the sound wave would appear to go through all kinds of contortions. From the perspective of the observer who is at the point where the tone is being generated - the wave would appear to move evenly through space - at the same speed in all directions. From the perspective of an inertial observer - listening to a tone coming from an approaching train, the pitch appears higher. How can the wave be compressed in the space of one observer, and not in the space of the other. If there is an observer behind the train, they will hear the pitch as lower - so the wave appears to be stretched out.



    Similarly with light. Light from distant stars, travelling away from us, is red-shifted. The wave length appears to us as stretched out. If you left the star, travelling along side the light, at the speed of light, the wave length would appear to you as constant - it wouldn't appear stretch.

    From the point of the observer on earth. The length of the wave length, appears to be longer. And the time it takes the light to travel a distance of its' wavelength appears to be longer.

    I had a brutal physics teacher at school. lot's of wrong headed ideas (filling my head with wrong headed ideas )- one was the Doppler effect was caused by air pressure of the inertial air mass resisting the the approaching sound wave - forcing the sound wave to compress - like pushing a spring against a wall. Of course that would mean the formula for calculating the frequency change wouldn't make sense.


    On a plane the difference is nanoseconds, not seconds.

    Yes, I know it's nanoseconds. If you read what I said in my post.


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    #100
    shizz
    Registered Users Posts: 1,506 ✭✭✭shizz


    krd wrote: »
    The Doppler effect is related to relativity.



    The tone appears compressed from the perspective of an inertial observer. In reality, there can be no such thing as an inertial observer - we're all moving in space. If you were truly inertial in space, the sound wave would appear to go through all kinds of contortions. From the perspective of the observer who is at the point where the tone is being generated - the wave would appear to move evenly through space - at the same speed in all directions. From the perspective of an inertial observer - listening to a tone coming from an approaching train, the pitch appears higher. How can the wave be compressed in the space of one observer, and not in the space of the other. If there is an observer behind the train, they will hear the pitch as lower - so the wave appears to be stretched out.



    Similarly with light. Light from distant stars, travelling away from us, is red-shifted. The wave length appears to us as stretched out. If you left the star, travelling along side the light, at the speed of light, the wave length would appear to you as constant - it wouldn't appear stretch.

    From the point of the observer on earth. The length of the wave length, appears to be longer. And the time it takes the light to travel a distance of its' wavelength appears to be longer.

    I had a brutal physics teacher at school. lot's of wrong headed ideas (filling my head with wrong headed ideas )- one was the Doppler effect was caused by air pressure of the inertial air mass resisting the the approaching sound wave - forcing the sound wave to compress - like pushing a spring against a wall. Of course that would mean the formula for calculating the frequency change wouldn't make sense.





    Yes, I know it's nanoseconds. If you read what I said in my post.

    From my understanding the Doppler effect isn't relative in the same way time is. It's cause by the moving source producing sound waves closer at each successive stage because the source is moving in the direction of the waves travel. Of course if you were behind the source you would hear a lower tone because each successive wave is produced further away then the last one. Also, of course if you kept in line with the source you wouldn't hear a change in pitch as you are on the side of it or within it so you are always an equal distance away so these changes can't effect what you hear. So yes the sound you hear is relative with your position but it is not linked with Space and time relativity.

    Another way to see how it differs from relativity is, if something was moving a lot faster than you and you could observe someone within that object that was moving that fast, you would see them move a lot slower within it as time for them has slowed down. (obviously exaggerated) But as they move towards you and move away you won't notice any change in how slow they are moving, unless the object slowed down. At least this is how I understand it so Im open to corrections.


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    #101
    opinion guy
    Closed Accounts Posts: 11,001 ✭✭✭✭opinion guy


    baraca wrote: »
    Is there many more possible errors?

    General rule that applies to any and all science: there are always more possible errors.


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    #102
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    shizz wrote: »
    From my understanding the Doppler effect isn't relative in the same way time is.

    It's cause by the moving source producing sound waves closer at each successive stage because the source is moving in the direction of the waves travel.

    No, the source is not producing sound waves that are closer together at each successive stage. Relative to the source, if the source maintains the same velocity and direction, the wavelength of the sound waves will remain constant.

    Think of it another way. If you were a person on a train. And sound source was in a stationary position somewhere outside the train. As you approached the source, the tone would appear higher - as you passed it the tone would drop.
    The source does not know that you are approaching or receding, the waves don't know either.

    It's actually counter intuitive.

    The Doppler effect is how a wave appears to the observer.

    And it happens with light too. If a star is moving away from you, or think of it another way, the star is not moving, and you are flying away from the star. Your velocity relative to the light from the star will effect how see the wavelength of the light. The wavelength will appear longer.


    It's really counter intuitive. If the wave length from a star was 1 metre. then if the star was moving away quickly enough - the wavelength could appear to us as 2 metres. But as far as the photon is concerned the wavelength is 1 metre.

    We can still see the light from the big bang, 13 billion years ago. And can calculate the time of the big bang by how stretch out the wavelength has become.
    Another way to see how it differs from relativity is, if something was moving a lot faster than you and you could observe someone within that object that was moving that fast, you would see them move a lot slower within it as time for them has slowed down. (obviously exaggerated) But as they move towards you and move away you won't notice any change in how slow they are moving, unless the object slowed down. At least this is how I understand it so Im open to corrections.

    I've never liked that example. As it doesn't actually explain anything.

    If people were on a spaceship, and having a party, if you could always see them. If they accelerated away from you, as they travelled faster, they would first become reddish looking, then eventually, they would become invisible, the light would be radio waves. I don't know if that would mean, it would appear their motions are slower.


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    #103
    Curly Judge
    Registered Users Posts: 2,708 ✭✭✭Curly Judge


    The Doppler effect explains the symptoms of sound wave behavior in a source approaching or departing from you at speed.
    It is purely a symptom and has no effect on how the source emits the sound wave signal, any more than a high temperature has an effect on how a flu starts.
    Ditto with the red shift!
    Therefore to say that the red shift is a relativistic phenomenon is probably correct but it is not relativistic per se.
    I think? :confused:


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    #104
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Curly Judge wrote: »
    The Doppler effect explains the symptoms of sound wave behavior in a source approaching or departing from you at speed.
    It is purely a symptom and has no effect on how the source emits the sound wave signal, any more than a high temperature has an effect on how a flu starts.
    Ditto with the red shift!
    Therefore to say that the red shift is a relativistic phenomenon is probably correct but it is not relativistic per se.
    I think? :confused:

    See, this relativity stuff is confusing.

    There is an evolution to the theory of relativity; Galilean relativity, Newtonian relativity, then Einstein's relativity. Einstein builds on the previous ideas. I'm slowly hacking away at Einstein's stuff - where it gets a little more tricky.


    Anyway, what I've been talking about is actually called the Relativistic Doppler effect. Time dilation does occur.

    http://en.wikipedia.org/wiki/Relativistic_Doppler_effect

    If you're not confused, you don't understand it.

    See, how you intuit the world. The whole world appears as if time is the same everywhere, and space is the same everywhere - when it just isn't.

    Like my school physics teacher had to believe that the Doppler effect, with sound, was to do with the air resisting the sound wave. Of course, this meant the equations in the school book didn't make sense - but just memorise them and do the exam - their devilry is beyond you. Once you grasp what's really happening, it's actually disturbing; space and time are not absolute as they appear.

    It's funny, people were still clinging to an idea like the Aether up until nearly the 20th century.


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    #105
    roosh
    Registered Users Posts: 2,552 ✭✭✭roosh


    Rejection of FTL neurtino result

    The rejection of the claim is based on the expectation that the neutrinos should have lost discernable amounts of energy, had they travelled faster than light. Just wondering, is this expectation something that arises from the standard model, or what is it that leads them to conclude that they should've lost discernable amounts of energy?


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    #106
    ZorbaTehZ
    Registered Users Posts: 2,149 ✭✭✭ZorbaTehZ


    roosh wrote: »
    Rejection of FTL neurtino result

    The rejection of the claim is based on the expectation that the neutrinos should have lost discernable amounts of energy, had they travelled faster than light. Just wondering, is this expectation something that arises from the standard model, or what is it that leads them to conclude that they should've lost discernable amounts of energy?

    No, as far as I'm aware; for instance if you assume quantum mechanics and FTL propagation, then you get continuous emition of cerenkov radiationfor particles travelling FTL. But as far I know, Cohen & Glashow consider instead "forbidden processes" that can occur in FTL propagation, one of which causes a big energy loss. I don't know how (or if) these two gel together, since I don't know enough particle physics. Some blogs have been compiling lists of (otherwise obscure) papers of the last 20 years that have investigated the consequences of FTL propagation. But regarding the C&G paper, to quote Bell "it has a good pedigree" - the latter is a nobel laurate after all (if that counts for anything!).


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    #107
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    roosh wrote: »
    Rejection of FTL neurtino result

    The rejection of the claim is based on the expectation that the neutrinos should have lost discernable amounts of energy, had they travelled faster than light. Just wondering, is this expectation something that arises from the standard model, or what is it that leads them to conclude that they should've lost discernable amounts of energy?

    Is the implication of the neutrinos emitting Cerenkov radiation that the loss of energy would cause them to slow down?

    If I've got this right - they haven't run a different experiment, they're just saying the neutrinos should have lost energy through Cernenkov radiation and throwing off electrons.


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    #108
    Curly Judge
    Registered Users Posts: 2,708 ✭✭✭Curly Judge


    My reading of what they said is that if the neutrinos had not exhibited Chernenko radiation then they could not have been traveling FTL.
    Have I got it wrong?


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    #109
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Curly Judge wrote: »
    My reading of what they said is that if the neutrinos had not exhibited Chernenko radiation then they could not have been traveling FTL.
    Have I got it wrong?

    I know very little about this. Chernenko radiation is something that can be seen in nuclear reactors - I saw it in a documentary. In the documentary they said the blue light/glow in the reactors water was Chernenko radiation. I think given off by neutrons released in the reaction.

    I would suppose, if the neutrinos are emitting Chernenko radiation, they have to be slowing down, or shrinking (do they shrink?). They can't be producing "free energy".

    In the experiment, I don't think they were measuring the neutrinos emission of radiation, just their arrival times.

    I think the other team are just saying, it's impossible because the Chernenko radiation would mean the neutrinos would have to lose energy, so they would have to slow down.

    The whole thing could simply be they have a wrong bias set in their measuring equipment. They have to account for the time lag in the electronics of their measuring equipment - if they've over biased for the delay, they could easily get a FTL result.


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    #110
    FarmerGreen
    Registered Users Posts: 1,134 ✭✭✭FarmerGreen


    Light has a certain speed in a vacuum, in a denser medium like glass, much less, 0.7 say.
    Its called the velocity factor.
    Neutrinos dont interact with matter.
    So, shooting a Neutrino beam through miles of rock (which it wont interact with) and expecting it to come out the other end as if it had travelled at the speed of light in this medium is, well, pushing it a bit.

    Maybe I'm wrong.


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    #111
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    FarmerGreen wrote: »
    Light has a certain speed in a vacuum, in a denser medium like glass, much less, 0.7 say. Its called the velocity factor.

    I was talking to someone a while back (a physicist), they told me light could be slowed to a stop, in super cooled crystals. Personally, I didn't study enough to get to the point of understanding why light slowed down in different mediums (or maybe I did but can't remember -there's a lot I can't remember)
    Neutrinos dont interact with matter.

    They have to interact with matter - otherwise, we'd have no way of telling they're there. The universe could be filled with particles that have no interaction with matter, and we'll never know they're there - because they will have no interactions with the observable universe.

    So, shooting a Neutrino beam through miles of rock (which it wont interact with) and expecting it to come out the other end as if it had travelled at the speed of light in this medium is, well, pushing it a bit.

    Maybe I'm wrong.

    I'm assuming neutrinos can pass through miles of rock is because they're so small their probability of hitting anything is slim.........Which leaves me wondering who do they hit the detector? What is the detector?

    I'm just assuming. I would like to know the answer to that one.


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    #112
    Podge_irl
    Moderators, Sports Moderators Posts: 25,292 Mod ✭✭✭✭Podge_irl


    krd wrote: »
    They have to interact with matter - otherwise, we'd have no way of telling they're there. The universe could be filled with particles that have no interaction with matter, and we'll never know they're there - because they will have no interactions with the observable universe.

    Which is essentially what dark matter is - only it interacts via the gravitational force but nothing else.
    krd wrote: »
    I'm assuming neutrinos can pass through miles of rock is because they're so small their probability of hitting anything is slim.........Which leaves me wondering who do they hit the detector? What is the detector?

    I'm just assuming. I would like to know the answer to that one.

    The detector only detects a minute fraction of the total number of neutrinos.


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    #113
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Podge_irl wrote: »
    Which is essentially what dark matter is - only it interacts via the gravitational force but nothing else.

    A gravitational interaction would be an interaction with matter. If dark matter exists - if it was made up off darkions, it would just be recognised by their gravitational interaction. But that's a puzzle isn't it. Why don't they clump together and form darkstars and dark planets. Maybe because they don't exist. Or maybe they powerfully repel each other by some force that doesn't interact with anything in our world - and form gravity fogs. I don't know. It would explain why its' so hard to find even one darkion.
    The detector only detects a minute fraction of the total number of neutrinos.

    They're measuring pulses of neutrinos - they just need to see a fraction of the neutrinos within the pulses - and the shape of the recording will show, they're looking at the neutrinos from CERN - a neat square wave.

    I'm not sure what detector they're using but I was looking at typical neutrino detectors on wikipedia. I would assume they're using a container with some liquid, surrounded by highly sensitive scintillation detectors (spark detectors - optical sensors). I would also assume they have sensors in there that can specifically pick up Cherenkov radiation.

    My limited understanding, neutrinos will travel faster than the speed of light through the medium in their detector because of its' refractive index. So there should be Cherenkov radiation - which should be hard to miss. They should be able to see lovely pulses of it, that correspond with the pulses from CERN....It should be virtually impossible to miss (if it's there)

    If they haven't seen the Cherenkov radiation, or haven't bothered looking for it. They may have been very sloppy.


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    #114
    Podge_irl
    Moderators, Sports Moderators Posts: 25,292 Mod ✭✭✭✭Podge_irl


    Our inability to find a "darkion" (not a terminology I'm familiar with) is not even remotely unusual. We don't detect individual particles by their gravitational interaction as it's simply a far too weak effect.

    Neutrinos will not travel through a medium FTL due to any refractive index.


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    #115
    krd
    Banned (with Prison Access) Posts: 3,455 ✭✭✭krd


    Podge_irl wrote: »
    Our inability to find a "darkion" (not a terminology I'm familiar with) is not even remotely unusual. We don't detect individual particles by their gravitational interaction as it's simply a far too weak effect.

    Dark matter is only seen in gravity calculations in astrophysics. Where the gravity exists in calculations based on observations, but the matter itself has not been observed.

    Which is strange for many reasons - if there's so much of it, why can't we see any of it. If it's the same gravity as ordinary matter and there's so much of it - why aren't we seeing dark stars. Dark galaxies. If there's so much of it there why isn't that happening.

    The individual particles may be too small to measure their gravitation interaction. But the astrophysics are measuring a huge gravitational interaction, for matter that can't be seen.
    Neutrinos will not travel through a medium FTL due to any refractive index.

    the refractive index n = speed of light in a vacuum / speed of light in medium.

    n = c/Vp. It's the phase velocity in medium.

    From the explanations I've seen of Cherenkov radiation, if a particle like a neutron, travels faster than the phase velocity of light in a medium, then it will cause Cherenkov radiation. Supposedly, something like the equivalent of a sonic boom from a jet travelling faster than the speed of sound.


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    #116
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    Perhaps it has something to do with the method through which neutrinos travel as opposed to how photons travel. Perhaps it is the case that a neutrino is an idealised photon and that the limit to the speed of light is just a little higher than we thought.

    By way of an analogy, consider that space is a collection of points that exhibit a repulsive force such as to give rise to spontaneous expansion. Also, if we consider 'mass' as being bound energy and energy as being spacial vibrations, we can see that expansion is pervasive; space expands and so therefore mass and energy undergo expansion too and this maintains perspective i.e., each point of space can be considered a physical entity and over time, the volume of space increases as the density of repulsive points decreases.

    Now take the case of an incandescant light-bulb; as electrons interact with the tungsten filament at a sub-atomic level, energy causes vibrations in the space local to the filament. In other words, the repulsive points that define space are swirled about; the normal expansion of space is interfered with and the paths of local points are altered. This in turn causes local space to interact with itself in a slightly different way and at low energy levels, the spacial-field just becomes slightly distorted.

    However, as energy increases so too does the agitation of local space and at a high enough energy level, it is possible for 'points' of space to be pushed between other points so hard that an area of 'high pressure' is suddenly created and other local points 'feel' resistance and adjust their expansion path accordingly. But this high-energy point has a directional component and this means that the repulsive pressure is greater behind it than it is in front; space behind close the gap and the high energy point is forced through the next gap, then the next, in a kind of chain reaction that causes a wave to propogate and describes the photon.

    Now, the photon does lose energy at a very small rate but this is almost exactly cancelled by the fact that as the points in space move apart, their repulsive force has less and less of an effect.

    The thing is though, the space ahead of the photon is expanding and so a device that detects it is always moving away from the emitter in some respect; the 'real' distance between two points is always increasing and this increase is manifest as red-shift. Or to put it another way, from the perpective of a space point, light is constantly slowing down.

    In this model though, there is a statistical probability for another consequence of spacial vibration. Instead of being pushed between points an excited space point might be made to collide with another point travelling the same direction. The chain reaction that followed would be like a Newton's cradle effect affecting space points directly. If the photon was light enough, it might actually be able to make used of the expansion energy itself such as to be unaffected by expansion at all.

    A photon and a netrino set of from a point 'A' at the same time and are to be detected at some point, 'B' at some time later. Between points A and B there is a certain amount of space and therefore a certain number of space points which are constantly moving apart; that number can be 'P'. For the photon during flight, the number of space points passed each second will decrease; from its perspective, the volume of space is increasing. For a neutrino, however, the number of space points it passes remains constant since it experiences constant acceleration. The volume of space seems to remain constant fron its point of view. It seems likely that 'old' neutrinos could have accelerated to speeds far in excess of the speed of light over time. That's a mad notion isn't it?

    Could it be that a photon travels 'through' space, between points, whereas neutrinos travel 'on' space, jumping from point to point and at each point picking up enough energy to counter expansion?

    Perhaps a neutrino is simply a special case of photon; a photon that makes direct use of vacuum energy for a constant rate of acceleration.

    I wonder, do neutrinos become red shifted over distance?

    This could explain why neutrinos pass through matter too.


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    #117
    Morbert
    Registered Users Posts: 3,457 ✭✭✭Morbert


    Looks like it might have been a loose cable. Oops


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    #118
    darjeeling
    Registered Users Posts: 962 ✭✭✭darjeeling


    Morbert wrote: »
    Looks like it might have been a loose cable. Oops

    Embarrassing, if that's the final conclusion. On the plus side, it won't be necessary to overturn all of physics.


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    #119
    Curly Judge
    Registered Users Posts: 2,708 ✭✭✭Curly Judge


    Morbert wrote: »
    Looks like it might have been a loose cable. Oops

    :confused:


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    #120
    Seifer
    Registered Users Posts: 2,265 ✭✭✭Seifer


    Curly Judge wrote: »
    :confused:

    http://news.sciencemag.org/scienceinsider/2012/02/breaking-news-error-undoes-faster.html


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    #121
    himnextdoor
    Closed Accounts Posts: 1,042 ✭✭✭himnextdoor


    Seifer wrote: »
    http://news.sciencemag.org/scienceinsider/2012/02/breaking-news-error-undoes-faster.html

    It seems odd that no-one noticed that the data carried by the fibre optics was arriving later than expected; the neutrinos weren't arriving early, the light was arriving late!

    A 60 nS delay equates to an extra 18 metres or so of extra distance travelled by light along the fibre-optic cable. What with GPS and relativity, shouldn't that anomaly have been spotted first?

    Even horse-racing officials go to the trouble of analysing a 'photo-finish' before publishing results.

    I think that this is very poor; how much research money needs to be spent on proving that Einstein knew what he was talking about?


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