Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Geezer on 22/11/2011 23:16:36
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The experimental results suggest that neutrinos are "Faster than light". Why do you think that is the case?
Please provide a summary of any opinions you would like considered and we'll add them to the list of options.
You can only vote once, but you can change your vote.
I've started with a couple of suggestions to get the ball rolling.
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Quote from Soul Surfer
"Syhprum That is an interesting and reasonably plausible idea"
I notice that despite this endorsement from an authoritative source my suggestion has not been included in the poll ?
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Quote from Soul Surfer
"Syhprum That is an interesting and reasonably plausible idea"
I notice that despite this endorsement from an authoritative source my suggestion has not been included in the poll ?
My fault! These were only intended to be a selection.
Just post how you would like your voting option to read and we'll add it to the list.
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No need it has just been destroyed by Imatfaal,s logig
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I think that some sheepies were grazing on the mountain and intercepted the neutrinos. They used their sheepy magic to speed up the neutrinos.
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Any mass with very high energy can travel faster than light.
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My theory is that there is only one photon that travels infinitely fast and is thus everywhere at once. Its speed is the speed we happen to measure. Ditto for the neutrino, we measure it as having a faster speed.
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Clocks are like chocolate sheep, Swiss do better...
More seriously, a missing delay in electronics or a problem of synchronization with satellites (20 meters is not that much). GPS are controlled by military people, don't ask too much... [:o)]
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Are we asking the correct question ? Should we be asking what slows down photons as they move thru inter stellar space but does not affect Neutrinos ,does the small density of gasses present provide an answer (1000 atoms/M^3), should talk we about the "new" c the speed of Neutrinos.
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In my original post on this subject (23-09-11)I suggested a gravitational time dilation anomaly
see http://www.thenakedscientists.com/forum/index.php?topic=41198.msg367930#msg367930
It would seem I am not alone in this thought as mentioned in Nature Journal (05-10-11 based on an original paper published 28-09-11)
see http://www.nature.com/news/2011/111005/full/news.2011.575.html
The experiment
see http://xxx.lanl.gov/ftp/arxiv/papers/1109/1109.4897.pdf
This includes details of how the timing was accomplished.
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Mike,
Give us some "one-liners" and we'll add them. If we keep this up long enough, somebody is sure to be right.
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Geezer
I voted for the gravitational time anomaly and was just explaining why.
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
Very close to my thoughs - but I voted systematic error. The watches are very good and easily able to time accurately enough ; the problem isn't the machinery it's the decision that signal x rather than signal y is the point at which to start or stop the clock. The stopping seems a simple system with less assumptions (from my lay reading) but the starting the clock running seems to have lots of potential for systematic error. Poor accuracy should lead to a blurred picture - we have a time-shifted picture, we were starting the clock 60ns late consistently
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I think its just not quite easy as we think to get accurate numbers for this. I mean there is still disputes on the exact time of creation of the neutrino, maybe a math or technical problem. I don't think it represents a huge change that needs to be done on modern physics.
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The most interesting idea I've seen so far discuss the 'creation' of a neutrino as the effect making the 'jump'. Treating it as 'matter waves' as I presume. If that is the case maybe we can relate it to the way 'inflation' is thought to work. After all, with the 'expansion' we will have an effect where it's possible that some stars never will shine on earth, as the space 'expands' faster than light speed in a vacuum, depending on its distance from us.
And if particles is defined through their 'surrounding', then those might become different when high energies are involved at that first instant of creation? Not that I know of course :) But if you assume that a creation of a 'matter wave' will be as fast no matter how 'big' we later measure it to be, only energies differing its possible size?
Maybe ::))
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I think its just not quite easy as we think to get accurate numbers for this. I mean there is still disputes on the exact time of creation of the neutrino, maybe a math or technical problem. I don't think it represents a huge change that needs to be done on modern physics.
Einstein's followers cannot create modern physics without Einstein. Therefore you will fail. [:D]
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
It would be a bit embarrassing if it turned out that was the cause, but I suspect it's quite tricky to properly synchronize two clocks at different locations. Anyone know what the procedure is, and how much tolerance is acceptable for this experiment?
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Geezer
OPERA claimed six standard deviations.
See http://www.nature.com/news/2011/111005/full/news.2011.575.html
This is a PDF about the experiment as published by OPERA.
http://xxx.lanl.gov/ftp/arxiv/papers/1109/1109.4897.pdf
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If in fact photons are slowed by the small amount of inter stellar gas could this not solve the supernova event anomaly as the density of gas in the local region is about 1000 times higher than in inter galatic space
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
It would be a bit embarrassing if it turned out that was the cause, but I suspect it's quite tricky to properly synchronize two clocks at different locations. Anyone know what the procedure is, and how much tolerance is acceptable for this experiment?
Nah - synchronizing the clocks is a comparative doddle (using doddle almost completely wrongly).
Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested (there remains the possibility that Gran Sasso didnt follow the instructions properly).
I seem to remember that with the upgraded beacons and after the swiss and german metrology institutes (now I bet they are a bunch of fun and hoopy guys) got involved that the max error was single nanaoseconds
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If in fact photons are slowed by the small amount of inter stellar gas could this not solve the supernova event anomaly as the density of gas in the local region is about 1000 times higher than in inter galatic space
The refraction/scattering by gas/dust that affected light but not the neutrinos was indeed the cause of the slight delay in observations from SN1987a. The neutrinos were a few hours earlier than the photons - but if Gran Sasso speed differentials are correct then the neutrinos should have been 3 years or so early - maybe they were and we never noticed them or maybe different energy neutrinos behave differently
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
It would be a bit embarrassing if it turned out that was the cause, but I suspect it's quite tricky to properly synchronize two clocks at different locations. Anyone know what the procedure is, and how much tolerance is acceptable for this experiment?
Nah - synchronizing the clocks is a comparative doddle (using doddle almost completely wrongly).
Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested (there remains the possibility that Gran Sasso didnt follow the instructions properly).
I seem to remember that with the upgraded beacons and after the swiss and german metrology institutes (now I bet they are a bunch of fun and hoopy guys) got involved that the max error was single nanaoseconds
Well yes, but how does it actually work? If science was based on "following the instructions", we'd still be hanging from a gumm tree.
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Imatfaal
has any research been on the slowing of photons by low density gas I know that it almost impossible to produce a vacuum as low as interstellar space but are there any figures published as to how c varies as near vacuum is approached so that any trend might apparent.
We should not be too surprised at photons being slowed down we see examples of it happening around us all the time the very reason we can see anything is due to the slowing down as they pass thru the lenses of our eyes.
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I don't know if Gran Sasso, 730 km away, uses Carrier phase tracking? (http://en.wikipedia.org/wiki/Global_Positioning_System#Carrier_phase_tracking_.28surveying.29) But "Tracking carrier phase signals provides no time of transmission information. The carrier signals, while modulated with time tagged binary codes, carry no time-tags that distinguish one cycle from another. The measurements used in carrier phase tracking are differences in carrier phase cycles and fractions of cycles over time. At least two receivers track carrier signals at the same time. Ionospheric delay differences at the two receivers must be small enough to insure that carrier phase cycles are properly accounted for. This usually requires that the two receivers be within about 30 km of each other. Carrier phase is tracked at both receivers and the changes in tracked phase are recorded over time in both receivers." and that's not 700 km
Still "All carrier-phase tracking is differential, requiring both a reference and remote receiver tracking carrier phases at the same time.
Unless the reference and remote receivers use L1-L2 differences to measure the ionospheric delay, they must be close enough to insure that the ionospheric delay difference is less than a carrier wavelength.
Using L1-L2 ionospheric measurements and long measurement averaging periods, relative positions of fixed sites can be determined over baselines of hundreds of kilometers.
Phase difference changes in the two receivers are reduced using software to differences in three position dimensions between the reference station and the remote receiver. High accuracy range difference measurements with sub-centimeter accuracy are possible. Problems result from the difficulty of tracking carrier signals in noise or while the receiver moves. Two receivers and one SV over time result in single differences."
It's? Maybe, maybe not, working.
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I am sure they did it many many times and averaged out varying ionospheric conditions.
It is possible to compute c from measurements of magnetic and electrostatic phenomena how accurately can these be measured and how closely does the the measured value of c compare.
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I voted for the watches because it's closest to what I think happened: The chronometer wasn't started and stopped accurately enough
It would be a bit embarrassing if it turned out that was the cause, but I suspect it's quite tricky to properly synchronize two clocks at different locations. Anyone know what the procedure is, and how much tolerance is acceptable for this experiment?
Nah - synchronizing the clocks is a comparative doddle (using doddle almost completely wrongly).
Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested (there remains the possibility that Gran Sasso didnt follow the instructions properly).
I seem to remember that with the upgraded beacons and after the swiss and german metrology institutes (now I bet they are a bunch of fun and hoopy guys) got involved that the max error was single nanaoseconds
Well yes, but how does it actually work? If science was based on "following the instructions", we'd still be hanging from a gumm tree.
Both ends have atomic clocks - whilst one satellite is overhead and both sites are receiving the signal, a record is made of the offset/delay between each clock and the gps signal (which is also atomic clock based)
If you then subtract the delay of Cern from the delay of Gran Sasso you end up with the difference between the two clocks (and the signal time & its error). As we know the signal propagation time and error very accurately (it is the basis of GPS) we can calculate the difference between the clocks. Only real error introduced is through differences in atmospheric conditions (which can be covered by repeating regularly and at night/day), or and by the ephemeris error. The max error for intercontinental long range common view is about 10 nanoseconds - for such a short baseline the major error (ephemeris) is lowered significantly
And frankly Geezer - scientific experimentation is very much about following instructions. You need to be consistent in your operations; and when one area of expertise has developed a technique and it has been found to be accurate then you use that knowledge. ie when a group of nuclear physicists want to know how to measure time over a great distance they use a technique developed by the NIST/USNO, and it is checked and implemented by a national Metrology institute - so in effect they just follow instructions. So as long as Gran Sasso followed the technique carefully and did not vary the protocol then the validity of the result and more importantly the error has already been shown by experts/academics.
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We already know that the speed of light varies based on the medium. And there is apparently some interaction of light with local space... causing the space where the measurement is taken to influence the actual measurement of the speed of light.
So...
if there is an asymptotic maximum speed for particles in local-space, it isn't too surprising to find particles that interact less with what is around them, and thus travel slightly faster than light.
The big question I would have is whether all neutrinos from natural sources distant from Earth travel to Earth at the same speed, or perhaps they are dependent on the relative velocity of the source.
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And frankly Geezer - scientific experimentation is very much about following instructions. You need to be consistent in your operations; and when one area of expertise has developed a technique and it has been found to be accurate then you use that knowledge. ie when a group of nuclear physicists want to know how to measure time over a great distance they use a technique developed by the NIST/USNO, and it is checked and implemented by a national Metrology institute - so in effect they just follow instructions. So as long as Gran Sasso followed the technique carefully and did not vary the protocol then the validity of the result and more importantly the error has already been shown by experts/academics.
Fully agree that a lot of it is simply following the instructions, and very rigorously at that. That usually works very well, but when there is an anomaly, everything is up for grabs. Anomalies (real or apparent) force scientists to ask very uncomfortable questions that move science forward.
My only point was that if nobody ever challenged the "instructions", the Earth would still be at the centre of the Universe.
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Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested
I'm sure these guys know what they are doing, but I found it slightly disconcerting that the description says things like "A and B, receive a one-way signal simultaneously"
If they know it's simultaneous, why bother? Seems a bit circular to me, but then, I'm well known for being nitpicky.
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Clifford - not quite sure of the effects you are talking about - could you elaborate? The problem with measuring neutrinos is that we are so bad at detecting them that we can only be certain of a source in very rare circumstances. Supernova SN1987a is one such event - as Syhprum explained the neutrinos arrived a few hours before the light did, it is possible we missed the "othersort of neutrino" that were superluminal. But to work out how fast Neutrinos travel in space we need to know precisely what caused them and when/where that was - and there are precious few opportunities for that.
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Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested
I'm sure these guys know what they are doing, but I found it slightly disconcerting that the description says things like "A and B, receive a one-way signal simultaneously"
If they know it's simultaneous, why bother? Seems a bit circular to me, but then, I'm well known for being nitpicky.
Doesn't say they receive the same bit of the signal simultaneously - or that the signals are synchronized.
If Mrs Geezer puts on her favourite Balck Sabbath album at full volume at the other end of the house it is quite acceptable to say that you and she are listening simultaneously - although with the finite speed of sound, combined with the magnificence of geezer manor she might hear each of OO's dulcet tones a few seconds before you.
In fact if you did a bit of measuring (distance, air pressure, humidity etc) you could tell which of your two clocks is slow. ie you both look at the clocks in your respective rooms and note the time of the very last bit of Paranoid.
If you clocked it at 15 seconds exactly past the hour, and Mrs G at 10 seconds past exactly - Mrs G is 3.2 m from the stereo and you are 340 m in the other direction (it's a nice dry day at your beach house by the way and about 60F due to the aircon) - after you and Mrs G compare notes; you can work out that your clock is 4 seconds slower than Mrs G's.
Common view relies on a signal being received simultaneously - but possibly not in synch. The fact that the message is the same - and you can the compare notes afterwards allows you to workout the difference in your clocks without worrying about synchronization. The common view part allows you to remove the clock on the satellite from the equation - if I haven't screwed up, the above example would still work if your played Ozzie and friends at 45 or 78. The only sources of error are where the satellites actually are (and we know that fairly well) - and the possibility that one leg of the signal gets bounced around a bit more than the other. At 734 km baseline these errors reduce to fractions of a second (2.3ns)
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Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested
I'm sure these guys know what they are doing, but I found it slightly disconcerting that the description says things like "A and B, receive a one-way signal simultaneously"
If they know it's simultaneous, why bother? Seems a bit circular to me, but then, I'm well known for being nitpicky.
Doesn't say they receive the same bit of the signal simultaneously - or that the signals are synchronized.
If Mrs Geezer puts on her favourite Balck Sabbath album at full volume at the other end of the house it is quite acceptable to say that you and she are listening simultaneously - although with the finite speed of sound, combined with the magnificence of geezer manor she might hear each of OO's dulcet tones a few seconds before you.
In fact if you did a bit of measuring (distance, air pressure, humidity etc) you could tell which of your two clocks is slow. ie you both look at the clocks in your respective rooms and note the time of the very last bit of Paranoid.
If you clocked it at 15 seconds exactly past the hour, and Mrs G at 10 seconds past exactly - Mrs G is 3.2 m from the stereo and you are 340 m in the other direction (it's a nice dry day at your beach house by the way and about 60F due to the aircon) - after you and Mrs G compare notes; you can work out that your clock is 4 seconds slower than Mrs G's.
Common view relies on a signal being received simultaneously - but possibly not in synch. The fact that the message is the same - and you can the compare notes afterwards allows you to workout the difference in your clocks without worrying about synchronization. The common view part allows you to remove the clock on the satellite from the equation - if I haven't screwed up, the above example would still work if your played Ozzie and friends at 45 or 78. The only sources of error are where the satellites actually are (and we know that fairly well) - and the possibility that one leg of the signal gets bounced around a bit more than the other. At 734 km baseline these errors reduce to fractions of a second (2.3ns)
Ah! Right, I see what you mean. It might have been better if they had left out "simultaneous" and said "A and B receive the same transmission" or similar.
How accurately do the distances have to be known for this to work, or does it not require any knowledge of distance? Or does the distance measurement depend on a highly accurate common view of time?
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As far as clocks.
It would be easy enough to put the two clocks together.
Synchronize them.
Separate them and run the experiment.
Bring them back together and verify that they are still in sync.
Or, perhaps have a third physical "master clock", that would be moved from one location to the other.
And, then just repeatedly verify that the "slave clocks" on each end match the master clock.
If jet aircraft affect atomic clocks, then carry them in shielded containers in trucks, trains, or cargo ships on the ground.
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It is not Jet aircraft that disturb atomic clocks but the reduced gravity at altitude and the speed of travel cause time dilation effects which of course you cannot shield against.
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As far as clocks.
It would be easy enough to put the two clocks together.
Synchronize them.
Separate them and run the experiment.
Bring them back together and verify that they are still in sync.
Or, perhaps have a third physical "master clock", that would be moved from one location to the other.
And, then just repeatedly verify that the "slave clocks" on each end match the master clock.
If jet aircraft affect atomic clocks, then carry them in shielded containers in trucks, trains, or cargo ships on the ground.
Clifford
I think Syhprum has covered most of points in your post - however one other thing, they did move an accurate clock between the two. I would recommend a quick scan of the experimental write up (Mike helpfully posted it above) you can read about the timing on pages 7-9. Basically common view synchronization is using a third clock - ie the one on the gps satellite
As Geezer and I mentioned above - when you want great accuracy in a technique you go to those who have great expertise, and the way that the metrologists do this synchronization of clocks is incredibly accurate. The Atomic clocks spread over the USA are accurate to within 1 ns of each other - bearing in mind that some are in Flagstaff Arizona and others are at sea-level you cannot just move one to another as a clock at 2000m and one at sea-level will run at different rates
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Metrology institutes around the world have long established the common view GPS method (http://tf.nist.gov/time/commonviewgps.htm) of synchronization/comparison. This algorithm and protocol for synchronizing geographically remote clocks is not new and has been exhaustively tested
I'm sure these guys know what they are doing, but I found it slightly disconcerting that the description says things like "A and B, receive a one-way signal simultaneously"
If they know it's simultaneous, why bother? Seems a bit circular to me, but then, I'm well known for being nitpicky.
Doesn't say they receive the same bit of the signal simultaneously - or that the signals are synchronized.
If Mrs Geezer puts on her favourite Balck Sabbath album at full volume at the other end of the house it is quite acceptable to say that you and she are listening simultaneously - although with the finite speed of sound, combined with the magnificence of geezer manor she might hear each of OO's dulcet tones a few seconds before you.
In fact if you did a bit of measuring (distance, air pressure, humidity etc) you could tell which of your two clocks is slow. ie you both look at the clocks in your respective rooms and note the time of the very last bit of Paranoid.
If you clocked it at 15 seconds exactly past the hour, and Mrs G at 10 seconds past exactly - Mrs G is 3.2 m from the stereo and you are 340 m in the other direction (it's a nice dry day at your beach house by the way and about 60F due to the aircon) - after you and Mrs G compare notes; you can work out that your clock is 4 seconds slower than Mrs G's.
Common view relies on a signal being received simultaneously - but possibly not in synch. The fact that the message is the same - and you can the compare notes afterwards allows you to workout the difference in your clocks without worrying about synchronization. The common view part allows you to remove the clock on the satellite from the equation - if I haven't screwed up, the above example would still work if your played Ozzie and friends at 45 or 78. The only sources of error are where the satellites actually are (and we know that fairly well) - and the possibility that one leg of the signal gets bounced around a bit more than the other. At 734 km baseline these errors reduce to fractions of a second (2.3ns)
Ah! Right, I see what you mean. It might have been better if they had left out "simultaneous" and said "A and B receive the same transmission" or similar.
How accurately do the distances have to be known for this to work, or does it not require any knowledge of distance? Or does the distance measurement depend on a highly accurate common view of time?
Two distances involved - not sure which you are asking about.
Distance to satellite. You do need to know where the satellite is and the distance (and more importantly the error) to each of the base-stations; but the speed of the signal is so damn high that even estimates with high ephemeris error will lead to a nano-second error at such a short baseline
Distance on baseline. As you know the distance to a common known point (the gps sat) then you do know the baseline - but it is not part of the calculation
I am not aware of the error algorithms - but everything I have read suggested that at over 3000km you need to start being careful of errors close to 10ns. But 730km is actually quite a short baseline distance for this technique and the max error is 2.3ns. The subtraction of one data set from the other means that errors are cancelled not accrued - most of the error in a signal coming from a satellite 22000 km away to two posts 730km apart will be the same.
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In the days before telegraphs etc London watch makers had their timepieces synchronised by a courier carrying a watch synchronised at Greenwich to their establishments.
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Bulk jumpers [:o]
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Two distances involved - not sure which you are asking about.
Distance to satellite. You do need to know where the satellite is and the distance (and more importantly the error) to each of the base-stations; but the speed of the signal is so damn high that even estimates with high ephemeris error will lead to a nano-second error at such a short baseline
Distance on baseline. As you know the distance to a common known point (the gps sat) then you do know the baseline - but it is not part of the calculation
I am not aware of the error algorithms - but everything I have read suggested that at over 3000km you need to start being careful of errors close to 10ns. But 730km is actually quite a short baseline distance for this technique and the max error is 2.3ns. The subtraction of one data set from the other means that errors are cancelled not accrued - most of the error in a signal coming from a satellite 22000 km away to two posts 730km apart will be the same.
Thanks!
What I'm (sort of) getting at is that, for this experiment, both the distance and time have to be very accurately known. However, if I understand properly how this works, the accuracy of the time synchronization depends on a very accurate measurement of the baseline. If the baseline is a bit off I think it will introduce an error into the time synchronization, although it's probably very small.
It's probably highly unlikely that would account for the observed results, but it might be a contributing factor.
BTW, you only know the distance from the satellite to the receiver if they have a common view of time, and the speed of the signal really has nothing to do with it.
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Two distances involved - not sure which you are asking about.
Distance to satellite. You do need to know where the satellite is and the distance (and more importantly the error) to each of the base-stations; but the speed of the signal is so damn high that even estimates with high ephemeris error will lead to a nano-second error at such a short baseline
Distance on baseline. As you know the distance to a common known point (the gps sat) then you do know the baseline - but it is not part of the calculation
I am not aware of the error algorithms - but everything I have read suggested that at over 3000km you need to start being careful of errors close to 10ns. But 730km is actually quite a short baseline distance for this technique and the max error is 2.3ns. The subtraction of one data set from the other means that errors are cancelled not accrued - most of the error in a signal coming from a satellite 22000 km away to two posts 730km apart will be the same.
Thanks!
What I'm (sort of) getting at is that, for this experiment, both the distance and time have to be very accurately known.
Completely - it's the be all and end all
However, if I understand properly how this works, the accuracy of the time synchronization depends on a very accurate measurement of the baseline. If the baseline is a bit off I think it will introduce an error into the time synchronization, although it's probably very small.
You need to know the 3d coordinates of each basestation very accurately. This the GPS system, using multiple view, is very good at this and there is a claimed accuracy - that I do not think many experts in the field argue with - of 2cm. This allows you to calculate your baseline. It also allows you to calculate the errors in the common single view time synchronization of the two clocks
It's probably highly unlikely that would account for the observed results, but it might be a contributing factor.
The bulk of the acknowledged error - and possibly the source for more - is the measurement from the GPS basestation to the actual receivers. This was old fashioned manual survey and the 10km is uncertain by 20cm m/l. But the time difference between estimated arrival and actual arrival was 60ns which dwarfs the error margins .
BTW, you only know the distance from the satellite to the receiver if they have a common view of time, and the speed of the signal really has nothing to do with it.
- it means that errors in position of the gps basestations and the ephemeris error of the gps-sat do not translate into large differential time lags that screw up your common view synchronization
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How easy would it be to move either the transmitter or receiver to New Zealand & repeat the experiment?
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Then you will have to consider tectonic movements too :)
And sheep's getting in the way (or is that kangaroos?)
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How easy would it be to move either the transmitter or receiver to New Zealand & repeat the experiment?
You could start again from scratch. You need a hi-power proton synchrotron - a graphite block and a km long tunnel - the tunnel is directional so pointing it through the earth would not be easy. The receptors are also not moveable. You could rebuild new ones with a longer baseline - but there is really no need; if the experiment methodology was misconceived then that can be shown in CERN/OPERA, and will also be shown when FermiLab/MINOS give their results next year. If the accuracy was poor - this can be rechecked with different protocols and other staff. The error was small compared to the difference found - the problem isn't with significance of results , its the results themselves. A longer baseline would be great - but not necessary yet.
Then you will have to consider tectonic movements too :)
And sheep's getting in the way (or is that kangaroos?)
Sheep in NZ Roos in OZ
Tectonic movement will not make a difference. The positions of the GPS basestations is calculated as a point in three dimensional space - the distance between them can be calculated very accurately at an almost instantaneous rate. The baseline distance is not worked out by plotting each basestation on a globe and then working out the cord distance - the system of GPS-sats create a 3d coordinate system and you can work out a distance.
You will need to take into account the rotation of the earth - which will affect the position of the basestations - but not the straightness of the neutrino beam.
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Two distances involved - not sure which you are asking about.
Distance to satellite. You do need to know where the satellite is and the distance (and more importantly the error) to each of the base-stations; but the speed of the signal is so damn high that even estimates with high ephemeris error will lead to a nano-second error at such a short baseline
Distance on baseline. As you know the distance to a common known point (the gps sat) then you do know the baseline - but it is not part of the calculation
I am not aware of the error algorithms - but everything I have read suggested that at over 3000km you need to start being careful of errors close to 10ns. But 730km is actually quite a short baseline distance for this technique and the max error is 2.3ns. The subtraction of one data set from the other means that errors are cancelled not accrued - most of the error in a signal coming from a satellite 22000 km away to two posts 730km apart will be the same.
Thanks!
What I'm (sort of) getting at is that, for this experiment, both the distance and time have to be very accurately known.
Completely - it's the be all and end all
However, if I understand properly how this works, the accuracy of the time synchronization depends on a very accurate measurement of the baseline. If the baseline is a bit off I think it will introduce an error into the time synchronization, although it's probably very small.
You need to know the 3d coordinates of each basestation very accurately. This the GPS system, using multiple view, is very good at this and there is a claimed accuracy - that I do not think many experts in the field argue with - of 2cm. This allows you to calculate your baseline. It also allows you to calculate the errors in the common single view time synchronization of the two clocks
It's probably highly unlikely that would account for the observed results, but it might be a contributing factor.
The bulk of the acknowledged error - and possibly the source for more - is the measurement from the GPS basestation to the actual receivers. This was old fashioned manual survey and the 10km is uncertain by 20cm m/l. But the time difference between estimated arrival and actual arrival was 60ns which dwarfs the error margins .
BTW, you only know the distance from the satellite to the receiver if they have a common view of time, and the speed of the signal really has nothing to do with it.
- it means that errors in position of the gps basestations and the ephemeris error of the gps-sat do not translate into large differential time lags that screw up your common view synchronization
I thought I read that they actually did a survey transit to determine the positions. Surely that could introduce some serious errors, or did I get that wrong?
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You will need to take into account the rotation of the earth - which will affect the position of the basestations - but not the straightness of the neutrino beam.
Ahhh... so if you aligned it on the equator, say from South America to New Guinea, then measured the deflection due to the Coriolis effect, you could make an exceptionally accurate real-time geo-clock. That is, assuming everything could be monitored in real-time.
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I think Syhprum may have cracked it!
http://www.thenakedscientists.com/forum/index.php?topic=42298.msg374847#msg374847
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I thought I read that they actually did a survey transit to determine the positions. Surely that could introduce some serious errors, or did I get that wrong?
The survey was merely to determine the offset of the detectors and the sources from the two GPS base-stations. It was about 10km of the total of 730km - but the error in that survey was the vast majority of the entire error of the set up.
re Syhprum's unit post - I hope and pray that, for the sake of scientific dignity, that it doesn't turn out that one bozzo was using mm and the other bozzo was using cm and that if they had both used the same unit the 60ns/18m disappears
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I thought I read that they actually did a survey transit to determine the positions. Surely that could introduce some serious errors, or did I get that wrong?
The survey was merely to determine the offset of the detectors and the sources from the two GPS base-stations. It was about 10km of the total of 730km - but the error in that survey was the vast majority of the entire error of the set up.
re Syhprum's unit post - I hope and pray that, for the sake of scientific dignity, that it doesn't turn out that one bozzo was using mm and the other bozzo was using cm and that if they had both used the same unit the 60ns/18m disappears
Perhaps the surveyors were distracted by a flock of particularly attractive sheep?
I think I figured the difference comes out at around 27 ppm, so a little bit of extra coax here or even a few kinks in a cable there and Bob's your uncle, although I'm sure they've gone over this till they are completely sick of it.
BTW, it would only take about 6m of cable (even less if it's optical fibre) to account for that time difference.
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BTW I think information travels faster in the type of optical cable used for long distance circuits that it does in coaxial cable. best check
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BTW I think information travels faster in the type of optical cable used for long distance circuits that it does in coaxial cable. best check
You're right. I'm being a bit pessimistic.
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I voted for "There is only one neutrino that travels infinitely fast and is thus everywhere at once" because I like the idea of someone else bringing infinity into the discussion. [;D]
However, I also quite like the thought that they may have found the long soughtafter tachyon. Can we be sure that neutrinos don't always travel just a little faster than light.
Hang on, though, shouldn't that mean they travel backwards through time?
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I voted for "There is only one neutrino that travels infinitely fast and is thus everywhere at once" because I like the idea of someone else bringing infinity into the discussion. [;D]
However, I also quite like the thought that they may have found the long sought after tachyon. Can we be sure that neutrinos don't always travel just a little faster than light.
Hello Bill - welcome back.
The neutrinos from Supernova SN1987a got to earth at the correct predicted time - ie a few hours (not years) earlier than the light; the light has to contend with the gas/dust cloud surrounding a huge exploding star, the neutrinos whip straight through. So at present we think neutrinos travel at a significant proportion of the speed of light (99.9 and more nines)
Hang on, though, shouldn't that mean they travel backwards through time?
You cannot have Special Relativity, Faster than Light, and Causality all at the same time. So we would say that for some reason these neutrinos do not seem governed by Special Relativity - this is a bit of a blow, but not too bad. Sr is already limited to flat space so another limit ain't that bad
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You cannot have Special Relativity, Faster than Light, and Causality all at the same time.
Confused!!! Are you saying that if something could travel faster than light, it would not travel backwards through time?
Thanks for the "welcome back". I hope to have a little more spare time for asking silly questions, at least for a while.
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I exactly don't know how scientists create right formulae.But now I think it is impossible to create formula of energy of such fast massive object, because we are captives of relative kinematic slowing of time. Development needs an experiment with a synchronization of atomic clocks on a satellite.
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You cannot have Special Relativity, Faster than Light, and Causality all at the same time.
Confused!!! Are you saying that if something could travel faster than light, it would not travel backwards through time?
Thanks for the "welcome back". I hope to have a little more spare time for asking silly questions, at least for a while.
What I am saying is that the failure of causality, ie the travelling backwards in time, is a result of plugging FTL speeds into the ideas of special relativity. BUT SR does not deal with massive objects going light speed and deals with nothing going FTL. You cannot extrapolate SR into a realm of FTL travel because SR has an axiom that speed limit is that of light. I do not know what happens if you could get a massive object above SoL - but I am sure that you cannot use SR to predict it.
Personally I think that FTL travel is not feasible and OPERA Gran Sasso has made a mistake. The Yanks are repeating the experiment in Fermilab/MINOS - and iff that comes in with agreement to OPERA then all bets are off - but I just don't think it will
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You cannot have Special Relativity, Faster than Light, and Causality all at the same time.
Confused!!! Are you saying that if something could travel faster than light, it would not travel backwards through time?
Thanks for the "welcome back". I hope to have a little more spare time for asking silly questions, at least for a while.
. The Yanks are repeating the experiment in Fermilab/MINOS - and iff that comes in with agreement to OPERA then all bets are off - but I just don't think it will
Your forecast may be wrong again.Because massive object with very high energy can move some space. :P
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Hi Imatfaal. Let's consider Einstein's formula of speed
v=[c (E^2+2Emc^2)^1/2]/(E+mc^2)
v - speed of massive object
E - kinetic energy of the massive object
m - mass of the object
c - light speed
I suspect that if we insert very big energy and very small mass then speed can be more than light speed. But my calculator is unable precisely to count such numbers . :-\
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:( I am wrong because
( E^2+2Emc^2)^1/2 < (E^2+2Emc^2+m^2c^4)^1/2
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I tried to figure out which were actually bigger, neutrinos, or photons thinking that speed was related to mass. However, I think the neutrinos are actually slightly larger than the photons.
With stellar phenomena, different energy photons (wavelengths) including Gamma all arrive at Earth at the same time. So energy alone doesn't account for the difference of speed.
There also seems to be a rather high error rate in the measurements. One question related to other discussions. Essentially all of our current measurements of the speed of light are "2-way" measurements. The speed from the source to a mirror and back.
One should be able to do good one-way speed of light experiments using geosynchronous satellites, but I'm not sure if these have been done.
Anyway, perhaps the neutrino experiments are one-way speed experiments that would be biased by the time of day they are being collected (and thus Earth's orientation in space).
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I tried to figure out which were actually bigger, neutrinos, or photons thinking that speed was related to mass. However, I think the neutrinos are actually slightly larger than the photons.
Larger? Gotta be more specific. For many years neutrinos were thought to be massless - this would mean they travelled at light-speed. It was later found that due to the strange oscillation of the neutrino between the different flavours (electron, mu and tau) that they must have a finite mass. As they do have mass they cannot travel at the speed of light - especialy not at above the speed of light
With stellar phenomena, different energy photons (wavelengths) including Gamma all arrive at Earth at the same time. So energy alone doesn't account for the difference of speed.
of photon. but we do not know this is the case for neitrinos. to reconcile opera/gran sasso with SN1987a there must exist neutrino of certain energies that travel at a fraction (below 1) of the speed of light
There also seems to be a rather high error rate in the measurements. One question related to other discussions. Essentially all of our current measurements of the speed of light are "2-way" measurements. The speed from the source to a mirror and back.
The errors in the measurements seem pretty robust at the moment and any glaring mistakes would have been well publicised. many of the claimed errors after the opera/gran sasso announcement turned out to be erroneous!
One should be able to do good one-way speed of light experiments using geosynchronous satellites, but I'm not sure if these have been done.
OK - I would have to read up on that, not sure I know what you mean
Anyway, perhaps the neutrino experiments are one-way speed experiments that would be biased by the time of day they are being collected (and thus Earth's orientation in space).
Not sure I quite understand what you mean - FYG the experimental data was collected over many days and at different times. I would have hoped that any diurnal anomaly would have been spotted very early on.
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Are the neutrinos also travelling faster than the speed of light as it would be outside of the Earth's gravity well, or are they only travelling faster than light in the sense that they're going faster than light that's being slowed by the Earth's gravity?
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Whew!!!
Ok, Ok, Ok.
With mass, there seems to be some odd units, generally in eV (or energy, I think).
Photon Mass: <1×10−18 eV/c2 (http://en.wikipedia.org/wiki/Photon)
Neutrino Mass: between .2 eV and 2eV (http://en.wikipedia.org/wiki/Neutrino#Mass)
So... can we equate energy and mass? Unless speed can account for energy differences?
Ahh, I think I had misinterpreted this from Wikipedia (http://en.wikipedia.org/wiki/Faster-than-light_neutrino_anomaly)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fen%2Fthumb%2F2%2F2a%2FOPERATimeBin.jpg%2F200px-OPERATimeBin.jpg&hash=d954cc4d6e1bfee23474664725926cd4)
So, this is difference between the Neutrino speed and the calculated speed of light for 20 tests. All show the Neutrinos going faster than light, but range from difference of 40ns to 90ns faster than light. It still is a fairly wide range, and doesn't really seem to follow a "Normal Distribution", at least with the number of trials in the image.
Yes, it does sound like the experiment was being run 24 hrs a day. However, only the results from 20 neutrinos were used, I think... When?
One should compare these results with cosmological neutrino sources. For example, a supernovas generate a pulse of both neutrinos and light. Not necessarily at the same time, but one would expect if they were traveling at the same speed, that the photons and Neutrinos would arrive similarily for supernovas 1 thousand lightyears away and those 1 million lightyears away
Now...
For one-way speed of light. It is a big issue.
Here is the Michelson–Morley experimental setup:
http://en.wikipedia.org/wiki/Luminiferous_aether
http://en.wikipedia.org/wiki/Michelson-Morley_experiment
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2Fthumb%2F0%2F06%2FMichelson-Morley_experiment_%2528en%2529.svg%2F425px-Michelson-Morley_experiment_%2528en%2529.svg.png&hash=df1dfb004707f2bda8829cdc85cf5422)
The problem is that if you consider the frame bound, one-way speed of light to be:
C+X/C-X in the X direction, and C+Y/C-Y in the Y direction.
Then, the Michelson-Morley bounces light all over... but it all comes down to every X+ is countered by an X-. Every Y+ has an equivalent Y-. At best, all the experiment demonstrates is that the two-way average speed of light, C, is the same in both the X and Y directions which could be demonstrated with a much simpler design.
Obviously the issue is to create a device big enough with a high enough shutter speed to measure the one -way speed of light (in two directions), with the definition, of course, being in a vacuum.
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I believe that one could create a wheel shutter device that would do reasonably well at measuring the speed differential between the one-way speed of light. X+ & X-. The problem is that it would be difficult to get the accuracy necessary. But, perhaps in the near future, with higher speed motors and better magnetic bearings, it will be possible to construct such a device that is a few meters long.
Here is where I presented my concept for 1-way light speed measurements using satellites.
http://www.thenakedscientists.com/forum/index.php?topic=42756.msg377479#msg377479
To avoid redundant arguments, I'll refer you to that post. The idea is that every 12 hours, the relative positions of satellites A&B reverse. So, timing errors cancel out.
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Whew!!!
Ok, Ok, Ok.
With mass, there seems to be some odd units, generally in eV (or energy, I think).
Photon Mass: <1×10−18 eV/c2 (http://en.wikipedia.org/wiki/Photon)
Neutrino Mass: between .2 eV and 2eV (http://en.wikipedia.org/wiki/Neutrino#Mass)
So... can we equate energy and mass? Unless speed can account for energy differences?
Energies can be given in eV (electron volts) - due to mass energy equivalence we can measure masses in eV/c2. The c2 is nearly always missed off because in most particle physics we use more natural units in which we put the speed of light as equal to one.
Ahh, I think I had misinterpreted this from Wikipedia (http://en.wikipedia.org/wiki/Faster-than-light_neutrino_anomaly)
(https://www.thenakedscientists.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fen%2Fthumb%2F2%2F2a%2FOPERATimeBin.jpg%2F200px-OPERATimeBin.jpg&hash=d954cc4d6e1bfee23474664725926cd4)
So, this is difference between the Neutrino speed and the calculated speed of light for 20 tests. All show the Neutrinos going faster than light, but range from difference of 40ns to 90ns faster than light. It still is a fairly wide range, and doesn't really seem to follow a "Normal Distribution", at least with the number of trials in the image.
I don´t think that 20 results are enough to say what sort of distribution
Yes, it does sound like the experiment was being run 24 hrs a day. However, only the results from 20 neutrinos were used, I think... When?
20 results refers to the retest done in October - with the very short bursts to overcome any problem of phase-shifting
One should compare these results with cosmological neutrino sources. For example, a supernovas generate a pulse of both neutrinos and light. Not necessarily at the same time, but one would expect if they were traveling at the same speed, that the photons and Neutrinos would arrive similarily for supernovas 1 thousand lightyears away and those 1 million lightyears away
Been done - that was why I mentioned trying to consolidate results from Gran Sasso and SN1987a (Supernova 1987 a). The neutrinos from that Supernova arrives a few hours ahead of the light - which would be expected as they do not have trouble get through the gas/dust/etc surrounding the Supernova. If they travelled at the Gran Sasso speed they would have been here years earlier.
Now...
For one-way speed of light. It is a big issue.
/snipped for now - will have a look later
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Ok,
The experiment that I described with geostationary satellites essentially is an East/West experiment in the plane of the Earth. That should detect the frame-drift of the speed of light in Earth's plane which would reverse on a 12 hr (sidereal) period.
The OPERA Gran Sasso experiment is more or less a North/South experiment.
So, in a 24 hour period, the installation would more or less describe a cone in space. Thus, you wouldn't get the reversal that I had suggested.
If there was a positive frame-shift in the speed of light, then one would see it waxing and waning with the timing of the direction based on the sidereal day.
Plotting the times on a sidereal day should generate a sine wave.
Plot the hours of the sidereal day on the X axis, and the speed differential on the Y axis.
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I added a new voting option.
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I added a new voting option.
The techies will now dig out a memo they sent 10 years ago complaining about cheap components and lack of staff to check connexions - that the boffins passed to the bureaucrats with an exasperated sigh - and it can all be blamed on management, who will then give themselves a pay rise to make sure they pay more attention next time.