ChatterBank11 mins ago
Neutrinos faster than light experiment
Leaving aside the possible ramifications of the results or whether those results are to be believed, what is it about the experiment that means this result has only been obtained this year?
Has it necessitated scientific / technological advances - such as increasing accuracy of time measurement - so that the same experiment couldn't have been done even 5 years ago?
Or is it something more mundane, such as no-one doing this type of experiment over such a large distance until now?
Has it necessitated scientific / technological advances - such as increasing accuracy of time measurement - so that the same experiment couldn't have been done even 5 years ago?
Or is it something more mundane, such as no-one doing this type of experiment over such a large distance until now?
Answers
from wiki
In the early 1980s, first measurements of neutrino speed were done using pulsed pion beams (produced by pulsed proton beams hitting a target). The pions decayed producing neutrinos, and the neutrino interactions observed within a time window in a detector at a distance were consistent with the speed of light. This measurement has been...
In the early 1980s, first measurements of neutrino speed were done using pulsed pion beams (produced by pulsed proton beams hitting a target). The pions decayed producing neutrinos, and the neutrino interactions observed within a time window in a detector at a distance were consistent with the speed of light. This measurement has been...
10:40 Sat 19th Nov 2011
from wiki
In the early 1980s, first measurements of neutrino speed were done using pulsed pion beams (produced by pulsed proton beams hitting a target). The pions decayed producing neutrinos, and the neutrino interactions observed within a time window in a detector at a distance were consistent with the speed of light. This measurement has been repeated in 2007 using the MINOS detectors, which found the speed of 3 GeV neutrinos to be 1.000051(29) c at 68% confidence level, and at 99% confidence level a range between 0.999976 c to 1.000126 c. The central value is higher than the speed of light and is consistent with superluminal velocity; however, the uncertainty is great enough that the result also does not rule out speeds less than or equal to light at this high confidence level. This measurement set an upper bound on the mass of the muon neutrino of 50 MeV at 99% confidence.[37][38] Currently the detectors for the project are being upgraded, and new results are not expected until at least 2012.
The same observation was made, on a somewhat larger scale, with supernova 1987A (SN 1987A). 10-MeV antineutrinos from the supernova were detected within a time window that was consistent with a speed of light for the neutrinos. So far, the question of neutrino masses cannot be decided based on measurements of the neutrino speed.
In September 2011, the OPERA collaboration released calculations showing velocities of 17-GeV and 28-GeV neutrinos exceeding the speed of light in their experiments. In November 2011, OPERA repeated its experiment with changes so that the speed could be determined individually for each detected neutrino. The results showed the same faster-than-light speed. More analyses and studies are underway.
In the early 1980s, first measurements of neutrino speed were done using pulsed pion beams (produced by pulsed proton beams hitting a target). The pions decayed producing neutrinos, and the neutrino interactions observed within a time window in a detector at a distance were consistent with the speed of light. This measurement has been repeated in 2007 using the MINOS detectors, which found the speed of 3 GeV neutrinos to be 1.000051(29) c at 68% confidence level, and at 99% confidence level a range between 0.999976 c to 1.000126 c. The central value is higher than the speed of light and is consistent with superluminal velocity; however, the uncertainty is great enough that the result also does not rule out speeds less than or equal to light at this high confidence level. This measurement set an upper bound on the mass of the muon neutrino of 50 MeV at 99% confidence.[37][38] Currently the detectors for the project are being upgraded, and new results are not expected until at least 2012.
The same observation was made, on a somewhat larger scale, with supernova 1987A (SN 1987A). 10-MeV antineutrinos from the supernova were detected within a time window that was consistent with a speed of light for the neutrinos. So far, the question of neutrino masses cannot be decided based on measurements of the neutrino speed.
In September 2011, the OPERA collaboration released calculations showing velocities of 17-GeV and 28-GeV neutrinos exceeding the speed of light in their experiments. In November 2011, OPERA repeated its experiment with changes so that the speed could be determined individually for each detected neutrino. The results showed the same faster-than-light speed. More analyses and studies are underway.
There have been experiments and observations before that demonstrated that we don't have neutrino's travelling faster than light.
I don't think you'll find many researchers that think they do.
However it is possible that they've stumbled onto some new physics which is quite exciting.
The neutrinos are produced by hitting protons against a target - pions are commonly produced in such collisions and they decay with a known probability to produce neutrinos.
For example the first suggestion was that the assumption regarding the way that they decay was incorrect and the experiment was altered to account for this - nope we've still got faster than light neutrinos.
Next theory please!
Of course it could be something mundane like a computer system flaw but they'll have been over all the obvious stuff with a fine tooth comb.
I don't think you'll find many researchers that think they do.
However it is possible that they've stumbled onto some new physics which is quite exciting.
The neutrinos are produced by hitting protons against a target - pions are commonly produced in such collisions and they decay with a known probability to produce neutrinos.
For example the first suggestion was that the assumption regarding the way that they decay was incorrect and the experiment was altered to account for this - nope we've still got faster than light neutrinos.
Next theory please!
Of course it could be something mundane like a computer system flaw but they'll have been over all the obvious stuff with a fine tooth comb.
Measurement of time is not the issue here, the measured propagation difference between the neutrinos and light is 60 nanoseconds (billionths of a second) which believe it or not is an absolute age when it comes to accurate measurement of time and this has been possible for decades.
Sub-nanosecond is still tricky though as electronic components have inherent 'jitter' but this is not a factor when dealing on the nanosecond scale.
To put it into context, a 1Gb Ethernet connection on a home router transmits and receives more than 1 billion pulses per second (1 per nanosecond) from each connected port and still makes perfect sense of them all.
Sub-nanosecond is still tricky though as electronic components have inherent 'jitter' but this is not a factor when dealing on the nanosecond scale.
To put it into context, a 1Gb Ethernet connection on a home router transmits and receives more than 1 billion pulses per second (1 per nanosecond) from each connected port and still makes perfect sense of them all.
Has anyone thought about how this will affect weights and measures? A metre is defined in terms related to the speed of light in terms of metric and a litre is defined in terms of a cubic decimetre. If light is faster, a metre will be longer and litre will also increase. Imperial measures are now defined in terms of metric units some of them will increase too.
Bear in mind (as mentioned by various scientists on the radio) tachyons have always been a theoretical possibility, as it was never a problem to go faster than light as long as you never went below it. So anything up to the speed couldn't break it, but then if you started beyond it then that was a new level and unlimited. Finding a particle long expected which conforms to a tachyon is interesting but not outside known physics. If it was then I don't think we would be able to measure it as yet.
THECORBYLOON // Has anyone thought about how this will affect weights and measures? //
There is no suggestion that the speed of light is wrong. Only that a particle might, and it is still a big "might" be able to travel faster than light.
The speed of light is involved in fundamental formulae that define Mass and Energy and Time. These would be very messed up if the speed of ight was wrong.
There is no suggestion that the speed of light is wrong. Only that a particle might, and it is still a big "might" be able to travel faster than light.
The speed of light is involved in fundamental formulae that define Mass and Energy and Time. These would be very messed up if the speed of ight was wrong.
I think the mass relationship would be the very least of the worries if the speed of light were breeched!
Seriously this is not going to happen there are plenty of experiments and theoretical reasons why this is fixed.
The real possibility is a step forwards in something much more mundane regarding pion behaviour.
I doubt you'd find a single researcher at CERN that seriously thinks there are faster than light neutrinos
Seriously this is not going to happen there are plenty of experiments and theoretical reasons why this is fixed.
The real possibility is a step forwards in something much more mundane regarding pion behaviour.
I doubt you'd find a single researcher at CERN that seriously thinks there are faster than light neutrinos
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