Quizzes & Puzzles11 mins ago
Faster than Light.
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On the news a few weeks ago, scientists said there was a particle that was found to go Faster than light. If it is true, it would throw Physics up in the air. However, they said they had to conduct more experiments to confirm it. Anyone know if they have? And why would it make backwards time travel theoretically possible?
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Actually what they were saying was that they measured this and were really asking for help about why the measurements were wrong.
Almost nobody thinks that they actually have found particles moving faster than light.
Basically as you go closer and closer to the speed of light time slows down.
This may sound strange but there's good evidence for it.
Muons are the classic example - these are created in the high atmosphere when cosmic rays hit. They are only very short lived so we should see very few. In fact we see lots and it's because they move so fast time slows for them.
The maths behind this is rather complex but faster than light travel does imply going backwards in time and that messes up cause and effect.
So no I doubt that is happening, however there may be something else happening that we don't understand that is throwing up this result which may be very interesting in its own right.
Almost nobody thinks that they actually have found particles moving faster than light.
Basically as you go closer and closer to the speed of light time slows down.
This may sound strange but there's good evidence for it.
Muons are the classic example - these are created in the high atmosphere when cosmic rays hit. They are only very short lived so we should see very few. In fact we see lots and it's because they move so fast time slows for them.
The maths behind this is rather complex but faster than light travel does imply going backwards in time and that messes up cause and effect.
So no I doubt that is happening, however there may be something else happening that we don't understand that is throwing up this result which may be very interesting in its own right.
Could Mike Soloman have a point?
///Speed in relation to what? Is the speed of light supposed to be absolute or relative to its immediate surroundings? Remember the test route is travelling in space due to movement of the earth.
Maybe the calculations need to include speed of rotation of the earth, rotation around the sun, and movement of our solar system in space.///
///Speed in relation to what? Is the speed of light supposed to be absolute or relative to its immediate surroundings? Remember the test route is travelling in space due to movement of the earth.
Maybe the calculations need to include speed of rotation of the earth, rotation around the sun, and movement of our solar system in space.///
The researchers have spent the past three years trying to explain the measurements. I have no doubt they have considered any effects of the movement of the planet.
The speed of light is constant regardless of the frame of reference and is always measured the same. Two people moving at high speed in different directions measure the speed of the same photon and come up with the same answer.
They will disagree on both the distance it travelled and the time it took but they will calculate the same speed.
I often see it said that the maths of Relativistic Time Dilation is complex. In fact both the concept and mathematics is incredibly simple and anyone who says otherwise doesn't really understand it.
Put simply, there is only one speed in the Universe, the speed of light. Objects perceived as stationary are travelling through Time at the speed of light. As their speed through Space increases their speed through Time decreases in a simple Pythogoran relationship.
Using the familiar 3:4:5 triangle we see that something travelling through Space at 3/5 of the speed of light will travel through Time at 4/5 of the usual rate.
Applying this formula to something exceeding the speed of light does not find a negative value for Time but an impossible one. This is why the researchers don't believe that the neutrinos travelled faster than light.
The speed of light is constant regardless of the frame of reference and is always measured the same. Two people moving at high speed in different directions measure the speed of the same photon and come up with the same answer.
They will disagree on both the distance it travelled and the time it took but they will calculate the same speed.
I often see it said that the maths of Relativistic Time Dilation is complex. In fact both the concept and mathematics is incredibly simple and anyone who says otherwise doesn't really understand it.
Put simply, there is only one speed in the Universe, the speed of light. Objects perceived as stationary are travelling through Time at the speed of light. As their speed through Space increases their speed through Time decreases in a simple Pythogoran relationship.
Using the familiar 3:4:5 triangle we see that something travelling through Space at 3/5 of the speed of light will travel through Time at 4/5 of the usual rate.
Applying this formula to something exceeding the speed of light does not find a negative value for Time but an impossible one. This is why the researchers don't believe that the neutrinos travelled faster than light.
> Applying this formula to something exceeding the speed of light does not find a negative value for Time but an impossible one. This is why the researchers don't believe that the neutrinos travelled faster than light.
Correct. That is why they're trying to figure out where their calculations went wrong. Under present understanding, there's simply no way that their calculations could be correct...
Correct. That is why they're trying to figure out where their calculations went wrong. Under present understanding, there's simply no way that their calculations could be correct...
I know a bit about accurate timekeeping, I supply and work with the exact models of clocks used for this experiment and assumed the problems in the results would be with the issues of measuring small timeframes but I must admit I was surprised at how much faster the neutrinos were measured (60 nanoseconds).
Sub-nanosecond timeframes are still tricky but there are no problems measuring to nanosecond accuracy, let alone a 60ns. The measurement granularity is far better than 60ns and as long as all the clock path delays are factored in correctly no other outisde influence that I know of will cause an error of this magnitude.
The earth's rotation will cause clocks to run at different speeds due to relativity - if the clocks are in such positions on the earth that they are 'rotating' at different speeds - but the effects are negligable over the timeframe of this experiment.
I do not know the troubleshooting that they have done on this but the first thing I would do is to send something else round the tube - such as light - and see if that also shows a clock offset of 60ns. This is so basic that this will have been done but if that shows that the clocks are synchronised then I am now as mystified as they are...
Sub-nanosecond timeframes are still tricky but there are no problems measuring to nanosecond accuracy, let alone a 60ns. The measurement granularity is far better than 60ns and as long as all the clock path delays are factored in correctly no other outisde influence that I know of will cause an error of this magnitude.
The earth's rotation will cause clocks to run at different speeds due to relativity - if the clocks are in such positions on the earth that they are 'rotating' at different speeds - but the effects are negligable over the timeframe of this experiment.
I do not know the troubleshooting that they have done on this but the first thing I would do is to send something else round the tube - such as light - and see if that also shows a clock offset of 60ns. This is so basic that this will have been done but if that shows that the clocks are synchronised then I am now as mystified as they are...
The measurements are not taken "around a tube". The speed of the neutrinos is measured through the Earth to a detector located in a cavern over 700 km away.
This distance was measured with painstaking accuracy on equipment that decteted the movement of tectonic plates in real time. These plates move at speed comparable to fingernail or hair growth and the anomaly represents about 18 metres so the distance is not the issue.
The problem probably lies with the signal to start the clock. The neutrino burst is not detected at the starting line but the clock is started by the detection of other decay products expected to be produced at the same time as the neutrinos.
Personally I think it will turn out that the neutrinos are actually released before the decay of the original particles which hang together momentarily after the release giving the neutrinos a head start on the other decay products.
This in itself would be a ground breaking observation and need some good explanation.
The original experiment (at CERN) is to be replicated at the Fermi Laboratory's Tevatron facility. However they need to upgrade their timing equipment which won't be complete until 2014. So don't hold your breath waiting for the answer.
This facility was recently superceded by the LHC and they have decided to abandon the search for the Higgs Boson in favour of the neutrino speed anomaly and leave the Higgs to the LHC.
Ultimately I expect they will have to build a second neutrino detector in line with the synchrotron and the existing detector to measure the speed between detections. I have very little doubt this arrangement will clock them below the speed of light.
(BTW A synchrotron requires charged particles so light or neutrinos cannot be sent around the ring.)
This distance was measured with painstaking accuracy on equipment that decteted the movement of tectonic plates in real time. These plates move at speed comparable to fingernail or hair growth and the anomaly represents about 18 metres so the distance is not the issue.
The problem probably lies with the signal to start the clock. The neutrino burst is not detected at the starting line but the clock is started by the detection of other decay products expected to be produced at the same time as the neutrinos.
Personally I think it will turn out that the neutrinos are actually released before the decay of the original particles which hang together momentarily after the release giving the neutrinos a head start on the other decay products.
This in itself would be a ground breaking observation and need some good explanation.
The original experiment (at CERN) is to be replicated at the Fermi Laboratory's Tevatron facility. However they need to upgrade their timing equipment which won't be complete until 2014. So don't hold your breath waiting for the answer.
This facility was recently superceded by the LHC and they have decided to abandon the search for the Higgs Boson in favour of the neutrino speed anomaly and leave the Higgs to the LHC.
Ultimately I expect they will have to build a second neutrino detector in line with the synchrotron and the existing detector to measure the speed between detections. I have very little doubt this arrangement will clock them below the speed of light.
(BTW A synchrotron requires charged particles so light or neutrinos cannot be sent around the ring.)
As I understand it, the 'tube' they're sending neutrinos through is miles of solid rock. This might present a bit of a problem with trying to calibrate their measurements against a beam of light.
Also, considering the distance (732km) involved the discrepancy is in the range of parts per billion of the speed of light.
As I understand it some of the clocks used to derive the measurement in question are in relativistic motion with respect to the experiment and that relativistic motion might not have been totally and correctly factored in. I remain highly sceptical of superluminal speeds being confirmed.
http://www.technology...com/blog/arxiv/27260/
Also, considering the distance (732km) involved the discrepancy is in the range of parts per billion of the speed of light.
As I understand it some of the clocks used to derive the measurement in question are in relativistic motion with respect to the experiment and that relativistic motion might not have been totally and correctly factored in. I remain highly sceptical of superluminal speeds being confirmed.
http://www.technology...com/blog/arxiv/27260/
All motion is relativistic. It is just that it is a very small contribution at ordinary speeds.
The Relativistic effects on Time are very well understood, being integral in the operation of GPS systems so I doubt that would be an issue at all. Many experts have had a look at the setup including completely independent time keeping expert teams.
The only people considering genuine faster than light measurements have been made are those who don't understand the science and just how unlikely that would be.
The Relativistic effects on Time are very well understood, being integral in the operation of GPS systems so I doubt that would be an issue at all. Many experts have had a look at the setup including completely independent time keeping expert teams.
The only people considering genuine faster than light measurements have been made are those who don't understand the science and just how unlikely that would be.
An interesting, if slightly misinformed link there Mibs with regards to the clock synchronisation. I must admit I didn't read the bit about the neutrino path being through rocks and assumed it would be possible to use another medium to test for clock offsets.
The link you give speaks about the effect of relativity on the GPS clocks but timing receivers use multiple satellites (and multiple constellations such as GLONASS) and long-term averaging of the received timecodes to reduce the effects that this, and other clock errors on individual satellites, has. If the ground clocks are moving away from some satellites then they are moving closer to others, making it easy for the receiver, which has a stable internal reference itself to see that this is happening.
It is also possible to synchronise cesium clocks with each other and, using battery power supplies, to transport them to the individual sites, this will elminate the reliance on GNSS systems to provide the timing reference. I would assume this has already been done, if not then that would be my next move.
However, my original point was that 60ns is a large offset and the mechanisms to synchronise clocks are well understood so I would be surprised if it turns out that clocking errors are source of the anomalies here - as opposed to measurement errors which I do not know anything about!
The link you give speaks about the effect of relativity on the GPS clocks but timing receivers use multiple satellites (and multiple constellations such as GLONASS) and long-term averaging of the received timecodes to reduce the effects that this, and other clock errors on individual satellites, has. If the ground clocks are moving away from some satellites then they are moving closer to others, making it easy for the receiver, which has a stable internal reference itself to see that this is happening.
It is also possible to synchronise cesium clocks with each other and, using battery power supplies, to transport them to the individual sites, this will elminate the reliance on GNSS systems to provide the timing reference. I would assume this has already been done, if not then that would be my next move.
However, my original point was that 60ns is a large offset and the mechanisms to synchronise clocks are well understood so I would be surprised if it turns out that clocking errors are source of the anomalies here - as opposed to measurement errors which I do not know anything about!
ll_billym, You might recall the debacle of the satellite which crashed on Mars due to the mixed use of metric and 'English' units of measurement in determining the offset for insertion of the satellite in a correct orbit. I'm not saying that such is the case with 'faster than light' observations but where so many variables must be taken into account it's to be expected that human error is the most likely suspect for having reached an obviously premature and most likely foregone conclusion should this observation ultimately prove to be incorrect.
Silly yes, but in solving mysteries of this sort, isn't 'silliness' typically the case?
Regardless, there certainly appears to be a debacle.
'Ghosts' in the machine, no doubt! ;o)
Fascinating and educational in the least.
Silly yes, but in solving mysteries of this sort, isn't 'silliness' typically the case?
Regardless, there certainly appears to be a debacle.
'Ghosts' in the machine, no doubt! ;o)
Fascinating and educational in the least.
OK firstly Rov's point -it can't be sped up by the motion of the Earth this is precisely what has been demonstrated time and time again in the Michalson Morely experiment that kicked off special relitivity (Even if Einstein claimed he was unaware of it)
A side note here - in the last few years we actually discovered that neutrinos must have a mass because they "switch" flavours between electron/muon/tau types and they must have a mass to do this. It's just so small no one has measured it.
So they're facinating little devils - they should actually travel slightly slower than c because of this.
I guess the real hope is that there is some new physics here, but really difficult to speculate on what it might be, some pretty smart guys are stumped on this so it's unlikely to be something silly like imperial-metric calculations.
That would pretty much kill your career so they'll have tripple checked all the silly possibilities!
A side note here - in the last few years we actually discovered that neutrinos must have a mass because they "switch" flavours between electron/muon/tau types and they must have a mass to do this. It's just so small no one has measured it.
So they're facinating little devils - they should actually travel slightly slower than c because of this.
I guess the real hope is that there is some new physics here, but really difficult to speculate on what it might be, some pretty smart guys are stumped on this so it's unlikely to be something silly like imperial-metric calculations.
That would pretty much kill your career so they'll have tripple checked all the silly possibilities!
The results are not preliminary and were not leaked to the media. This is not a case of three weeks on. They have been trying unsuccessfully to come up with an explanation for a long time. Having exhausted their ideas the team went public looking for more input.
It is a very different situation from the Mars lander. Something went wrong with the lander, they went looking for a reason and found it. Something is wrong with the neutrino speed, they went looking and looking and looking but have not found it.
As Jake says, everything has been triple checked. Two independent teams have gone through the measurements and come up with the same answer.
It is a very different situation from the Mars lander. Something went wrong with the lander, they went looking for a reason and found it. Something is wrong with the neutrino speed, they went looking and looking and looking but have not found it.
As Jake says, everything has been triple checked. Two independent teams have gone through the measurements and come up with the same answer.
www.newscientist.com get the news fast. It turns over quickly so you need to search for the older stuff or follow links on the story to the older articles. Unfortunately you need to be a subscriber for some stories especially if it is not current. There is a middle level of a free subscription that gets you a bit more too.
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