The scientists who appeared to have found in September that certain subatomic particles can travel faster than light have ruled out one potential source of error in their measurements after completing a second, fine-tuned version of their experiment.
Their results, posted on the ArXiv preprint server on Friday morning and submitted for peer review in the Journal of High Energy Physics, confirmed earlier measurements that neutrinos, sent through the ground from Cern near Geneva to the Gran Sasso lab in Italy 450 miles (720km) away seemed to travel faster than light.
The finding that neutrinos might break one of the most fundamental laws of physics sent scientists into a frenzy when it was first reported in September. Not only because it appeared to go against Albert Einstein's theory of special relativity but, if correct, the finding opened up the troubling possibility of being able to send information back in time, blurring the line between past and present and wreaking havoc with the fundamental principle of cause and effect.
The physicist and TV presenter Professor Jim Al-Khalili of the University of Surrey expressed the incredulity of many in the field when he said that if the findings "prove to be correct and neutrinos have broken the speed of light, I will eat my boxer shorts on live TV".
In their original experiment scientists fired beams of neutrinos from Cern to the Gran Sasso lab and the neutrinos seemed to arrive sixty billionths of a second earlier than they should if travelling at the speed of light in a vacuum.
One potential source of error pointed out by other scientists was that the pulses of neutrinos sent by Cern were relatively long, around 10 microseconds each, so measuring the exact arrival time of the particles at Gran Sasso could have relatively large errors. To account for this potential problem in the latest version of the test, the beams sent by Cern were thousands of times shorter – around three nanoseconds – with large gaps of 524 nanoseconds between them. This allowed scientists to time the arrival of the neutrinos at Gran Sasso with greater accuracy.
Writing on his blog when the fine-tuned experiment started last month, Matt Strassler, a theoretical physicist at Rutgers University, said the shorter pulses of neutrinos being sent from Cern to Gran Sasso would remove the need to measure the shape and duration of the beam. "It's like sending a series of loud and isolated clicks instead of a long blast on a horn," he said. "In the latter case you have to figure out exactly when the horn starts and stops, but in the former you just hear each click and then it's already over. In other words, with the short pulses you don't need to know the pulse shape, just the pulse time."
"And you also don't need to measure thousands of neutrinos in order to reproduce the pulse shape, getting the leading and trailing edges just right; you just need a small number – maybe even as few as 10 or so – to check the timing of just those few pulses for which a neutrino makes a splash in Opera."
Around 20 neutrino events have been measured at the Gran Sasso lab in the fine-tuned version of the experiment in the past few weeks, each one precisely associated with a pulse leaving Cern. The scientists concluded from the new measurements that the neutrinos still appeared to be arriving earlier than they should.
"With the new type of beam produced by Cern's accelerators we've been able to to measure with accuracy the time of flight of neutrinos one by one," said Dario Autiero of the French National Centre for Scientific Research (CNRS). "The 20 neutrinos we recorded provide comparable accuracy to the 15,000 on which our original measurement was based. In addition their analysis is simpler and less dependent on the measurement of the time structure of the proton pulses and its relation to the neutrinos' production mechanism."
In a statement released on Friday, Fernando Ferroni, president of the Italian Institute for Nuclear Physics, said: "A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny. The experiment at Opera, thanks to a specially adapted Cern beam, has made an important test of consistency of its result. The positive outcome of the test makes us more confident in the result, although a final word can only be said by analogous measurements performed elsewhere in the world."
Since the Opera (Oscillation Project with Emulsion-tRacking Apparatus) team at Gran Sasso announced its results, physicists around the world have published scores of online papers trying to explain the strange finding as either the result of a trivial mistake or evidence for new physics.
Dr Carlo Contaldi of Imperial College London suggested that different gravitational effects at Cern and Gran Sasso could have affected the clocks used to measure the neutrinos. Others have come up with ideas about new physics that modify special relativity by taking the unexpected effects of higher dimensions into account.
Despite the latest result, said Autiero, the observed faster-than-light anomaly in the neutrinos' speed from Cern to Gran Sasso needed further scrutiny and independent tests before it could be refuted or confirmed definitively. The Opera experiment will continue to take data with a new muon detector well into next year, to improve the accuracy of the results.
The search for errors is not yet over, according to Jacques Martino, director of the National Institute of Nuclear and Particle Physics at CNRS. He said that more checks would be under way in future, including ensuring that the clocks at Cern and Gran Sasso were properly synchronised, perhaps by using an optical fibre as opposed to the GPS system used at the moment.
This would remove any potential errors that might occur due to the effects of Einstein's theory of general relativity, which says that clocks tick at different rates depending on the amount of gravitational force they experience – clocks closer to the surface of the Earth tick slower than those further away.
Even a tiny discrepancy between the clocks at Cern and Gran Sasso could be at the root of the faster-than-light results seen in September.
Comments
18 November 2011 3:14AM
Can someone explain in layman's terms how you measure anything this accurately? down to billionths of seconds?
Man made machinery/tech must introduce flaws/delays or whatever and have limits?
If I press "Q" on my computer keyboard how to measure the time to display the appropriate pixels on screen to the billionth of a second? What bit of hardware would do that?
I understand how computer code works to create, say, a 60 second countdown on screen but I can't visualise a way to say "But stop counting down when you get to exactly 1 billionth of the 60th second and display a message on screen" and the hardware does that.
I get that a piece of hardware can detect anything (light/sound/x rays/orange juice) I just don't get how it can also report back "It took me 1 billionth of a second to detect that orange juice, dude, not a fraction faster or slower." - where's it looking (hardware/software) to figure out that's how long it took?
18 November 2011 3:20AM
I have sent this message from the future to tell you it's all bullsh!t ....
18 November 2011 3:24AM
Reality will always slip through the nets of our theories.
18 November 2011 3:26AM
If Einstein's theory of special relativity is indeed flawed, then we are into a paradox here, because this experiment is at least partly grounded in the theory itself, doesn't it? How do you test the theory if some or all of the methods you are using, such as the way you measure time lapses, accept the theory as fact?
Time to hotwire the Tardis into a Paradox machine otherwise our version of reality is toast!
18 November 2011 3:31AM
It doesn't mean time travel is neccesarily possible just Einstein was wrong we need a new interpretation. But only if the findings are correct they still need to be repeated and tested again elsewhere to be more sure it isn't a problem with faulty equipment at OPERA.
18 November 2011 3:40AM
I believe these results are literally the message from the future that their existence predicates the possibility of.
The message of the message? Who Knows? Perhaps it's
'Chill out you idiots, there is actually a future waiting for you'
Yeh, I wish.
18 November 2011 3:45AM
Perhaps a simple explanation would be that some particles travel faster through solid objects, i.e. "the ground", just like sound waves travel faster through solid or more dense medium.
Check back yesterday for more updates.
18 November 2011 3:47AM
Measuring time: all timemeasurements revolve around counting oscillations. A traditional clock measures oscillations of a pendulum, while watches used a spring. Now the high accuracy clocks count oscillations of a microwave produced by Caesium: http://en.wikipedia.org/wiki/Atomic_clock.
As for this idea that you simply throw out Einsteins theory because it is wrong - that is hopefully just a joke. We still teach Newtonian mc mechanics in schools because it is much simpler than relativistic mechanics and gives the same results for most situations on earth. Einsteins theory will still have predictive power, but it appears to be flawed in one area of prediction.
18 November 2011 3:48AM
@Ken,
It is through use of a special type of clock called Atomic Clock i.e. the most accurate clock in the planet.
Excerpt from wikipedia
An atomic clock is a clock that uses an electronic transition frequency in the microwave, optical, or ultraviolet region of the electromagnetic spectrum of atoms as a frequency standard for its timekeeping element.
It is able to measure time in a great accuracy and it has an uncertainty of 2.3 x 10^-16 (again, from wikipedia so might be questionable here but let's just say it's true...)
18 November 2011 3:49AM
They should measure the other way around. If they get the same result than that guy should eat his pants :)
18 November 2011 3:57AM
More acid (LSD) please. Then I will be able to explain time travel and prove that I have done it!
18 November 2011 3:58AM
Any explanation of theoretical particle physics given "in layman's terms" isn't likely to amount to more than an extremely weak anecdote, in pretty much the same way that "pressing q on your keyboard" and "bits of hardware" doesn't come close to expressing the complexity of what you're trying to describe.
Besides, if you really wanted an answer to your question, you wouldn't be asking at the bottom of an article designed to be read by people who generally don't give much thought to particle physics.
Google is your friend.
18 November 2011 4:24AM
What a patronising response, it's a fair question.
18 November 2011 4:36AM
Cue deluge of comments along the lines of 'I've come from the future to say...". Looks like we already have a couple of entrants so far. How delightfully tedious.
18 November 2011 4:41AM
It was speculated that the neutrinos' speed could be a result of their lacking the ability to interact strongly (if at all) with virtual particles, unlike photons. Could anybody knowledgeable in the area comment on this? I'm also rather perplexed by the fact that neutrinos, unlike photons, have non zero mass. I thought only mass-less particles can travel at the speed of light? At least!
18 November 2011 4:43AM
I actually found it an interesting question from KenBarlow. It made me think. Even if it hadn't got any satisfying answers, I still would have enjoyed reading it.
And it did generate some satisfying answers.
Except for yours, Greenstrings.
Do keep asking, Ken.
18 November 2011 4:53AM
Hey, I'm from the past. But even then, personal computer chips ran at 3 billion cycles per second allowing measurements in the billionths of a second to be measured simply by counting timing pulses in your laptop.
Back then, you would measure the delays inherent in your equipment and improve that stuff until you could calculate very accurately how much delay it added to the measurements.
You keep doing that until the possible errors in your experiment were much smaller than the 60 billionths of a second discrepancy that you measured. Then write a paper and tell others about it.
Oh, survey equipment taken off the shelf uses the timing of light pulses to measure distances accurate to a few mm - and light takes just one / one hundred billionth of a second to cross that distance.
Just sayin...
18 November 2011 5:05AM
That is certainly groundbreaking when it comes to contrived acronyms.
18 November 2011 5:09AM
I recently listened to an interesting interview with Saul Perlmutter, who recently co-won the Nobel Prize for research showing that the universe is speeding up as it expands (rather than slowing down). He and other researchers posit a form of energy called "dark energy," which causes the space to expand, effectively pushing the objects in space further and further apart from each other, at a faster and faster rate. Because Einstein's theory of general relativity "...is so successful down to many digits of precision," Perlmutter thinks it might need to be tweaked slightly to explain this acceleration, rather than thrown out altogether. Maybe this finding with the neutrinos is another case where Einstein's theory could be modified slightly to accommodate new information. You can find Perlmutter's interview here: http://www.npr.org/2011/11/14/142248148/exploring-supernovas-leads-to-physics-nobel-prize
18 November 2011 5:27AM
Interesting times ahead !!!
May we all live to enjoy this new physics varied applications.
Hats off to all the Scientists once agian.
18 November 2011 5:30AM
If time travelling were possible we would already have been visited by our future selves.
18 November 2011 5:32AM
That only mass-less particles can travel the speed of light is the problem. But massive particles can get very close. Consider the singular cosmic ray particle - thought to be a single proton - that entered our atmosphere in the 1990's at a speed that was exquisitely close to speed of light. Look up the "oh my god particle."
18 November 2011 5:39AM
I have to agree a little with greenstrings on this one. Unfortunately, this is a fairly non-trivial answer.
Accuracy and timing of measuring an event has a lot to do with fast and accurate clocks (Atomic clocks) and high processing power. As materials and computing technology advance, our ability to process and record the analogue world gets better and better.
The hardware used in this experiment is extremely sensitive and has the capability to capture data quickly. Coupled with the timing of an atomic clock, in theory it would be possible to sample data from these detectors every few oscillations of the Cesium atom in the atomic clock.
I recently go the change to play around with a Phantom Cam that can capture 1000000 frames per second of video. That's about 100 nanosecond between each image. It fills up a 96GB storage unit in about 5 seconds, but it is an example of how precise timing and powerful processing can achieve these rates.
There are other articles on the web that can probably explain this process much better than me, however.
18 November 2011 5:45AM
It's extremely difficult for most of us to get our head around the idea of, for example, 'non zero mass' . Experimentally demonstrated in radioactive decay there appeared to be a loss of mass unaccounted for. Whilst protons and electrons were easily measurable, being electricalyl charged, this was not the case for the disappearing mass, which then became known as neutral ( having no electrical charge) and having a non-zero mass. SInce these particles are not electrically charged it then becomes possible for them to travel through matter, e.g. the ground, without being affected by the electrically charged particles within the atoms that make up the ground.
Please anyone! Have I started to understand? Does any of the above make sense?
18 November 2011 5:57AM
Are they sure the time discrepancy isn't due to gravitational variations along the path of the neutrino beam? I suppose in order to make sure they'd have to repeat the same experiment in several different locations in order to rule out that possibility.
18 November 2011 6:04AM
GrassicGibbon
Exactly, if time travel were possible we'd already know wouldn't we....
18 November 2011 6:10AM
KenBarlow: "Can someone explain in layman's terms how you measure anything this accurately? down to billionths of seconds?"
Because we have the level of technology that allows us to make such measurements.
Much more mysterious is HOW and WHY the likes of the Mayans also made vast numbers of highly precise calculations concerning equally tiny if not tinier subatomic scales, all seemingly done without the technology or even the conceptual framework responsible for our own efforts?
18 November 2011 6:24AM
Einstein, for reasons of personal belief, sought a universe that had certain qualities. Like timelessness. In order to make his mathematics create such a universe he created a term called the cosmological constant which was to balance gravity and allow a timeless universe to exist. He later rejected that constant, calling it his greatest blunder. The recent finding that the expansion rate of the universe is accelerating is accommodated by Einstein's cosmological constant term.
I'm no expert, but the neutrino issue, if verified, is more of a violation than an adjustment. Still, scientific theories are always subject to modification with newer and better observations. That's what makes it interesting.
18 November 2011 6:41AM
"We don't serve faster than the speed of light particles in here!" Says the Barman.
A Neutrino walks into a bar.
Sadly not my own but from the New Scientist.
I believe the latest results from Opera might mean we are all made of string?
18 November 2011 6:49AM
CERN desperately trying to make itself useful. Its multi billion dollar chocolate tea pot.
18 November 2011 7:02AM
a) You don't need to believe in special relativity to work a particle accelerator. You just need a particle accelerator. And some particles.
b) The way you test a theory is by using it to make predictions and then seeing if reality bears them out. You predict neutrinos don't travel faster than light. If they do, then you're wrong. See?
18 November 2011 7:07AM
Ugh.
It shouldn't take much to explain that some things are possible, but not practical.
Ever consider the possibility that particles can travel back in time, but that the energy requirements for people to do so would be too great?
18 November 2011 7:09AM
When the particles arrive at Gran Sasso before they leave CERN, then I'll believe in time-travel.
18 November 2011 7:09AM
First of all, atomic clocks work on the basis of tuning into the frequency of the radiation emitted when an electron transitions from one energy level to another. The SI unit standard defines 1 second as the amount of time taken by a Caesium atom to go through ~9 billion transitions of this kind in a sequence. That means you get a frequency of ~9 GHz for measuring the passage of time down to ~100 picoseconds resolution in this case (using the peaks of this ~9 GHz waveform to time-stamp events). There are other atoms with different frequencies. Various factors like temperature affect this characteristic but they can be controlled sufficiently well.
However, this is purely relative and when you have two clocks, A and B, in separate locations then they have to be carefully synchronised so that they don't drift apart in their timekeeping with respect to each other. One way to think about this (though it is a very crude way) is by imagining two cars travelling side-by-side on the motorway. All we're interested in is their relative speed and nothing else. If they're not physically bound then they'll constantly move back and forth relative to each other on the motorway and may even drift apart. The idea of synchronising clocks is like binding these cars physically together so that they move at nearly the same speed (which stops them from wandering).
So once you have a way of getting a time-stamp for some event at location A (say the start of a neutrino pulse) and you have a properly synchronised clock at location B that also gives you a time-stamp for the same event (say the arrival of the corresponding neutrino pulse from A), then you have measured the time-of-flight of the event to go from A to B! It's really that simple, in principle. In practice, however, there're all these sources of error that need to be calibrated, checked, double checked and independently validated. But as long as you have atomic clocks with upwards of GHz resolution and as long as they're synchronised accurately (in this case, using GPS satellites to relay a synchronisation signal from A to B and vice versa) then you're ready to start timing individual events like sub-atomic particles :)
18 November 2011 7:19AM
Well the explanation is obvious isn't it? Clearly God designed neutrinos to do this and who are we to question His work.
18 November 2011 7:30AM
Neutrinos still faster than light in latest version of experiment
Yay!
So exciting. Now we know how Father Christmas does it. Neutrino powered reindeers.
18 November 2011 7:31AM
Strange but true........
Many years ago (1992 think,) I was watching television when the picture faded and a female voice said something like 'do not be alarmed,this is a test transmission from 2021 (I think it was 2021) and it was a bank (I think Barclays)...it continued for about 30 seconds then the programme faded back in again. I never found anybody else at the time who had seen it and often thought about it since. Maybe....just maybe.......
18 November 2011 7:36AM
Time Travel is simple all you need is a 1.21 jiggowatt energy burst going to your flux capacitor while travelling at 88mph.
Or you need a TARDIS...
how the research into bigger on the inside technology going?
18 November 2011 7:41AM
.
Here, in SW France, you could measure it by the change of the seasons.
18 November 2011 7:42AM
Prepare to eat those shorts Prof Jim!!
18 November 2011 7:42AM
.
Would you go on holiday to the black hole of Calcutta?
18 November 2011 7:46AM
The potential for exceptionally complicated paradoxes due to time travel would be enough to blow anyones mind.
You could argue it's not possible, simply because it hasn't happened. If it were possible in the future, then would we not have had visitors from that time?
There's been numerous science fiction stories that explore the possibility of 'time police'
If a person from the future arrives back in time and changes events, we would be none the wiser, now imagine if this change of events prevented the discovery of time travel. It would therefore have been impossible to travel in time in the first instance.
Now there's a complicated paradox starting here.
The time police are aware of this possibility, so to prevent this from happening, they have already travelled further back in time to establish the invention of time travel.
Now it's getting messy and my brain is already starting to hurt...
18 November 2011 7:49AM
Scientists driving, riding and walking backwards into the past out of academia and back into the lunatic asylum?
18 November 2011 8:01AM
Just because something doesn't seem intuitive does not mean it is not possible.
18 November 2011 8:06AM
Great opportunity to test a paradox theory...
1/ do it over a long distance
2/ measure speed
3/ destroy one of the pulses on arrival at destination
4/ measure to see if the destroyed pulse is in fact taken out of existence before its arrival or maybe before it's fired...............
Basically, could it be destroyed on its arrival meaning it's destroyed before it gets there?
18 November 2011 8:07AM
Just to clarify one tiny but essential misreporting in this and most other articles on this: assuming the results are genuine, it doesn't contradict special relativity by itself. It contradicts SR together with the impossibility of time travel. If other words, if the results are right, either SR is wrong or time travel is possible (or both).
Nearly all the physicists assumes causality is more essential than SR. If time travel is possible, then causality doesn't hold. So if you do assume causality, the results do contradict SR.
18 November 2011 8:12AM
This is quite clearly the work of Cameron and his fat-cat chums, looking for more time in which to rob the tax-paying worker blind.
18 November 2011 8:14AM
I have to say even if it is accurate its probably academic at best.
We may be able to send data back through time but if we are only gaining sixty billionths of a second over 720km, its not going to give me time to buy the winning lottery ticket it :)
even over a light year (10×10to15 metres) according to my potentially dodgy maths its only going to gain you 8 days, but then you have to get some one out there in the first place to receive the data.
Still it means any colony on alpha century will get its mail a month ahead of the 4 years it would normally have taken, so some good may come of it.
18 November 2011 8:15AM
If the theory that each and every atom in the universe is accelerating away from each and every other atom is correct, then didn't the point of departure of the neutrino get a little bit further away from the point of arrival during the course of the experiment?
Also, how did the delivery people get those large consoles through those narrow doors in the TARDIS? Tough job.
18 November 2011 8:17AM
-- The physicist and TV presenter Professor Jim Al-Khalili of the University of Surrey expressed the incredulity of many in the field when he said that if the findings "prove to be correct and neutrinos have broken the speed of light, I will eat my boxer shorts on live TV". ---
All right, but you must eat them raw; no soups or sauces, unless it be the natural ones after wearing those shorts for a week.
Enough scientific arrogance.