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Proud Mary

Fri Nov 18 2011, 08:40PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Neutrinos still faster than light in latest version of experiment

Finding that contradicts Einstein's theory of special relativity is repeated with fine-tuned procedures and equipment

Alok Jha, science correspondent,
guardian.co.uk,
Friday 18 November 2011

Scientists working at the Cern laboratory have again recorded neutrinos travelling faster than light

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 â€“ around three nanoseconds â€“ 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 â€“ maybe even as few as 10 or so â€“ 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 â€“ 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.

Conundrum

Fri Nov 18 2011, 10:13PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

In poor Albert's defence, neutrinos hadn't been discovered at the time he wrote both his General and Special theories, they were added on later to explain inconsistencies in some nuclear decay chains which couldn't be explained away by simple gamma emission.

Well it looks like the jury is still out on exactly what is going on here but the higher dimensional theory sounds promising.

It does make me wonder, if radioactive decay is linked to neutrino flux weakly in some isotopes, could this be tested experimentally by monitoring a given heavy element of known mass with a long half life, and correlating spikes in activity with known neutrino emitting events?

Carbon_Rod

Sun Nov 20 2011, 02:15PM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

Albert likely would have muttered something about people assuming space-time is locally flat.

People must now focus on excluding sources of error, and data verification using a separate apparatus.

In my opinion, 60ns seems too round to occur arbitrarily from an invalid constant, and seems awfully near the fundamental of a 16MHz Xtal on a sensor grind someplace. However, I have not resolved any sources of error that could exceed even 10% of the measurement LHC reported.

Interesting experiments,

Ash Small

Sun Nov 20 2011, 02:26PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I've been wondering if the neutrinos aren't 'expelled' before the proton impact, ie, maybe the neutrinos are 'oscillating' but re-combine, normally, but when a proton approaches (or whatever the exact method of production is), the neutrinos 'escape'.

Would a mechanism such as this (or similar) give the neutrinos a sufficient 'head start'?

plazmatron

Sun Nov 20 2011, 02:42PM

Registered Member #1134 Joined: Tue Nov 20 2007, 04:39PM
Location: Bonnie Scotland
Posts: 351

The only problems I can conceive of, that may skew the results of the experiment are:

As `Carbon-Rod` already pointed out space-time isn't locally flat. And in fact is decidedly "lumpy" at the earths surface, as well as curved.

The second is that the entire experiment is in motion, and not static. The earth rotates as around 1,674.4 km/h at the equator, and travels through space in orbit at around 108,000 km/h. Thus if a pulse of neutrinos was fired from a point on the earths surface, the earth would have moved somewhat, before the arrival of the neutrinos at the detector.

Checkout the Sagnac effect with interferometers, and ring lasers.

Les

Tetris

Sun Nov 20 2011, 04:24PM

Registered Member #4016 Joined: Thu Jul 21 2011, 01:52AM
Location: Gainesville, FL
Posts: 660

The cake is a lie. We have to rewrite every single science textbook on the planet if this is true!

EDIT: No. They found out that it was a missing GPS cable. Einstein was proved right again.

Ash Small

Sun Nov 20 2011, 08:25PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

"In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known. In other words, the more precisely one property is measured, the less precisely the other can be controlled, determined, or known.

Max Born states, in his Nobel Laureate speech:
To measure space coordinates and instants of time, rigid measuring rods and clocks are required. On the other hand, to measure momenta and energies, devices are necessary with movable parts to absorb the impact of the test object and to indicate the size of its momentum. Paying regard to the fact that quantum mechanics is competent for dealing with the interaction of object and apparatus, it is seen that no arrangement is possible that will fulfill both requirements simultaneously."[1]

Published by Werner Heisenberg in 1927, the uncertainty principle was a key discovery in the early development of quantum theory. It implies that it is impossible to simultaneously measure the present position while also determining the future motion of a particle, or of any system small enough to require quantum mechanical treatment.[2] Intuitively, the principle can be understood by considering a typical measurement of a particle's position, which involves the scattering of light or other particles off of the target, and this involves the probabilistic exchange of energy. The uncertainty principle is a fundamental property of quantum systems, not a statement about the observational strength of current technology.[2] Some uncertainty about such particles is unavoidable. One can at least, however, identify the average momentum and position of particles (using weak measurements).

The principle states specifically that the product of the uncertainties in position and momentum is always equal to or greater than one half of the reduced Planck constant Ä§, which is defined as the the re-scaling h/(2Ï€) of the Planck constant h. Mathematically, the uncertainty relation between position and momentum arises because the expressions of the wavefunction in the two corresponding bases are Fourier transforms of one another (i.e., position and momentum are conjugate variables). In the mathematical formulation of quantum mechanics, any non-commuting operators are subject to similar uncertainty limits."

Carbon_Rod

Mon Nov 21 2011, 02:53AM

Registered Member #65 Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155

@plazmatron The transfer takes 0.003 s and excluding frame drag:
Earth's rotation max. error:
0.003 s * 465.1 m/s = 1.3953 m
1.3953 m / 299792458 m/s = 4.7 * 10^-9 s

Earth's gravity avg. error:
1/2 * (9.80665 m/ss * (0.003 s )^2 ) = 4.41 * 10^-5 m
4.41 * 10^-5 m / 299792458 m/s = 1.47 * 10^-13 s

LHC Observes:
6.0 * 10^-8 s * 0.299792458 m/ns = 17.98 m off mark (approx.)

The results must stand as significant if and only if the LHC instrument is not faulty somehow.

@HighVoltageChick
When someone finishes Portal a cake did appear in the credits.

AndrewM

Wed Feb 22 2012, 11:13PM

Registered Member #49 Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362

"Nevermind"

ConKbot of Doom

Thu Feb 23 2012, 02:32AM

Registered Member #509 Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329

Well, I'd certainly like to be a fly on the wall for them finding the loose connection, and for the re-test results.

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