MERGED: Pillar of Physics challenged

[rodsky]

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Something to additionally ponder on, re the "mistakes" that can occur in experimentation.

The Reference Frame: Potential mistakes in the Opera research

-RODION

[TwoStepsFromHeLL]

Natalie Wolchover, Life's Little Mysteries Staff Writer
Date: 12 October 2011 Time: 09:21 AM ET

Einstein's Theory May Put Brakes on Faster-Than-Light Neutrinos | LiveScience

Just days after Albert Einstein's theory that nothing moves faster than light was called into question by a startling neutrino experiment, the long-dead physicist might have come to his own rescue.

Einstein's general theory of relativity contends that a slight difference in the force of gravity at two different places causes clocks in those places to tick at different rates. Carlo Contaldi, a theoretical physicist at Imperial College London, argues that when physicists recently measured neutrinos traveling at 1.000025 times light-speed between Switzerland and Italy, they didn't fully correct for this effect, and that failing to do so could have caused their shocking results.

"I think there are significant questions as to whether or not their clocks were synchronized correctly," Contaldi told Life's Little Mysteries, a sister site to LiveScience. His paper, posted online to the physics arXiv preprint site on Sept. 30, is one of the first to challenge the neutrino experiment's process.

In the OPERA experiment (Oscillation Project with Emulsion-tRacking Apparatus), physicists working at the Gran Sasso National Laboratory in Italy — a lab buried almost a mile underground — timed the arrival of muon neutrinos coming from CERN, a physics facility near Geneva, Switzerland, 451 miles (731 kilometers) away. To the astonishment of the entire world, the neutrinos clocked in 60 nanoseconds sooner than a light beam traveling the same distance would have done.

This was remarkable because neutrinos have mass (although very little), and, as Einstein taught the world, massive objects would seem to need infinite energy to travel at light speed, let alone faster. If Einstein was wrong, most modern physics theories topple with him.

But Contaldi contends that OPERA's clocks, rather than its neutrinos, may have been out of whack. Gran Sasso and CERN are at different distances from the center of the Earth, so the force of gravity varies slightly between the two labs. In an effect known as "gravitational time dilation," gravity causes time to drag, just as it stretches space. The different gravitational strengths at the two labs therefore mean that clocks at CERN run slightly slower than clocks at Gran Sasso. And on the lightning-fast timescales involved in the OPERA experiment, a small difference in the clock speed is significant enough to matter.

Pasquale Migliozzi, a physicist on the OPERA experiment who acts as the group's spokesperson, told Life's Little Mysteries and Contaldi that the OPERA team matched up their clocks in Gran Sasso and Geneva by synchronizing them with a third clock — that of a GPS satellite. In their setup, the neutrino departure and arrival times were both measured by the same GPS satellite, and the times were logged on GPS receivers in the two labs. The team brought in METAS, a Swiss metrology institute, to calibrate the receivers at the two locations, and Migliozzi said that the time measurements using this method should have been accurate to within 2 nanoseconds.

But Contaldi says that GPS synchronization is not nearly that accurate, because GPS satellite signals are themselves subject to gravitational time dilation. GPS receivers make corrections to account for this, but nonetheless the clock signals are only guaranteed to be correct on the order of 100 nanoseconds. Therefore, Contaldi argues, they can't be used to time events that happen faster than that.

"From what I've seen, my estimate is that there are tens of nanoseconds of uncertainty in GPS synchronization, and from what I can tell, [the OPERA scientists] assume [their clocks] were perfectly synchronized," Contaldi said. If he is right, then an error range of tens of nanoseconds would greatly reduce the significance of a measurement in which neutrinos beat light by tens of nanoseconds.

Contaldi concedes that the OPERA team may have made more of an effort to synchronize its clocks than it elucidated in the first draft of the paper. But if so, he says, it is crucial that those physicists explain it. "I hope they are preparing a more in depth discussion of how they took their clocks to be synchronized."

Migliozzi didn't comment on Contaldi's further inquiries, but the back-and-forth is likely to continue. The OPERA scientists have not purposely withheld information about their experiment and have welcomed criticism from the outset. Even they admit that the details of their experimental setup are more likely to be flawed than are the fundamental laws of physics.

[rodsky]

I find it funny that we actually have a topic here in the Science section several months ago, that discussed this issue on different clock values due to gravity and distance from the center of the earth.

https://www.istorya.net/forums/scienc...gravity-2.html

-RODION

[TwoStepsFromHeLL]

: unsa d i clock ila gamit. why maka apekto man ang gravity sa time.

[fritzd]

A very interesting read. I invite everyone to read this. It's not so long.

Subluminal neutrino news from Italy (Blog) - physicsworld.com

[jackson428]

very interesting... this could change things

[fritzd]

Another interesting read.

Physics - Not So Fast

[neshem]

Update on the 15,000 Neutrinos That Seemed to Outrace a Beam of Light

Update on the 15,000 Neutrinos That Seemed to Outrace a Beam of Light | Dr. Kaku's Universe | Big Think

wala pa ghapon kaayo..calibration pa ghapon..but in the link some Photographs of the OPERA (Oscillation Project with Emulsion Tracking Apparatus )

[TwoStepsFromHeLL]

: naa na pud lain nga expirement : link - Neutrinos Still Seem Faster than Light | Faster-Than-Light Neutrinos Pass Another Test | Life's Little Mysteries

The Italian physicists who announced two months ago that they had detected particles called neutrinos traveling faster than light now say they've done it again — and using an improved experimental setup. Many more tests will be needed, however, before the physics community accepts the revolutionary result as final.

"The experiment OPERA [Oscillation Project with Emulsion-tracking Apparatus], thanks to a specially adapted CERN beam, has made an important test of consistency of its result," said Fernando Ferroni, president of the Italian Institute for Nuclear Physics (INFN), which runs the lab where the experiment was conducted. "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."

In both runs of the OPERA experiment, a beam of neutrinos — strange subatomic particles that don't interact with normal matter — was sent from the CERN Laboratory in Geneva, Switzerland, to the INFN Gran Sasso Laboratory near Rome, and arrived at their destination 60 nanoseconds faster than a beam of light would have done. That's shocking, because much of modern physics relies on Einstein's theory that the speed of light is the universe's speed limit. [10 Results of Faster-Than-Light Discovery]

However, since OPERA first publicized its results in September, physicists around the world have scrutinized nearly every aspect of the experimental setup, pointing out several potential flaws that, when corrected, might reveal that OPERA's neutrinos are traveling at less astonishing speeds.

The new test has addressed only one of those concerns.

Physicists had pointed out that the proton pulses that were used to generate the neutrinos that left CERN were of quite long durations, at 10.5 microseconds. Individual neutrinos received at Gran Sasso could have come from protons early or late in the proton pulse, creating uncertainty in their exact travel time, detractors said.

Thus, the OPERA team repeated their experiment using proton pulses that were 3,000 times briefer than last time, giving greater precision to the start time of neutrinos. With the beam tightened up, the neutrinos still arrived at Gran Sasso 60 nanoseconds faster than light would have. "This test confirms the accuracy of OPERA's timing measurement, ruling out one potential source of systematic error," the INFN statement said.

However, many potential sources of error remain. For example, Ronald van Elburg of the University of Groningen in the Netherlands has argued that the Italian scientists failed to account for the fact that the GPS satellite they used as their timekeeping device is moving. If they had corrected for the motion of the satellite as Einstein's theory of special relativity requires, they would have measured the neutrinos arriving 64 nanoseconds later, van Elburg asserted. [Neutrinos: Not So Fast, Some Say]

The OPERA team responded that they had correctly used the GPS to synchronize their clocks at CERN and Gran Sasso. However, they now admit the possibility that there could be flaws in their timekeeping:

"One of the eventual systematic errors is now out of the way, but the search is not over. There are more checks of systematics currently under discussion, one of them could be a synchronization of the time reference at CERN and Gran Sasso independently from the GPS, using possibly a fiber," said Jacques Martino, director of the National Institute of Nuclear and Particle Physics of French CNRS.

Most physicists hope to see other groups, such as MINOS (Main Injector Neutrino Oscillation Search) at Fermilab in Batavia, Ill., conduct an independent test of neutrino speeds with similar experimental setups.

"OPERA is to be congratulated for doing some important and sensitive checks, but independent checks are the way to go," said Rob Plunkett, co-spokesman for MINOS, in a statement to the press. According to the journal Nature, MINOS could be ready to conduct such a test in early 2012.

[TwoStepsFromHeLL]

: pero need pa jud siguro sila og more expirements para ma prove jud