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OPERA and Italian comrades

Physics-related: I recommend you an enthusiastic interview with Sven Heinemeyer on supersymmetry.
Yesterday, I summarized the current situation with the OPERA experiment in Lidovky, a leading Czech daily. A copy of the Czech text appeared on The Invisible Dog two days later.

All the people who responded to my article by e-mail included the term "Italian comrades" in the subject line of their e-mails. And all the people wrote me about units – people, including engineers, are not used to the units used in particle physics.




I used the phrase "where the Italian comrades made a mistake" which is a variation of a popular scene from a 1999 Czech historical film comedy, Cosy Dens (Pelíšky) about a few interacting households in 1967 that either liked the communist regime or not.



At 8:40, a pro-communist enthusiastic father says "These are spoons developed by the East German researchers, do you know?". He's proving once again that the Soviet bloc is ahead of the imperialists. As the spoons melt, his wife tells him "I told you to leave them for the ice cream. This is no spoon for a hot coffee!". At 9:38, the pro-capitalist traditional chap says "I would only like to know where the comrades from East Germany have made a mistake."

Full translation of my essay

Contemporary physicists failed to beat Einstein once again

In September 2011 an explosive report began to propagate through the physics circles. An Italian experimental team called OPERA disproved Einstein's special theory of relativity by proving that certain invisible particles, neutrinos, are moving faster than light which is not allowed to anyone according to Einstein (it's as illegal as the journeys backward in time). But was it possible to trust the result?

Neutrinos were being produced in a decay of other particle species (the so-called pions and kaons) which themselves originated in a soup of interacting protons in one of the smaller accelerators of the European Organization for Nuclear Research (CERN) near Geneva. The neutrino beam was directed through the rocks to Central Italy. Neutrinos are penetrating through the matter almost as if they were ghosts which makes it hard to detect them. Only a few thousand neutrinos from CERN were caught in a cavern in Gran Sasso where the particles hit atomic nuclei.

With the help of GPS navigation devices, the physicists were able to measure the approximately 730-kilometer distance traversed by the neutrinos with a 20-centimeter accuracy. By dividing the distance by the time, also measured by GPS, they could calculate the speed of the neutrinos' motion. It exceeded the speed of light in the vacuum by 0.002% which means that the neutrinos reached their destination about 60 ± 10 nanoseconds before they were predicted to do so by special relativity.

Self-confidence in both camps

About one hundred experimental physicists (who originally studied the so-called neutrino oscillations) were boasting their self-confidence that they have avoided all conceivable mistakes. Nevertheless, most theorists dismissed their big claims: relativity has been verified by many methods and so far, it has perfectly passed all these tests. Moreover, the speed of neutrinos was previously almost directly measured by the observations of supernovea, accelerator experiments, and other experiments.

People like me would claim that the Italian comrades had to make a mistake somewhere. And indeed, on Wednesday, the Science Magazine published rumors – which were later confirmed by official spokesmen – that a relevant problem has been found. In fact, they found not one but two mistakes: a bug in their reading of the GPS sychronization impulses and especially loosely connected fiber optic cables that were connecting a GPS device with a computer card inside a computer. Although the precise numbers haven't been published yet, it seems extremely likely at this point that especially the optic cable problem will account for those incorrect 60 nanoseconds almost exactly.

[Addition for TRF: when the cable problem is fixed, the measured time will be icnreased by up to 100 nanoseconds which could even be too much, but dozens of nanoseconds will be subtracted by the other, synchronization problem, so the extra total correction may be very close to 60 ns in the right direction and we will land much closer to the time predicted by relativity at the end.)

Message

There are several lessons we may learn. First, experimenters aren't infallible. In a similarly complex experiment, the mistake could have been hiding at many places and in one or two of them, a mistake was indeed present. Second, the large size of a team doesn't guarantee that the physicists will avoid all mistakes. The perceived responsibility of each member is lower than it is in a smaller team or individual work. And because the job is ultimately divided in between them, some of the tasks may be assigned to "weaker links" in a chain and a mistake that no one will notice may occur. As a proverb says, the best work is a team work but two members are already too many. Third, it will be hard to disprove relativity and a few other pillars of modern science, especially because these theories are probably completely exactly valid.

Fourth, and this is especially important for the job of journalists, sensational claims about unbelievable discoveries are propagating more easily, and that's why the readers should evaluate such claims even more carefully. The vision of a radical discovery may bring fame as well as money to the scientist(s) as well as everyone who helps the shocking gospel to spread. This fact is a source of a certain "echo". A sensible reader should "filter out" such echos if he sees that someone could have "improved" the arguments in favor of a sensational claim.

The importance of labs such as CERN

The OPERA team isn't a part of CERN but CERN decided to informally incorporate OPERA and it is helping OPERA with press releases, among other things. The main experiment that is taking place at CERN is of course the experiment at the Large Hadron Collider (LHC), a circular tunnel of 27-kilometer circumference which is filled with superconducting magnets helping to accelerate protons nearly to the speed of light. From the products of trillions of collisions, detectors and physicists may pinpoint the properties of elementary particles in Nature.

The cost of the LHC collider was about $10 billion (particle physicists from the whole world were "saving" the money for 20 years or so) and it is consuming as much energy as all households in Geneva. An ordinary person could misunderstand why so much money has been "wasted" for similar things. However, the largest experiment in the human history should be compared to other expenses; for example, the amount is 40 times lower than the debt of the Greek government.

As physics fans know, marvelous things are happening and will be happening at the LHC. At the end of 2011, the gadget nearly discovered the "God particle", the Higgs boson, whose mass turned out to be 125 GeV. The discovery will almost certainly be announced sometime in Spring 2012 [after some more collisions] and the waiting is probably just a formality. However, the LHC may discover additional particles that underlie all the phenomena in the Universe. Aside from those, labs such as CERN occasionally discover new and wonderful things such as the web (the Internet). And those may be good enough reasons to pay for such experiments.

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