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Do neutrinos move faster than the speed of light?

2 Oct

Quite recently, 23 Sept. 2011, CERN issued a press release reporting an anomaly in the time-of-flight of neutrinos.

The experiment, called Oscillation Project with Emulsion-Racking Apparatus (OPERA), aims to detect neutrinos obtained by smashing fast particles againts protons from the Europeans particle physics laboratory. The detector consists in a 1300-metric-ton particle detector.

Neutrinos travel underground from CERN to Grand Sasso in Italy along 732 km.

«As the particles hardly interact at all with other matter, they stream right through the ground, with only a very few striking the material in the detector and making a noticeable shower of particles.

Over 3 years, OPERA researchers timed the roughly 16,000 neutrinos that started at CERN and registered a hit in the detector. They found that, on average, the neutrinos made the 730-kilometer, 2.43-millisecond trip roughly 60 nanoseconds faster than expected if they were traveling at light speed. “It’s a straightforward time-of-flight measurement,” says Antonio Ereditato, a physicist at the University of Bern and spokesperson for the 160-member OPERA collaboration. “We measure the distance and we measure the time, and we take the ratio to get the velocity, just as you learned to do in high school.” Ereditato says the uncertainty in the measurement is 10 nanoseconds.»

Antonio Ededitato, a physicist at the University of Bern and the spokesperson of the 160 collaborators of the OPERA project, is prudent. He said “I would never say [that relativity is wrong]”. You can access the relevant papers published in the frame of the OPERA project in this site.

The problem of measuring speed is that we both need distance and time-of-flight. For the last one quantity the experimenters used the time given by Global Positioning System. The common GPS source of errors are:

  • Ephemeris errors: they occur when the satellite doesn’t correctly transmit its exact position in orbit;
  • Ionosphere conditions: when satellites travel through this region above the Earth their signal are slowed down due to the plasma medium that constitutes the ionosphere;
  • Troposphere region: it affects the signla propagation due to the variations of temperature, pressure, and humidity;
  • Timing errors: they may occur if the GPS receiver clock is not an atomic clock;
  • Multipath erros: the satellite signal can be reflected from any hard surface, sucg as buildings) and delay the travel time of the signal;
  • Poor satellite coverage.
Time and distance are measured by means of triangulation with 4 satellites. Diferent sources of errors are inherent to the method. Read here to learn more.

Science attempts to improve our vision of Nature and its working, and the speed of light is considered the maximum speed with which any meaningful signal may propagate in space. The apparent possibility that any object can travel faster than light reminds me of the famous mathematician Grothendieck, Field medal (the Nobel prize of mathematics), who disapeared sudenly in 1970 somewhere in village of the Pyrennés.

One story goes that Alexander Grothendieck is “convinced that the Devil is working to falsify the speed of light”.  Grothendieck told to Leila Schneps, wife of Pierre Lochak, both mathematicians at the Université de Paris-Jussieu, that he was willing to share his research into physics with her if she could answer one question: ‘What is a metre?’ …He refuses to work in physics sustaining that physics made possible the horror of Hiroshima. Alain Resnais made a dramatic and beautiful movie about the horror of it in his movie “Hiroshima, mon amour”, based on the work of the French writer Marguerite Duras. We always endure a catarsis when watching this movie (trailer here).

Grothendieck great contribution to mathematics  was to enlarge our concept of “geometric point”. This concept goes back to Leibniz for who the constituents of all things (material or spiritual) are monads without internal structure and it is their relationship that make the “structures”. Grothendieck concept of “point”. For this understanding we need the concept of space X: A space X described using the notion of topos T(X) of sheaves over X. A given point a is a point of X.

Despite the possible errors due to the method of measurment itself, or the methaphysical problems intrinsically related to the knowledge of the working mechanisms of nature, already some tentative explanations are advanced to explain the supraluminal effect, for example see this paper from Robert Alicki attempting to explain the effect on statistical grounds.

It is expected much ado about this effect, but for one thing I am sure, physics is well behind the development of mathematics and not taking due advantage of its progress.

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