OPERA Redux

The members of the OPERA collaboration have taken to heart one of the primary criticisms leveled at their experimental method: the possibility that the particle bunches used might be so long as to introduce sampling errors in their timing measurements. To address this the team have continued their measurements for an additional few weeks, reducing the burst durations from 10.5 microseconds to a mere 3 microseconds. Twenty new neutrino events were detected with the new configuration. (Only 20? Yep. Remember, neutrinos rarely interact, making them extremely difficult to detect.) The result? Once again, the neutrinos from CERN still appear to be arriving at Gran Sasso 60 nanoseconds sooner than expected.

Of course, the bunch length is the only thing changed in this latest run. If there is some systemic error in the experiment, it is still there.

And there is widespread suspicion that there is some systemic error involved in these results. While physicists are giddy about the prospect of new physics to explore, as I pointed out in my previous post on this subject, that excitement is tempered by skepticism. Ultimately, it will be up to other teams to replicate this experiment with different equipment to either validate or refute these results. Already, teams at MINOS and T2K are gearing up to attempt this, but it will take a few years for that to happen.

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About Glen Mark Martin

MCSE-Messaging. Exchange Administrator at the University of Texas at Austin. Unrepentant armchair physicist.
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6 Responses to OPERA Redux

  1. Hendriks says:

    You can do it 100 time more but the measurment will give you the same result! The 60 nanoseonds earlyer ariving is caused by the gravity of the earth. The neutrino’s takes a bowed way and this way takes 60 nanosec. ( 18 meters) more as the straight way. It is impossible to take the straight way 730 km. The neutrino’s are ariving earlyer with the speed of light, 60 nanosec, before Gran Sasso,but following the bowed line and have to make the rest of the 60 nanoseconds to make, to arive in time at.Gran Sasso.
    2 lines, the straigt and the bowed line, but the straigt line is no way because of the gravity!
    J.Hendriks

    • glenmartin says:

      The distance measurement used by the OPERA team is the straight-line distance through the earth from CERN to Gran Sasso. This makes sense in view of the fact that neutrinos can travel through the bulk of the earth largely unobstructed since they couple so weakly with matter (which is also what makes them tremendously difficult to detect).

      If the neutrinos were to be constrained (for whatever reason) to travel along an arcing path, they would arrive later than expected, not sooner, so the opposite effect would be seen.

      As for gravity, the tiny mass the of neutrinos is far too minuscule for gravity to alter their trajectory significantly over such a relatively short distance.

      • Hendriks says:

        I like to explain the time and distance and the speed of light.
        Distance CERN and Gran Sasso 730 km. Time straight line 10.500 nanosec. In seconds this is 0.0024 . 60 nanosec before Gran Sasso takes 18 meter. Speed of light 300.000 km/sec.
        You can’t faster go then 300.000 km/sec. 730/300000=0.0024sec.
        The straight line is 730 km is impossible to go by the neutrinos because of the gravity caused by earth. The neutrinos must take a bowed way .The straightway is impossible to go.
        10.440 + 60 = 10.500 nanosec.= 0.0024 sec.
        Cern.——————————————————————…………. Gran Sasso. 10.500 nanosec.
        730 km (straight way is impossible) +60 nanosec.18 m= bowed line.
        When the neutrinos arrive it look like they went faster the speed of light, because of the distance 10440 in the straightway, but they took the bowed way and this way was 18 meters longer! This real way was made by the speed of light C=300.000.
        730+18 m./300000=10500 = 0.0024 sec. (bowed distance/C=time)
        You have to calculate with the real (bowed)way 730+18 m. the neutrinos made and not the (straight)distance 730 km. from CERN and Gran Sasso!
        So Einstein is still alive! His point of view the speed of light is approved and the gravity of the earth has a CERN-machine to calculate with the gravity from Geneva CERN to Gran Sasso.

  2. Hendriks says:

    Hello mr.Glenmartin,
    The neutrinos are detected earlyer at18 meter before the end when you calculate the straigt line, but they took the bowed line, but they have to make even 18 meters more to reach the end!
    This time 60 nanosec. and distance is 18 meter exactly to go. 730km +18 meter
    As you know neutrinos have mass and even as light the gravity will have influence on this neutrinos. They can’t follow a straigt way. The calculation that is made over 730 is the mistake, The way the neutrinos folowed is 730km. +18 meter.. They followed the real way and this was the bowed way 18 meter longer than 730 km.!

    • glenmartin says:

      Certainly, all objects travelling within a gravitational field, even those with a tiny mass such as neutrinos, or massless objects such as photons, will have their trajectories modified by gravity. But, let’s look at the numbers. Using rounded off values and classical approximations (since the order of magnitude is what is needed to make my point), with a time of flight in the neighborhood of 2.43 x 10^(-3)s, and given that the vertical deflection due to gravity of any object near the earth’s surface is given by (1/2)gt^2 (where g=9.8m/s^2), we find that gravity would vertically deflect the trajectory of the particles travelling from CERN to Gran Sasso by a grand total of 2.9 x 10^(-5)m. That is about 3/100ths of a millimeter. This would increase the trajectory length by a minuscule amount, certainly not by the 18 meters you are indicating. For all practical purposes, the trajectory can be treated as a straight line.

      But, even if the actual travel distance were 18 meters longer than thought, this would result in the neutrinos arriving LATER than anticipated, not sooner as observed by the OPERA team.

  3. Pingback: Last Nail in the Coffin for Superluminal Neutrinos | Whiskey…Tango…Foxtrot?

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