• Neutrinos still superluminal

    By now, you must have heard about the “BREAKING NEWS” that neutrino velocity measurement conducted by the OPERA experiment was flawed because of a faulty cable connection.

    If you think about this, a loose/faulty connection (as mentioned in various media outlets) would result in a delay in the signal. So, one would record a greater time measurement than the actual value. If one rectifies it, the new measurement should show a shorter time measurement than the one previously recorded. As we all know that speed is distance/time, a smaller corrected time value should give a HIGHER value of the speed and not smaller.

    But there is more to this story. According to this report in Nature, there is another mistake in measurement. It is caused because of a faulty oscillator which synchronizes the GPS clocks. OPERA is out of sync! I don’t know the details, but as stated in the report, fixing it would increase the time measurement and therefore REDUCE the neutrino speed.

    So, now we have two opposite effects. One would increase the speed and the other would decrease it. Would these effects cancel out? Calculations will tell! I am sure, the quantitative analysis will soon tell us how these two mistakes are going to affect the measurement, but the actual measurements need to be made again and we probably will have to wait for a couple of months for the results. In the mean time, people are coming up with their theories on why neutrinos can and can’t travel faster than light. Here is a link for your entertainment.

     

    • Jake

      I guess we shouldn’t be surprised — the damn things are already wacky enough. I mean, traveling at 99.wholebunchof9s of the speed of light but with only a little dab of mass. Violates something, don’t you think? What’s the rest mass, a planck mass? (I guess there is no such thing — planck length and possibly planck time — someone should propose a definition for planck mass)

      But … still, universe being the way it is, the superluminality will almost certainly be human error, rather than real. Is it just me, or is it always the cheesiest answer?

    • http://www.tifr.res.in/~atri Dimitra Atri

      Jake, nature is full of surprises. The best guess on neutrino mass is a few eV or even lower. Planck mass is already defined, just google it. It is very high, compared to the mass of subatomic particles we know.

    • Jake

      Dimitra — By saying nature is full of surprises, are you suggesting that I should be a little more open-minded about superluminality? So far the universe seems to be staying inside its limits — but usually questions about superluminality are concerned with being able to get somewhere quicker than light, and that’s actually a different sort of question.

      I asked Google about Planck mass, and I see that the way it’s defined fits within the other Planck definitions, but it’s unsatisfactory. I was looking for a “least possible mass” statement, to match “least possible length” and “least possible time,” and of course Planck mass is considering something rather different — but having thought about it for a bit, I realize that at Planck scales, mass is an iffy concept, probably doesn’t apply at those sizes, and least mass … well, rhetorically, how much mass would a Higgs boson have? I suspect that’s a meaningless question.

      Can a neutrino exist at rest? I know we can’t stop one, slippery as they are, but I mean in theory. I’ve Googled a bunch of things on neutrinos, and get into a closed loop pretty quick.