Review: Measurement of the neutrino velocity with the OPERA detector in the CNGS beam (AKA faster than light neutrinos)

Astronomy Twitter Journal Club resumed after a short holiday with a discussion of the paper that everyone is talking about at the moment.

There are some interesting links to read from our preview post, and you can also read the full Tweet archive of the meeting.

I also interview Ben Still (a neutrino physicist) for The Pod Delusion Episode 104 about this story.

Thank you to everyone for taking part. It was a fun and lively discussion!

On to the review.

What do we think of the release of this paper

First thoughts: I think in a year or so from now they’ll look back on the press release etc as a bit embarrassing. – StephenSerjeant


Possibly, but do you think they had much choice – wikimir

Do you think? They don’t believe it themselves. Surely they just want someone to tell them what they did wrong – kashfarooq

They simply need help in understanding their experiment – antisophista

As I understand it, they’d already spent a year checking their results. Suppose they didn’t know what else to do – astronomyjc

I think it makes sense to have some input from the wider community – chris_tibbs

The adherence to “good scientific practice” is indeed admirable. This is a teachable moment for our 100-level courses! – @spj4

I didn’t like the PR but think OPERA team are doing everything right in science circles. – StephenSerjeant

On the publicity

On the plus side, the whole world is talking about physics and neutrinos. That’s pretty cool! People are suddenly comfortable mentioning SN1987a in conversation! – kashfarooq

I helped out at the @royalobs open day last weekend & several people asked me about the story…unfortunately they did so with a “so everything you study is now wrong, haha” smirk! – astronomyjc

It was a question in the pub quiz I went to last night! – kashfarooq

True but inevitable press coverage was “Einstein wrong!?” Perh press release could have hedged more? – StephenSerjeant


Neutrinos from this supernova arrived 3 hours before the light was detected optically. This 3 hour delay is because the journey of the light was being impeded by the atmosphere surrounding the dying star, whereas the neutrinos escaped without interacting with this material.

For SN1987a the 60 ns they observe cannot account for the observed 3 hours delay. You’d expect the neutrinos from SN1987A to arrive several years before the photons – antisophista

Using their figures, 4 years +/- 1 year – kashfarooq

I think there’s a misconception that SN1987A rules it out: measurement was inspired by arXiv:0805.0253 consistent with SN – StephenSerjeant

do the SN 1987A neutrinos cast sufficient doubt on this result to rule it out or don’t help because they were less energetic? – astronomyjc

SN1987a rules some things out. But the energy diff (10GeV OPERA vs 10MeV SN) would mean a time difference of just 0.1 seconds. [Source]  – kashfarooq

What if we just didn’t notice neutrinos arriving 4 years before the light?

Could we have received the neutrinos from SN1987a 4 years earlier and have not noticed them??? Is that possible? Did we have neutrino detectors in 1983? – DVDGC13

There were no detectors capable of detecting SN neutrinos in 1983 – kashfarooq

so… then if they arrived here we missed them… am I right?? – DVDGC13

Raises the interesting poss. that we may have already detected bursts of neutrinos from future supernovae – astronomyjc

for GRBs it is even better… neutrinos should arrive several thousand years before we observe the actual GRB – antisophista

[Ben Still has written a blog post discussing this: Supernova Neutrinos in 1983 and 1987?]

Replicating the experiment and more papers

Is there any other detector that could attempt to replicate the CERN results? – astronomyjc

T2K can once they have two years more data… – kashfarooq

There have already been 3 FTL neutrino papers on the arXiv! – astronomyjc

Even more papers – antisophista

Some concluding thoughts


So, if the FTL neutrinos are real what are the implications? How much of the textbooks do we have to rewrite?! – astronomyjc

Who thinks they have found something, and who thinks there is a measurement error? – kashfarooq


I’ll bet Special Relativity is right even if FTL neutrinos exist – probably just #QuantumGravity effect?! – AntonyRyan77

The results imply new physics. They can’t be explained with diff energy or diff types of neutrino – kashfarooq

For once, one could say that the speed of light is *not* the limiting speed predicted by special relativity – antisophista

I think the first thing to do would be to determine if it is only neutrinos that can travel FTL. – chris_tibbs

I don’t think anyone is yet in a rush to rewrite causality or Lorentz invariance 😉 – StephenSerjeant

I think it’s too soon to tell. It raises interesting possibilities, but need proof that it’s not measurement error – astronomyjc say the problem is synchronising the clocks by lugging a time-transfer device from CERN to OPERA – StephenSerjeant

99.9% prob it’ll be a systematic IMO but interesting 1st ex of crowd-sourcing professional experimental phys analysis?- StephenSerjeant

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4 Responses to Review: Measurement of the neutrino velocity with the OPERA detector in the CNGS beam (AKA faster than light neutrinos)

  1. Jarek says:

    I disagree that if neutrinos could travel a bit faster than light, they would have to sustain this velocity for astronomical distances. If a single one of their high order electric or magnetic moment would be nonzero, it would mean that there should be created some Cherenkov radiation.
    So electromagnetic field should finally slow them down to the speed of light, probably in extremely slow rate.

  2. Pingback: Was Einstein Wrong? That’s the Wrong Question « Galileo's Pendulum

  3. Pingback: The 21st Floor » Blog Archive » Ben Still Interview: Faster than Light Neutrinos

  4. Eric Becherer says:

    I’m just a layman, and I hope my questions don’t insult, but my interest and lack of sleep compels me to ask.

    Q…Were the Neutrinos actually measured at a faster than light speed, or did they just show up before the light?
    I am sure that the fact that light travels slower on earth than in a vacuum (because it is effected by the matter in the atmosphere’s refractive index) has already been addressed, but could something else be slowing the light down, I.E. gravity waves, or dark matter? if so, we may have a new detection process.
    Was the path of light longer than the path of Neutrinos (because of the curvature of the earth…light bent, Neutrinos straight)?

    Thanks for your time.

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