back to article OPERA review serves up a feast for physics geeks

Let’s get the “big news” out of the way first: there’s a lot of excitement due to one paper published on Arxiv.org, which asks whether the CERN OPERA experiment – the one that seemed to detect superluminal neutrinos – took into account the “satellite reference frame” in its calculations. So the short version of the paper is this …

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Anonymous Coward

The thing about this I'm enjoying most

is watching the process of scientific review being done out in the open

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Headmaster

Pay attention ...

... climatologists of East Anglia.

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Boffin

Just one thing, Cardinal...

The journalists and their editors worldwide may be clueless idiots - they usually are - but by interpreting the findings of OPERA (if true) as requiring a major paradigm shift in physics, they were simply doing their job.

Shouldn't a real "science journalist" be examining the orthodoxy with the same scrutiny and vigour when the observational evidence undermines the dominant hypothesis? Richard, since this paper has been published you have been beside yourself with alarm and distress that relativity is being questioned, or not as useful as we thought:

>> El Reg: As you might expect, the story has been greeted by “break the laws of physics” and “Einstein wrong!” headlines all over the world. This is both bad science and bad for science, and needs to be dealt with.<<

http://www.theregister.co.uk/2011/09/22/cern_spots_ftl_neutrinos/

Relativity didn't "disprove" Newton, while quantum theory has co-existed with relativity. We are always coming up with new and better hypothesis based on observational evidence.

A hypothesis that discards observational evidence is a dogma. You're at risk of sound religiously dogmatic.

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Gold badge

"Richard, since this paper has been published you have been beside yourself with alarm and distress that relativity is being questioned, or not as useful as we thought:"

That's not the impression I've been getting. Perhaps the difference is that I know just how much is riding on this. Special Relativity is a purely logical conclusion forced on you if you accept the laws of electromagnetism discovered by Maxwell in the 1860s. Einstein's contribution was "merely" to point this out. (It is a measure of how painful the mixing of space and time is for most people that his contribution is reckoned by most people to be a separate discovery, and a *physics* discovery, and one worthy of a part-share of a Nobel prize.)

Prior to fixing the laws of electromagnetism, the only fundamental laws known were those of mechanics. Since settling on Maxwell's laws, the only new field to be opened up which *doesn't* depend on EM, is thermodynamics. (This goes much wider than physics. Modern chemistry is now theoretically grounded in quantum theory, as it relates to the behaviour of electrons and atoms. Large parts of biology are now explained with chemistry, to the extent that a chemistry A-level is more important than a biology one if you want to take the latter subject at university level.)

If Maxwell is wrong, the experimental measurements don't go away. You are left with a metric fuckton of results that we depend on in everyday life for which you need to explain why they are still true even though Maxwell is wrong.

You need a bloody sight more than 5 sigma on *one* experiment to persuade the community that they've been talking bollocks for the last 150 years and should start again.

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Boffin

Say that every time I hear a knock on the door and open it that there's someone there. I conclude that there is a person outside knocking on my door, and if I question that person then they confirm it. One day I hear my door knocking, and I open it to find no-one there. I don't suddenly throw out the concept of someone knocking on the door or treat it as something that will rock my world-view, I look for reasons as to how it might fit into my evidence-based knowledge. Being sceptical doesn't mean that every time your world-view is challenged you assume that it must be wrong and that you have to discard everything previously immediately, it just means that you're willing to consider all possibilities. The correct explanation is not the one which fits the most recent problem, but the one which fits *all* the preceding evidence as well. I've compared creationism and climate change denial before, so I won't do that here, but if you take the view that you should discount just how well something is established by evidence when looking at new results you fall into the same trap that creationists do when they claim that radiometric dating is flawed because such-and-such was dated incorrectly.

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Thumb Up

Richard Chirgwin I love you

What you lack in alliterative headline writing and lego art, you more than make-up for in high quality impartial science coverage. Great article.

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c Can't Be Measured Using Light "in a vacuum"

The OPERA results and Einstein's relativity can both be correct as long as the definition of "c" is re-evaluated. When light travels through air or water it travels slower than "c". So to measure "c", the speed of light was measured "in a vacuum". Why, until now, hasn't anyone said "Wait a minute, according to quantum mechanics, there's no such thing as a vacuum, so that measurement must really be slower than 'c'"?

In a vacuum, a quantum soup of particles is constantly coming into and out of existance. Light interacts with these particles. Neutrinos interact with matter alot less, so the speed of nutrinos in the earth's crust could actually be closer to "c" (but still a bit slower). The speed of neutrinos in a vacuum would begin to approach the real value of "c".

In addition to these temporary particles, a vacuum may also contain a Higgs field, which could be another factor in slowing the speed of light below the real value of "c".

Jim Burrill

jburrill {at} gmail {dot} com

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Anonymous Coward

probably true

but this opinion has been expressed by several different people, even here in the reg comments on the original article, so i suspect it has been taken into account by the actual boffins.

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Silver badge

Because c is not the speed of light in a vacuum, it is the speed of light.

Heisenberg was merely the first to knife the Cesar which was the impartial observer, Al joined him with Relativity (both versions). Since observer cannot escape his medium, the variable refers to the speed in the medium. The highest speed for a medium is the medium of vacuum, and hence the speed most frequently quoted. This does also lead to corrections for media which are always neglected for student exercises, but which professional boffins are expected to include.

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Go

earth rotation?

If Mr. Kuhn of Cambridge should be correct, albeit only for 2ns, with the planets rotation influencing the result (in relation to what point?), then surely the earths travel around the sun, the solar system orbiting the galactic centre and the general speed of expansion of the universe (ok, maybe not that, that's not really a speed in the usual sense, more a stretching of space) should have an influence, too.

These speeds could add to the earths spin, or subtract, depending on the composite direction of all the vectors, which I can't calculate.

Mr. Kuhn, your call to check whether that accounts for the missing 58ns.

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Anonymous Coward

travelling relative to each other, rotating around the earths axis at different latitudes will have more of an impact than say, the differences relative to the sun...

so if that isnt included in the 2ns figure, then the error is going to be <1ns different, not 58ns more...

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Hmm, that's all well and good, but when will I be able to buy a star trek transporter?

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Silver badge

I thought relativity already allowed tachyons?

I thought faster than light fitted relativity ok as long as the particle in question only ever went faster than light. Even if the faster than light observation is correct then it doesn't disprove relativity unless they've also seen the same neutrino going slower.

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How do you label a neutrino?

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Facepalm

Tiny post it notes.

Only the yellow ones though, the neon coloured ones seem to use bad glue.

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Anonymous Coward

Maybe it's not bad. Perhaps it's simply that they don't have enough Gluon?

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Silver badge

Yes, it does allow tachyons, mathematically. They would need an infinite amount of energy to slow down to C.

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Silver badge

Mathematically perhaps.

But the philosophical principles underlying it, no.

Remember the key observational data which lead to this is the failure of the Michaelson-Morley experiments to be able to detect changes in the speed of light that ought to result from the fixed external reference of the ether. Furthermore, for pulsar binaries we had the observational data to that the blips occur in standard orbital fashion. If Newtonian physics held, the blips for heading away from us and heading toward us should arrive at more chaotic times than they do. We clearly get blip away, blip away, behind, blip toward, blip toward, front, rinse and repeat. The the away is red-shifted relative to the median red-shift for the central object, the toward is blue-shifted relative to the median red-shift, but the arrival times are in the proper sequence.

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WTF?

Title is optional for commoners

OK, I can't think of a better place to ask two incredbly stupid questions about this whole matter...a better place, that is, for a masochist cursed with insatiable curiosity.

I've no idea where else I could find anyone willing (however snarkily) to answer. Reg readers may not suffer fools gladly, but they nonetheless graciously allow us to hang about the throne room for amusement value. (Note: I have no dental insurance at present, so please avoid really violent kicks to the teeth.)

1) Considering the earth's magnetic field appears to be reversing, as it does from time to time, and certainly the geomagnetic field is far weaker than it was even a couple of thousand years ago, is there even the slightest possibility magnetic fluctuations associated with the reversal are screwing with the results somewhere along the line?

2) Lacking the math to ask any question properly, i must resort to silly analogies. So. let's say Stan Laurel is a neutrino, and Oliver Hardy is a beam of light. Both depart Pittsburgh at the same time on the same train. But when they arrive, the "door" is too narrow for them to exit simultaneously (and, in fact, a little too narrow for Ollie alone). So Stan slips onto the arrival platform a teensy bit ahead and Ollie pops loose right behind him.

The question is (I think, having kind of lost track while youtubing old Laurel and Hardy routines): did the experiment somehow use an arrival aperture that allowed the neutrino to "enter" first, even though strictly speaking both neutrino and light arrived at exactly the same time? Except the neutrino slipped through the door ahead of the light, or at least rang the doorbell first?

Wow, words really don't work for this, do they? Now I wish I'd advanced beyond high school calculus, instead of going into music (well...OK, that's a lie. I don't. I mean, the parties were GREAT!)

c

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Anonymous Coward

1) ... magnetic fluctuations associated with the reversal ...

The measurements were made over a three years period, not at a single point, to the magnetic fluctuation would have to be the same for three years.

2) ... did the experiment somehow use an arrival aperture that allowed the neutrino to "enter" first...

The neutrinos where sent through rock so there was no race between a light beam and a neutrino beam.

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Anonymous Coward

Hi,

in regards to your questions:

1) Neutrinos do not have an electric charge and therefore they do not feel magnetic fields (or only feel it very weakly). The speed they fly at will limit effects in addition as they only feel the magnetic field for a very short amount of time. If there were such effects (possibly also affecting the hardware used instead of the neutrinos), the effects would be expected to be much much smaller than what we are currently seeing here and they would be

The key point, however, is that the theory of relativity says that you can not accelerate any massive object to the speed of light, because you would need an "inifinite amount of energy" to get it from just below the speed of light in vaccum to the speed of light in vacuum. The higher the speed is the more energy you will need to make it even quicker. So even if the magnetic field would be accelerating (and not decelerating) the neutrino, it would not be accelerating it infinitely, so couldn't account for the 60ns we're currently seeing.

2)The experiment does not measure the speed of light. In fact it can't, as most of the distance the neutrinos cover is through solid ground, light would be stopped dead by that. The speed of light in vacuum referred to here is a theoretical value which is used as a reference, not a measurement made on earth (as this would definitely not be measuring the speed of light n vacuum. ;))

It's more like the British Railway telling you, if you start in Pittsburgh you'll need at least 4h to get to London by train, yet you arrive after 3h. Seemingly impossible given the rules and regulations of the British Railway.

regards kathrin

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Anonymous Coward

re: "Seemingly impossible"

All railway companies/organisation outside of Japan have always played fast and loose with the concept of time...

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Happy

Ah, now I see...

Many thanks to you and the previous AC for cogent and genuinely useful answers - my insufficiently-informed curiosity is now assuaged, and what a relief THAT is :-)

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Bronze badge

The Earth Still Turns

According to Special Relativity, there is no such thing as simultaneous events at light speeds or if there were, you would not be able to prove it. Also, weird schtoff happens whenever you spin something on its axis and then try to deal with other things in relation to the spinning object while they move at near light-speed. We mere mortals nearly always get confused under such circumstances.

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Anonymous Coward

I've proven it by experimentation

This describes an experiment performed to identify how an object spinning at speeds approaching that of light can affect the measurement of other objects that are introduced into the system, and the sufficient comprehension thereof by the experimentor.

Firstly, we must identify inputs and assumptions.

Light Speed - c.

The only way I could effectively measure this is to find some light and then see how fast it travels.

The only light to hand was that inside a pocket torch.

I threw this across the room and measured it with a stop watch.

Time taken for the light to cross the room = 1.4s.

Distance thrown = 4 m.

My value for c = 2.85 m/s

The torch was broken in the experiment.

Given this value, I set out to examine a spinning object, and if I can accelerate to approaching light speed.

Through observation I identified that a spinning human will have rotational speed at the fingers approaching 2.8m/s, or c.

The experiment the proceeded to measuring something in relation to the spinning object.

This took the form of an extended tape measure and a balloon full of water passing through the air nearby (to give sufficient mass not to be affected by relativistic gravity effects).

The 2 things to be identified :-

* What strange effects are there in a spinning system approaching the speed of light.

* How confused could the experimentor become and still gather valid data.

-- Results --

The results were as expected, strange effects were observed, and the experimentor failed to fully understand the results as they were on going, requiring subsequent analysis and processing.

Firstly, the human experimentor (me) span up to the required speed holding the tape measure (extended). This gave the tip of the tape measure a measured rotational speed in _excess_ of light speed!

The balloon was then released and began its approach to the spinning object.

Unfortunately measuring the approach of the balloon was curtailed when it, inexplicably, exploded.

The experimentor is still perplexed by this. After cleaning up the water, it was identified that not all of the balloon was present. It appears that some has become converted directly to pure energy.

This will form the basis of a subsequent paper entitled "Cold Fusion from water balloons".

Given these results, I come the conclusion that strange things happen when spinning at light speed, and that I as a the performer of the experiment am unable to fully explain the results.

Dr Bo Gus (Ins. ANE)

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Joke

A better test for c

Measure the distance from a light-switch to the light it controls (important!)

Start the stopwatch when you flick the light-switch - and stop the stopwatch when the light comes on.

For further verification use a larger room.

Note, for the best results the room needs to be in a vacuum, or at least have a vacuum in it (I use a hoover).

If you don't have a large room then set up n mirrors, such that each mirror reflects the light to you in the longest path possible, in this instance you will need to measure the total light path, ie from mirror to mirror, not the distance to the light bulb.

Good luck.

NB: if you want to stop the balloon bursting then freeze the water (friction, even in a partial vacuum, at light speed will cause it to defrost) first.

NNB: If the balloon can't hold frozen water then try using a carrier bag.

ttfn

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Anonymous Coward

Title is misleading

I came in here to harp on about how good my favourite browser is. Very disappointed.

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Paris Hilton

Backwards in time

"One of the first things that got everybody excited when the OPERA results first hit the wires was that the possibly-superluminal neutrinos traveled “backwards in time”. By my admittedly-poor understanding of relativity, this was mostly a journalistic construct, since in a human time-frame, the neutrinos still arrived after they left."

Yes but they might have travelled in time for some part of that journey. We don't know whether or not neutrinos are Majorana particles, which would make them their own anti-particles, but we do not that neutrinos change flavour as they travel. If they became anti-particles travelling backwards in time for *part* of their journey, they could perhaps go faster than light.

This is by my admittedly-poor understanding of quantum mechanics :)

Paris, because we have to travel backwards in time to remember why there is a Paris icon.

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Bronze badge

Superluminality is poop science

And here I was hoping we could do away with causality. Causality hasn't been kind to me and I'd be chuffed to see it go.

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Gold badge

"This is by my admittedly-poor understanding of quantum mechanics :)"

Don't worry. If you are seriously considering particles changing from normal to tachyon and back then you've gone well beyond anyone else's understanding of quantum mechanics, too.

Doesn't mean it isn't true. Just means we've no theory with which to investigate the possibility further.

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Anonymous Coward

I just got

a message from the future saying it was all a fake.

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I will just be pulling your leg when I send that.

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Coffee/keyboard

Joke icon missing....

... despite being well-deserved!

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Anonymous Coward

Question for the author:

What is being done to design a more rigorous experiment? I imagine that there are attempts being made to replicate the results? Can you fill us in on those?

Would using a pair of atomic clocks be a better solution than GPS?

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Triangle vs Sector?

My first thoughts were that the 60ns difference equates to about 18m distance, have they accidently used the curved-surface distance between the two points that the GPS systems would give instead of the straight-line distance of a chord through the earth's surface. The distance descrepacy would be about the same magnitude.

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Bronze badge

r.theta - 2.r.sin(1/2.theta) = 18m possibly?

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Anonymous Coward

Nope... Using rough figures, if radius of the world is 6371000 metres and the arc length is around 733 metres (google maps based rough estimate), then the difference is on the order of around 35cm.

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Boffin

Yup... And travelling at c(vacuum) for 733 meters takes about 2.445 microseconds:

(733 metres) / (0.299792458 metres per nanosecond) = 2.44502482 microseconds

... A much larger interval than 60ns.

And even if c for the experiment's reference frame was somewhat slower, because the neutrinos were travelling through the Earth's interior (including the atmosphere) for part of the trip (and not a true vacuum), the time to traverse those extra 733 metres would still probably be a lot larger than 60ns.

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Facepalm

Quantum Effect on Neutrinos?

For preamble, I once measured the speed of light to 4 significant digits. This was a royal pain in the arse as the undergrad lab setup was only good for 2 significant digits at best. I spent most of my report write up trying to explain away my accidental accuracy. Had I not done so, I would have been penalized for making ridiculous claims.

Relevancy? It highlights that looking in from the outside I am not going to come up with an explanation for experimental error down in the 5th or 6th digit. More knowledgeable and informed people will need to do that.

Now, my theory...

1. There is some evidence of neutrino mass although the result has an imaginary component (in the mathematical sense).

2. The speed of light is restricted to massless objects.

3. Relativity allows for tachyons but 'c' is a lower speed limit and higher speeds are actually associated with lower energies. (As E->0, v->infinity)

4. Neutrinos appear to oscillate between flavours (electron, muon or tau).

5. Energy must (probably) be conserved.

Hypothesis: At least one flavour of neutrino travels faster than the speed of light. Neutrinos oscillate in a quantum manner between between these flavours at a rate wherein the average speed over any significant time period is equal to 'c'.

The Opera observations are measuring a slight variance from 'c' because the location is close (in a scientific sense) to the source and the causative particle collisions preferentially create 'fast' neutrinos. Distance has been insufficient to average out the travel times to 'c' as has been observed in distant super-nova neutrino experiments.

Every good theory requires testable conditions so...

Neutrino observations will depend on separation, energy levels and particle collision type. Thus,

a) If there are accelerator and neutrino detection systems with different physical separations, the resultant neutrino speed delta should be non-linear with distance. (Closer = faster neutrinos but harder to measure.)

b) Paradoxically (or perhaps not so much), lower energy neutrinos (from lower energy collisions?) could produce a greater delta.

c) Collision experiments that preferentially produce different neutrino flavours should result in a different delta - including a strong possibility of sub-luminal neutrinos (which should be equally 'Gasp!' inducing.)

Hopefully at some point in the future, I can show my grandkids this post on a waybackmachine in some university basement and tell them, 'If I had stuck with my maths there could have been a Nobel in it for me...'

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Alert

I was wondering

I'll preface this with the fact that my knowledge of quantum physics and relativity are both rather shaky, but I did have this thought:

Given the references to the Supernova, in which case the Neutrinos travelled 160k or so light years and arrived 3 hours before the light itself; and comparing with the OPERA experiment where the difference was relatively bigger (scaled up to 160k light years, the OPERA result would have meant the Neutrinos arriving about 4 years ahead of the light); I have to wonder if matter plays a part.

Hypothesis: Neutrinos are able to travel slightly faster than c through matter (whether by quantum tunnelling or some other method).

This would mean that the Neutrinos in OPERA would travel slightly faster than C for a significant part of their journey, whereas those from the supernova would travel faster than C for a very small part of their journey (as there's not a lot of matter in space - but there is a little space dust and the like). So then the effect would be more pronounced in OPERA than it was with the supernova - as observed.

I've put a post on my blog about it that lays it out perhaps a little more clearly (http://thoughtsonmorality.blogspot.com/2011/10/those-neutrinos.html)

Anyone know if this is possible, or measurable?

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Boffin

It all averages out

The hypothesis assumes that all satellites are approaching the observation locations.

In fact the satellites spend half their time departing the observation locations.

The satellite reference frames shift from X+ metres per second to X- metres per second - after allowing for the orbital separation etc etc.

Using the quaint relativistic terms (I prefer Doppler myself) The average reference frame velocity is zero. Even if the satellite is offset to track not over the sites but to one side or the other.

Hence, nil effect.

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