Neutrinos faster than light?
Published: 11 October 2011 (GMT+10)
Flickr: CERN Control Center
Will relativity need revising?
Headlines were buzzing with reports that neutrinos have been clocked travelling faster than light, and even more with claims like “Einstein’s theory busted by new discovery”.1 But did neutrinos really break the light speed barrier, and are there implications for creation models?
Researchers at CERN (Switzerland) generated neutrinos (see box), ghostly neutral particles, and shot them through the earth to the Gran Sasso National Laboratory (LNGS) in Italy, travelling a straight line distance of 732 km. This was the CERN neutrinos to Gran Sasso (CNGS) experiment; also called Oscillation Project with Emulsion-tRacking Apparatus (OPERA). Its aim was to observe neutrino “oscillations” between the three varieties or ‘flavours’ (see box). In particular, this experiment generated the type called ‘muon-neutrinos’, and the experimenters hoped to observe them changing into ‘tau-neutrinos’.2
But what they observed was unexpected: the neutrinos apparently arrived at the detectors 60 nanoseconds faster than light,3,4 which implied that they travelled 0.0025% faster than light, or one part in 40,000.5 This is not supposed to be possible under Einsteinian relativity. Brian Cox, the TV presenter and physicist we responded to in Doom and gloom from the BBC, said:
“If it is confirmed it will be the most important discovery in physics in at least the past 100 years. It is a very big deal, it requires a complete rewriting of our understanding of the universe … it is such an extraordinary claim that it is difficult to believe.”6
This seems like too small a difference, but it was larger than their experimental uncertainties. The researchers seemed to be very careful with their analysis. One Ph.D. physicist in Australia, John Costella, had thought their statistical analysis was wrong, but then retracted and commended the statistical analysis.7
But Costella urged some caution:
“the OPERA result—if its estimates for systematic errors withstand scrutiny, and if it is subsequently confirmed in future experiments—would arguably be the most important discovery in physics in almost a century.” [Emphasis added]
The CNGS researchers themselves were likewise commendably cautious:
“Despite the large significance of the measurement reported here and the stability of the analysis, the potential great impact of the results motivates the continuation of our studies in order to investigate possible still unknown systematic effects that could explain the observed anomaly. We deliberately do not attempt any theoretical or phenomenological interpretation of the results.”
We see here an example of what the physicist and philosopher of science Thomas Kuhn discussed in his famous book The Structure of Scientific Revolutions: that normal science is usually conducted within a framework of assumptions or a paradigm. In this case, the paradigm is Einsteinian Special and General Theories of Relativity.
Real scientists don’t tend towards a naïve falsificationism as proposed by Popper, and immediately jettison a theory because of one anomalous result. This is actually a healthy dogmatism: while no theory of science is infallible, by the same token, no single experiment is either. One report cited several skeptical scientists:
“ ‘That’s possible, but it’s far more likely that there is an error in the data. If the CERN experiment proves to be correct and neutrinos have broken the speed of light, I will eat my boxer shorts on live TV,’ Prof Jim Al-Khalili, professor of Physics at Surrey University said according to The Telegraph.
It’s the usual story: extraordinary claims require extraordinary evidence. The theories of relativity have passed all experimental tests and predicted very important results, so it would be unreasonable to abandon it on the say-so of one experiment.
Furthermore, previous measurements of neutrino speed suggest that neutrinos travel very close to the speed of light. For example, when supernova SN 1987A was observed, the neutrino speed was observed to agree to one part in 450 million.9 Even the small difference was attributed to matter impeding light while the ghostly neutrinos barely interacted with the matter. If the neutrinos had really been travelling as fast as the experiment showed, under the usual assumption that a light year of distance requires a year of travel (which is known to be questionable10), they would have arrived over four years earlier.11 However, the CNGS experiment generated neutrinos with about a thousand times the energy of the supernova neutrinos.12 Why only those neutrinos above a certain energy should be faster-than-light is a puzzle. But some theorists have invoked a hypothetical neutrino condensate that would enable certain neutrinos to have an effective velocity above c.13 Then again, other theorists have argued against superluminal neutrinos, according to an article published after most of this article was written:
In a terse, peremptory-sounding paper posted online on September 29, Andrew Cohen and Sheldon Glashow of Boston University calculate that any neutrinos traveling faster than light would radiate energy away, leaving a wake of slower particles analogous to the sonic boom of a supersonic fighter jet. Their findings cast doubt on the veracity of measurements recently announced at CERN that clocked neutrinos going a sliver faster than light.23
Would it disprove relativity?
As shown above, the jury is still out on the experiment. However, let’s assume that the experiment is confirmed and shown to be a real occurrence. What would it mean? Well, not as much as many people think. Actually, relativity prohibits particles from accelerating past the light barrier, because the energy required would be infinite. But there are theories of faster-than-light particles called tachyons (from Greek: ταχύς tachys = fast), that would be created in their faster-than-light state. Thus they are immune from this objection. Furthermore, it is impossible for tachyons to cross the light barrier from the other side, so that part of relativity is safe: this barrier stands. The objection to tachyons is rather that they would travel backwards in time, so they would possibly allow signals to be sent to the past. This would violate the principle of causality. But then, as Dr Costella explained in another paper, antiparticles are well known, and one formulation is that they are ordinary particles travelling back in time.14 Other theorists have proposed an explanation that doesn’t violate causality.15
Flickr: Adam Nieman.
Globe of Science and Innovation at CERN.
But more mundanely, let’s remember what happened with Newton’s laws when they met relativity and quantum mechanics. They remain extremely useful for most purposes, so are still heavily invoked. But at high speeds and high gravity, we must use relativistic equations instead, and for very low masses, quantum mechanics is required. Further, the equations of relativity must collapse to correspond with Newtonian ones at ordinary speeds—after all, they clearly work very well. Similarly, quantum mechanical equations must likewise approach those of classical physics at ordinary masses (many times that of atoms).
Similarly, it is most likely that relativity equations will still prove useful, even if we must refine them where neutrinos are concerned, maybe due to some yet-to-be discovered physics. Similarly, the previous refinement of relativity by Moshe Carmeli for galactic distances16 leaves most applications at normal distance scales untouched.
Application for creationists?
There are a few things to learn from this. One of them does NOT seem to be a solution to the distant starlight problem: the tiny difference for high-energy neutrinos does not really help; fortunately there are other ideas.10 However, when some 1970s creationist scientists proposed that light travelled much faster than today, they were attacked for their alleged ignorance that nothing could go faster than light at its current speed.17 Now plenty of scientists have no problem in theory with tachyons, and some have proposed that light was much faster in the past to rescue the big bang from its horizon problem.18
A more important one is the grip of the paradigm: creationist arguments are often ruled out of court because they contradict the ruling paradigm of evolutionary materialism. But a major difference is that scientists are free to criticize relativity, and healthy debate is regarded as healthy even by those scientists who disagree with the CNGS paper. Conversely, dissenters against evolution are routinely fired or have their grades reduced. This was documented in the movie Expelled, and in Dr Jerry Bergman’s book Slaughter of the Dissidents.
One reason for the difference is that evolution is a belief system about origins, about history, which is not open to experimental testing, whereas the speed of neutrinos is open to experimental testing.
However, the major reason for the difference is that relativity makes no ethical demands of its followers, but if creation is true, that might imply that we are accountable to our Creator! This is what prominent evolutionists don’t want. Philosopher Thomas Nagel is more candid than most:
“I want atheism to be true and am made uneasy by the fact that some of the most intelligent and well informed people I know are religious believers. It isn’t just that I don’t believe in God and naturally, hope there is no God! I don’t want there to be a God; I don’t want the universe to be like that.”19
In conclusion, this result is fascinating science, but little to do with creationist science per se, except to illustrate how scientists really work, regardless of arcane definitions of science.
What are neutrinos?
Wolfgang Pauli first proposed this particle in 1930, to explain why beta decay seemed to violate physical laws. That is, when a neutron decayed into a proton and electron (beta particle), the decay seemed to violate the laws of conservation of momentum, angular momentum and energy. To solve this problem, Pauli proposed a tiny neutral particle that Enrico Fermi later named the “neutrino”, and this carried off the observed differences in these quantities. The neutrino has the symbol ν, the Greek letter nu.
However, these neutrinos proved most elusive. Because they interact only via the short-range ‘weak nuclear force’, ordinary matter is almost transparent to them. It wasn’t until 1956 that a neutrino was detected by a similar reaction in reverse: a neutrino (extremely rarely) reacting with a proton, producing a neutron and a positron. And it was another four decades before this work was rewarded with the 1995 Nobel Prize for Physics.
Actually, later standard models of particle physics say that the above particles were anti-neutrinos, because of the Law of Conservation of Lepton number, a lepton meaning a small particle.20 Both electrons and neutrinos have lepton number +1, while antimatter equivalents positron (anti-electron) and anti-neutrino have a lepton number of –1. So when an electron is generated (+1), as in beta decay and nuclear fission, an antineutrino must be produced (–1); while positive beta decay and nuclear fusion produce positrons (–1), so also emit neutrinos (+1), so that the overall lepton number (0) is unchanged. Or in the detection reaction, an anti-neutrino (–1) plus proton makes a neutron plus positron (–1).
Then other leptons besides electrons were discovered: the mu particle (muon μ) and tau particle (tauon τ)—heavier and very unstable versions of the electron. It turned out that they had their own antineutrino counterparts as well.
For a long time, standard models of particle physics argued that the neutrinos had precisely zero rest mass, so should travel at precisely the speed of light, c. This raised a problem for theories of the sun’s energy output: if nuclear fusion were the only source of power, then it was producing only a third of the number of neutrinos— the ‘Solar Neutrino Problem’. But it seemed to be solved by evidence that neutrinos can ‘oscillate’ between the three ‘flavours’: electron-neutrino, muon-neutrino and tau-neutrino.21 But this required that neutrinos have some mass, contrary to standard models. The most recent estimates of the combined mass of the three varieties is less than 0.28 eV (electron volts).22 To put this into perspective, an electron is two million times heavier with 0.511 MeV, while a proton is 1836 times more massive than an electron at 938 MeV
The OPERA experiment was actually designed to observe neutrino oscillation, as the name suggests. It generated beams of muon-neutrinos that were sent through the earth, and hoping that some would change into tau-neutrinos, which would then interact with a neutron and produce a proton plus tauon. This tauon would give a distinctive signal.
- Particles seen to travel faster than light, www.news.com.au, 23 September 2011. Return to text.
- CNGS – CERN neutrinos to Gran Sasso: On the track of particle ‘chameleons’, public.web.cern.ch, 2008. Return to text.
- Adam, T. et al., Measurement of the neutrino velocity with the OPERA detector in the CNGS beam, static.arxiv.org/pdf/1109.4897.pdf, accessed 29 September 2011. Return to text.
- A useful account comes from a NASA engineer, Laughlin B., Neutrinos and the Speed of Light — A Primer on the CERN Study, wired.com, 26 September 2011. Return to text.
- The time difference was (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns, implying that the fractional difference between neutrino speed and light speed (v − c)/c = (2.48 ± 0.28 (stat.) ± 0.30 (sys.))×10−5 or 0.00248%. Return to text.
- Nair, D., Particles Faster-Than-Light: Most Embarrassing Claim of Modern Science Ever? ibtimes.com, 24 September 2011. Return to text.
- Costella, J.P., Why OPERA’s claim for faster-than-light neutrinos is not wrong, johncostella.wordpress.com/, 25 September 2011. Return to text.
- Nair, op. cit. Return to text.
- Adam et al., op. cit. provide the following references: Hirata, K. et al., Phys. Rev. Lett. 58:1490, 1987; Bionta, R.M. et al., Phys. Rev. Lett. 58:1494, 1987; Longo, M.J., Phys. Rev. D 36:3276, 1987. Return to text.
- Big bang advocates know full well that it is not, since they have their own Horizon Problem. See Creation Answers Book ch. 5: How can we see distant stars in a young universe? Return to text.
- SN 1987A is 168,000 light years away; 168,000 × 2.48×10−5= 4.2 years. Return to text.
- 17 GeV vs. 10 MeV. Return to text.
- Mann, R.B. and Sarkar, U., Superluminal neutrinos at the OPERA? arxiv.org/PS_cache/arxiv/pdf/1109/1109.5749v1.pdf, 27 September 2011: “It is natural to ask why neutrinos are different from other particles. One reason emerges from the observation that if neutrinos form condensates to explain the cosmological constant [ref.], background neutrino condensate dark energy can, in principle, affect the dynamics of the neutrinos compared to other particles. For example, a νµ with momentum p can collide with a condensate [anti-]νµ−νµ pair and bind with the [anti-]νµ. The liberated νµ, located at a distance x away from its condensate partner, will continue with momentum p due to momentum conservation. As this process is repeated, the net effect is that the νµ “hops” through the condensate at an effective speed greater than unity, resulting in a different maximum attainable velocity for the neutrinos. Since no other particles couple to the νµ, they do not experience this effect.” Return to text.
- Costella, J.P., Do OPERA’s tachyonic neutrinos make sense? johncostella.wordpress.com/, 27 September 2011. Return to text.
- Mann and Sarkar, op. cit.: We argue that the recent measurement of the neutrino velocity to be higher than the velocity of light could be due to violation of Lorentz invariance by the muon neutrinos. This result need not undermine special-relativistic foundational notions of causality. Return to text.
- Hartnett, J., A 5D spherically symmetric expanding universe is young, J. Creation 21(1):69–74, 2007; Has ‘dark matter’ really been proven? Clarifying the clamour of claims from colliding clusters, 8 September 2006. Return to text.
- There are problems, but this is not one of them. See for example Wieland, C., Speed of light slowing down after all? Famous physicist makes headlines, J. Creation 16(3):7–10, 2002; creation.com/cdk. Return to text.
- Albrecht, A. and Magueijo, J., Time varying speed of light as a solution to cosmological puzzles, Physical Review D (Particles, Fields, Gravitation, and Cosmology) 59(4):043516-1–043516-13, 1999; Magueijo, J., Faster Than The Speed of Light: The Story of a Scientific Speculation. Basic Books, 2003. They propose that light was 60 orders of magnitude faster in the very early stages of the big bang. Return to text.
- Nagel, T., The Last Word, Oxford University Press, New York, 1997, p. 130. Return to text.
- The word originally referred to a small coin. The ‘widow’s mite’ mentioned in Mark 12:42 would have been a lepton. See Cardno, S. and Wieland, C., Clouds, coins and creation: An airport encounter with professional scientist and creationist Dr Edmond Holroyd, Creation 20(1):22–23, 1997; creation.com/holroyd. Return to text.
- Lisle, J., ‘Missing’ neutrinos found! No longer an ‘age’ indicator, J. Creation 16(3):123–125, 2002; creation.com/neutrinos. Return to text.
- “Neutrinos are likely half as massive as previous estimates suggested”, sciencedaily.com, 12 July 2010. Return to text.
- Castelvecchi, D., Superluminal Neutrinos Would Wimp Out En Route, blogs.scientificamerican.com, 2 October 2011. Return to text.
Looks like it was a loose cable! Talk about jumping to conclusions!
Jonathan Sarfati: If true, then it would reinforce what I said in the article, that no single experiment is infallible! However, it does seem to cancel out the previous explanations above.
Thanks for this very balanced, thoughtful and well explained article, Jonathan. I have been mulling over this new discovery myself and wondering what the significance of it really is in the great scheme of things, and your explanation has really helped me.
Many thanks once again.
An article on the arxiv.org site thinks they have solved the faster than light problem by using relativity. Relativistic effects only made it seem to travel faster. See Faster-than-Light Neutrino Puzzle Claimed Solved by Special Relativity.
Jonathan Sarfati: Thanks for this. I suspect that there will be many papers on this for some time yet.
Jonathan Sarfati: Ditto: this refers to the research in the above article.
Thank you for great article. Though I do wonder would there be a real world application?
Jonathan Sarfati: Not sure yet, but many discoveries in pure science later on proved to have real-world applications that were not dreamed of at the time. For example, there was almost half a century before Einstein’s paper on stimulated emission had practical application in lasers (the word was an acronym for Light Amplification by Stimulated Emission of Radiation). See this section of “Should creationists accept quantum mechanics?”