“We don’t allow FTL neutrinos here”, said the barman. A neutrino walks into a bar.
Oh, galleons, you had to know this post was coming.
The science world is all aflutter over the latest news released from CERN- it seems that one of their experiments has recorded neutrinos traveling at faster than light (FTL) speeds.
And, while the media is really running with this (kind of surprising, considering their typical reluctance to really highlight the latest tidbits from the world of science), I’m concerned that people are getting the wrong idea about just what CERN shared. Hell, I read an article that interchanged CERN and the LHC, despite the fact that the LHC is not responsible for the neutrino findings.
Let’s get the facts, galleons.
We’ve already discussed the basics of neutrinos in a previous post, so I’m not going to rehash that here. Suffice to say that neutrinos are nearly massless, don’t interact much with anything (making them hard to detect), and have no electrical charge. They come about as a result of radioactive decay and nuclear reactions.
And they has flavors.
Lightspeed, on the other hand, is a topic we haven’t covered. And while I don’t plan to go into too much depth on it, it’s worth mentioning the basics again as a refresher for everyone. The speed of light (299,792,458 m/s) is a constant, one of the most important constants in physics. This constant shapes the theory of relativity, and it is the limit for how fast matter or energy can travel. In fact, much of modern physics rests on the idea that nothing can exceed this limit.
And it’s been tested time and time again, with no experiment ever producing a particle that broke the speed limit.
But then OPERA came along…
OPERA (Oscillation Project with Emulsion-tRacking Apparatus) is a CERN experiment that is out to study tau and muon neutrinos. They work in conjunction with the Laboratori Nazionali del Gran Sasso (an Italian particle physics laboratory), which you may remember from that previous neutrino post as the laboratory that observed the first flavor-changing neutrino event. OPERA uses a high-energy beam (For the record, how often do you hear about particle physics using a low-energy beam? At this point, I feel specifying this is pretty much unnecessary) of muon neutrinos produced at CERN and pointed at the Gran Sasso laboratory. Their purpose is to study neutrino oscillations (those same flavor-changing instances mentioned previously).
A mere two days ago, OPERA researchers dropped a fucking bomb on the physics community- some of their neutrinos appear to be exceeding the speed of light.
And that’s why everyone is flipping the fuck out.
I waited to post this until after CERN had released an official statement, the publication of the actual research, and a live webcast Friday morning regarding the details of the experiment. When it comes to something this monumental, I wanted to get the information directly from the source.
Here’s the gist:
In addition to working on the neutrino oscillation situation, the detectors at CERN and Gran Sasso are ideal for measuring neutrino velocity with an incredible degree of accuracy, what with the super-upgraded timing systems in place (their synchronization between the two facilities gives them nanosecond accuracy) and the geodesy campaign that allowed measurement of the distance between the two facilities to a precision of a mere 20 cm (CERN and Gran Sasso are about 730 km apart… the irony of using an approximate distance here when discussing precision measurements is not lost on me, so, if you must know, the actual distance is 730.53461 km).
Light travels this distance in 2.4 milliseconds. Using recorded data from the last three years (2009-2011), the OPERA research shows neutrinos arriving at the Gran Sasso laboratory sixty billionths of a second earlier (with an error margin of plus or minus ten billionths of a second). And this isn’t just an event that occurred once or twice- it’s a consistent finding.
“This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.”
And that last bit is the most important part of all, dear galleons. I frequently geek out about possible bits of science awesome, but, as I’m sure you are all aware and probably sick of, I end nearly every science post with a comment on how, while the discovery might be incredibly interesting and potentially revolutionary in its field, it will first have to pass rigorous further experimentation. While I’m not impugning the methods of the initial experiment, mistakes can be made. Details can be overlooked. And, quite often, they are. It takes a hell of a lot for a proposed idea to become an accepted scientific theory, and the publication of one study is just the tiniest baby step down a long, long road.
This concept is one that gets glossed over frequently when the media reports on scientific stories. They’ll throw in the perfunctory comments about how further experimentation is needed, but all the language in the piece will be sculpted to sensationalize the result. “OMG, the world as we knows it is threatened!!!1!”
And while, if eventually proven accurate, these findings do have the potential to reshape the rules physicists have been operating by for all these years, we still have to be incredibly hesitant about embracing these findings as a reality. Hell, even the researchers themselves are being super cautious. The final paragraph of their paper reads:
Despite the large significance of the measurement reported here and the stability of the analysis, the potentially great impact of the result 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.
But if that doesn’t tell you these are some prudent physicists, take this into account: The researchers are not technically claiming a discovery, even though they are actually within their rights to.
Physicists can claim a discovery if the chances of their result being a fluke of statistics are greater than five standard deviations, or less than one in a few million. The Gran Sasso team’s result is six standard deviations.
The results of such a discovery are too radical for them to feel comfortable doing so. Instead, they have published their findings in order to open them up to intense scrutiny from the rest of the scientific community.
The idea of the speed of light being the matter/energy speed limit is not one scientists are terribly willing to just chuck aside. As Jim Al-Khalili, a physicist from the University of Surrey, rather hilariously put it:
…let me put my money where my mouth is: 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.
A huge problem with this result is the fact that it completely contradicts a previous neutrino speed limit found when radiation from a supernova explosion reached Earth in February 1987. Most energy streaming forth from supernovas are neutrinos. Now, remember that neutrinos (like me) are surly little devils and rarely interact with other matter. This means that they can escape an exploding star almost immediately, while photons of light (which are more social than neutrinos) can take about three hours to get out. In 1987, trillions of neutrinos arrived just three hours before a star visibly went supernova (so, three hours before the photons arrived).
If neutrinos can travel faster than light, and do so with the consistency mentioned in the OPERA findings… why didn’t a bunch of neutrinos show up even earlier?
“If neutrinos were that much faster than light, they would have arrived [from the supernova] five years sooner¹, which is crazy,” says Marc Sher of the College of William and Mary. “They didn’t. The supernova contradicts this [new finding] by huge factors.”
While all it takes is one verified experiment to send any theory toppling over (thus why they are theories), years and years of experimentation upholding a theory is hard to ignore. So, treating our known speed limit as ‘innocent until proven guilty’ via further study and experimentation, many scientists have already begun to speculate on just how the OPERA findings could come about.
First (and most likely), it could simply be a measurement error. For example, while we can pinpoint when the neutrinos arrived in Gran Sasso with great accuracy, their departure time is a bit fuzzier. This is because the neutrinos are generated by slamming a proton beam into a bar-shaped target, which sparks a subatomic cascade. If neutrinos were produced at one end of this bar instead of the other, it could obscure their time of flight.
Alan Kostelecky, an expert in the possibility of faster-than-light processes at Indiana University, actually put forward a theory in 1985 predicting that neutrinos could travel faster than the speed of light by interacting with an unknown field that lurks in the vacuum.
Which, to me, sounds a little Higgs-y.
The most popular non-error based solution to this is that the neutrinos tunneled through other dimensions, which reduced the distance they had to travel to reach the target. Or maybe, just maybe, there was something even crazier going on. Maybe those neutrinos tunneled into another dimension where special relativity no longer applied.
Now, I’m a big fan of the string theory (as you know), but string theory is far from the only theory currently floating about that incorporates a myriad of dimensions beyond our standard four. While string theory posits that the universe is built of vibrating, one-dimensional strings… there’s also M-theory, which extends that idea to vibrating, multidimensional forms. While a 1-brane is a string (the 1 indicating its dimensions), a 2-brane would be a membrane.
And expanding further on these brane-y concepts, we have the idea that the universe itself is a brane. A big ol’ four-dimensional brane, floating about in higher-dimensional space-time (“bulk”). For ease of imagining, say our universe is a two-dimensional brane, all pancake-y, floating about. Point A is on one end of the pancake, with point B on the other. In order to travel from point A to point B, you have to travel the entire length of the pancake universe. Now, fold that pancake back over onto itself, so that you have a shape resembling a hard taco shell. If you were to leave point A, tunnel out into the “bulk” between the sides of the taco shell, then tunnel back in at point B… well hell, you just saved yourself a hell of a lot of traveling, now didn’t you?
There are scientists who spend their time theorizing about these short-cuts, primarily because such a short-cut would lead to time traveling. And, deep in their hearts, all scientists are just sci-fi nerds- they want phasers and teleportation and time travel just like the rest of us do. Now, the above scenario actually isn’t possible in our universe, and not just because our universe is not a two-dimensional pancake, but would instead be a four-dimensional brane. No, it’s not possible because a folded universe flies in the face of Einstein’s special relativity, which relies on perfectly flat space with Euclidean geometry.
But, a group of physicists named Päs, Pakvasa, and Weiler came up with the idea that, while our universe is a flat, four-dimensional brane, it’s floating around in some severely warped “bulk.” Special relativity would still apply in our flat brane, but the larger dimensions could be so distorted that special relativity would no longer apply. Which means that anything traveling through the higher dimensions could break one of the principles of special relativity: it could travel faster than the speed of light.
On the subject of neutrino-dimensional travel, Ethan Dicks, former researcher and associate on IceCube (a neutrino observatory), had the following to say:
Not having seen their evidence yet, I would initially wonder if the neutrinos didn’t take some “shortcut” during the muon-tau oscillation. After all, the important phrase is nothing can go faster than light *in its medium*. If the neutrinos are doing something unfathomably bizarre, perhaps the speed of light still holds, but we don’t understand the medium or the path the neutrinos took.
Or maybe the neutrinos were just sick of Switzerland.
These are just a few ideas bouncing around just two days after the OPERA findings were announced. It’s going to be a field day for scientists as they work both toward replicating/proving/disproving the data and finding explanations to account for the findings if they are indeed accurate.