Wednesday, October 5, 2011

Space Week 2011 #2: "Hmm... That's Funny..." or "Dem Wacky Neutrinos"

Greetings, everyone.

Before jumping in to today's topic I'd like to point out that yesterday (Oct. 5th) was the birthday of one of my favorite living scientists and public intellectuals, Neil de Grasse Tyson. For those of you who don't know about him, he is currently the director of the Rose Center for Earth and Space at the American Museum of Natural History in New York City. He has held that position for several years, and over that time he has been one of the leading promoters of astronomy and planetary science to the general public as well as a likeable and articulate advocate for skepticism, critical thinking, and the scientific method. A couple of years ago I wrote that Tyson has in the estimation of many, myself included, come to occupy the place in our culture once filled by the late Carl Sagan, so it was fitting that earlier this year PBS announced that he is being tapped to host an updated version of Sagan's epic Cosmos series from 1980. I can't wait to see it.. Also, just so you know, both he and I would agree that the fact that his birthday happens to fall during Space Week is a simple coincidence. Uncanny certainly, but nothing more.

To start off today's discussion, I will refer to another person I greatly admire, Isaac Asimov. One of the towering science fiction writers of the 20th century, he also wrote a great deal of non-fiction (about 75% of everything he wrote, actually), and while I can't remember in what essay or article I read it, a quote of his seems very applicable to the recent news about neutrinos: "The most exciting phrase to hear in science, the only one that heralds new discoveries, is not 'Eureka!', but rather, 'Hmm... that’s funny...'."

While particle physics does not usually make headlines, a couple of weeks ago some jaw-dropping results from an experiment conducted by the Center for European Nuclear Research (CERN, the acronym for the laboratory's name in French) were made public and set the media on fire. Situated on the border between France and Switzerland, CERN had been sending a stream of neutrinos to an underground detector several hundred miles away in Italy. It was a pretty routine experiment to see how often one type of neutrino changed into another, but the folks in Italy noticed that the neutrinos were arriving just slightly a bit sooner than they should have been. Now neutrinos are thought to have no mass, and so like other massless particles (photons, principally) they travel at the speed of light. Thus their early arrival at the Italian detector, even if only by a few billionths of a second, appears to indicate that these neutrinos were traveling faster than light. Let that sink in for a minute. For more than a century one of the cornerstones of physics has been that nothing, yeah you heard that, nothing travels faster than light. The speed of light has been measured countless times, with ever growing degrees of precision and accuracy, and countless experiments have been conducted which without exception have confirmed this absolute speed limit. So if the CERN findings are confirmed it means we need to seriously rethink the two main theories that underpin our understanding of the Universe: Einstein's Relativity (both Special and General) and the Standard Model, which is the basis for quantum physics.

Lost in much of the ballyhoo that attended the CERN announcement was the fact that the potentially trailblazing results were not even related to what the original experiment was studying. So somewhere some scientist saying "Hmm...that's funny..." (or its French equivalent) is what started all of this. Now interestingly enough, it appears that this was not the first time neutrinos were observed breaking the light barrier. A few years ago a similar experiment that was conducted by Fermilab in Illinois produced the same eyebrow raising data when the neutrinos reached the detector at the Soudan Underground Mine facility in northern Minnesota (I've been there, it is a cool place, especially if you are a Battlestar Galactica fan). However those results were within the boundaries of experimental error, and so did not generate nearly as much publicity. But in the wake of the CERN announcement they are being revisited and laboratories around the world are racing to replicate the results. At the moment, the jury is still out on whether we will have to incorporate a new factor into the equations that describe reality, and it may be that some other team will find something that explains the discrepancy, but that is how science works. The CERN scientists combed over their results for six months, trying their best to account for anything that may have introduced an error or affected their calculations, and only after their searches turned up nothing did they reveal the findings to the rest of the scientific community. While nothing is sacred in science, you want to be pretty damn sure your observations are spot on when they could challenge a theory as rock-solid as Relativity, and if those observations can't be replicated then they will go down as a (for now) unexplained fluke and the theory will continue to be the standard.

Even though it has only been a couple of weeks since the announcement, many possible explanations for our supraluminal neutrinos have already been proposed. Some involve extra dimensions they take a shortcut through, others more prosaic things like flaws in equipment calibration, but all are highly technical so I'll spare the details. How will this all play out? I have no idea, but in order to truly make one's peace with the Universe you have to get comfortable with uncertainty, and not just in the narrow Heisenbergian sense. These are the sorts of situations that get science buffs like me extremely excited, because this is when science is at its best. For in science the news that something we thought was true might be wrong, even in only the most tiny of ways, is cause for exhilaration, not dread, and I can only imagine how the scientists actually working on the CERN results are feeling. We live in interesting times, folks, and have once again been reminded that the three most revolutionary words in the English language, or most any other for that matter, are "Hmm...that's funny..."  

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