Dr. Alvaro de Rujula, a preeminent theoretical physicist, spent time last week talking via Skype to George Benedetti's science class at Foran High School about a recent experiment that might have overturned one of Einstein's theories.
Scientists at the world's largest atomic particle smasher, the European Center for Nuclear Research (CERN) had some evidence that a tiny sub-atomic particle, the neutrino, traveled faster than the speed of light. Neutrinos are one of the fundamental particles that make up the universe; they are similar to the more familiar electron, but they do not carry an electric charge. Science's current understanding is that nothing can go faster than the speed of light. If neutrinos could beat this limit, it would certainly be news that would shake the scientific world, local scientists explained.
Benedetti's physics class had been following the news of the CERN experiments in the New York Times, and Benedetti, a career engineer-turned-teacher, was duly impressed: this could be big news. But, like all scientists, he was skeptical about the initial findings.
Benedetti explained, “The scientists fired many batches of neutrinos from CERN in Switzerland, right through the Alps mountains and two thirds of the way down the length of Italy to a detector — a distance of about 450 miles. Neutrinos are so tiny and non-interacting that they can pass through almost anything. They measured a velocity that exceeded the speed of light by 60 billionths of a second.”
In his 1905 theory of relativity, Einstein proposed that nothing could go faster than light. Since then, his theory has been tested many, many times and always found to be correct. It is now a foundation of modern science. If it was wrong it would be truly revolutionary.
“In science,” Benedetti continued, “big results require big proofs. The CERN scientists weren't ready to believe their own results, so they repeated the experiment. Same results. At this point, they announced their extraordinary measurement so that other scientists could check them. This was when I heard of the results and discussed how exciting it might be with my class. I thought it would be a great lesson to them in how science works. Every claim, even if put forth by some of the world's greatest scientists, even if it comes from extensive and intricate experimentation, must be put out there to be checked and cross checked by all the other experts in the world.”
Within weeks, on Feb. 23, another New York Times article appeared. The CERN scientists had found that, within the hundreds, if not thousands, of pieces of experimental equipment and wires, one connector was loose and that had introduced the 60 billionth of a second error. A competing group had independently measured the neutrinos' flight time and had found that it was exactly the speed of light. Einstein's theory held.
“It was a great lesson in the way scientific truth-seeking is self correcting,” Benedetti said. “The kids really grabbed on to this. The idea that scientists could be wrong, that scientists ask for help, that competition and criticism can be friendly and can lead to the truth — all of that was invaluable in teaching the kids what doing science really entailed and how important it is to apply the same skeptical attitude in all the other areas of their life.”
Benedetti got the idea of getting his kids directly in touch with the real scientists, and Skyped CERN. Last Tuesday, a good natured Dr. de Rujula chatted with Foran students about the errors that compromised the results: a cable problem and an American-made clock, and he explained to them that mistakes happen, and that's why scientists test and retest their findings.
Dr. de Rujula said that since Einstein's theory had been so well tested and because this ”was far too much to believe,” his group should have been more careful with the experiment.
But, “It's a normal thing to make errors,” he told the students, “provided one is able to recognize them.”
Getting these astonishing results and then being able to announce them was sort of “like having your cake and eating it too,” Dr. de Rujula said. “This cake was too big to be eaten.”
Responding to a student's question, the scientist explained how the particle accelerator they used in the experiment worked. In simple terms, scientists give the particles a little “kick.” then another “kick” before sending them on their way.
Students asked questions about the safety of the particle accelerator, and the practical application of CERN's research. Dr. de Rujula said the accelerator is safe, and he said it sometimes takes years to realize the practical use of science. General relativity, or the general theory of relativity, for example, was published by Albert Einstein in 1916. In it, Einstein figured out that time goes more slowly where gravity is stronger. So, a clock on a satellite — away from earth's gravity — runs faster than a clock on earth. This correction has to be used to reach the accuracy required for GPS systems. Without this, ships, planes, missiles and cars would not know where they were. So, it took from 1916 until the development of GPS for Einstein's general Relativity to become useful.
The CERN scientists plan to conduct their experiment again, this time watching for the two factors they said threw their results.
“That was cool,” Benedetti said to his students as the scientist, speaking from Switzerland, signed off. His students agreed.
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