Monday, November 21, 2011

Did they or didn't they? Did neutrinos break the speed of light?


Scientists at the Cern laboratory in Switzerland announced that their experiments revealed neutrinos can travel faster than the speed of light.  Before we jump into the whats and hows, why is this important?

First, let's consider another speed, the speed of sound.  When we first built airplanes, they were very slow.  However, we knew rifle bullets broke the speed of sound, so it was at least possible.  Eventually, we built jet aircraft that broke the sound barrier.  With light speed, we're still at the stage where we don't know if going faster is possible.  But as we've talked about before, if we're going to reach distant planets, we need spaceships that go light speed or faster.

To experiment on the light speed problem, scientists at Cern in Geneva, Switzerland, shot neutrinos through a tunnel to a special barrier 454 miles/730 kilometers away in San Grasso, Italy.  A neutrino is a tiny object that has almost no mass, and doesn't carry a positive or negative charge.  Also, neutrinos have so little interaction with matter that they are nicknamed 'ghost particles.'

In the first experiments, clusters of neutrinos arrived in Italy 60 billionths of second faster than light travels.  Twenty recent experiments using shorter clusters of neutrinos achieved similar results. 

There are two problems with all this.  The first problem is that exceeding the speed of light violates Albert Einstein's theory of Special Relativity.  This states that no matter what your motion is relative to a light source, the speed of light is the same for all observers.  We are so certain of the speed of light that we used it to make up the meter for measurement.  But back in 1905, Einstein's theory actually contradicted the science of the time.  So there is the possibility that Special Relativity does not hold for neutrinos.    

The second problem is that measuring an amount like 60 billionths of a second at two points 454 miles apart is tricky.  It seems that even a small error could cause a 'mistake' to look like a 'result.' 

There aren't many labs in the world set up to detect neutrinos, but a few of them will be performing their own tests to verify the Cern results.  Fermilab in the United States, Gran Sasso in Italy, and the T2K experiments in Japan will all conduct their own tests, so in the next year or two we may learn more.

In tough economic times, it's easy to think we should cut science funding because we can't always see an immediate application for their results.  And if neutrinos can go faster than light, it may not make any change in our lives right away.  But simply knowing that it can happen opens up a whole new realm of possibilities.

(Here is a helpful BBC article on the experiments, and one from Physics World.  Also, a wiki article on specialrelativity.  The pic is from the BBC article.)

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