FASTER THAN LIGHT NEUTRINOS

Faster Than Light Neutrinos

Faster Than Light Neutrinos

Over the past two months, we've talked more about neutrinos than ever before thanks to an extraordinary claim that neutrinos have been observed to move faster-than-light! And as you well know, no particle is allowed to travel through spacetime faster than the speed of light in vacuum, no matter how much energy you put into it!

Here's a brief refresher for you as to what's been going on. CERN, the home of the world's most powerful particle accelerator, has (as sort of a side-project) been producing a beamline of high-energy protons, and firing them in a very specific direction.

(The OPERA collaboration's recent paper.)

What happens to these protons? They smash them into a "fixed target," and the protons are moving at such high energies that they can produce all sorts of extremely high energy, unstable particles! More specifically, the vast majority of these particles wind up moving at somewhere around 99.999% the speed of light, with a good number of them decaying into muons and -- to be specific -- muon neutrinos.

These neutrinos then travel through the Earth for about 732 km, before winding up at the OPERA detector beneath the mountain of Gran Sasso in Italy. The very interesting thing, of course, is that the OPERA team found that the neutrinos arrived about 60 nanoseconds too early! What basically happened is they created a series of large pulses of muons and neutrinos over a time period of a couple of years. They calculated, based on their measurement of the distance between the source and the detector and their understanding of their electronics, just how long it should have taken the neutrinos to arrive at the detector.

What they determine is that, if you take the light-travel-time between the source and the detector, then factor in a 986 nanosecond delay for all of the known factors that can affect the arrival time (e.g., the electronics, GPS timing, effects of general relativity), you should get a perfect match of the detected neutrino signal with the source signal.

But they didn't! They found that you need a 1043 nanosecond delay, for a surprising result that the neutrinos arrive around 60 nanoseconds early. If this is true, it means that the neutrinos traveled just a tiny bit faster than what we think of as the speed limit of the Universe: the speed-of-light in a vacuum. How much faster? Just 0.002% faster than light.

Like many others, I immediately speculated that this team was fooling themselves with some sort of error, spoke publicly about it, and kept reporting on the latest tests and developments. (Even my car got in on the action.)

After all, their delay was based on the data shown in the above graphs. Is it really compelling that you couldn't shift that graph by 50 or 60 nanoseconds -- just one of those bins -- and still get a very good fit? Hardly.

So, they did a very clever re-test, which would ...