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Message Encoded in Neutrino Beam Transmitted through Solid Rock

The views expressed are those of the author and are not necessarily those of Scientific American.


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neutrino-detector

MINERvA detector. Credit: FNAL

Neutrinos are having a moment. They’re speeding across Europe (just how fast is under review), they’re changing flavors in China and, now, they’re carrying rudimentary messages through bedrock in Illinois.

A team of physicists encoded a short string of letters on a beam of neutrinos at Fermi National Accelerator Laboratory in Batavia, Ill., and sent the message to a detector more than a kilometer away. On the journey the neutrinos passed through 240 meters of solid rock, mostly shale. What was the word they transmitted in the preliminary demonstration? “Neutrino.” The experiment is described in a paper posted to the physics preprint server arXiv.org.

Neutrinos have been proposed for a variety of communication scenarios in which radio waves or optical signals fall short. Neutrinos rarely interact with ordinary matter, and they easily pass through solids that would screen out most other particles. So neutrino beams could be used to send messages through the Earth, or to communicate with a planetary rover parked on the far side of Mars, out of radio contact.

But the very slipperiness that makes neutrinos so intriguing for communication also makes them incredibly hard to use. Almost all of the neutrinos in a beam zip right through even the largest detectors. In the Fermilab experiment, the physicists fired a proton beam into a carbon target to produce a shower of particles called pions and kaons that quickly decay into neutrinos. For every pulse of 22.5 trillion protons, the physicists registered an average of 0.81 neutrino with the 170-ton MINERvA detector.

In other words, even with the benefit of a world-class proton accelerator and a mammoth particle detector, neutrino-based communication is far from efficient. By representing their one-word message in bits of ASCII code using a series of on-off pulses to communicate digital 0s and 1s, the physicists achieved a data rate of approximately 0.1 bit per second. At that rate it took more than six minutes to accurately relay the simple message “neutrino,” and that’s omitting the extra bits needed to synchronize the signal transmission. Transferring the entire 5.8 petabytes of data stored at the nonprofit Internet Archive would take about 15 billion years—just a shade longer than the age of the universe.

About the Author: John Matson is an associate editor at Scientific American focusing on space, physics and mathematics. Follow on Twitter @jmtsn.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. Koltrast 10:03 am 03/16/2012

    Maybe SETI should tune in on neutrinos instead. Magnetic radio waves are probably “stone-age” stuff.

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  2. 2. jtdwyer 12:50 pm 03/16/2012

    The article states:
    “So neutrino beams could be used to send messages through the Earth, or to communicate with a planetary rover parked on the far side of Mars, out of radio contact.”

    Sorry, but one of the critical characteristics of neutrino detectors is mass, generally necessary to increase the probability of physical interactions (detections) between neutrinos and other matter. Rather than a small focusing dish antenna, a neutrino detector on Mars would require many tons of dense material, making direct communication with a rover mounted neutrino receiver problematic…

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  3. 3. jtdwyer 1:00 pm 03/16/2012

    By the way, as long as we’re speculating about off-planet neutrino detectors, one of the fundamental problems with estimating neutrino propagation speed using Earthbound detectors is that the actual propagation time/distance of neutrino beams cannot be directly compared to that of light, since photons cannot propagate through the Earth.

    A neutrino detector on the Moon, for example, could be used to directly compare the traversal time of a neutrino beam from Earth with that of a laser beam. In this way the actual speeds could be determined. The neutrino’s propagation path would still be much more susceptible to gravitational effects (because of their proposed non-zero mass) than would photons, but a much more direct comparison could be made over a much more significant distance.

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  4. 4. blackbird79 8:59 pm 03/16/2012

    …Yes, but when are they going to find something with the penetrating power needed to push a scientific concept through the skull of a Republican voter?

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  5. 5. LarryW 9:34 pm 03/16/2012

    +1 to blackbird79

    A little math. Knowledge is to the Republican mind as neutrinos are to solid rock.

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  6. 6. jwdavis0507 3:54 pm 03/17/2012

    I can’t believe that readers of Scientific American would care anything about politics or waste their time blogging.

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  7. 7. jtdwyer 7:15 pm 03/17/2012

    jwdavis0507 – I have to wonder if I’m wasting my time attempting serious comments, what with all the clever political pundits…

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  8. 8. Don Quixote 12:58 pm 03/18/2012

    “Knowledge is to the Republican mind as neutrinos are to solid rock”
    “Fiscal responsibility is to the Liberal mind as global warming is to..”, oh wait, you’ve probably drank the Kool-Aid on that one so the analogy would be lost.

    How about we stick with real science conversation vice the politics?

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  9. 9. bucketofsquid 10:11 am 03/19/2012

    The blogs need a report abuse option.

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  10. 10. B.T.See 1:59 pm 06/1/2012

    I felt easy after knew about the faulty optical fibre of CERN, however, i still wonder about the finding of ICARUS that neutrinoes were travelled at the same speed of light. I believe a mass should not travel at the same speed with light as it will violate the theory of relativity too. I tried my best to understand it and think about an explaination. I assume neutrinoes are existing and decaying simultaneously and what we detected is actually the sum of neutrinoes’ decaying vectors but not the real particles of tiny mass.

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