10-04-2017, 08:31 PM
Neutrinos in Long Distance communication
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Introduction:
No interstellar communication is going to be quick; hence it is obviously better to send messages that travel at the highest possible velocity. Usually this leads to the conclusion that we should communicate with radio or other electromagnetic waves. But one nuclear particle - the neutrino - travels at the speed of light, and the possibilities of using neutrinos as the vehicle for interstellar communication should be carefully explored. Neutrinos turn out to have many advantages for this purpose, along with their major difficulties, and we think that investigation of neutrino communication should not be ignored. We note that we are here exploring possibilities whose realization would be in the distant future. Nonetheless, since most other communicating civilizations would be far more advanced than our own, it is an interesting exercise to examine alternative means by which interstellar communication may have evolved.
What are neutrinos?
Neutrinos are particles with no charge but with certain energy and a certain spin.
Neutrinos travel at the speed of light.
Neutrinos are the most elusive particles which we know. They have a very low probability of interacting with any other matter. In fact, neutrinos on the average can penetrate four light years of lead before being stopped.
Why do we need to opt for neutrino communication?
Neutrino detection schemes, are broad band, that is, the apparatus is sensitive to neutrinos of a wide energy range. The fact that neutrinos pass through the earth would also be an advantage, because detectors would be omni directional. Thus, the whole sky can be covered by a single detector.
Though the means of detecting neutrinos are now relatively insensitive, we must remember that we are in the dawn of the age of neutrino detection. It is only 23 years since the first antineutrinos were detected. It is almost a hundred years, on the other hand, since the detection of radio waves, and our sensitivity to them has increased manifold. We can expect that in the next decades we will be better able to detect neutrinos from space, both those arising naturally from astronomical phenomena and those carrying messages from extraterrestrial civilizations.
Communicating with nuclear-powered submarines which can remain underwater essentially indefinitely is a major challenge because seawater is opaque to most of the electromagnetic spectrum. Neutrinos have previously been proposed as a solution to this problem, because these subatomic particles can pass easily through all matter. By doing so, data rate of about 100 bits per second could be achieved under water.
Detection:
The resulting neutrinos may be used to carry information. The SuperKamiokande detector is a much larger version of the original Kamiokande detector and is located in the same mine. The active detector in the SuperKamiokande experiment contains32,000 tons of pure water and 11,200 specially designed tubes for observing electrons scattered byneutrinos. This new super-detector finds a rate
ObservedSuperK=.47+.02
predicted
This new rate is in good agreement with the previous measurement but is more precise.Since the Japanese water experiments (Kamiokande and SuperKamiokande) and the chlorine experiment are both primarily sensitive to the same 8B neutrinos, it is difficult to understand why the discrepancy between observation and calculation is so much greater for the chlorine than for the water experiments. The most likely interpretation is that some new physical process happens to neutrinos that affects the lower-energy neutrinos observed in the chlorine experiment more than it affects the higher-energy neutrinos observed in the Kamioka experiment. This interpretation has been strengthened by the fact that the Super Kamiokande experiment finds strong evidence that neutrinos produced by cosmic rays in the atmosphere change their type when they travel distances comparable to the earth's radius.