Military applications of neutrinos by 2050?

Will the neutrino fields find a military use by 2050? In order to count the technology must directly use neutrinos (what I mean is described more carefully below). The technology must clearly be consequential from a military/security standpoint. It doesn't have to actually have been used, as long as the threat of its use is plausibly affecting behavior.

Because obviously this one could be ambiguous, I won't be betting in this market. Feel free to pose hypotheticals and request clarification.

No technology that is currently publicly known to be deployed by the military counts. Technology that is still "in the works" could count.

Vaguely conceivable things that would induce a YES resolution (not that I'm claiming any would work, just to demonstrate resolution criteria):

  • "Neutrino bomb". Not that it's a very good weapon, but with a high enough flux, yes, it'd count.

  • Neutrino-based remote sensing.

  • Using neutrinos to disrupt other military systems.

Things that will not count towards a YES resolution:

  • Misinformation about neutrinos. If in 10 years everybody's saying how big of a threat neutrino bombs are, and I'm confident that this is false, that won't count---even if the misinformation itself is having military consequences.

  • Things that can be described without the word "neutrino". If there's an effective field theory that doesn't mention neutrinos that adequately describes the weapon, then that doesn't count. This rule is tricky, and is meant to exclude things like "nuclear weapon but we modeled some process involving neutrinos slightly more accurately".

I'll try to resolve YES liberally.

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bought Ṁ15 of YES Paper suggests using neutrinos for submarine navigation. It also suggests using CEνNS to increase the neutrino cross-section. They say at the end, "we expect that in the time frame of 10 to 20 years, technological progress will make it possible to develop a proof-of-concept system."

bought Ṁ30 of NO

Would using neutrino detectors to verify compliance with an arms control agreement count as a “military application”?

predicts NO

@TomBouley dammit, that hadn't occurred to me!

@TomBouley probably yes; for instance, it might fall under "remote sensing" and "plausibly modify behavior".

predicts NO

@TomBouley the range is much too short for that. IIRC the largest detector in the world could detect a nuclear reactor a couple of miles away at most.

predicts NO
predicts NO

Scanning a narrower area with the neutrino beam could give the enemy info about where the sub is. Sub hunting cruisers could carry bigger detectors than subs.

predicts NO

@JonathanRay what's the connection?

predicts NO

@ScottLawrence Neutrino physics

bought Ṁ260 of NO

Back of the envelope it would take 10^16 times more energy than radio to transmit the same data to subs

predicts YES

@JonathanRay This seems wrong. Attenuation due to seawater should effectively make radio comms with subs under a few 10s (100s?) of meters infeasible at reasonable wavelengths. Subs already can deploy fairly large towed radio arrays, but I think you start to need many km of antenna at operational depths.

predicts NO

@QuantumObserver one light-year of lead only stops half the neutrinos. Water has 1/11 the density and high energy muons can penetrate about 100m of water, so the fraction of the neutrinos that could plausibly be detected by the sub in the method described by the paper is ~ (100m / 22 light years) = 5*10^-16. Then you have to factor in the inefficiency of neutrino production (~10^-2) and flavor occilation (0.33?) <2*10^-18 of the beam energy pointed directly at the sub is actually detectable by the sub. Then you have to account for the ground station not knowing where the sub is and needing to scan across the whole ocean (let's call that a factor of 1/ earth's surface area in m^2 = 2*10^-15) So the ground station needs to use ~ 2.5*10^32 more energy than the sub can see.

bought Ṁ576 of YES


I don’t agree with your final part re: the surface if the earth. I would expect the message senders to know the location of a submarine to within like (100ish km)^2.

But what you’ve calculated is that a neutrino message is attenuated by 180 dB, fine. What you didn’t do was the attenuation calculation for radio waves through sea-water, so you didn’t show that it takes 10^16x more energy than radio to transmit the same message in neutrinos.

It’s actually annoyingly hard to find relevant details for UHF or VHF radio propagation in sea water. You end up needing to do a little calculating, but I think enough info is out in published work that this is doable.

predicts NO

@QuantumObserver So if we adjust the search area down to 100km^2 then the sub sees 2x10^-23 of the energy used by the transmitter. Let's assume we have a perfect detector and a perfect beam modulation so 1 muon = 1 bit of information. 105 MeV x 2 x 10^23 = 1 GwH per bit. Maybe it could be worth it to spend $100,000 of energy per bit to transmit to subs, maybe $1 million per usage if it's just used as a 10-bit bell-ringer to tell a specific sub to come up to a depth where it can receive an ordinary transmission. Maybe I could see the military doing that. 100km^2 seems generous though, because it's only a 10km square and these transmissions would take many hours during which the sub could have moved hundreds of km.

predicts YES

@JonathanRay I finally have some time to write down some numbers for people reading these threads (if any such people exist).

There are a bunch of resources for this, but this PDF from 1987 about underwater radio communication for amateurs is probably the easiest to start with.

Assuming some average sea water conductance of 4 Mhos and a transmission frequency of 10 kHz, you end up with an attenuation of around 3 dB/m through sea water. That is to say, you lose half of your signal strength for every meter of travel through sea water for 10 kHz signals.

For reference, the chart at the link below provides useful reference for power scales in dBm:

-174 dBm (4 zW) is the thermal noise floor for 1 Hz bandwidth at 20C. I estimate the thermal noise floor to be something like -134 dBm at 10 kHz, at 100m below the surface of the ocean. I believe this value has a square root dependence of bandwidth and temperature, so a mere 20C change in temperature for Polar oceans is not going to matter nearly as much as a 10,000x increase in bandwidth.

Wikipedia claims the test depth for a Virginia class fast-attack submarine is 240m. I assume operational depths are better than this. I'll just stick with 100m for now. So the sea water attenuation of a 10 kHz radio signal is going to be like 300 dB, and we need to receive -134 dBm to be at the thermal noise floor. Ideally, we would receive more power to have better SNR. That means the emitter power needs to be 146 dBm. That is to say, the emitter power needs to be 400 GW.

Other issues are: 10 kHz radio waves have like 30 km wavelengths, so the antenna receiving these signals would have to be quite large. We can do better by going to lower frequencies. Say 1 kHz? By going to 1 kHz waves, I think you get 10 dB lower thermal noise and 1/3 the attenuation per meter. So you end up requiring an emitter with much less power.

In fact, from this wikipedia article., I learned that the US, USSR, CCP, and India are the only nations to have built ELF facilities. The American one operated at 76 Hz ( with very low bandwidth. The original concept required dedicated powerplants to run it, but the successor (Project ELF) seemed to only require 2.6 MW. Honestly, I am not entirely clear on how submarines could reasonably detect these signals at operational depths without huge towed arrays.

It seems like this was discontinued in favor of improving VLF technology (according to the Navy). I can only assume this actually means that they've already adopted neutrino technology 😂.

predicts NO

I agree 10khz sucks which is why they use lower frequencies than that. By your own numbers switching from 10khz to 1khz would reduce the transmission power required by a factor of 2^70 which seems absurdly large.

predicts YES

Hell yeah @JonathanRay , let’s go

bought Ṁ1,000 of NO

Why this will never ever happen:

For detecting nuclear tests on the opposite side of the world a seismograph gets you many orders of magnitude higher sensitivity at many orders of magnitude lower cost.

There isn’t any neutrino source/detector combo strong enough to send more than a few bits per hour to the opposite side of the world and in latency it only saves (pi/2-1)12700km/c = 24 milliseconds. Maybe high frequency traders would go to the trouble but the military wouldn’t.

predicts NO

@JonathanRay and the bit rate would have to go up by many, many orders of magnitude for the lower latency to actually accomplish anything.

predicts YES

@JonathanRay buy into my limit orders then! 🙏

Communication with ballistic submarines is a hard problem - this seems possible to solve it.

@JonathanRay a seismograph does not prove that the exposion is nuclear though. Imagine a regional power faking having nukes by exploding conventional explosives underground. If everyone believes you have nukes they will be less likely to attack you, and if you are determined enough you can probably amass the equivalent of a few kilotons (for instance the US exploded ~1/2 a kiloton of TNT in Neutrino detection would prove the explosion is nuclear.

predicts NO

@NadiaMatsiuk Buryin 10,000 tons of tnt to fake it would be pretty obvious on spy satellites and very expensive and even without the spy satellites it wouldn’t be very convinving in the absence of other credible intel of a nuclear program existing

bought Ṁ8 of YES

@JonathanRay A kiloton (by weight) of ammonium nitrate would cost about a million USD, a factor of two more, roughly, if you want to match the energy of 1 kiloton TNT. Cost does not seem to be a factor for a state actor. On the other hand the point you raise about intel seems convincing.

predicts NO

@NadiaMatsiuk That’d be 10,000ish cubic meters of AN. 500 semis full. The excavation and loading should be obvious from satellites

predicts YES

@JonathanRay use a natural occurring cavern or a former mining site. Work only under cloud cover. Amass explosive slowly (better use a very stable compound). Hard to escape human intelligence though.