[HN Gopher] Nuclear radiation used to transmit digital data wire...
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Nuclear radiation used to transmit digital data wirelessly
Author : sizzle
Score : 193 points
Date : 2021-11-12 18:33 UTC (1 days ago)
(HTM) web link (www.lancaster.ac.uk)
(TXT) w3m dump (www.lancaster.ac.uk)
| Ekaros wrote:
| Now I actually wonder how to do it over a wire. That is use
| nuclear radiation to transfer data...
| nukenuke wrote:
| For those wondering, will not really work over long distances (>
| 100 m) since fast neutrons will thermalize quickly in air and
| other materials. This means they scatter around approaching a
| random walk and lose energy, which makes the transmission beam
| harder to detect.
|
| This is really mostly feasible for ~single wall transmission.
| mgsouth wrote:
| How far can you go until the losses are over 160 dB? Reason I'm
| asking is that LTE Cat-M (low-bandwidth IoT) go that low, or
| lower [0]. GLONAS (GPS) receivers deal with over 180 dB of loss
| [1]. It depends on the power level in the transmitter, and how
| well the receiver can lock on to very faint, but expected,
| patterns in the noise. One of the tricks is to re-transmit,
| sometimes literally thousands of times.
|
| [0] https://www.altair-semi.com/wp-
| content/uploads/2017/02/Cover...
|
| [1] https://en.wikipedia.org/wiki/DBm -- Satellites
| transmitting +55 dBm, receivers seeing -127 dBm.
| yummypaint wrote:
| The neutrons used here have a maxwellian energy distribution
| associated with fission. A single bit will contain neutrons
| with energies from nearly thermal up to a few MeV. These
| neutrons are not relativistic at all. For reference a 1 MeV
| neutron travels a meter in about 70 ns. This means the spread
| in the neutron spectrum and the transmission distance will
| conspire to place a fundamental limit on the data rate. Can't
| have neutrons from neighboring bits mixing together too much.
| This doesn't even include intermediate scattering which will
| make things harder.
| p1mrx wrote:
| This sounds like something Cave Johnson would do. "Science isn't
| about 'Why?', it's about 'Why not?'"
| kazinator wrote:
| That could be a fun activity for Boy Scouts; one boy, standing
| outside of the concrete shed, is watching a geiger counter, and
| the other sends Morse Code by moving a leaden lid up and down on
| a sample of Plutonium.
| laurent92 wrote:
| There was a nuclear badge in the boys scouts, and one kid
| actually got it, to the dismay of his mother.
|
| More generally, had nuclear not been demonized as part of the
| fear of mutual destruction ideology (I'm not saying it was
| wrong), maybe we would have lived in a parallel world where
| tinkering with radioactive elements would have been more
| widespread, and innovation wouldn't have stalled for 60 years.
| Maybe we'd have a lot of nuclear-in-a-box batteries by now.
| aYsY4dDQ2NrcNzA wrote:
| https://en.wikipedia.org/wiki/David_Hahn
| orbital-decay wrote:
| The paper is here:
| https://www.sciencedirect.com/science/article/pii/S016890022...
|
| Key takeaway here is novel fast neutron generators [1] that are
| flat and electronically modulated, so they are potentially good
| for data transmission through metallic vessels (ship hulls for
| example) that doesn't require vessel penetration and isn't
| heavily regulated like californium isotopes.
|
| The researchers wanted to demonstrate the data transmission in
| practice, but used a more conventional setup instead (a Cf-252
| source mechanically modulated by a HDPE slab).
|
| [1] https://ieeexplore.ieee.org/document/6275497
| irq wrote:
| > electronically modulated
|
| Is it really electronic modulation when the modulation is
| handled by pneumatically moving a polyethylene block? I would
| call that mechanically modulated. Electronic modulation would
| be, say, a transistor switching the output on/off.
| orbital-decay wrote:
| [1] in the post above links to a different paper (referenced
| in OP), which describes exactly that. The researchers in the
| OP used mechanical modulation instead (which is far less
| interesting)
| hasmanean wrote:
| Could they have used a Farnsworth fusor as a neutron source
| and electrically modulated it at radio frequencies?
| servytor wrote:
| I was imagining a Monty Python scene where someone was using two
| halves of lead, like coconuts, and slamming them repeatedly over
| the radioactive material.
| Arrath wrote:
| Shades of the Demon Core.
| _Microft wrote:
| The Demon Core also came to my mind when reading GP's
| comment. For those unaware, the Demon Core was a piece of
| radioactive material and received its name after two people
| died in different accidents while experimenting with it on
| criticality .
|
| https://en.wikipedia.org/wiki/Demon_core
| danbruc wrote:
| In case someone else is wondering, they modulated the neutron
| beam by pneumatically moving a polyethylene block in front of the
| Californium source which sits inside a one cubic meter water tank
| and can be pneumatically moved close to one of the walls for
| activation. The data rate was about one bit every ten seconds.
| nickpeterson wrote:
| This sounds like a line from the turbo encabulator.
| JadeNB wrote:
| > This sounds like a line from the turbo encabulator.
|
| In case you're one of the lucky 10,000:
|
| https://www.youtube.com/watch?v=Ac7G7xOG2Ag
| version_five wrote:
| At this bitrate, and over short distances - maybe 1m, a
| rotating permanent magnet (or a powerful electromagnet) could
| also be competitive. It wouldn't work for anything with a high
| magnetic permeability (like iron) but for non magnetic metal or
| water a static field would penetrate at least a short distance,
| enough to go through a wall.
|
| (BTW, I've imagined that in the distant future, we'll have
| gravity wave generators and detectors that don't have the same
| constraints as EM based data transmissions. I don't know how
| realistic this is.
| aaaaaaaaaaab wrote:
| But we already have gravity wave generators. E.g. I've just
| generated some by waving my arm!
| Tepix wrote:
| Please prove it by measuring the resulting gravity wave :-p
| aardvarkr wrote:
| A gravity wave occurs at the lowest of the lowest of low
| frequencies. In order to produce such a wave the object
| resonating would have to be many many miles long and be
| stronger than any material known to man as well as incredibly
| heavy. Think of a very long cable woven from a neutron star.
| That's about what it would take :)
|
| The concept has of course been written about a fair bit on
| science fiction. The dark forest trilogy comes to mind and
| used a gravity wave generator built into the hull of a
| massive ship whose purpose was to alert alien life to the
| existence of the earth.
| hasmanean wrote:
| A string made of collapsed matter. You could pluck it like
| a guitar and it would vibrate with gravity waves. As long
| as nothing else on earth was as dense as the string, the
| gravity waves would propagate easily through ordinary
| matter like sound waves through air.
| fouronnes3 wrote:
| Reminds me of that paper I read a long time ago, about how we
| could detect advanced alien civilizations by analysing pulsar
| signals. The hypothesis was that they would put massive
| devices in orbit of pulsars to modulate their high energy
| signals to use as ultra long range communication. Presumably
| pulsars would be the only strong enough carrier wave.
| hoten wrote:
| What would the throughput be on something like that?
| version_five wrote:
| Now I'm imagining a future where some modulated binary star
| merger is being used to stream episodes over Netflix.
|
| Hopefully we manage to find a way to miniaturize things.
| Andrew_nenakhov wrote:
| Imagine waiting hundreds of years for the new episode to
| reach your distant star system
| hasmanean wrote:
| Really you only have to wait one week for each episode to
| reach you.
| shawnz wrote:
| I'm holding out for neutrino based communication:
| https://physicsworld.com/a/neutrino-based-communication-
| is-a...
| 14 wrote:
| The interesting bit I picked up from that article is "A
| neutrino could easily pass through 1000 light-years of
| lead, so an ocean would pose no problem whatsoever."
|
| That is crazy no wonder they are so hard to detect.
| thedrbrian wrote:
| This will blow your mind.
|
| https://en.wikipedia.org/wiki/Super-Kamiokande
|
| >Mounted on an inside superstructure are about 13,000
| photomultiplier tubes that detect light from Cherenkov
| radiation. A neutrino interaction with the electrons or
| nuclei of water can produce an electron or positron that
| moves faster than the speed of light in water, which is
| slower than the speed of light in a vacuum. This creates
| a cone of Cherenkov radiation light, the optical
| equivalent to a sonic boom. The Cherenkov light is
| recorded by the photomultiplier tubes
| brian_cloutier wrote:
| Two parts really blow your mind:
|
| - the images are stunning, especially if you search for
| "super kamiokande boat"
|
| - even with 50 kilotons of water they record just tens of
| events per day: https://www.slac.stanford.edu/econf/C0805
| 263/Slides/Raaf.pdf
| magicalhippo wrote:
| And they had an unfortunate incident[1] resulting in the
| loss of 7000 out of the 11200 photon multiplier tubes.
|
| Incompressible fluids are no joke.
|
| [1]: https://www.nature.com/articles/35106691
| lwhi wrote:
| This is interesting ..
| https://www.abc.net.au/news/2019-06-17/inside-super-
| kamiokan...
| dghughes wrote:
| > A neutrino interaction with the electrons or nuclei of
| water can produce an electron or positron that moves
| faster than the speed of light in water, which is slower
| than the speed of light in a vacuum.
|
| This is the important but I think confusing part for many
| people.
|
| The electron/positron is not moving "faster than light"
| (nothing can) it is moving faster "than the light" in
| that specific medium (water).
| tialaramex wrote:
| It _is_ moving faster than light, but c, the "speed of
| light" constant, is only called that because it's the
| speed of light in a vacuum and water isn't a vacuum. The
| constant c is actually a fundamental constant of our
| universe relating spatial and temporal dimensions, which
| is why going faster isn't possible (that's time travel)
| but the velocity of photons in one medium or another is
| just an observable fact like the viscosity of a
| particular brand of jam.
| [deleted]
| kingcharles wrote:
| That's about the same speed I get when I run out of "high
| speed" data on my mobile phone plan.
| titanomachy wrote:
| I _was_ wondering, thank you! Surprised the article didn 't
| bother with even a sentence to explain this.
| op00to wrote:
| I figured it was something like a trombone mute. Not sure why
| that was the image I got of how they did it.
| soheil wrote:
| Don't see why they can't improve it to use a piezoelectric
| material to modulate the neutron beam. That would achieve a far
| higher data rate.
| IshKebab wrote:
| Presumably because the neutrons are only emitted
| sporadically.
| yosito wrote:
| Sounds like a more radioactive version of smoke signals.
| kingcharles wrote:
| In Soviet Russia all email radioactive.
| [deleted]
| dang wrote:
| Could you please stop posting unsubstantive and/or flamebait
| comments? You've unfortunately been doing it repeatedly, and we
| ban such accounts because we're trying for a different sort of
| discussion here.
|
| I don't want to ban you, so if you wouldn't mind reviewing
| https://news.ycombinator.com/newsguidelines.html and taking the
| intended spirit of the site more to heart, we'd be grateful.
| Trias11 wrote:
| Please delete my post I can't
|
| Apologize for it
| dang wrote:
| Ok, I've deleted it and collapsed my reply. Thanks.
| bricss wrote:
| 252G?
| lucb1e wrote:
| That sounded a lot like U-235 or U-238 (I only know that
| because of Dan Brown's book where "the difference is three",
| for those that get that reference, so that's like my level of
| physics understanding right there). Not sure how to get to
| Californium's radioactive, um, configurations, I typed U-235
| into Wikipedia, found a link to "isotopes of" which listed all
| of Uranium's, then near the bottom was a handy table with all
| the "isotopes of" links to other elements, Californium's code
| is apparently Cf so I found the right link and... 252 has a
| note saying "most common"! I think I get your reference :D but
| also, while typing this I realized I probably took the long way
| of getting there... indeed, re-opening the article, it's also
| right there, heh.
| daly wrote:
| Submarine communication. Acoustic signals can be detected at VERY
| long distances. These signals cannot.
|
| Spy communication from inside a nuclear facility.
| spikels wrote:
| Imagine a neutrino based communication system. It could always
| take the shortest route: a straight line thru anything, the earth
| for example. No connections but probably huge transmitters and
| receivers.
|
| https://cerncourier.com/a/long-distance-neutrinos/
| Cyder wrote:
| neutrino messaging was mentioned in The Hummingbird Project...
| Good movie
| tantalor wrote:
| It's a smoke signal.
| jhallenworld wrote:
| But won't the range be limited by neutron decay?
| jjk166 wrote:
| Thermal neutrons move at approximately 2000 m/s, with a half
| life of about 612 seconds. Decay is a non issue but scattering
| does put some limits (mean free path of a 14 MeV neutron in air
| is about 140 meters), though if your goal is just to get a
| signal through a wall you don't need particularly long range.
| chaxor wrote:
| As many have pointed out, this doesn't seem practically useful.
| However, if you add an "i" and flip the "n" and "o" on that
| messenger particle, I could see it being greatly useful.
|
| Neutr _ino_ communications could travel into every nook and
| cranny, very fast and far indeed.
| folli wrote:
| The radiation in the article is modulated by shielding and
| deshielding the neutron source. How would you modulate a
| neutrino?
| jjk166 wrote:
| Neutrino beams are produced by having a muons circulate in an
| accelerator with long straight sections. As the muons decay,
| they release neutrinos moving approximately in the same
| direction the muon was. You modulate the neutrinos by
| modulating the muon beam. The simplest way to do this is to
| introduce or take away muons from the beam, but another
| option is changing their energy. Muons have a half life of
| approximately 2 microseconds in their inertial reference
| frame, but from the standpoint of an observer, relativity can
| make them seem to live much longer. Decrease the energy to
| the beam energy such that they're moving slower and it is as
| if their half life decreases, causing them to decay more
| frequently and thus produce more neutrinos.
|
| The real issue is the detection end. Because of how little
| neutrinos interact with matter, you need a lot of neutrinos
| to pass through a detector before you can expect to see a
| signal, and then you need to distinguish that signal from
| noise.
| mrfusion wrote:
| Could we simply use another muon beam as a detector?
| bally0241 wrote:
| You don't modulate the neutrino beam itself, but you could
| modulate the pion production beam. For typical neutrino beam
| experiments this is done with a large magnetic horn which
| focuses/defocuses (+/-) charged pions which then decay to
| (anti)neutrinos and (anti)leptons. By changing the current in
| the horn you could modulate the intensity of the beam to send
| data.
|
| Needless to say this is woefully impractical, would require
| an extremely large neutrino flux and detector, and would have
| an absolutely abysmal bit-rate. Not to mention you'd likely
| only be able to send messages in one direction. But it could
| be done.
|
| see: https://www.fnal.gov/pub/today/archive/archive_2014/toda
| y14-...
| retzkek wrote:
| It was actually demonstrated (over relatively short
| distance) using the MINERvA detector at Fermilab:
| https://arxiv.org/abs/1203.2847
| therein wrote:
| That's the question and precisely what would make it novel
| and interesting.
|
| If you can easily modulate the source of your signal as is
| the case with the neutron source, it becomes as uninteresting
| as morse code.
| manpagereader wrote:
| Why modulate it at all? Just use CW.
| speed_spread wrote:
| There is speculation about usage of neutrinos for wireless
| financial trading faster than ground lines. One could transmit
| information in straight line without having to bother with
| earth's curvature.
| foxes wrote:
| Is this really a good idea? Also reminds me that neutrons will
| degrade a material over time:
|
| https://en.wikipedia.org/wiki/Neutron_embrittlement
| manpagereader wrote:
| We used to do this by opening a port in the shield over an x-ray
| source and detecting it with the predecessor of digital x-ray
| sensors back in the lab, sending morse code.
| yummypaint wrote:
| Not great for long distances unfortunately, as your source will
| always be isotropic. One could also do this with neutrons with
| either 241am alphas on beryllium modulated electronically, or
| with d2 beam incident on d2 target, or proton beam on a tritiated
| titanium foil target. All should allow for faster modulation. The
| beam based methods also allow for control of the outgoing energy.
| gnufx wrote:
| If you're allowed an accelerator, perhaps something like
| https://en.wikipedia.org/wiki/ISIS_neutron_source if not in a
| confined space.
| trhway wrote:
| >241am alphas on beryllium modulated electronically
|
| sounds like a primitive logic gate to me :) One can imagine a
| self powered logic circuits built along this way.
| gh02t wrote:
| I don't _want_ to hate on this research but my first thought
| was "well duh of course you COULD but why WOULD you?" This is
| basically just Morse code with a neutron source. That this is
| possible is obvious to anybody with a passing familiarity with
| nuclear engineering, but equally clear is the lengthy list of
| downsides. Just because nobody has done it doesn't make it
| novel.
|
| This is no doubt meant as a proof of concept and an
| electronically controlled neutron generator would solve some of
| the problems, but I still can't think of any use for this that
| isn't better solved some other way.
| 14 wrote:
| I know nothing about nuclear energy but I immediately thought
| about the Tokamak. The article said it could be useful for
| scenarios where penetration of a wall of a device would be
| problematic. I thought I wonder if the Tokamak had the need
| to be sealed in some way and being able to send a signal
| inside it wirelessly would help. Maybe they need a completely
| sealed room but they also need to trigger a switch but no one
| can be in the room and typical communication can not
| penetrate it. You just need one bit to make it through to
| flip that switch from a 1 to a 0. This would be the perfect
| device. Ya I know that probably has no use for the Tokamak
| and I can't think of a scenario where you need a completely
| sealed device with no holes but still need to send a signal
| inside. Like in the article they also mentioned submarine
| communications. You sound smart but surely if they could just
| do other forms of communication they would have already the
| US military budget is massive. Currently subs float a device
| to the surface so they can talk. The article says this slows
| them down and risks exposing them. Beside the couple
| mentioned in the article already I'm sure there has to be
| more use cases someone smarter then your or I can see.
| gh02t wrote:
| Neutron transmission is not useful in any of these
| scenarios. Not in a fusion reactor because a fusion reactor
| produces a ton of neutrons itself, many orders of magnitude
| higher than any transmission you'd be able to make so it'd
| be drowned out (most neutron generators use fusion to
| produce neutrons too so they're probably also at similar
| energies to what the reactor makes). Plus the problem with
| the inside of a tokamak vessel is that it's a super extreme
| environment and not much can survive in there and like I
| said in another comment you still have to power your
| neutron generator.
|
| Neutrons are also relatively short ranged and more-or-less
| isotropic in emission (not able to be focused effectively),
| meaning you need really high fluence (=dangerous) to
| transmit more than a few _meters_. For submarines, water
| actually attenuates neutrons _extremely_ quickly making it
| completely useless there. And also let 's not forget that
| neutrons activate materials and make them radioactive for
| long periods even after you stop with the neutrons. For
| totally sealed rooms there are better solutions (e.g an
| acoustic transducer). On top of all this, the physics of
| neutrons mean this will always be very low bandwidth.
|
| None of the applications mentioned in the article are
| remotely credible, IMO, and this is my area of expertise.
| Perhaps there is some application where this is the best
| solution. My point is that at best it's _extremely_ niche;
| the article makes it out like this is revolutionary but it
| is definitely not nor is it even particularly interesting.
| This is not military research with an intended application,
| this is someone slowly moving a block of plastic back and
| forth in front of a californium source in a university lab
| and a press release declaring victory. The actual article
| published by the scientists in NIM is much more reasonable,
| but the one linked here is greatly playing up the utility.
|
| A fairly reasonable analogy that captures some of the
| downsides of using neutrons for this is that you could also
| transmit information by shooting at a metal plate with a
| pellet gun and having someone listen for the pinging sound.
| Sure it's possible, but the list of drawbacks is pretty
| long.
| hasmanean wrote:
| Next step: move from CW(code word) to CDMA. Hedy Lamar owns
| the patent on CDMA with punch cards but you could own the
| neutron patent.
| gh02t wrote:
| CW is "continuous waveform" not "code word" at least in the
| context of radio and is probably the only way this can
| work. You can't really modulate neutron energy/frequency
| with any sort of fine control, so most of the fancy
| techniques with radio waves are out. CDMA is sorta
| possible, but bandwidth is always gonna be low.
| bnegreve wrote:
| > I still can't think of any use for this that isn't better
| solved some other way.
|
| What about this?
|
| "In some safety-critical scenarios, such as concerning the
| integrity of reactor containments, and metal vaults and
| bulkheads in maritime structures, it can be important to
| minimise the number of penetrations made through such metal
| structures for communications cabling. The use of neutrons
| for information transmission through such structures could
| negate the need for such penetrations and is perhaps also
| relevant to scenarios where limited transmissions are
| desirable in difficult circumstances, such as for emergency
| rescue operations."
| gh02t wrote:
| Yeah I read that, but it's not going to be good for that.
| For one thing that isn't going to work in a nuclear reactor
| core because the neutron background is orders of magnitude
| higher than any neutron generator could hope to produce.
| For the other uses they mentioned... I mean like I said
| there's no reason it wouldn't work (over short ranges) but
| there are simpler solutions that don't involve [very
| dangerous] neutron radiation. Plus a neutron generator
| requires a decent bit of power to run (they're basically a
| compact particle accelerator) so you're back to needing a
| vessel penetration. And the idea that such a device would
| be useful for emergency rescue operations is frankly silly.
| smartscience wrote:
| That's still more than a bit of a stretch considering the
| drawbacks, such as making that vault or bulkhead material
| radioactive even after the neutron beam has been shut off.
| In practice the duraction of the induced radioactivity
| varies considerably depending on the material; just hope
| it's not an alloy that includes cobalt.
| cycomanic wrote:
| Well what about mechanical waves /sound waves. I mean we
| are talking about rates of less than a bit per second. Just
| have a small hammer ping your metal container. Will go much
| further is much cheaper and can easily do a higher data
| rate.
| toast0 wrote:
| You can probably do something with optical communications
| through a thick, leaded glass window, depending on your
| containment needs.
| andylynch wrote:
| The 'safety critical maritime structures' they are
| talking about are probably pressure hulls on nuclear
| submarines. They are well equipped to handle radiological
| material and really want to be quiet.
| titanomachy wrote:
| More moving parts than an electrically-modulated neutron
| source. But this was my first thought as well.
| R0b0t1 wrote:
| Piezoelements would work well. Not really a moving part
| in the traditional sense, with worn surfaces from
| friction.
| lazide wrote:
| Piezoelectrics?
| gh02t wrote:
| Acoustic was also my first thought. Neutron generators
| are quite complicated and relatively delicate. Meanwhile
| acoustic transducers (e.g. piezo) are super simple and
| low power.
| andi999 wrote:
| The danger zone for humans is smaller though.
| sizzle wrote:
| Great insight for us laymen. Curious, how are you so
| knowledgeable about such an esoteric topic? are you a nuclear
| physicist or...?
| xattt wrote:
| They have Q clearance(1), at least.
|
| (1) https://news.ycombinator.com/item?id=29204027
| yalogin wrote:
| So we can be assured of internet coverage even in the case of a
| nuclear holocaust? Google and Facebook are launching the balloon
| based service and selling ads tomorrow :)
|
| On a serious note what can the practical implications be to f
| this?
| awiesenhofer wrote:
| I already have an existing IPoAC/RFC1149 connection, can I run
| this one simultaneously or would it cause too many drops on the
| old line?
| kazinator wrote:
| Speaking of mechanical devices to selectively obstruct radiation
| ...
|
| I had a manager who is a clever fellow. He used some construction
| toy with electrical motor abilities to rig together a test
| apparatus whereby a mobile device was placed into a steel cooking
| skillet, and the apparatus was periodically lifting the lid.
|
| This caused the device to go into and out of mobile coverage,
| allowing for testing of in-and-out-of-coverage transitions, and
| reproducing problems reported with respect to them.
| jjcm wrote:
| This seems like non-news? They're just using the amplitude of
| neutron emission to encode data. This isn't unique at all to
| radioactive decay - they're basically just using AM radio tech
| over radioactive decay instead of radio waves. It doesn't provide
| any benefits, it's more just a "neat!" thing.
| MobiusHorizons wrote:
| Don't high velocity neutrons irradiate the materials they go
| through? I would imagine this could lead to interference in long
| lived installations. Also how would this be safe in a maritime
| environment?
| rbanffy wrote:
| In essence, they have invented the cellphone that actually causes
| cancer ;-)
| daniel-cussen wrote:
| I've heard there's a lot of prior art.
| rbanffy wrote:
| Neutron bombardment is unhealthy, but it was never used for
| communication until now.
| daniel-cussen wrote:
| I mean about a cell phone that causes cancer, it's too late
| to patent that.
| raldi wrote:
| The article doesn't state what distance they were able to
| transmit over.
| java-man wrote:
| During the Cold War, I've heard rumors of one directional
| communication system with submarines using neutrinos.
|
| I don't know what the utility of the system described in the
| article though - neutrons will be absorbed pretty quickly, so
| the communication must have a very short range.
| perihelions wrote:
| How could a _nuclear-powered_ submarine possibly host a
| neutrino detector? You 're sitting meters away from one of
| the brightest neutrino sources on the planet!
| java-man wrote:
| please see my comment below in this thread.
| djsbs wrote:
| "... using neutrinos"
|
| "... neutrons will be absorbed..."
|
| I made the same confusion for a second. Neutrons are easily
| absorbed. Neutrinos (little neutrons) are almost impossible
| to interact with (and therefore absorb)
| ed wrote:
| It takes something like 18 light years of lead to attenuate a
| neutrino beam by half, so they'd need a pretty big receiver
| :)
| Accujack wrote:
| It's possible to detect neutrinos with a scintillation
| chamber, but in general only a tiny fraction of neutrinos
| passing through would be observed. They really don't
| interact with regular matter much.
|
| However, it's the transmitter that would be nearly
| impossible, because blocking neutrinos or affecting them in
| such a way as to modulate the beam would be extremely
| difficult.
|
| I think we can probably rule out neutrino based
| communications during the cold war, especially since VLF
| did the job just fine.
| jjk166 wrote:
| Modulating neutrinos is easy. You just control the
| production rate. For example ramping a fission reactor up
| and down will create pulses of neutrinos (though it's not
| terribly efficient). For practical neutrino
| communications, you'd want to use a muon beam to generate
| your neutrinos. The neutrinos are emitted roughly in the
| same direction the muons were moving when they decay, so
| you can make a directional beam, and by controlling the
| number of muons decaying at any given point in time,
| either by directly controlling the number of muons or how
| much time dilation they experience in the beam, you can
| ramp up and down neutrino production.
| java-man wrote:
| The "rumor" referred to an array of scintillators dragged
| behid the submarine, with the ocean water as a detecting
| medium. In theory, with clear enough water and large
| enough detector volume, that idea might work. I vaguely
| recall data rate of less than one bit per second.
| cozzyd wrote:
| Sure you can detect neutrinos that way, especially at
| higher energies. But you're going to be swamped by
| natural neutrinos (e.g. atmospherics), unless you have
| quite the beam. And how do you know where to point the
| beam?
| ISL wrote:
| The data-rate would be far below 1 bps. The event-rate in
| SuperK [1] from the _Sun_ was ~0.1 /day/kiloton of water.
|
| Signalling to submarines would require a Fermilab or
| T2K-caliber accelerator with an ability to direct a beam,
| with a properly-oriented pion-decay hall, generally in
| the known direction of the submarine _and_ highly-
| synchronized clocks (or a clever time-structure strategy)
| to allow coincidence-detection for background-
| suppression.
|
| For scale, the MINOS detector [2] detected a couple
| thousand events with a couple of years of beam-time.
|
| [1] https://en.wikipedia.org/wiki/Super-
| Kamiokande#/media/File:N...
|
| [2] https://arxiv.org/pdf/1103.0340.pdf
| extrapickles wrote:
| That sounds a lot like the ELF radio system they used,
| which basically was used to order submarines to surface
| (or near enough) to receive new orders as the bandwidth
| was <1 baud.
|
| https://en.m.wikipedia.org/wiki/Extremely_low_frequency
| bostonsre wrote:
| Yea, I'm curious about this as well and what bit rate they were
| able to achieve. Wondering if it could be used for high
| frequency trading in the future since I would think neutrons
| going straight from source to destination would be faster than
| any other communication method (no idea if this would be too
| dangerous or not tho).
| djsbs wrote:
| With neutrons, no. They're slow, isotropic and thermalize
| easily.
|
| With neutrinos that'd be a different story. They travel at
| the speed of light (or just below it - depends who you ask)
| and they aren't readily absorbed by anything. Therefore they
| can travel through the earth instead of around it.
|
| Problem?
|
| Generation, modulation and detection of neutrinos.
| cozzyd wrote:
| https://arxiv.org/abs/1203.2847
| bostonsre wrote:
| Yep, I was still asleep, good call.
| gnufx wrote:
| > They're slow, isotropic
|
| Not necessarily, if produced with an accelerator.
| (Potentially a nuisance to gamma-ray spectroscopists,
| generating spurious anisotropic scattering peaks.)
| Otherwise, yes.
| darig wrote:
| 1 bit every 10 seconds would never be used for HFT
| [deleted]
| sobellian wrote:
| I would be very surprised if neutrons travel faster than a
| microwave beam.
| xvedejas wrote:
| Radio waves already travel at the speed of light, I'm curious
| what speed-up you're imagining? A shortcut through the earth
| is the only option I can think of to beat radio's latency.
| cozzyd wrote:
| Yeah, you would significant time on some routes (e.g. NYC
| to Sydney or whatever), but in practice, the modulation
| time is probably going to kill you even if the neutrinos
| make it there faster. In the most extreme case (antipodal
| communication), the neutrinos take 43 ms to traverse the
| Earth and radio takes 67 ms to go around the Earth (ok, in
| practice a bit more since your fastest path would be via
| LEO satellites, and each hop adds a bit of latency, but it
| could be made small). But RF signals have MHz-GHz of
| bandwidth and huge SNR.
|
| To take advantage of being 20 ms early, you'd need to be
| able to detect neutrinos at greater than 50 Hz from the
| other side of the world. For context, the planned 40 kton
| DUNE far detector a mere 1300 km from the world's most
| powerful neutrino beam at Fermilab, will have a neutrino
| rate from the beam of a few a day. So yes, highly
| impractical.
| bjowen wrote:
| If you managed to crack the detection problem, you'd
| still likely be so saturated with solar / background
| neutrinos as to confound any real prospect of a signal.
| cozzyd wrote:
| There are two handles on this: reconstructing the
| energy/direction and making sure it's consistent with the
| beam and gating on the beam duty cycle (since at least
| the beams I'm familiar with produce neutrinos in short
| bunches, but I'm no expert).
|
| You can also add modulation to the beam to encode more
| information to help discriminate against backgrounds but
| that might require even more rate...
| scheme271 wrote:
| Radio waves in a vacuum travel at c. They move more slowly
| in things like copper. Light in fiber cables travel at
| about 2/3 c so a neutrino beam would be faster and
| potentially have a shorter distance by going through the
| earth. Actually designing and implementing a communications
| system using neutrinos is an exercise left to the reader.
| News-Dog wrote:
| Electrostatic positional modulation of a heavy water droplet
| ultrasonic suspended over the aperture of the radiation source?
| tyingq wrote:
| 0.1 Baud? Hah!
| dang wrote:
| " _Please don 't post shallow dismissals, especially of other
| people's work. A good critical comment teaches us something._"
|
| https://news.ycombinator.com/newsguidelines.html
|
| (We detached this subthread from
| https://news.ycombinator.com/item?id=29203516.)
| tyingq wrote:
| Got it, though it wasn't meant as a dismissal...just
| surprise.
| dang wrote:
| Ah. These things don't always come across.
| [deleted]
| GekkePrutser wrote:
| It raises the question... Why? It's not practical and very
| unwelcome for many obvious reasons. Like really in what
| environment does it make sense to introduce radiation just for
| the sake of data transfer?
| pm90 wrote:
| Just because it doesn't have any immediate applications right
| now doesn't mean it won't in the future.
| RosanaAnaDana wrote:
| Space?
| OldHand2018 wrote:
| "In some safety-critical scenarios, such as concerning the
| integrity of reactor containments, and metal vaults and
| bulkheads in maritime structures, it can be important to
| minimise the number of penetrations made through such metal
| structures for communications cabling. The use of neutrons
| for information transmission through such structures could
| negate the need for such penetrations and is perhaps also
| relevant to scenarios where limited transmissions are
| desirable in difficult circumstances, such as for emergency
| rescue operations."
| ericpauley wrote:
| I don't buy it. Clearly one has to run power to this
| transmission device. Once you've drilled a single hole for
| this all it takes is one tiny wire to vastly exceed the
| data capacity of this system. You could probably even send
| data at far higher bitrate over the existing power cable
| itself.
| jjk166 wrote:
| You don't need to penetrate the wall if you have power
| sources on both sides of the wall.
| klyrs wrote:
| Why is that obvious? Couldn't they use an RTG to power
| the device without the need for a wire?
|
| Though... it does seem like a piezoelectric transducer,
| or even a relay, could transmit an audio signal through a
| solid metal bulkhead much more efficiently.
| curryst wrote:
| Submarines often track each other via noise. I don't
| think you want to make noises loud enough to be heard
| through a solid metal bulkhead on a regular basis, since
| the same will likely be true outside the submarine. Those
| bulkheads are also structural components, I believe, so
| the metal is quite thick, and the sound would likely echo
| through the submarine and drive the sailors mad.
| djsbs wrote:
| Use a magnet instead then. Flip it over with the pneumatic
| arm.
| 27182818284 wrote:
| The first trans-atlantic telegraph message took 16 hours to
| send.
| pishpash wrote:
| Probably military applications too if it evades conventional
| detection.
| sizzle wrote:
| There can be many innovative use cases in industry or
| military applications where wires cannot penetrate the
| surface of an object and other signals are too weak to
| penetrate the object to transmit data about something mission
| critical.
|
| This warrants future investigation at the very least, however
| impractical it may be. Quantum computers may also benefit
| from this technology, etc.
| tyingq wrote:
| It would be interesting to see what places some other
| alternative like sound, light, laser, VLF, etc, aren't
| viable options.
| djsbs wrote:
| You're basically right.
|
| Miners trapped in a cave not penetrated by E&M waves?
|
| Wont work.
|
| Signal from inside a reactor?
|
| No. No logic can modulate the signal in said reactor that
| isn't destroyed by the radiation.
|
| If you have a pneumatic arm to modulate this thing, use it to
| flip a magnet. That'll better penetrate any shield than
| neutrons.
| jjk166 wrote:
| Why wouldn't it work for the miners or the reactor?
|
| Neutrons pass through rock quite well.
|
| Reactors are basically just giant neutron transmitters, by
| modulating reactor output you also modulate their neutron
| output.
|
| Flipping a magnet definitely won't penetrate a shield
| better than neutrons, in fact because of Gauss' law it
| probably won't penetrate at all.
| djsbs wrote:
| Rock's absorption of neutrons doesn't matter. Neutron
| thermalize. Since rock has mostly low atomic weight
| isotopes, it thermalizes them very well [1]. Once they
| are thermal they scatter easily.
|
| Gauss' law is for the electric field. The magnetic field
| is very difficult to block and we have incredibly
| sensitive magnetometers (probably ones that can detect
| magnetic anomalies of a submarine from space)
|
| In fact, thats pretty much how deep submarine
| communication works very low frequency fields. Thats why
| I proposed a magnet: a basically static field that cant
| be blocked.
|
| Is my proposal practical? Well, typically not. But if the
| alternative is neutron communication, I dont see why not.
|
| [1] to a first approx think of thermalizing as momentum
| exchange upon collision. If you're similar in mass to the
| colliding mass you'll exchange more momentum. Assuming
| rock is mostly silicon, w/ a mass 28 times larger than a
| neutron. And there's at least a km of rock above miners.
|
| [2] throttle a reactor to modulate neutron? Oh boy!
|
| EDIT: actually the crust is mostly oxygen, atomic mass
| 16. That only strengthens my argument.
| londons_explore wrote:
| I believe the theoretical throughput of a modulated neutrons
| is _very_ _very_ high - substantially higher than the
| electromagnetic waves we send today.
|
| Given that, perhaps the people of 1000 years from now will be
| using them to do data transfer because electromagnetic waves
| are far too primitive and low bandwidth.
| gnufx wrote:
| On the basis of what physics?
| jfoutz wrote:
| I like to point at the signal fire in lord of the rings.
| Absurdly elaborate communication system that can only one shot
| a single bit. But it's far far faster than any alternative. And
| if both sides understand the meaning of the message, it could
| be worth it.
|
| I could see a regular pulse being a useful monitoring system
| for (whatever they care about). no pulse, send help.
| jjk166 wrote:
| Although the beacon system (technically a form of semaphore)
| could likely have been much better optimized.
|
| For example, if a single pyre went unattended or was
| otherwise unable to light their fire (for example say an orc
| band attacked it), the whole system would fail, and there
| would be no way of knowing that it had failed. Consider also
| the possibility that one of the teams may have been able to
| light their fire, but for fear of drawing enemy attention to
| themselves, choose not to. Same effect. A more failsafe
| option would be to have the fires constantly burning with the
| light being cut off as the signal bit. This could be
| accomplished quickly and easily by having some shutter that
| drops down and blocks the fire's light. If one of the
| stations were abandoned or damaged, its fire would go out,
| alerting the network that something was amiss. This also
| means that the cowards who don't want to alert orcs to their
| position need only stop tending their station when in danger,
| and they are free to flee.
|
| Of course once you have some shutter in place to quickly
| block out light, you can presumably raise and lower the
| shutter. With an appropriate protocol, you can essentially
| achieve a visual telegraph. If each station maintains two
| fires, you can achieve bi-directional communication. This is
| also good for eliminating false positives for the main alert
| function if one fire just goes out for some reason.
|
| It's interesting that real life semaphore systems like
| Phryctoria or the Byzantine Beacons did not implement fail-
| safe methods.
| AlotOfReading wrote:
| Logistically, fail-safes are expensive. Keeping a fire
| burning for days and years takes a lot of firewood, which
| in turn requires manpower. Having two fires also places
| limitations on the distance they can be due to the angular
| resolution of the human eye. That'd be anywhere from 5-10
| miles on basic assumptions. A signal fire can be seen from
| farther if you have the elevation and a smoke signal
| doesn't even require that (+ carries more information).
| spoonjim wrote:
| You don't have to use a fictional example of a signal fire...
| it was used in ancient China to send exactly this message:
| "Send the army"
| jfoutz wrote:
| Neat! I didn't know, thank you!
| FredPret wrote:
| This is probably the tech that drives the Pip-Boy
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