This seems nonsensical to me. Just like internet protocols, any radio transmission is built on a layer of protocols that envelope the actual data being transmitted.
Encryption is applied on the data layers not to hide that something is being transmitted, but what is being transmitted.
However scientists aren't even trying to detect signals with any sort of data in it, but merely radio emissions that look like they might come from something with an intellect.
If we haven't found anything like that yet, and encryption is supposed to be the reason, then that means that encryption would have to be applied at the most basic protocol layer in such a way that even the physical properties of the emission look like the universe's background radiation. Is there currently human technology that does anything similar to this?
What if it's such advanced protocol layering and encryption that those alien signals appear to us to be "cosmic noise"? Surely an advanced civilization would have advanced communication capabilities we haven't even considered.
> What if it's such advanced protocol layering and encryption that those alien signals appear to us to be "cosmic noise"?
Another interesting way to speculate is the "under our nose" concept, which is the concept that the existing distribution of stars and galaxies, as well as the recorded background noise, might be the byproduct of alien intervention. Binary star systems are a popular speculative example of "starivore" civilizations that consume entire stars that have been moved into the alien civilization's own star system, and perhaps some combination of multiple stars in a single system are not "naturally" occurring in the absence of alien influence. To an unsuspecting observer, some forms of distant astronomical-scale engineering could be mistakenly interpreted as natural astrophysics that the observers then incorporate into their standard models when refactoring to account for all of the observed data... Usually the simple explanations are correct, but when your models require really insane updates to handle the observed data, perhaps there are other explanations? At the same time though, what recourse would we have if 99% of the visible universe was already astro-engineered?
If binary star systems were systems in which stars were moved into the system, we should see evidence of stars being moved and consumed. I have also read about stars being created (e.g., starting a fusion process with all the hydrogen and helium in Jupiter, Saturn, etc.).
There is currently no evidence which suggests stars are being moved. We should see either large gravitational tugs or engines such as Shkadov thrusters. The latter should be plainly visible. The former should be easily detected by extrasolar planet detection methods. Unless the tugs are spherical, the light curves of the tugs would definitely pique interest. In any case, moving a star seems a rather extreme and expensive measure. It is probably more effective to consume the star onsite and use the energy locally or send only the energy back.
There seems to be no evidence of stars being consumed, either. Dyson spheres (or swarms) have actually been searched for locally by comparing visible and infrared wavelengths over sections of the sky. None have been found. Intergalactic searches have also been done by looking for galaxies which glow too brightly in the far infrared. No luck.
It is not just a question of a mistaken belief that the artificial is natural. The properties of light are the same here on Earth as they are billions of light years away. Further, for all those galaxies and stars to be engineered in the same way aross billions of light years (with some points being unable to communicate with others since the Big Bang), is all but impossible. Life would have to evolve at effectively the same rate and come up with the same solutions in all those hundreds of billions of galaxies (and yet somehow be different here in the Milky Way). Given the variety of life on Earth and the variety of solutions it has evolved, that seems unlikely.
There are hundreds of billions of galaxies at various distances from Earth. When we look out at those different distances, we are also looking out at time. So we have something of the full spectrum of galactic evolution. Even if these events happened "long ago" we should be witnessing them somewhere.
Locally, if these events happend long ago, surely they would have been here by now, harvesting our star.
Yeah, I was gonna say. In addition to making it hard to detect it also makes the channel robust to some kinds of noise and fading. See Chirp Spread Spectrum for example http://nanotron.com/EN/CO_techn-css.php
Someone said that if any object in the Universe has a non-zero second derivative of velocity (aka jerk, or "acceleration of acceleration") it's a sign of intelligent life.
Something similar should exist in the information theory. An encrypted signal can't be "too random", there should be some metric that distinguishes an intelligently designed signal from a random one. With spread spectrum and other tricks they can make it harder but not impossible to detect and separate from pure noise.
What is that metric? I have no idea, just trying to theorize. At least the opposite should be true, that for example the cosmic microwave background can not carry any useful/meaningful information other than just "signatures" of the particles that emitted the signal. So there should be some metric that's different for CMB and any signal that has something else in it.
Edit: I don't think the metric in question is entropy, although someone might convince us that it is. The problem with entropy is that, an object that consists of just a few types of atoms may emit a signal that would look very "orderly". That signal would be the spectrum with a few distinct frequencies in it typically emitted by those atoms.
It's computationally distinguishable from noise iff you have the decryption key.
The key word here is "computationally". A signal encrypted with a non-OTP symmetric key can be distinguished from noise without the key — unfortunately, for modern key sizes (128, 196, or 256 bits), the cost of doing so is prohibitively expensive for even arbitrarily advanced civilizations, unless (as Brice Schneier put it) they are building computers out of something other than matter that occupy something other than space.
Because the only way to make your signal appear more random is to add more redundancy. In order to make it look like an absolute random signal you'd have to add infinite redundancy.
> Someone said that if any object in the Universe has a non-zero second derivative of velocity (aka jerk, or "acceleration of acceleration") it's a sign of intelligent life.
Not sure what someone could possibly mean by that. Pretty much every celestial body has non-zero jerk. For instance, earth's acceleration is (to pretty good approximation) a constant times the $-e_r/r^2$, and the time derivative of that is definitely not zero.
It is not. $e_r$ is a rotating vector, not constant. Also $r$ is not really constant either.
Actually, if you think about it, the only plausible way you could have something in space with zero jerk and non-zero acceleration would be an interstellar ship maintaining constant acceleration, so the suggested rule is almost exactly wrong.
A more advanced civilization will have gotten much better at avoiding the energy waste of sending a signal except to where they want it to go.
The Drake equation of detecting intelligent life based on their signal emission needs a few extra terms for accounting for energy efficiency or perhaps even deliberate discretion (https://xkcd.com/1377/).
If we did pass through their data laser or whathaveyou, then perhaps it would be unintelligible encrypted information, but that's not something that seems likely to happen (even if things aligned perfectly, other star systems - particularly those with radio emitting civilizations - are probably too noisy to try to transmit through).
The physics of electromagentism doesn't diverge all that much when you're talking about stray signals from alien satellites or radio arrays. So long as you use the radio spectrum to send signals out to satellites or interplanetary systems (probes, colonies, whatever) you're going to get spotted. Laser signaling may be the only alternative I can think of that wouldn't be so easily detected and probably lower power too, but that's it.
The only other alternative I can hazard speculation on is possibly gravity wave signaling? It's a bit of a stretch in my mind since the only real way to do that is to assume certain kinds of unproven particles like gravitinos (these are supposedly able to be interacted with in superconducting materials last time I read about them).
Even without any encryption, a perfectly compressed signal will be indistinguishable from random noise. Of course, it might still be distinguishably artificial depending on how it is encoded, but I believe that the SETI searches that have been done to date would not find that kind of signal.
> Is there currently human technology that does anything similar to this?
Steganography. Not "background", in the sense that images are generally considered useful, but it is hiding information in a place that a casual onlooker would not think to look.
> Encryption is applied on the data layers not to hide that something is being transmitted, but what is being transmitted.
That's exactly why this encryption would be strong. Initially, no one thinks to look for signals that don't look like signals.
Yes, I believe so. Suppose the form of encryption is a one-time pad which specifies which frequencies upon which to transmit each bit. The signal on each frequency is well within the range of background noise. However if listening on a expected successive sets of frequencies bits may be read.
> Is there currently human technology that does anything similar to this?
Any sort of steganography tries to achieve something similar. I wouldn't be surprised if something similar would be used in military radio communications.
Hollywood IT proposes that people who know nothing about computers all "know" that every computer thing that has ever been invented is trivially interoperable with every other computer thing that has ever been invented on a fast hollywood movie timescale given a sufficiently advanced computer mage to recite some incantations and be treated as socially inferior if its a plot requirement. I think everyone here is experienced enough to laugh at that.
There is an EXTREMELY close analogy in EE / telecom land where people with no domain specific knowledge think all radio hardware, modulation methods, protocols, are all trivially interoperable with each other. Sure... go ahead and try to listen to trunked public service comms using a spark gap era coherer detector, good luck with that. Or try to listen to 60s era SSB voice using 30s era AM receiver. Higher order PSK/QAM is indistinguishable from white noise on a non-phase oriented receiver. This is all before we get into weirdness like trivial line coding, think of old T-1 circuits and B8ZS "scrambling" to get around the clock sync limitations of AMI line coding. Try to use an aircraft NDB receiver on GPS satellites or vice versa in order to navigate. Or connect an accurate clock built to sync to WWVB to the GPS constellation instead, or again vice versa. Telecom, being usually run at the limit of hardware when it was new, is even less interoperable than "computers in general". Given poor interoperation pragmatic results on our own planet, the odds of communicating with space aliens is basically zero, even the odds of detecting are almost zero.
> Hollywood IT proposes that people who know nothing about computers all "know" that every computer thing that has ever been invented is trivially interoperable with every other computer thing that has ever been invented on a fast hollywood movie timescale given a sufficiently advanced computer mage to recite some incantations and be treated as socially inferior if its a plot requirement. I think everyone here is experienced enough to laugh at that.
Yes, although the details are important.
On a theoretical scale without any time limits and any space limits, anything every invented is interoperable with every other computer every invented. Hollywood is not really wrong there but just tosses out the practical issues because of the rule of cool. And "no time and space limits" is just wishful thinking as every computer has those constraints.
Of course, trying to hook up a Mac to a alien computer for transferring a computer virus is not impossible. It's just highly unlikely to succeed within a few hours of preparation. But it would have made a less entertaining movie. ;-)
I am far from a HAM or radio pro, but doesn't SDR actually make some of this possible? Not using ancient sets to listen to modern signals, but using one set of kit to rule them all, as it were?
Only kind of. If someone hasn't seen fit to write the code for a 240 hz morse code filter, you don't get one. Or a very advanced AGC filter. Those are "easy" because you could modify an existing set of code, assuming open source application. GNUradio has a compile/run architecture although you can build rather highly configurable real time systems so it's "close" to programming in real time.
Harder is something like "digital radio monodiale" which aside from having an unfortunate acronym is a digital shortwave voice modulation scheme... without having the specs in front it would be very hard to decide where to start. There are military intelligence people who do exactly this stuff with captured enemy signals, given an enormous head start of knowing the rough technology level of the other side and maybe some stolen documents. Still its not easy for them. A good analogy would be imagine a radio intelligence officer in WWII heard some 8VSB over the air broadcast TV from 2015... honestly I think you'd end up with question marks for at least 50 years trying to figure that signal out in 1940.
Right now, perhaps we are getting a 40 dB below the noise digital data signal from space aliens. Without any idea how to build the specific demod, we're going to get nowhere, and a level that low below the noise floor will not show up on any normal waterfall so we'd likely miss it.
Existing modes tend to reflect hardware ability. So some gear some of the time is stable enough to use WSPR modulation which is an ultra low bandwidth digital mode for HF (shortwave)... some gear drifts in frequency too much to use it, today. Oscillator stability can be improved to make it work, but replacing the IF stages with A/D converters won't do it, takes more than just doing demodulation in software with SDR instead of in hardware to fix the root frequency stability problem. Its possible space aliens modulation method would assume close in phase noise or IMD performance beyond 2015 capabilities, because for them its trivial star trek dilithium crystal stuff or whatever, but we're not going to invent the noise free monochromatic oscillator for another 150 years or whatever, so the front end performance of our radios wouldn't be good enough even with a preprogrammed SDR on the back end to demodulate. Another example, we don't have the technology today or the legal framework to do "real" beyond ultra wide band RF work, but there's no reason to think space aliens wouldn't.
Then we have almost no chance to detect it anyway unless we almost spot on between sender and receiver. But this is a similar constraint to detecting exoplanets with the transit method. Star, planet and Earth have to be in one line for this method to work.
We are detecting lots of potential planets with this method, so if technical alien civilizations were as abundant as planet we should have detected a few already. ;-)
BTW, we ourselves stopped to do the "blasting a signal in every direction" like we used to 50 years ago. With fiber optics, satellites, and other modern technology, we are leaking much less electromagnetic radiation. The chance of another civilization picking up us is shrinking.
A slightly-off-topic thought related to the Fermi question.
What actually is the point of communicating at sub-luminal speed between star systems or galaxies, other than CETI projects? The delay between transmissions would make such communication impractical for day-to-day purposes.
Perhaps this is one possible explanation for the apparent lack of such signals. Either the aliens don't bother much with communicating at galactic scales, or they have developed a system of doing so at super-luminal speeds that eludes our current understanding of physics.
If this is correct then you would expect most artificial radio signals to be easy to detect and decipher, because the only plausible use for such signals is long-term communication with alien civilisations. And you might also not expect to find many of them.
Seems logical to me that a civilization advanced enough for interstellar travel would have solved the problem of the extremely slow radio wave for interstellar communication. I would think we shouldn't be limiting such possible civilizations with the limitations we currently face.
Don't even have to be encrypted. Just compressing the data makes it hard to separate from noise.
Turbo Codes and LDPCs used to transmit data over noisy channels (like NASA uses in deep space satellite communications or UMTS and LTE networks) look just like noise. I don't think Seti or astronomers have ever tried to analyze noise for some alien codec that might be transmitting.
"I don't think Seti or astronomers have ever tried to analyze noise for some alien codec that might be transmitting."
They can't. "It looks like noise" isn't a metaphor, it's a mathematical truth... it is indistinguishable from noise.
This is, IMHO, another one of those cases where people like to do a bit of social signaling with their fashionable misanthropism, but we actually know quite a bit about this problem. The optimal solution for using the electromagnetic spectrum for signaling, even with our current level of technology, is to use it in such a way that it looks like noise due to compression and due to not using any more power than necessary, in any direction other than the necessary one. Of course aliens do not sit there using four or five (if not six) orders of magnitude more power than necessary by broadcasting in all directions instead of using a directional beam, and of course they do not sit there and transmit in an uncompressed format that is an obvious signal, so of course we don't see their transmissions. It would be bizarre if it were otherwise. We have no reason to believe that aliens, who live in the same universe as us and are subject to the same engineering constraints as us, would be particularly prone to missing this incredibly obvious optimization.
(Math may be the one true cross-universe universal, but within this universe engineering is pretty universal too.)
Problem - humans have been doing all of the above for decades, occasionally as a deliberate attempt to communicate, but mostly by accident.
So I can't see how your comment has any basis in fact.
You're only going to compress a data channel if you're in a hurry. When a message is going to take decades or centuries to get somewhere, you're more likely to keep the encoding as simple as possible to increase the chances of reception.
Besides that, I can't imagine radio being used for interstellar communication at all. It's fine for "Is anyone there?" but unless your aliens live at geological rather than biological rates, it's far too slow for almost anything else.
Compressing increases bandwidth, which is forever going to be at a premium. If you want to improve reception reliability, you put error correction on top of that. This is all off-the-shelf tech here on Earth, to say nothing of what aliens can come up with.
"Besides that, I can't imagine radio being used for interstellar communication at all. It's fine for "Is anyone there?" but unless your aliens live at geological rather than biological rates, it's far too slow for almost anything else."
Well, it's the fastest thing available unless you're basically willing to hypothesize magic. Anyone willing to do so is welcome to do so, and I'm serious about that; I just advocate that you be aware that you've switched to advocating magic. There's a difference between reasonable speculations based on real physics and arbitrarily advanced engineering, vs. new physics that despite all our research we still have little more than a whiff of, if that, and keeps crawling into ever more exotic energy domains to even peek at.
I think we are talking about overhearing communication between aliens speaking the same "language", where compression makes even more sense over a difficult channel. Consider data transmitted from spacecraft in our own solar system. The signal is quiet, and the bitrate is very slow. They could send uncompressed data if it is were easier to receive, but instead they recognize the bitrate as a physical constraint and optimize for information per bit. Uncompressed data could provide an advantage in terms of redundancies making errors more apparent and often recoverable, but error correction algorithms are both more robust and more efficient.
The point is that compressed transmission actually is simpler, and a formalized error correction scheme is much more reliable than relying on redundancies that arise by chance.
What about the parent comment belies anything factual? There is no data on alien transmissions, and the efficiency of compression and formalized redundancies just is, as a result of the math, not as a finding of collected data, even if real world data confirms what is mathematically understood.
Is there any point of this article? (serious question)
Or perhaps this was just some light-hearted conversation which has been reported as "news" because Snowden was involved. I can as well say that we have not yet heard from the aliens because we are yet to discover the Mass Relays and the Citadel (apologies to those who have not played the Mass Effect series of video games and this statement makes no sense).
Kind of a facile statement. Radio waves are radio waves. The spectrum is the spectrum.
Any intelligent aliens are very likely to be using the electromagnetic spectrum for wireless communications. They might use it in somewhat different ways, but the technology is still essentially the same.
For intraplanetary communication, yes, I'd agree. But those signals shouldn't be strong enough for us to detect (otherwise, what a wasteful species).
Now, for interplanetary signals, radio does not look that interesting.
There's the problem that it, like everything else, is jut too damn slow. So just the assumption that long distance communication is common is already iffy.
Then, radio is either too hard to manage, or has a too long wavelength. Yes, some hyper intelligence out there may think differently, but from our current understanding, it looks way more likely that such hyper intelligence will still find it easier to send matter, neutrinos, or whatever it is that composes most of the Universe.
>For intraplanetary communication, yes, I'd agree. But those signals shouldn't be strong enough for us to detect (otherwise, what a wasteful species).
Many of our radio signals are detectable from terrestrial sources such as radio and air TV stations. Even Ham radio signals throw out enough power for their signals to be easily detected beyond our solar system.
Eh, not really "easily." If a comparable civilization was located around Alpha Centauri, we would have to focus the equivalent of an Arecibo radio telescope at it for many months, maybe a year, to detect its presence. That's "easy" in the sense that we could do it, but it's also very expensive to do and we won't do it without having at least some idea that a civilization exists there already. The farther out we go from Earth, the harder it is, and it gets impossible (in the sense that we lack the resources to do it) very quickly with increasing distance.
For interplanetary communication, tight beams would make way more sense than broadcast. And unless one of those beams is directed at us, we aren't likely to intercept it. This is really what SETI is looking for because it's the easiest thing to look for.
Yeah, but the fact remains that it's more likely we'll get a random stray signal before we'll get an intended broadcast from another civilization. I just don't see it as being one of those things any civilization is likely to do (what's the point of communication with another civilization at such extreme distances?).
Assuming an advanced alien civilization can detect and interact with neutrinos in some way, neutrino communications could be very cost effective. They need only focus a beam from the flood of neutrinos coming from their parent star.
Lacking that, I can't imagine sending matter would be very cost effective relative to radio.
Radio spreads. You can get a small chunk of matter very near c with a small part of the energy needed to send an easily detectable UV light bean to Alpha Centaury.
That's true but I found the statement interesting. It makes sense to me that scrambled transmissions would be less likely detected among cosmic noise and even if there are protocols for finishing and ending the transmissions they might be small in scope and hard to detect. I'd never though about it that way, so it was interesting.
Anyone remotely interested in this idea should check out Stanislaw Lem's His Master's Voice [1], which is an entire (short) novel about how and why an extraterrestrial message would be encrypted. It's worth mentioning how why turns out to be the most compelling question.
A brilliant book which made me think that this is how science is really done. One of the questions is whether there is a message at all. How this message is first suspected (due to non-pseudorandom behaviour of a fraudulent table of random numbers) itself is a fresh idea. I found the various hypotheses in this book itself to be a very nice. IIRC, there is also an "opera singer" hypothesis that it is not the content of the message which matters, but its frequency.
Or it might be that advanced civilisations use more advanced means of communication. In such a vast universe, clearly superluminal communication speeds, should they be attainable, would be used. Maybe we just need to "tune in" properly.
Or both. Yes, I don't believe higher civilisations use the same means of communication we use today, just as we don't use the same as we did some centuries ago.
That might be true if you only consider technologically facilitated means of communication, otherwise simple direct speech probably still makes up the largest part of it, just like it did some centuries ago.
Though, strangely enough, only when you count it from the performative side. That is I bet overall more words are spoken each day than written down (or otherwise technically transmitted). On the receiving end, ie. hearing/reading, due to the "broadcast" nature of newspaper, radio, TV and the internet, maybe more communication is technologically facilitated than not. That is more words are read or listened to than heard directly from another person. I wonder if and when that happened.
This is possible but extremely unlikely, hence an unscientific assumption. You always assume the likely. That is is more likely that you are in the middle.
You could argue that ONE of the steps to intelligent life is unlikely, incredible more unlikely as we assume. But the questions remains: Why are they not here? I am afraid we may not like the answer, whatever it is.
The answer is obvious to me: the chances of life are very small. The universe is very big (that's some underestimation). So it is likely, that we are not alone in the universe, but we may be so far apart in terms of space and time that there will be no contact ever.
Just take a look how far our signals have travelled since we began transmitting — they only covered a small part of our own galaxy.
Another reason is that unless they want to communicate with other species, they'd use only the minimal signal strength that is required for the signal to reach its destination, not a signal strength that is several orders of magnitude higher.
That and our limited brain capacity, which prevents us from recognizing and/or understanding a message from an advanced alien civilization.
I like the thought, but encryption is not enough to hide it from us, it'd require steganography.
If all communication itself on Earth were encrypted, how much of a visible signal would we still emit? You wouldn't be able to decypher the communication, but you'd still see that something is happening that's requires a structuring intelligence behind it. Unless they pay special attention to not only encrypting their communication but masking it as a natural phenomenon, steganographically.
If I shout an encoded message to you in a restaurant, the other people won't know that I told you to order the creme brulee, but they will know that I told you something. I'd have to discreetly tap my plate in order to mask it.
And even aside from that, you'd need to mask all other emissions, even those not designed to facilitate communication. On earth, you don't have to intercept and decrypt a rocket launch command, you can tell by the infrared (or whatever) emissions on your spy satellite.
Years ago, I attended a talk from a professor about a networking system using the Lego blocks metaphor. In his examples, he had a block labelled "encryption" and another labelled "compression" and talked about how you could arbitrarily compose the blocks in the system.
To my eternal regret, I didn't call him on the fact that those two blocks are not arbitrarily composable.
Both encryption and compression make the resulting data look random (and you can't compress encrypted data), and compression seems to be a much more likely candidate.
P.S. And spread-spectrum transmissions, as someone else mentioned.
Encryption is applied on the data layers not to hide that something is being transmitted, but what is being transmitted.
However scientists aren't even trying to detect signals with any sort of data in it, but merely radio emissions that look like they might come from something with an intellect.
If we haven't found anything like that yet, and encryption is supposed to be the reason, then that means that encryption would have to be applied at the most basic protocol layer in such a way that even the physical properties of the emission look like the universe's background radiation. Is there currently human technology that does anything similar to this?