There is a construction fleet that has turned up on earth, to prepare it for extraterrestrial visitors (it's the new galactic place to be).

In order to assist the locals (us) in understanding what is happening, the construction fleet has a Wikipedia page that is broadcast around the globe sends a signal that has accessible information about its purpose and intent. While the signal that is sent is intended to be easy and obvious to discover, we are simply not advanced enough to find it easily.

What sort of signal could this be based on, that would make it difficult to find, but could be stumbled on by some kid in his basement?

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    $\begingroup$ This feels a lot like a plot element. Putting aside that "we are simply not advanced enough to have found it" and "be discoverable by a kid in his basement, but not by the world at large" are striking against each other. $\endgroup$
    – L.Dutch
    Apr 26, 2023 at 13:17
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    $\begingroup$ I'm not exactly sure what the question means by a Wikipedia page which is hard to discover. It's a Wikipedia page. Wikipedia pages are, you know, accessible from wikipedia.org; Wikimedia (the foundation who owns Wikipedia) actually publishes a full index of all the pages. Google will discover it in about five minutes. Moreover, a Wikipedia page is not a "signal" in any reasonable understanding of the word signal. $\endgroup$
    – AlexP
    Apr 26, 2023 at 13:19
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    $\begingroup$ @Michael B What do you mean by an alien Wikipedia page? Do you mean the aliens create a page that’s hosted on Wikipedia that describes their activities? Or are you saying that the aliens have created a page that is SIMILAR to a Wikipedia page that they’ve sent out in some proprietary alien signal? If it’s actually hosted on Wikipedia, then humanity would obviously be advanced enough to discover it. Whether it might fly under the radar and not be noticed is another question entirely. It could be that most people don’t notice it, especially if it’s disguised as a page about something else. $\endgroup$
    – Kal Madda
    Apr 26, 2023 at 13:30
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    $\begingroup$ (1) We'd see the alien ships. (2) We'd point radio antennae at them, and start recording. (3) Any regular "pulses" would be understood as "signals". (4) The aliens know we're not advanced. (5) If they want us to understand them, they'd start with simple signals, and then increase complexity. $\endgroup$
    – RonJohn
    Apr 26, 2023 at 14:10
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    $\begingroup$ @cconsta1 A reference to Hitchhiker's Guide To the Galaxy $\endgroup$
    – VLAZ
    Apr 27, 2023 at 6:24

4 Answers 4


I think most answers will have to assume a level of ignorance on the part of the aliens, which may be perfectly reasonable, especially for a "construction fleet". They are following some standard protocol, which happens to not take into account that the target planet has no such technology. They lift our language translation tables from some database but fail to notice that we are a "Tech Class 2" planet. It's meant to be "easy" for any member of the Galactic Federation or whatever, but no one told the construction company that we are not in the Galactic Federation and no one ever gave us the standard receivers or protocols.

Too common of a frequency, with too low power. Perhaps, for example, the aliens start broadcasting on the same frequencies used by Starlink*. This is coincidental. In the Galactic Federation, this frequency range is reserved for exactly this kind of important orbital information, and they transmit very low power because alien receivers are very sensitive and simply don't need higher power transmissions. So the aliens are sending the signal and the only one who notices at all is a handful of Starlink technicians trying to track down the source of some "interference". They are still debugging satellite transmitters trying to figure out why the signals are a little lossy.

SETI doesn't notice because SETI intentionally ignores common "human traffic" frequencies, by necessity.

Various federal agencies would eventually get involved but they aren't sitting around looking for interference and Starlink hasn't reported it to them yet.

Some kid in his basement happens to be the first to find it because he's a self-styled hacker and was trying, on his own, to decode Starlink signals. He's in an area with spotty coverage and notices that when no Starlink satellites are overhead, he still gets this faint and distinctly different signal, which he is able to decode and pull data out of: basically a live stream of a formatted text and image page, similar to a Wiki, being sent over and over in various Earth languages.

Another possibility is some compression scheme, which is "easy and obvious" from an alien point of view, but no one on earth can figure it out. Cue the standard "genius kid hacker" trope to be the first to decode it. In this case, everyone sees the signal, we just can't read it.

(* - note, I'm recommending something like a Starlink satellite to ground frequency, in the 10 GHz - 12 GHZ or 37 GHz - 42 GHz range, because lower frequencies are lower bandwidth so I suspect aliens trying to transmit any volume of information would probably avoid, say, FM radio frequencies. When selecting a frequency, see also, atmospheric absorption. Some frequencies are not suitable for space to ground transmissions and we can assume the aliens would avoid that. Also, the fact that there is already a "signal from space" on that frequency would help mask the obviousness of the alien transmission.)

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    $\begingroup$ That is a perfect answer, thank you kindly :) $\endgroup$
    – Michael B
    Apr 26, 2023 at 20:24
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    $\begingroup$ This sounds like a movie script from the 1980s or early 1990s. $\endgroup$
    – RonJohn
    Apr 28, 2023 at 14:33

They made it so obvious we thought it was a natural signal

According to the construction company's standard notice policy, they must give a notice that is about equivalent to 100 Earth years which must be broadcast continuously such that it can be observed anywhere in the solar system of interest, by any species that can see or detect the microwave spectrum. Also, you gotta cover the whole solar system just to make sure you don't accidently miss anyone.

As an added precaution, they don't want to risk anyone missing the message because of some confusing encoding method; so, instead of transmitting a binary pulsing string with some unknowable codex like we humans have a tendency of doing, this race transmits the message in such a way that it can be read like note. A continuous signal literally written into the night sky.

The problem is that this signal was already broadcasting by the time we first measured Cosmic Background Radiation (CBR); so, instead of waking up one day to some drastic change in the apparent background radiation of the universe... it has just always been there as far as we can tell and we've built all of our models and understanding about the universe around the assumption that this signal is just a part of nature.

Sorry science, turns out, we don't live in an expanding universe, that was just an alien message to let us know they are coming.

The reason no one ever realized it was an alien signal is that we were looking for natural patterns to explain it instead of unnatural patterns, and to us the exact portion of the CBR that contains the message just looks like random shapes. But lucky for us, AI is much better at finding patterns in randomness than we are.

So, in the not so distant future, a local politician with a completely unremarkable name like Chris Brian Rigden is running for office, and some mildly interested collage kid casually asks ChatGPT "What does CBR say about urban development"... and much to his surprise, ChatGPT auto corrects to try to find the answer to "What does the CBR say about urban development". So ChatGPT does its thing, finds the pattern contained in the CBR and delivers the alien message to a now very confused young man.


Option 1: Faint signal

The signal is sent with radio waves picked up by any FM radio. Unfortunately, the aliens greatly overestimated the sensitivity of human FM radios, so the signal is inaudible... unless you happen to be right next to one of the transmitting devices, which the aliens have scattered around the planet. It just so happens that one of the transmitters was placed very near the kid's basement, so when he tunes in to the right frequency on his pocket radio he can pick it up.

Option 2: Poor user interface

The aliens set up a web site on the public internet. However, the alien intern who set the site up in an afternoon had no understanding of human user interface design. As a result the website looks like trash and is practically impossible to navigate, the buttons are microscopic and the layout is broken, and a lot of code is buggy. No one bothered to look closer at the strange, buggy, poorly advertised website... except for this one bored kid in his basement.

Option 3: Obsolete technology

The aliens didn't set up a web site, they set up a Gopher site, so only a hobbyist in the obsolete Gopher protocol could discover it, and this kid happens to be one. Or it's a classic BBS site. This could be explained if the aliens put the system together decades ago, before arriving at Earth, based on transmissions from Earth from decades ago.

Option 4: Ultrasound

The aliens wanted the signal to be available to everyone on Earth without special equipment. Humans have ears, right? Sensing air vibrations is a thing humans can do? So they broadcast the signal as sound waves for humans to hear.

It just so happens that the sound waves they chose are so high frequency almost no one can hear them. People lose their ability to perceive high frequencies as they age, so only a kid could possibly hear it. It turns out that this particular kid has the genetic ability to hear unusually high sounds even for a kid, and also he happens to be fairly close to one of the sound transmitters.

Option 5: psychic signal

It's a psychic signal, but due to an oversight human brains are not capable of receiving it. The kid, however, can. Why? Several options.

  • He has a mutation that makes him capable of receiving the signal.
  • Certain bugs, such as stink bugs, can naturally receive the psychic signal, and retransmit it at a very short range in a form the human brain can perceive. The kid was playing with a stink bug and letting it crawl on his head, and that's when he started hearing the aliens.
  • The psychic signal acts via the human imagination. You have to be in the right frame of mind, which is imaginative play, like kids do, in order to receive it. The kid is pretending to be a pirate and he starts imagining there's a little alien on the imaginary pirate ship, and he imagines the little alien is talking to him, and he finds he can imagine asking it questions and then imagine it telling him funny things.
  • $\begingroup$ Option #3 is pretty good. Reminds me of Matthew Broderick using an IMSAI 8080 years after it was thoroughly obsolete. $\endgroup$
    – RonJohn
    Apr 28, 2023 at 16:48

Bandwidth. They're using their equivalent of WiFi, but it spreads the signal over a much wider part of the spectrum. Furthermore, it's using a very efficient compression technology.

Put these together and if you don't know the encoding it will not even look like a signal. They seeded low orbit with wifi nodes that don't require passwords and don't realize we don't know how to talk to them.

(Real world example: If you don't know the encoding system for GPS you would be hard pressed to find the signal as it's coming in 20db below the noise floor.)

  • $\begingroup$ The problem with faint and spread spectrum transmission is you end up drowned by "noise", such as we primitive terrestrials are still using. Remember our first "mobile phones" used to transmit 100 times the power we use now. If the aliens really use our own freqs, we'd be drowning out all of their signals with our primitive tech. $\endgroup$ May 2, 2023 at 3:54

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