Imagine an advanced alien race that seeded a planet with species capable of written communication. While the alien race is on the planet for a few generations it wants to remain mostly hidden from the species. But before it leaves it wants the species to be able to:

  1. Find out who seeded them
  2. Find the alien race across the universe
  3. Travel to the alien race across the universe

But only after the species has advanced significantly enough to build computational power of a certain level since the FTL travel technology requires more computational power than the computers in the rockets from the '60s.

How would an alien race hide information about its presence, location, and FTL travel before the species was ready for it? Specifically could this information be encoded in some written communication that wouldn't be discovered (the information not the communication) till the species could find patterns in said communication through their advanced computational power?

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    $\begingroup$ Maybe they could hide it in the DNA of the species :D $\endgroup$ – Sec SE - clear Monica's name Mar 12 '17 at 21:21
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    $\begingroup$ Just sayin, 2001 A Space Odyssey based on Arthur C. Clark's Sentinel did all of this if you subtract the FTL requirement and allowed the Aliens the ability to transport Humans to them but only when they have Space Travel. $\endgroup$ – Enigma Maitreya Mar 13 '17 at 2:56

When a vehicle travels faster than sound, it produces the sonic bang.

When a vehicle travels faster than light, it is reasonable to assume it can produce a "light" bang. This can be something similar to what happens for particles, and it is known as Cherenkov radiation. We can assume therefore than FTL travel will have its specific "fingerprint", of which the seeders are well aware, since they already master the technology. Let's agree to call this fingerprint "FTL trigger".

Therefore the seeders can set up a trigger tuned on the "FTL trigger". When the trigger is activated, the seal on the message is broken and the message itself becomes visible.

The message itself can be hidden on the Moon:

  • away from techtonics and weathering

  • easily visible by the entire world population

  • just 1 light-second away from Earth

  • conveniently located close to the testing ground for the FTL devices

  • $\begingroup$ If I read your link correctly something has to go faster than the phase velocity of light in a certain material, which is different from c, the speed of light in a vaccum. When reading your answer I first thought something was supposed to go faster than c and as far as I know that is not possible. It might be a good idea to elaborate this point in your answer in greater detail. $\endgroup$ – Sec SE - clear Monica's name Mar 13 '17 at 9:42
  • $\begingroup$ @Secespitus, I edited the answer. Since I don't know the FTL physics, I cannot tell if the Cherenkov radiation will apply to it, but still I think that FTL will show some peculiar phenomena which can be used as fingerprint. $\endgroup$ – L.Dutch - Reinstate Monica Mar 13 '17 at 9:51

Leave a present. When artificial radio waves are detected, blow up a mountain that the present is left under, and send your message in the skies on e.g. metallic plates in many many copies.

It's not hard to choose a mountain that will not have many people around when this happens, but draws attention nevertheless.

You can also think of many triggers besides radio.


The mother race could send some sort of constant signal through radio waves. The communication could be encrypted, and would also act as a compass pointing straight towards "home".

  • $\begingroup$ So, it's revealed once they invent radio astronomy. You might make that explicit. The location is revealed even without being abke to decrypt. And how do they learn to decrypt the main message at the right time when it should be revealed? $\endgroup$ – JDługosz Mar 13 '17 at 6:14

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