Premise: An alien visits Earth for a short time during the middle ages, leaving behind a device which contains a vast body of scientific knowledge. The device is locked so that it can't be opened until we make certain discoveries on our own.

Guidelines: The speed of light is absolute law; no hyperspace shortcuts, no faster-than-light travel. The best technology known to the aliens still requires lifetimes of travel time. They have cryogenics, so they don't age during flight, but in starting a journey, a traveler has to sever all ties with home. No one they leave behind will still be alive if they ever return. Trans-planetary commerce is impossible due to the distances and delays.

Note that the aliens have not discovered any means of communicating across interstellar distances at any greater than light speed. If they had, interstellar commerce would still be possible, and I'm trying to avoid that.

Questions: Given the danger of travel, the personal cost and the absence of commercial potential, why did the alien come to Earth? What knowledge is in the device and what is the key discovery we need to find in order to open it?

  • $\begingroup$ what about communication across light years? Anything about subspace communications? Are the aliens also doing any research into immortality? A 100,000 year journey might be subjectively months to an immortal. $\endgroup$
    – tls
    Jan 3, 2015 at 4:40
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    $\begingroup$ Why would an alien leave a teaching device on Earth? Maybe they just dropped it. Think about all the information we can have into a cellphone for example. You can have a whole library in your hard drive. $\endgroup$
    – Vincent
    Jan 3, 2015 at 6:08
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    $\begingroup$ Monoliths from 2001: A Space Odyssey? IIRC, they were teaching devices for the ape-men. Aliens left the thing behind to learn - to catalog information about the universe and its lifeforms. Maybe it's an experiment that benefits both parties? $\endgroup$
    – Kaz Wolfe
    Jan 3, 2015 at 11:51
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    $\begingroup$ Thanks to everyone who contributed to this question. I will be using your ideas as I continue to develop this story. You've made a big difference for me and I am grateful. Apparently, this kind of story-building question is off-topic for WorldBuilding and for StackExchange as well, as it neither leads to a definitive answer nor builds a canonical reference for future visitors. Despite the fact that other plot-locked authors will not able to benefit as I have through this question, I want to thank everyone for the help. $\endgroup$ Jan 4, 2015 at 18:31
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    $\begingroup$ On second thoughts, I've voted to reopen. This isn't really an idea generation of the problematic kind. We have the basics of the story, and it's missing one element. The question could stand to be better focused (what do you hope to see happen once we've opened the device? It would help a lot if you stated an objective.), but it is answerable even as it is. $\endgroup$ Jan 4, 2015 at 23:02

7 Answers 7


Given the danger of travel, the personal cost and the absence of commercial potential, why did the alien come to Earth

It's not like a single individual and a single ship would be a noticeable cost to a society capable of spaceflight. I'd imagine an alien society with some sort of self imposed duty to civilize the galaxy, akin to Victorian society and the "White Man's Burden", would find themselves with plenty of reason to try and enlighten other life forms even if it had a small cost attached. It can also be likened to a religious mission, where people left their homelands and built religious communities among natives when they could certainly expect a life harder than where they called home. Humans seem quite inclined throughout history to do things that aren't perfectly efficient or necessarily profitable out of ideology or altruism.

what knowledge is in the device and what is the key discovery we need to find in order to open it

I can't think of anything that would objectively answer this, but perhaps the ability to download a human consciousness, maybe it's a computer that can run at a certain speed to break the code, or maybe it's just finding a constant or formula that is essential to near-lightspeed travel. It could have a history of the contacting race (to make them seem great or maybe just to show us what mistakes to avoid), advertisement of some ideology (think like the intergalactic version of a free bible or communist manifesto), and almost certainly some technological and scientific knowledge. The technology needed to become a trans-planetary species would likely be included.

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    $\begingroup$ Perhaps they want to make sure that any future intelligence is taught to beleive in the one true flying spaghetti monster, having already converted all extant species. $\endgroup$
    – JDługosz
    Jan 3, 2015 at 5:49
  • $\begingroup$ "the ability to download a human consciousness." I think you mean upload, but that along with the sufficient computer as key, makes an excellent answer. Thanks! $\endgroup$ Jan 3, 2015 at 16:02

I thought of a few possible reasons, all with the motivation of spreading some sort of enlightenment to other races, including:

  1. an attempt to assist other races to form a certain 'standard' level of ethics throughout the galaxy, (possibly in an attempt to help everyone 'play nice' or for some other more specific reason, from self serving to more altruistic...)
  2. an attempt to instill a certain amount & sense of technological responsibility in those receiving the knowledge, (if the race gained the scientific advancement on their own, not with the accompanying lessons on responsibility, they might be more prone to abuse their new capabilities)
  3. an attempt to help other races not make the same terrible mistake(s) the originating race made, (maybe they caused an apocalyptic event which wiped out most of their race and devastated their planet etc... that might be pretty motivating)

I think it's just as valuable to consider the methods the device might use to accomplish the above. I propose the following scenario:

The scientific knowledge in the device is meted out in increments, much like a school class curriculum.
In the case of the device, however, the new lesson would be available after the previous one was mastered.
With each lesson there would be a moral aspect to it that would be part of the key to accessing the following lesson.
Without some proof that the moral lesson was also learned no advancement would be made.
In this way the device could be used to teach a set of ethics to whatever species it was given, along with the scientific knowledge.

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    $\begingroup$ Love the idea that the key to each lesson is the realization of the moral implications of the previous one. If handled carefully, this idea could become a self-help book, disquised as entertaining science-fiction. Thanks! $\endgroup$ Jan 3, 2015 at 16:06
  • $\begingroup$ @HenryTaylor glad you found the idea valuable :) $\endgroup$
    – MER
    Jan 3, 2015 at 22:18
  • $\begingroup$ +1 for point #3. That was the first thing I thought of when I saw this question. $\endgroup$ Jan 4, 2015 at 2:53
  • $\begingroup$ @MasonWheeler thanks! Seems like the most likely reason with the OPs assertion that, in their universe, inter solar system travel has such a steep personal price... $\endgroup$
    – MER
    Jan 4, 2015 at 6:52

In Dragon's Egg, an encyclopedia is given to the humans, with brief mention of the way you indicate: the key (to one section) is engraved on a pyramid on an extrasolar planet; the key is formed with the masses of certain fundamental particles to 5 significant digits; etc.

For computer power, look at existing key-aplification techniques used for passwords, or brute-force finding of a key of a specific strength.

For prerequisite understanding, use math problems that require the techniques that we need to have diacovered for ourselves before getting any "spoilers". For physical knowledge, can ask for results of a described experient that can't really be performed but calculated, like the neutrino flux of a particular stellar collapse situation.

As for records that last so long, that's another problem. Maybe it's on the moon.


The lack of FTL does not mean trade is impossible, you just have to think in longer terms. Since there is no FTL, yet the aliens are travelers, it is safe to assume they are a patient species who think in the long term. Possibly beyond their own life spans. It is even possible they work as a linear hive mind where multiple individuals make up their consciousness. If one dies, it can be replaced by a new one giving a sort of immortality. Look into A Fire Upon The Deep for this sort of entity. Another possibility is from Diaspora where they are effectively immortal, can alter their sense of time, and change their sense of what they find fulfilling ("I'm going to reprogram myself so the endless tedium of interstellar travel is FUN!").

Why did the alien come to Earth?

There are two possibilities, it was on purpose or it was not.

If it wasn't on purpose, it could have been...

  • a disaster such as a crash
  • a layover for fuel and supplies
  • they happened to be passing by and noticed signs of intelligent life

Crashing on a primitive planet, they may choose to enter sleep until humanity reaches a level of technology capable of making the supplies necessary to fix and fuel their ship. The device would open when it felt their manufacturing and base scientific abilities were up to task. For example, a person crashing in 500 AD and needing a new laptop battery and screen, even if they knew how to make one, would have to wait for enormous advances in material science alone to accomplish it.

If it was on purpose, it could have been...

  • to develop trading partners (like I said, they're patient and think very long term)
  • to develop military allies ("these Humans sure to reproduce fast, and they're good at fighting", this is the premise of the Yehat uplifting the Shofixti or the Asgard attitude in Stargate)
  • to have somebody to talk to, a different point of view
  • to spread their religion to
  • to use as slaves or vassals
  • a sense of obligation to educate the savages
  • bring Humans around to their way of thinking before they become a threat
  • to avoid common disasters brought on by technology
  • to avoid polluting their neighboring systems (this is the premise of Quarantine)
  • it was all a prank
  • it was all a mistake

What knowledge is in the device? What is the key discovery we need to find in order to open it?

The key is tied to what is in the device. The key would indicate Humanity is ready for the contents of the device, either to understand the content, or use it responsibly, or the conditions are so that they need it to save them.

Since they're so intertwined, I'm going to mix together keys and discoveries a bit.

  • a benchmark indicating we have reached a certain level of technology (when the Monolith buried on the Moon is exposed to sunlight it knows Humanity has achieved space flight)
  • we have the destructive power to breech the device
  • a certain dangerous technology is discovered (atmospheric levels of industrial pollutants indicate we're on an arc to destroy our environment, fluctuations in the Sun's energy output indicates we've begun harvesting plasma which will eventually lead to a nova) and the device contains how to make the technology safe, or advice to avoid it, or a safer alternative, or a warning beacon for the aliens to come save the day
  • a puzzle which requires a level of linguistic and mathematical advances to solve indicating we're now worth talking to
  • an indicator that society has achieved a certain benchmark of responsibility (I'm not sure how the device would detect this)
  • instructions on how to join intergalactic society (a beacon pointing at the nearest outpost, instructions to build a communication device, rules for trade)
  • there are enough Humans and we're ready for harvesting
  • the knowledge to create a valuable material or item which the aliens will come to take or trade for
  • we've achieved a level of technology where we can manufacture spare parts and fuel, it contains instructions to do so, we're now a colonial fueling station
  • their religious texts
  • military technology and propaganda about how evil their enemy is (which could backfire due to cultural and moral differences, "they allow their enemies to surrender and don't kill their wounded, they have no honor!")
  • we've developed to the point where we've become a threat, it's a bomb
  • the instructions require special devices to read: it's emitting radio waves; it's just under the surface and visible in x-rays; it requires knowledge of higher dimensional physics
  • it's a special device and the aliens have hidden it on a backwater planet where nobody would think to look (a la The Fifth Element)
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    $\begingroup$ Great Answer! Lots of useful stuff which will definitely go into my writing. Thanks! $\endgroup$ Jan 4, 2015 at 18:17

Does the alien have to visit herself? Couldn't she just send a "device which contains a vast body of scientific knowledge" in an unmanned space probe? You know, like we did in the Voyager probes?

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    $\begingroup$ This is a valuable idea but doesn't really answer the question. Notes like this should be left in comments. $\endgroup$
    – ArtOfCode
    Jan 3, 2015 at 15:20
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    $\begingroup$ @ArtOfCode: I agree, but you need to have 50 rep to post comments. $\endgroup$
    – b_russel
    Jan 3, 2015 at 17:41
  • $\begingroup$ Thanks b_russel, I had forgotten that rep limit, so I will reply to your answer as a comment. The only reason for the alien presence is to instill a significant cost to the alien's culture. If the device was as inexpensive to their culture as voyager was to ours, then it might just contain a gold-plated record with some political speeches on it. That would be extremely anti-climatic to the readers of my story. $\endgroup$ Jan 3, 2015 at 18:06


The alien species was under threat of possible extinction. The device contains detailed genetic engineering instructions that can be used to recreate the alien species, as well as a huge body of scientific, cultural, and historical information so that the newborns can learn about their 'family' and roots, and ensure that their accumulated knowledge survives as well.

The device (or rather the data within it) is locked in such a way that it can only be accessed by a society with the biological capability to bring the alien species back to life.

  1. Where do we know that the aliens has feelings? Maybe this travel does not have a personal cost to an alien.
  2. Maybe aliens have an ultimate ideal, like religions point out heaven on Earth, to spread scientific knowledge or explore deep space to find footsteps of creators. (I assume they still did not understand 'beginning of time', like us.)
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    $\begingroup$ Interesting, but can an advanced society evolve without social relationships and communal feelings? I think you just gave me the next question I'm going to post. Thanks! $\endgroup$ Jan 3, 2015 at 16:10

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