A futuristic, robot-like species has been observing the human race for thousands of years and has decided to remove them all from planet Earth. In what way could they do this, whilst also having the method they use allow three people to be left behind?

Okay, hopefully by providing a bit more context, there will be a few more answers. This alien race is, as I said, robot-like. They have actually been designed and created by another alien species, which the robots believe to have gone extinct. This supposedly extinct alien species believed that it has created the human race millions of years ago as an experiment, and sent the robots to remove the humans and allow life on the planet to continue without them. It has taken the robots an extremely long time to arrive at Earth.

Rather than simply murder them, the robots have been designed to feel compassion and emotion. As such, they decide to transport the humans onto an assortment of ships near Earth, and induce every one into a sleep-like coma, where they dream until their body withers away. The humans are kept in holding pens until the robots construct enough of these dream machines, hooking humans up to it in groups.

So the only thing I'm really interested in is how they get all the humans from point A to point B. I'm willing to accept an scenario where the three remaining humans are left behind on purpose, but really I'm after a way in which the robots could pull off this mass transportation.

  • 1
    $\begingroup$ What is our timeline? Are our three people adults? Are they near each other? $\endgroup$
    – Mormacil
    Apr 9, 2017 at 13:32
  • $\begingroup$ The three people are all adults, in the same city, and the teleportation happens instantaneously. $\endgroup$
    – Lenfred
    Apr 9, 2017 at 13:34
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    $\begingroup$ There are 7.5 billion people on Earth. A process which does something to all of them except three (and does nothing to anything else) is therefore 99.99999996% reliable; that's better than nine 9s -- that's impressively reliable; mind blowing reliable, actually. Note that at our present level of science and technology we cannot teleport anything bigger or more complex than a photon. We actually have no idea whatsoever how to teleport even one molecule of water... $\endgroup$
    – AlexP
    Apr 9, 2017 at 13:36
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    $\begingroup$ @lenfred Your transport mechanism gets all but 3. I think that means it is so reliable that leaving those 3 must be deliberate. Either they are special somehow (they were wallowing with pigs at the time, so the scanner picked wrong species) or one of your aliens deliberately sabotaged the system. I'll leave the question of how to do the transport to others. $\endgroup$
    – SRM
    Apr 9, 2017 at 13:59
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    $\begingroup$ If there are only six people left after a war or zombie apocalypse, the task becomes trivial. $\endgroup$
    – Spencer
    Apr 9, 2017 at 22:09

2 Answers 2


If the robot's creators really did create the human race, they might have coded four undeniable instincts into our brains such that when we breath in a particular chemical trigger, the following behaviors become irresistible...

  1. We suddenly distrust all the dangerous appliances and devices around us, leading us to turn them off as quickly as possible. That way, nobody leaves a stove or nuclear reactor running which might damage the planet once all the humans are gone.
  2. We become desperate to gather with others in wide open spaces under open skies. (Sort of the opposite of Agoraphobia).
  3. We become overwhelmingly forgiving and compassionate; understanding that others need to gather in the sunshine. So we facilitate their freedom to do so without hesitation. Unlocking prison cells and wheeling (or carrying) the unconscious and disabled out into the sunshine as we go.
  4. Once in the sunshine and in the company of a sufficiently large number of other people, we assume the fetal position and fall asleep. This last behavior minimizes the robots' difficulty in loading us into their space elevators.

Space Elevators? What space elevators?

Since the robot ships want to restore the Earth to its pristine, pre-human state, they wouldn't want to add more air pollution by using vehicles which need hydrocarbon-based engines or rockets for locomotion. Instead, their ships would stay in orbit and lower cable-bound loading platforms down to our planet's surface. These "space cargo elevators" would make comparatively short work of depopulating the planet.

Which leaves the issue of the three survivors...

  1. They might be victims of non-fatal brain injuries which destroyed the creators' coding without other serious negative effects.
  2. They might have a minor genetic mutation which has destroyed the creators' coding.
  3. They might be coma victims in an understaffed care facility, left behind by the triggered nurses who carried out all the other patients but never returned for the last three.
  4. They might be astronauts aboard the ISS, environmental scientists aboard a BioDome, or an undersea mining crew in a deep-water habitat. All of these people would not be subjected to the trigger until they returned to the Earth's natural atmosphere, and hopefully the trigger would bio-degrade by then.

The last survivor source actually illuminates a serious flaw in this answer. At any given time, the various superpowers of our world have vast fleets of submarines full of people who would not be exposed to the trigger. These would have to be targeted specifically by the robots and harvested by more direct/more violent means. ( I will leave the details of that for the OP to fill in ). Meanwhile, a deep ocean mining rig, having no military value, might easily be overlooked during the robots' handling of our military underwater vessels.

  • $\begingroup$ The problem with space elevators is that they only work over the equator, at least when connected to things in orbit. You might need bigger space infrastructure like an orbital ring. $\endgroup$ Jun 28, 2021 at 22:25

EDIT: This response was given to the question before an edit that adjusted the focus of the question. Originally, the question seemed to place more importance on the part about leaving three people behind, not about how to get everyone off of the planet.

They inject into the atmosphere a chemical that causes all people to immediately and instantly black out for a few weeks. During that time, they land a huge number of rockets and search the entire Earth, grabbing all of the people that they can find. And taking them into the rockets, where they launch all of the humans away. In the Gemini program, the capsule weighed about 1 ton per person, so they would need a lot of resources to get all of the capsules into space. From there, they can dock with a mothership and carry the people to another world, where those capsules undock on a suborbital trajectory to land the people on the new world. Hopefully, you have warp technology to get there quickly, if not, your aliens would need a lot of work to put humans in suspended animation chambers for the trip, then back out with another shot from the chemical that makes people black out.

However, their search uses advanced long-range biomedical sensors that sense human heart beats, which the blackout chemical does not cause to stop. However, some people (your three characters) started to suffer from hypothermia while in an area with high Hydrogen Sulfide concentrations. This causes your characters to effectively enter suspended animation until they heat back up later. It could be that it was only this cold because it was night when the aliens came by that area, and when day comes, it heats up enough that metabolism increases and the heart resumes beating, with people feeling just fine right afterwards.

Note: For people who doubt this, this phenomenon has been observed, but, as best I can tell, its reliability is still uncertain, so it is not used in medical procedures (but, because I am not a doctor, my information about current medical procedures might be incorrect)

  • $\begingroup$ I agree with your reason but there may be other means. It is safe to assume that the three were dead at the time of the great collection and then came back to to life. If all three are female and competent and they reach a few egg and sperm bank before backups fail they may even be able to restart humanity and cause the robots to have hysterics. Also there may have been many more that were missed and subsequently died or committed suicide. $\endgroup$
    – KalleMP
    Jul 20, 2018 at 20:34

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