A small group of alien biologists and scientists land on earth. They want to study us earthlings and our culture, society, etc. But they do not want to interfere with us, so they have to come up with a way to be able to study us up close without being noticed by us. But these aliens do not have cloaking devices small enough to be used on anything other than ships. What technology could they use to go unnoticed by the human population?

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    $\begingroup$ For me it fails a "book test": if you can write a book about it and still not fully answer, it's probably too broad $\endgroup$
    – Mołot
    Commented Dec 16, 2017 at 18:47
  • $\begingroup$ Radio waves that distort perception, of course: en.wikipedia.org/wiki/They_Live $\endgroup$ Commented Dec 16, 2017 at 21:05
  • $\begingroup$ why going unnoticed? If you install their camera at your home, you can watch Big Brother Alien and AlienFactor for free. <vomiting just thinking about it> ; though on second thoughts many would not notice the difference. $\endgroup$ Commented Dec 16, 2017 at 23:00
  • $\begingroup$ @RuiFRibeiro, "It's New York. Land anywhere. No one will care, or indeed, even notice." -- Ford Prefect $\endgroup$
    – Matthew
    Commented Sep 14, 2020 at 1:40

7 Answers 7


Without even advanced tech, there are billions of cameras recording the public, billions of phone conversations going on, and no telling how many stored videos easily available for every kind of human interaction (including every form of sex, fighting, talking, humor, etc).

Internal cameras surveil inside of buildings, workplaces, prisons, etc. Tapes are stored for years.

No matter what the aliens look like, they can watch anything from a dog's birthday party (filmed on the corner of my residential block) to sex to somebody literally being beaten to death. Or a board meeting, if you want that. Or Congress, or sports, or an actual autopsy in medical school.


It depends on the aliens; if the are visually similar to humans(or their technology allows them to do so), they could hide in plain sight using disguises; if not, they could set up potentially set up remote surveillance which they could monitor from a safe place.

If they don't need to be directly there, they could hack into our networked devices (Smartphones, webcams, Google Home/Amazon Echo equivalents etc.) or simply connect to the internet, many people put a surprising amount about their life online for anyone to see.

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    $\begingroup$ I second just sitting cunningly in orbit, hiding with the advanced alien tech. And using that alien tech to tap into satellite internet feed on the backbone. Even on Earth you could basically "listen" to the feed without sending any requests yourself. I'd imagine that it works even when being on the wrong business side of the satellite: you'd need to place an alien receiver like 1 km above it. For a directed signal that should go GEO orbit down, the parasite "leaf" at such a small distance should suffice for advanced alien tech™. Decoding the formats and languages is another story though... $\endgroup$ Commented Dec 16, 2017 at 18:40
  • $\begingroup$ @Oleg Lobachev, nice point on tech format and languages, but they are there to study these things, so they'll learn them. Also OP says they landed, so they'll more likely be monitoring everything from inside Area 52 while they send out their tech bugs to gather info. Are there any places earthlings do things that there aren't also flies on the wall? $\endgroup$
    – N2ition
    Commented Dec 16, 2017 at 21:03
  • $\begingroup$ Not only formats and languages. They'll have to break TLS first - without even knowing if any particular plaintext is actually correct - or that they should be applying an algorithm with a dynamically-changing-but-never-actually-transmitted parameters in the first place. Or they have to come before the https-everything era $\endgroup$ Commented Dec 16, 2017 at 21:11
  • $\begingroup$ Just look at the spec of Deflate. That stuff was designed to be readable, and yet there are bits (block header) that tell you how to interpret things (code length code length table that encodes a Huffman tree) that tell you how to interpret things (literal and length code length table, offset code length table, both encoding two other Huffman trees and themselves encoded with one) that tell you how to interpret things (the actual stream of blocks, encoded with not one but two Huffman trees at once) that tell you how to make the data you actually want. And then you have to interpret that. $\endgroup$ Commented Dec 16, 2017 at 21:17
  • $\begingroup$ @JohnDvorak We're still far from a "https-everywhere" $\endgroup$
    – Bergi
    Commented Dec 16, 2017 at 21:27

As an extraterrestrial visitor and xenoanthropologist, I have had some success in this matter.

My people look like miniature haystacks, about 10 cm wide and 4 cm high, in various colors of red, brown, tan, and white. I personally am a sort of pale yellow. We usually eat only at long intervals, but between meals we can wave our tendrils around and draw some nourishment from the air. We are spread quite thin over the populated worlds and there are fewer than a dozen of us on Earth.

When I first arrived I mostly watched people at a distance, from static blinds, usually on a window ledge or in a tree. For the first three years I didn't dare move except on Hallowe'en. During the fourth year a pair of bluejays made a nest in me. My advisor came 850 light-years to see if I was still alive.

Then I accidentally discovered that sometimes when I touch a human, I can influence his decisions and behavior. I'm not sure, but I suspect it eventually destroys the human's attention span. I don't know what my ethics committee would make of that because I haven't told them yet.

For the last twenty years I've been riding around on this guy's head and observing you all up close. I've made him take me everywhere, business negotiations, board meetings, we've been on TV, Jimmy Fallon, Charlie Rose -- I have so much data I'll be writing books for years.

You'd think somebody would notice a haystack alien riding on the head of a public figure, but so far I'm getting away with it. You Earth peoples is so dumb.

EDIT OMG I am so sorry so sorry I did not mean for this to happen. I just wanted him to take me to meetings with powerful or famous or influential people so my thesis would be more interesting. I honestly did not know what I was getting him into until we were actually riding down that escalator.

At first it was just a lot of fun making him yell out nonsense slogans and hearing the stupid crowd go wild. But it felt so good that after a few months I wanted it to never stop. Evidently my people get addicted to certain strong pleasant stimulations in the humans we ride around on.

Before I knew what was happening, my other colleagues on Earth were getting high on human adulation too. My collaborator in the U.K. is particularly out of control.

Our supervisory committee has become aware that something unethical is happening here but it will be almost five years before they can stage any sort of intervention.

I am so sorry this happened. Once my colleagues and I get clean and sober I promise that my people will come back and fix up all the damage we've caused.


Not to be too simplistic, but humans are a noisy bunch...

We've been throwing electromagnetic energy into space for quite a few decades now. Radio, TV, Internet, Satellite, Microwave, X-ray, you name it, it's still propagating out there in the great void.

They would only need to setup a few receiving dishes in various locations covering different frequencies, and they could tap into pretty much most of the history of the human race, especially if they managed to link into the internet and/or have an FTL drive.

Sending a stealthy drone in to add a transmissions link onto one or more satellites would give them said internet access.

To be honest, overcoming the language barrier again, and again, and again would probably be more challenging than tapping into our signals, at least until they figured out the dictionary apps we've already made.


Step 1 The aliens take a look at the encryption protecting our banking systems. Once they stop laughing, they make themselves squillionaires.

Step 2 They use their new wealth to get into real estate. Working through proxies (law firms and real estate agents) they buy apartment buildings, offices, shopping malls, hotels, schools, creches.

Step 3 They use their UltraExtremeNoLimit credit card to buy millions of smoke detectors etc. & use their ship-board 3d printer to add their alien science snooper sensors. This is a lot of work, but hey, grad students!

Step 4 They re-package the modded products and have their real estate corps maintenance crews install them everywhere.

Step 5 Their paper to the Intergalatic Social Sciences journal has a squillion byte appendix detailing every moment of the lives of 300M earthlinks is rejected by all referees as being unsupported by sufficient data.


Even if a cloaking device is so large that it needs to be housed in a structure as large as a ship, they could still build that large device on the ground (bringing in parts via transporter, cloaked shuttle craft, or building it in the middle of nowhere and then tunneling to where they need to be to observe).

This is was what the Federation did in the Star Trek episode Who Watches The Watchers -- they built an observation post hidden by a holographic wall (and then the holographic generator failed, exposing the observation team, so make sure you have a backup cloaking device).


Biological Robot Bugs and Other Creepy Crawlies

Bugs of some sort already exist in nearly every habitat Earthlings are found. They are small, many equipped with antennae already, and lots can fly, providing great 360 measuring opportunity. They are light enough that when the Earthlings are sleeping, they can even touch and travel around on them without detection; some are designed to live on or inside them even. That is about as up close as could be desired.

Unique modifications can even work to get added niche "interaction" without being perceived as interaction: lightning bugs encourage juvenile Earthlings to capture them and provide entry into homes in a jar for good vantage point (no need to hide to escape destruction), ants in an "ant farm" will also have a good in the home view, honey bee hives nurtured by bee farmers are a great cover for field work on gardeners and farmers, and leeches can join the medical science community by offering wound healing opportunities as a nifty way to study living blood cells and other body defenses.

And have you ever noticed how the dragonflies actually try to get our attention with their teasingly close in/dart away tactics? Very effective.

  • $\begingroup$ I've read a story where that was exactly done only with cockroaches. I'd go for cats instead, personally. ^^ The first thing the Google AI learned how to recognize visually was cats - that goes to show just how many cat memes / videos are on the internet. $\endgroup$
    – nijineko
    Commented Dec 18, 2017 at 16:41
  • $\begingroup$ @nijineko good point with cats, they like to hang out with the people too. For that matter, why limit to one species. Pick whichever one best fits environment, although energy required for larger complex animal robots will involve more resources, and the potential for discovery is also higher. At some point on that line they will indeed just go full on android person, but then you are entering definite interaction and potential interference territory. $\endgroup$
    – N2ition
    Commented Dec 19, 2017 at 14:02

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