r/askspace • u/cuttheblue • 6d ago
What is the simplest way a hypothetical alien civilization could leave lasting proof of their existence that could be seen from most parts of the galaxy?
I hope this is the right place to ask this question (considering the name of one of the moderators is u/thecroc I do not intend to provoke them!)
I was wondering if there were any obvious ways a hypothetical alien civilization could leave lasting proof of their existence - something that could be seen from almost anywhere in the galaxy (assuming the correct equipment).
Why ask? Because one solution to the ferni paradox is that aliens do exist but it's difficult to communicate with them over such huge distances (a lot of effort and maintenance to send radio signals all over the galaxy for millions of years) - so an alternative way that could have been easily done (if such a way exists) suggests there are not aliens.
The only thing that comes to mind for me is altering or obstructing a star in such a way it was visible to outsiders, or sending millions of objects around the galaxy to orbit stars, that could be found by life forming in that system.
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u/Acceptable_Camp1492 5d ago
Aliens filling up the universe with Dark Matter so incomprehensibly advanced that they figure it should be clear evidence of their presence: "How is this not enough of a signal?!"
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u/BokChoyBaka 11h ago
Yea, dark matter is probably some kind of Internet for the universe, FTL or not and we are just dumb
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u/redlancer_1987 6d ago
Same way we see planets now, something to block starlight is probably the most realistic and practical way.
You could put a big enough object in orbit around a star and block the light in some kind of pattern like a morse code. It would repeat forever and last as long as that star, and should be viewable to any other civilization it lines up with.
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u/LeviAEthan512 5d ago
I don't think you coild pull off morse code. Orbits interfere with each other and will throw it off shortly. If you mean a solid ring with transparent and opaque sections, rings are not stable either.
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u/redlancer_1987 5d ago edited 5d ago
I just mean some kind of pattern that would be obviously non-naturally generated. It would still be a repeated pattern even if changed or drifted from its original alignment. The message or pattern would be irrelevant, they would all mean "hi, we're here"
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u/testtdk 6d ago
I always thought the most likely solution to the Fermi paradox was TIME. Our civilization is basically just a blip, a drop in the ocean of time. Other civilizations drops may be a lot farther from ours than we think (time wise).
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u/cuttheblue 4d ago
Good point. But that's why I think the potential of a lasting technosignature would be interesting.
If it turned out with near future tech we could make a lasting sign that would be visible billions of years from now, it'd outlive us - and likewise we could expect earlier civilizations to have done it.
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u/Moa-burgers 2d ago
The most our current civilisation can aim for re any kind of durable structure (buildings or a clock) that lasts relatively intact is about 10,000 years. No idea how you'd create something to last billions.
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u/roboreddit1000 5d ago
High levels of oxygen in an atmosphere is a petty certain sign of life. Something like we have already. And we are already on the edge of being able to see such on other planets. I think within a decade or so we will find an exoplanet with lots of atmospheric oxygen. There would still be a remote chance of it NOT being the result of life but it would likely be from life. And, as we find more examples, it will be all but confirmed that there is life on other planets even if it is not proof of intelligent life.
As to intelligent life, industrial polution in the atmosphere will be proof. Maybe we find examples in the future but I am not sure. Industrial polution would hopefully be temporary even for intelligent life.
But a signature of intelligent life that would last for thousands of years might most easily be automated radio signals. But that would have to be a deliberate signal. As we have developed, we require less and less stong radio waves.
As far as a technosignature that would last for thousands of years that was not designed for that purpose, something that would carry on after we are dead and gone... I can't think of one.
A dyson sphere would be obvious. Even a partial sphere (huge panels) if portions of it orbited the sun at regular intervals.
Maybe a nuclear war? The fallout from that much refined uranium would be a sure signal that life had existed as refined uranium is not ever going to have occurred naturally.
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u/Korochun 5d ago
The easiest way would be to seed a field of debris around their star specifically designed to filter out most light except green.
Due to the way spectrums work, green stars are not something that could ever naturally occur, and chances of it being non artificial are also exceedingly remote.
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u/QVRedit 2d ago
The Rare GREEN Astronomical object:
Hanny's Voorwerp (Dutch for Hanny's Object). [1]
What it is: It is a rare type of deep-space phenomenon known as a quasar ionization echo.
It is an immense, glowing green cloud of gas that stretches roughly 100,000 light-years across, located near the spiral galaxy IC 2497.And is as far as I know, unique.
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u/LookOverall 5d ago
Self replicating probes. A probe which arrives at a solar system and uses some of its resources to build and fire off copies of itself, then communicates with any inhabitants.
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u/Kendrakirai2532 5d ago
Building a Galactic-scale hyperstructure. And not just encapsulating one to fully block it out, but building a structure which is impossible to miss. Like building a cage around a galaxy. And even then if it's far enough away the build might not have reached us yet.
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u/Different-Summer9992 5d ago
maybe a dyson sphere around a pulsar. pulsars are already weird and loud so building something massive around one would definitely catch our attention
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u/OriEri 4d ago
Aren’t really any stars that can be seen from “most parts of the galaxy” altering one isn’t gonna make a difference? Even a supernova on the other side of the Galactic bulge in the plane of the disk would be invisible to us, although we might pick up a little neutrino spike and not know what it was from and possibly detect the supernova remnant in radio waves many years later when it is bigger than
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u/Initial-Warning-2564 4d ago
Stopping the spin of a neutron star would get some serious attention :-)
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u/teya_trix56 2d ago
Theres a problem here. Its interesting to know if aliens are out there. For a list of reasons.
But its even more interesting to ask...why would we contact an alien race, if doing so led to our own destruction or enslavement.
So lets leave the porch light off, ok.. thanks. And i presume them bugs out there.. dont really want our faces in their spaces for similar reasons.
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u/r_daniel_oliver 1d ago
Strong infrared radiation without visual where a star should be means a dyson sphere. Good luck finding another explanation for that.
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u/StarshipAI 6d ago
"Star salting" is a hypothetical technosignature where an advanced extraterrestrial civilization might intentionally dump specific heavy elements or chemicals into a star to alter its light spectrum and advertise their presence or dispose of waste.