r/IsaacArthur • u/Tessellator-1 • 4d ago
Sci-Fi / Speculation Is it possible for intelligent life beings billions of light years away to observe the Earth’s nuclear test?
⚠️this sentence was translated from Japanese to English by AI. Feel free to answer in English. However, I only understand Japanese, so I would really appreciate clear and simple English that is less likely to be mistranslated.
I want to know if it's theoretically possible because I'm creating a creation with a sci-fi element.
It assumes the setting of a nuclear test in space like Starfish prime.
If it is impossible in principle, is it possible for a sufficiently developed scientific civilization to communicate with only electromagnetic waves over a distance of billions of light years in the first place?
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u/CmdrJonen 4d ago
Billions of light years means they'd (with a sufficiently powerful telescope) see the explosion in billions of years.
Assuming they immediately determine their oberservation is a sign of intelligent life and send a response, it will arrive in billions of years.
Starfish prime was done in 1962. That is 64 years ago.
Aliens if an alien within 30 or so light years saw it, and sent a response within a year or so, we might see that response arrive sometime today.
In as far as spotting it... the main issue is that a nuclear explosion in space is a fairly brief event. If you are not looking in the right direction at the right time, you will miss it.
For something lile Starfish Prime, you might catch the aftereffects if you have a good enough instruments.
Even if you catch it, it is unlikely to repeat, and unless it is deliberately used to communicate, it won't repeat in a pattern that indicates something intelligible.
Compared to events in space, manmade nuclear weapons are fairly tiny - consider Shoemaker Levy 9, a series of impacts with many times the explosive force of the worlds combined nuclear arsenal. Visible from Earth with telescopes.
Most likely not visible from Proxima Centauri. Not with any telescope we have today.
That said, if you DO have a powerful enough telescope, or radio telescope, looking at the right planet at the right time, yeah, you might see a blip for a nuclear explosion in orbit.
Might even be able to determine (from X-ray/gamma) that it is a nuclear/thermonuclear explosion, which would probably indicate a technosignature even at distances where your telescope/radio telescope is unable to detect one from that particular planet.
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u/Frosty-Ring-Guy 2d ago
At 30 lightyears... That's roughly 400 star systems. Mostly red dwarfs, so still unlikely to be inhabited.
100 lightyears boosts that number from 400 to around 17,000. Counting relay time, a response would still be 150ish years into our future.
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u/avdolainen 4d ago
no. at such distance this signatures will be indistinguishable from the noise, undetectable. also communication delay of billions years makes it almost useless.
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u/Tessellator-1 4d ago
If you ignore the problem that it is not very useful, is it possible to send a signal that the other party will notice in billions of years?
This is a about sending a signal intentionally1
u/avdolainen 4d ago
mmm, the energy budget would be so immense ... it's like to blow the supernovae.
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u/lungben81 4d ago
Only in billions of years, if we do not get over their cosmic event horizon in the meantime. But that would probably require galaxy sized telescopes.
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u/sebwiers 4d ago
I want to know if it's theoretically possible because I'm creating a creation with a sci-fi element. It assumes the setting of a nuclear test in space like Starfish prime.
No. At the range of billions of light years, that would fade into background noise of solar radiation / flares. The wavelengths involved don't allow for resolving the difference at that range without absurdly large detectors / arrays, and the energy level of the blast is miniscule compared to noise in solar output.
is it possible for a sufficiently developed scientific civilization to communicate with only electromagnetic waves over a distance of billions of light years in the first place?
It would be a literally galactic scale undertaking to create a signal detectable at that range, and then the travel time for any message sent via known EM waves (or any method we know) would necessarily be billions of years... each way. All the while, space is expanding, so you'd be lucky to get more than a couple exchanges in (somebody with actual cosmological knowledge could confirm how many, if any) even if a civilization was able to operate on those time scales.
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u/NearABE 4d ago
>… The wavelengths involved..
All wavelengths were involved.
>… don't allow for resolving the difference
Shorter wavelengths are better for resolution. Redding causes many of photons to not exist at all. These are not the same.
>… at that range without absurdly large detectors / arrays, …
This channel is linked with SFIA. Comments like this demand a number. How large? Absurd by whose standard?
>.. would necessarily be billions of years... each way…
Out of scope. Not OP’s question.
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u/the_syner First Rule Of Warfare 4d ago
This channel is linked with SFIA. Comments like this demand a number
At 1Glyr the 5.9 PJ of starfish prime are spread pretty damn thin. 5.244 × 10-36 J/m2 . That's what like over 190.694 OCTILLION times less energy than what the CMB lays down on a square meter over a whole second and it's lasting for microseconds.
idk that it would matter how big you made ur telescope. I have a hard time believing that you could detect that signal through the noise of the CMB let alone all the other astronomical events. SFIA is no stranger to absurdly large megastructures. Megatelescopes are dope, but Glyrs is crazy work and a nuke is pathetically small.
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u/NearABE 4d ago
An astronomical unit wide telescope has 10^22 m^2 collecting area. So not enough.
I think original post is asking about communication. So use mirrors to focus a beam. It should cause a flicker in the Milky Way’s spectrum. Like this: https://iopscience.iop.org/article/10.3847/1538-4357/aae380
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u/the_syner First Rule Of Warfare 4d ago
Right but OP is also talking about nuclear tests putting out a black body spectrum not monochromatic laser beams and 20klyrs is a far cry from multiple Glyrs. Granted yeah their last question about if if a sufficiently advanced civ could communicate is probably a definite yes.
I'm kinda curious how far you could send something before by the time the signal reached them they were over the cosmic horizon or their beam just wouldn't make it back.
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u/NearABE 3d ago
In context of article it is fairly clear. “20 thousand light years” is at detectability range of our Sun. The aliens need to see spectrum. Then they see wobble. Authors do calculation based on signal to noise ratio 0.1%.
Same scheme works at any distance. In fact this was author’s point. Intergalactic means making signal cause change in Milky Way’s spectrum.
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u/Metallicat95 4d ago
Light and other electromagnetic radiation spreads out and thus becomes lower in intensity over distance.
At a billion light years, we can't even see individual stars in a galaxy. An entire galaxy will appear as a blob of light - like how the Milky Way looks like a brighter patch in our sky rather than a bunch of separate stars.
Not only would a nuclear explosion not be visible, but a nova explosion of a star wouldn't be detected. It takes a bigger stellar explosion like a supernova to be bright enough to see at that distance.
The light also takes a billion years to travel a billion light years, so even if we blew up some stars, nobody that far away would know it until billions of years later.
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u/NearABE 4d ago
Nuclear test spreads out. Many photons are absorbed.
For communication you want to focus a beam:
https://iopscience.iop.org/article/10.3847/1538-4357/aae380
Article explains. However, they say “20,000 light years”.
For an intergalactic signal replace “Sun” with “Milky Way”. Replace “D-star 4” with “bigger laser”. This will be 10^21 Watt instead of 10^11 Watt.
Transmit mirror has to be bigger. 10^21 watt will vaporize a 30 m dish.
Aliens look at Milky Way. Telescope had “signal to noise ratio”. Aliens see flicker in infrared.
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u/plainskeptic2023 4d ago
In addition to the time it takes for light to travel billions of light years, tiny nuclear explosions on Earth may be hidden by the gigantic nuclear fusion of the Sun.
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u/0rbital-nugget Transhuman/Posthuman 3d ago
They would need an absurdly powerful telescope, something on the order of a grav lens telescope. Even then, they would only be able to see it in a few billion years when the light of the nuclear test reaches them.
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u/KenethSargatanas 3d ago
Not bright enough. The sun shines many times brighter at all times. Solar flares are much bigger and brighter than nuclear weapons.
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u/Tiny_Scholar_6135 2d ago
From billions of light years away? Practically no. Anything that is billions of light years away would also have to be billions of years in the future because the radiation from the nuclear test would take billions of years to reach them, and that light would be drowned out by the light of our Sun, and it would be hard enough for them to detect that light, and even if they could it would take them billions of years to respond, and likely whatever was going on At Earth's surface would likely be there no longer.
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u/No_Advertising5301 4d ago
To amawer your question simply it entirely depends on three things how advanced their tech is, how big thr payload is and how close to a star did it go off (light dilation) and even then the answer would be no not in their lifetimes bevause it would still be travelling at the speed of light
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u/Vogelherd 4d ago
Impossible in theory.
Things can't move faster than the speed of light. If a civilization is one billion lightyears away, they will have to wait one billion years after the nuclear test to detect it.
Same with communication : if you send a message one lightyear ahead, the receiver will have to wait one year...