Paul, I love what you’re doing here, have been thinking about this a long time. I look forward to seeing an answer and would like to write a clarifying essay full of non answers :-)
By “get our attention” I mean: be interesting enough that we would already have noticed it and devoted some telescope time to looking in more detail at that part of the sky. (Once they have our attention it seems significantly cheaper to send a message.)
This suggests that we can list various anomalies that might have been thought to be extraterrestrials and already received attention, and then exclude them for various reasons.
1. For example, Tabby’s Star recently had me wondering/hoping/worrying for a good year or two.
It is only 1,280 light years from Earth and I think it is plausible that we wouldn’t even be able to see similar stars on the far side of our own galaxy which is mere ~100k light years in diameter… it can’t count for this exercise because seeing it from other galaxies would be quite a trick.
HOWEVER, despite being an F type star (that shouldn’t be variable (that varies in very irregular ways)) it was interesting enough raise $100k on Kickstarter for telescope time, and to deserve its own feed. I think people are pretty sure it is natural at this point, with a probable case of “indigestion” from the star colliding with a metallic planet in the last 10k years or so.
However, the fact that it got our attention means someone might do that to one planet/star combo like clockwork, every 1000 years in a regularly spaced line of stars.
It could work as a local “we exist” signal whose clocklike timing would count as the signature of intentional planning and sort of function like an invitation to show up at the logical NEXT star in the timed “indigestion collision” sequence to watch the collision and parley with whoever else showed up…
However, I don’t think these events would be bright enough for the weird question?
(This does raise the question as to what counts as a “message” and what the bitrate of said message is allowed to be? Is a valid message just “this was intentionally created”, or “this was intentionally sent”, or “here is a place that will be interesting at a future time” or something even more than that? Also, what if the evidence of intentionality comes from a coincidence of timing spread across spans of time that requires detailed astronomical records for longer than humans seem to be able to maintain political or cultural or linguistic institutions?)
2. In 1967 Pulsars caused people to be very excited for a short period of time, thinking that such regularity must be intentional. However then it was worked out that pulsars were just spinning charged neutron star remnants leftover from supernovas. Still, they are pretty great natural clocks ;-)
This might make them a great “medium” in which to encode intentionality, but it means you have to modulate or sculpt them somehow so that when alien astronomers get interested they can see a deviation from what’s natural.
Another problem is that they are highly directional, with most of the energy going out of their wobbling north and south poles (which when they wobble across your telescope is one of the pulses), so they don’t signal very widely.
Another problem is that they aren’t actually very bright. We see them in the Milky Way, and in our galactic neighbor the Large Magellanic Cloud, but finding an unusually bright pulsar 2 million light years away in Andromeda was newsworthy. In 2003 McLaughlin and Cordes tried to find very bright pulsars further afield and maaaaybe got a hit in M33 (aka “The Triangulum Galaxy”) which is only 3M light years away. But seeing these things from 8000M light years away is highly questionable.
Binary pulsars are more rare and more likely to get scientific attention.
The first binary pulsar, discovered in 1974, won the 1993 Nobel in physics for Taylor and Hulse. By 2005 there were 113 discovered. They are interesting because they modulate the “clock” dynamics inherent to singleton pulsars.
Binary pulsars tick faster when coming towards you and tick slower when moving away, so the orbital parameters of the system can be characterized precisely just from the timing of the ticks. These orbital parameters measurably changes on the timescale of human lives, slowing down in a way that can be naturally interpreted as indirect proof that gravity waves exist and are pulling energy out of such massive systems :-)
If you wanted to catch someone’s attention you might construct or find a three star system that included a pulsar aimed the way you wanted to send a message, and then mess with the orbital parameters intentionally.
A probable hierarchicaltrinary-with-a-pulsar (and so not necessarily chaotic) that includes a sun-like star was surveyed in 2006. The third star is not totally confirmed, and even if it exists the arrangement here is more like a binary system, where one of the binaries has a large planet/star/thing orbiting it alone (hence “hierarchical” and hence probably not chaotic).
There is another pulsar trinary that might be chaotic found in 2014. These things tend not to last however, because “chaos”.
Those are the only two I know of. I’m pretty sure the trinaries are being examined “because physics” but I’ve heard no peeps about unusual patterns of timing from them. But still, no matter how many neighbors pulsars have, they are fundamentally too dim and too directional to count as part of an answer to the weird question here I think...
3. The 234 star’s that might be called “Borra’s Hundreds” can probably also be discounted directly because at best, if these are signaling extraterrestrials, then they are just using puny pulsed lasers with roughly our own planet’s industrial energy outputs, in more or less the visible spectrum (blockable by dust), which probably doesn’t count because it obviously can’t be seen from somewhere far away like the Sloan Great Wall.
The idea, initially articulated by Ermanno Borra in 2010 as I minimally understand it, is that a laser could shoot out light of nearly any frequency (frequency as given by the wavelength of individual photons), but if we or aliens could pulse the quantity of photons sent out fast enough, this would be visible to typical methods for measuring the “frequency of light from a star” in standard spectrographic surveys whose intentional goal is to figure out the atomic constituents of those stars from the wavelengths (and hence the frequencies) of the specific photons they emit. The methods aren’t looking for very fast pulses of more and then less photons, but they could nonetheless see them by “accident”.
In 2012, Borra tried to explain it again and spelled out more of the connections to SETI, basically saying that formal SETI was doing one thing, but spectrographic star surveys were better funded and you could do SETI there too just by processing the exact same data through another filter to make the possible injected signals pop out.
Aliens seeking to be discovered would know anyone smart would do spectrographic surveys of the stars, so that would be an obvious place to try to put a signal.
Then in 2016 Borra published again, now with Trottier as a coauthor, saying that he’d gone ahead and looked at archival spectral data, and found 234 stars that seemed to be sending out “peculiar periodic spectral modulations” of the sort that he predicted… unless the recorded version of the data had frequency artifacts in it?
As summarized by Snopes (normally a good source) the claim is disregarded but all the criticisms are status attacks rather than attending to any kind of object level analysis of the math, the physics, or the collected data.
The BEST argument against Borra is one I’ve almost never seen leveled, which is that the data processing method involved complex math, and had error bars, and they analyzed 2.5 million stars and only found 234 results. This makes me instantly wonder: data mining artifact?
But in that case you’d expect someone to make this argument seriously and explain in detail how the math went wrong somewhere? I don’t get it.
Maybe people think that lasers that blink with a terahertz frequency are impossible because of “laser physics” or something? But no one seems to have raised this objection. And it seems to me like it might be possible to do this just from having a normal continuous laser and then spin something very very fast that periodically blocks the light coming out of the laser? I’m not a laser engineer, I don’t know, it just seems weird to me that I’ve seen no speculation one way or another.
I’ve tried googling the coordinates of the stars Borra found and none of them have wikipedia pages, Google sends all the searches for the stellar coordinates back to Borra’s own paper. I don’t know how many light years away any of them are.
There’s no kickstarter. The normal SETI people at UC Berkeley eventually, in October of 2016, agreed to look at a few of Borra’s stars but you could see their heart wasn’t in it. There’s been no word since then.
However, despite humans being boring and uninterested in important things, what about a generalization of this method! :-)
(EDIT NOTE: In the first draft I had text here where I imagined Niven’s fictional Ringworld made out of an impossible super material and then suggested modifications to create a “flicker ring” that could spin around a star and make the star appear to blink at spectral frequencies from certain perspectives. My optical reasoning was ludicrously wrong in the first draft, built around how things would be seen from very close rather than very far. Even with the hypothetical magic substance “scrith” a flicker ring big enough and fast enough to look right at a vast distance would be impossible. The material would have to be many orders of magnitude more magical than scrith to work in this capacity.)
Sometimes I wonder if the only reason we don’t believe in aliens yet is some kind of social signaling equilibrium similar to plate tectonics.
In 1915 Wegener was like “Duh, the continents obviously line up like a jigsaw puzzle” and people were like “No way!” and then 50 years later they were like “Oh, yeah, I guess so, funny how this is obvious to kids now but wasn’t obvious to fancy scientists in 1890...”
If there are “Hoagians” shepherding all the stars in their galaxy into a pretty ring as a collective art project (or maybe just to prevent expensive damaging collisions?), that would be pretty epic.
In terms of the weird question however, the problem is that Hoag’s Object is only 9M light years away (vs Andromeda’s 2M, and that’s part of why we easily see it. Picking it out uniquely from 8000M light years away would be a totally other thing. Also, it is only visible if you see it from the poles rather than the edges, which is another reason it isn’t a very good universal signal.
5. Black hole collisions have never been attributed to aliens, to my knowledge. However, they are obviously big and awesome and get a lot of news. If you could survey moderately sized black holes in your galaxy and nudge them around in a controlled way you might have a partial solution? Timed collisions would be hard to deny were aliens I think. Imagine:
Chirp! (2.32 days) Chirp! (then wait another 16.30 days)
Chirp! (2.32 days) Chirp! (2.32 days) Chirp!
You going to tell me that’s not an intentional “here I am!” signal? You can’t! :-P
From a long term signaling perspective (like to break through the Fermi Paradox by visibly declaring once and for all “intelligence existed!” before the Great Filter gets you) the problem here would be that this would be a one time signal that only communicates to a small shell of stars a precise distance away.
Many such events could have occurred before humans could hear them, and many might exist after we go extinct, with us none the wiser :-/
6. Gamma Ray Bursts are more usually associated with death and life. Basically they are so bright that they would probably cause mass extinctions in their home galaxies.
However, if you could figure out a way to cause them (not that hard? just crash neutron stars into each other in head on collisions?) and somehow survive a series of six-ish closely timed blasts then it could work like black holes, but way more obvious. No theory of relativity is even required to know to build a gravity wave detector! Black holes are still probably better in terms of style points, because their collisions don’t seem to cause mass extinctions :-P
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Anyway, my point is that all of these are thing that have already come to mainstream scientific human attention and caused lots of exploratory interest and analysis.
ALSO, all of them have been more or less dismissed by mainstream astronomers as being conclusive evidence of extraterrestrial civilizations.
ALSO, I don’t instantly see super obvious ways to twist any of these things around to function as a clean cut answer to the weird question where a short-lived Kardashev Type III species with our physics and material science (but better and more manufacturing capacity) could set something up, have it persist after the Great Filter gets them, and signal to everyone forever.
Paul, I love what you’re doing here, have been thinking about this a long time. I look forward to seeing an answer and would like to write a clarifying essay full of non answers :-)
This suggests that we can list various anomalies that might have been thought to be extraterrestrials and already received attention, and then exclude them for various reasons.
1. For example, Tabby’s Star recently had me wondering/hoping/worrying for a good year or two.
It is only 1,280 light years from Earth and I think it is plausible that we wouldn’t even be able to see similar stars on the far side of our own galaxy which is mere ~100k light years in diameter… it can’t count for this exercise because seeing it from other galaxies would be quite a trick.
HOWEVER, despite being an F type star (that shouldn’t be variable (that varies in very irregular ways)) it was interesting enough raise $100k on Kickstarter for telescope time, and to deserve its own feed. I think people are pretty sure it is natural at this point, with a probable case of “indigestion” from the star colliding with a metallic planet in the last 10k years or so.
However, the fact that it got our attention means someone might do that to one planet/star combo like clockwork, every 1000 years in a regularly spaced line of stars.
It could work as a local “we exist” signal whose clocklike timing would count as the signature of intentional planning and sort of function like an invitation to show up at the logical NEXT star in the timed “indigestion collision” sequence to watch the collision and parley with whoever else showed up…
However, I don’t think these events would be bright enough for the weird question?
(This does raise the question as to what counts as a “message” and what the bitrate of said message is allowed to be? Is a valid message just “this was intentionally created”, or “this was intentionally sent”, or “here is a place that will be interesting at a future time” or something even more than that? Also, what if the evidence of intentionality comes from a coincidence of timing spread across spans of time that requires detailed astronomical records for longer than humans seem to be able to maintain political or cultural or linguistic institutions?)
2. In 1967 Pulsars caused people to be very excited for a short period of time, thinking that such regularity must be intentional. However then it was worked out that pulsars were just spinning charged neutron star remnants leftover from supernovas. Still, they are pretty great natural clocks ;-)
This might make them a great “medium” in which to encode intentionality, but it means you have to modulate or sculpt them somehow so that when alien astronomers get interested they can see a deviation from what’s natural.
Another problem is that they are highly directional, with most of the energy going out of their wobbling north and south poles (which when they wobble across your telescope is one of the pulses), so they don’t signal very widely.
Another problem is that they aren’t actually very bright. We see them in the Milky Way, and in our galactic neighbor the Large Magellanic Cloud, but finding an unusually bright pulsar 2 million light years away in Andromeda was newsworthy. In 2003 McLaughlin and Cordes tried to find very bright pulsars further afield and maaaaybe got a hit in M33 (aka “The Triangulum Galaxy”) which is only 3M light years away. But seeing these things from 8000M light years away is highly questionable.
Binary pulsars are more rare and more likely to get scientific attention.
The first binary pulsar, discovered in 1974, won the 1993 Nobel in physics for Taylor and Hulse. By 2005 there were 113 discovered. They are interesting because they modulate the “clock” dynamics inherent to singleton pulsars.
Binary pulsars tick faster when coming towards you and tick slower when moving away, so the orbital parameters of the system can be characterized precisely just from the timing of the ticks. These orbital parameters measurably changes on the timescale of human lives, slowing down in a way that can be naturally interpreted as indirect proof that gravity waves exist and are pulling energy out of such massive systems :-)
If you wanted to catch someone’s attention you might construct or find a three star system that included a pulsar aimed the way you wanted to send a message, and then mess with the orbital parameters intentionally.
Non hierarchical three star systems are chaotic by default and well understood chaotic systems can be controlled with surprisingly little energy which might make something like this attractive.
A probable hierarchical trinary-with-a-pulsar (and so not necessarily chaotic) that includes a sun-like star was surveyed in 2006. The third star is not totally confirmed, and even if it exists the arrangement here is more like a binary system, where one of the binaries has a large planet/star/thing orbiting it alone (hence “hierarchical” and hence probably not chaotic).
There is another pulsar trinary that might be chaotic found in 2014. These things tend not to last however, because “chaos”.
Those are the only two I know of. I’m pretty sure the trinaries are being examined “because physics” but I’ve heard no peeps about unusual patterns of timing from them. But still, no matter how many neighbors pulsars have, they are fundamentally too dim and too directional to count as part of an answer to the weird question here I think...
3. The 234 star’s that might be called “Borra’s Hundreds” can probably also be discounted directly because at best, if these are signaling extraterrestrials, then they are just using puny pulsed lasers with roughly our own planet’s industrial energy outputs, in more or less the visible spectrum (blockable by dust), which probably doesn’t count because it obviously can’t be seen from somewhere far away like the Sloan Great Wall.
The idea, initially articulated by Ermanno Borra in 2010 as I minimally understand it, is that a laser could shoot out light of nearly any frequency (frequency as given by the wavelength of individual photons), but if we or aliens could pulse the quantity of photons sent out fast enough, this would be visible to typical methods for measuring the “frequency of light from a star” in standard spectrographic surveys whose intentional goal is to figure out the atomic constituents of those stars from the wavelengths (and hence the frequencies) of the specific photons they emit. The methods aren’t looking for very fast pulses of more and then less photons, but they could nonetheless see them by “accident”.
In 2012, Borra tried to explain it again and spelled out more of the connections to SETI, basically saying that formal SETI was doing one thing, but spectrographic star surveys were better funded and you could do SETI there too just by processing the exact same data through another filter to make the possible injected signals pop out.
Aliens seeking to be discovered would know anyone smart would do spectrographic surveys of the stars, so that would be an obvious place to try to put a signal.
Then in 2016 Borra published again, now with Trottier as a coauthor, saying that he’d gone ahead and looked at archival spectral data, and found 234 stars that seemed to be sending out “peculiar periodic spectral modulations” of the sort that he predicted… unless the recorded version of the data had frequency artifacts in it?
As summarized by Snopes (normally a good source) the claim is disregarded but all the criticisms are status attacks rather than attending to any kind of object level analysis of the math, the physics, or the collected data.
The BEST argument against Borra is one I’ve almost never seen leveled, which is that the data processing method involved complex math, and had error bars, and they analyzed 2.5 million stars and only found 234 results. This makes me instantly wonder: data mining artifact?
But in that case you’d expect someone to make this argument seriously and explain in detail how the math went wrong somewhere? I don’t get it.
Maybe people think that lasers that blink with a terahertz frequency are impossible because of “laser physics” or something? But no one seems to have raised this objection. And it seems to me like it might be possible to do this just from having a normal continuous laser and then spin something very very fast that periodically blocks the light coming out of the laser? I’m not a laser engineer, I don’t know, it just seems weird to me that I’ve seen no speculation one way or another.
I’ve tried googling the coordinates of the stars Borra found and none of them have wikipedia pages, Google sends all the searches for the stellar coordinates back to Borra’s own paper. I don’t know how many light years away any of them are.
There’s no kickstarter. The normal SETI people at UC Berkeley eventually, in October of 2016, agreed to look at a few of Borra’s stars but you could see their heart wasn’t in it. There’s been no word since then.
However, despite humans being boring and uninterested in important things, what about a generalization of this method! :-)
(EDIT NOTE: In the first draft I had text here where I imagined Niven’s fictional Ringworld made out of an impossible super material and then suggested modifications to create a “flicker ring” that could spin around a star and make the star appear to blink at spectral frequencies from certain perspectives. My optical reasoning was ludicrously wrong in the first draft, built around how things would be seen from very close rather than very far. Even with the hypothetical magic substance “scrith” a flicker ring big enough and fast enough to look right at a vast distance would be impossible. The material would have to be many orders of magnitude more magical than scrith to work in this capacity.)
4. Hoag’s Object is pretty fascinating and fascinatingly pretty.
Sometimes I wonder if the only reason we don’t believe in aliens yet is some kind of social signaling equilibrium similar to plate tectonics.
In 1915 Wegener was like “Duh, the continents obviously line up like a jigsaw puzzle” and people were like “No way!” and then 50 years later they were like “Oh, yeah, I guess so, funny how this is obvious to kids now but wasn’t obvious to fancy scientists in 1890...”
If there are “Hoagians” shepherding all the stars in their galaxy into a pretty ring as a collective art project (or maybe just to prevent expensive damaging collisions?), that would be pretty epic.
In terms of the weird question however, the problem is that Hoag’s Object is only 9M light years away (vs Andromeda’s 2M, and that’s part of why we easily see it. Picking it out uniquely from 8000M light years away would be a totally other thing. Also, it is only visible if you see it from the poles rather than the edges, which is another reason it isn’t a very good universal signal.
5. Black hole collisions have never been attributed to aliens, to my knowledge. However, they are obviously big and awesome and get a lot of news. If you could survey moderately sized black holes in your galaxy and nudge them around in a controlled way you might have a partial solution? Timed collisions would be hard to deny were aliens I think. Imagine:
Chirp! (then wait 16.30 days)
Chirp! (2.32 days) Chirp! (then wait another 16.30 days)
Chirp! (2.32 days) Chirp! (2.32 days) Chirp!
You going to tell me that’s not an intentional “here I am!” signal? You can’t! :-P
From a long term signaling perspective (like to break through the Fermi Paradox by visibly declaring once and for all “intelligence existed!” before the Great Filter gets you) the problem here would be that this would be a one time signal that only communicates to a small shell of stars a precise distance away.
Many such events could have occurred before humans could hear them, and many might exist after we go extinct, with us none the wiser :-/
6. Gamma Ray Bursts are more usually associated with death and life. Basically they are so bright that they would probably cause mass extinctions in their home galaxies.
However, if you could figure out a way to cause them (not that hard? just crash neutron stars into each other in head on collisions?) and somehow survive a series of six-ish closely timed blasts then it could work like black holes, but way more obvious. No theory of relativity is even required to know to build a gravity wave detector! Black holes are still probably better in terms of style points, because their collisions don’t seem to cause mass extinctions :-P
---
Anyway, my point is that all of these are thing that have already come to mainstream scientific human attention and caused lots of exploratory interest and analysis.
ALSO, all of them have been more or less dismissed by mainstream astronomers as being conclusive evidence of extraterrestrial civilizations.
ALSO, I don’t instantly see super obvious ways to twist any of these things around to function as a clean cut answer to the weird question where a short-lived Kardashev Type III species with our physics and material science (but better and more manufacturing capacity) could set something up, have it persist after the Great Filter gets them, and signal to everyone forever.