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A search for technosignatures around nearby stars
- amerine 3y ago“All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature.” From the paper.
- deleted 3y ago[deleted]
- fbdab103 3y agoI would say it is a safe bet that if the authors had found something, the publication would be titled something significantly different.
- Qem 3y ago> Based on our observations, we found that there is a high probability (94.0-98.7%) that fewer than ~0.014% of stars earlier than M8 within 100 pc host a transmitter that is detectable in our search (EIRP > 10e12 W). A terawatt transmitter is one hell of a transmitter. That's about 10% of the power our entire civilization consumes, IIRC. The civilizations detectable in this search would have to be much more advanced than our own, to be able to dedicate such a large amount of power to a single transmitter.
- deleted 3y ago[deleted]
- gjhan 3y agoIt’s EIRP, not actual radiated power. If the beam is narrow this is achievable with moderate total power. The DSN transmitter in Canberra is capable of this EIRP on about 100 kW total power.
- Qem 3y agoThank you for the clarification. I was mistaken.
- ggm 3y agoThe assumption being "advanced" means "radiate prodigious amounts of RF in spectral ways we can detect, and see as information-rich". Because a truly advanced society probably doesn't needlessly pollute space with RF nobody else needs to see. On the other hand "yea, they're probably as dumb as we are"
- XorNot 3y agoA truly advanced society might be investing significant effort into making itself detectable to other civilizations though. Any civilization experiencing a substantial post-scarcity phase would be likely to have at least some off-shoot groups which use their substantial resources to engage in this activity. i.e. if energy was functionally free for the average man (because we had the Dyson swarm up and running or something), then what are the odds that some group wouldn't have used their time to build a transmitter to act as a beacon? Could we even stop them if they wanted to (i.e. even if we didn't want to broadcast locally, sending probes to Alpha Centauri and broadcasting from there would be a good way to conduct intelligence gathering on potential interstellar threats).
- ggm 3y agoWe've been broadcasting at quite detectable volume for "contact" (sagan) 100 light- years in a radiating spherical radius. We didn't even have to argue about it. Beaconing, assumes random dice throw (of who to beacon at) pays off. I'd say the odds are worse than lotto winning: Higher input costs, lower chance of success.
- XorNot 3y agoYou don't need to though: directed radio can be switched to point at different targets. In fact this would be preferable: i.e. blinking prime numbers out into the universe could be by switching radio targets to create the message.
- ggm 3y agoAgain, you assume that point-source RF which beacons to many places by switching aligns with when they're looking. You have to do a LOT Of hand waving around "better wiser Aliens can listen everywhere all the time" for this to pay off, and I would observe if this is such a brilliant technique, how come we haven't received the beams sent to us?
- ianburrell 3y agoEIRP is the power as if transmitting isotropically over the whole sphere. The actual power can be a lot lower if concentrated in one direction. Arecibo EIRP was 10e13. This means that civilization, like ours, could transmit to each star instead of all directions. But that would mean deliberately communicating.
- fnordpiglet 3y agoIn the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun, one which I doubt anyone is sending directional signals towards. I also wonder if we could recognize a signal from an advanced civilization. Wouldn’t compression and encryption make most signals tend towards appearing like noise?
- genewitch 3y agoI use kiwisdr when I want to test propagation as a receiver, and I tend to transmit carrier only or Morse, which is extremely narrow and I can get a lot of power in a narrow bandwidth. If I see a line or dashes on the receiver, I know my signal makes it through, and I can switch to a protocol that can "be heard below the noise floor" and see how good the "channel" I've made is. If I was in charge of letting the galaxy know we existed, it would just be a carrier or a solid tone as loud as I could make it. To get fancier I'd have the transmitter tap out the Fibonacci sequence as CW, as close to 1 second on pulses as I could conceivably make it - and I can get close with the kit I have now.
- fnordpiglet 3y agoOh I agree if I wanted to be known I would send out some highly structured signal. That assumes a lot though, particularly a desire to be known. I could imagine quite easily a counter scenario not even based on paranoia - maybe interstellar distances are so vast and the period civilizations try to be known in is so short that they all essentially give up on being known, and the chance of two civilizations overlapping in that window is much smaller than the length of an advanced civilization. Or, without watching every where all at once all the time we just won’t see them in their space life hubris phase that I feel we are likely exiting already. Realistically Drakes equation and a non Martian search for life has only been going on for 50 years. I doubt it’ll be going on in earnest for another 50. That’s a single human life span.
- natch 3y agoI think the really significant term in the Drake equation is the question of time overlap between our civilization and any civilizations in other star systems. In other words, the likelihood that they either lived before or (will live) after us is overwhelming, since the time scale of the universe is so vast compared to the time scale (with our one known example) of a civilization. Our timeline is like the blink of an eye, compared to the age of the universe. Very unlikely that nearby blinks would happen at exactly the same time, even with a 11,000+ multiplier.
- ldjkfkdsjnv 3y agoReminds me of the failing of the k-nearest neighbor algorithm. It works extremely well in low dimensionality, but given high dimensionality, its astoundingly bad. As you scale up the space and number of dimensions, the distances between individual chunks of data gets so large its hard to draw meaningful conclusions.
- nmca 3y agoI dunno I've done a lot of high-dim knn that were quite pragmatically useful
- ldjkfkdsjnv 3y agohttps://en.wikipedia.org/wiki/Curse_of_dimensionality https://en.wikipedia.org/wiki/Curse_of_dimensionality
- nmca 3y agoMaybe we're talking at cross purposes; what I mean is that PCA+KNN or other tricks mean that for high dim and large amounts of data you can get useful results; with the enlarged view of KNN as "anything where the last step is KNN" your statement that it's "astoundingly bad" is wrong. But for the narrow view of just KNN then sure cod applies.
- natch 3y ago
- readyplayernull 3y agoShouldn't we be looking for civiliations near black holes? Time dilation, which makes time pass slower when closer to the black hole, would result in a relatively "longer living" universe, and there's plenty of free energy and materials to harvest, and also the BH would be a natural trash can, basically solving all the energy/production/disposal/time-span problems of any civilization.
- deleted 3y ago[deleted]
- wwweston 3y agoIf you expect any outside civilizations might be hostile, wouldn't a slower frame of reference magnify the risk, both in terms of giving slower civ a disadvantage in adaptation/response times if any conflict did occur, and also in giving the faster frames more time to spawn hostile civilizations?
- kadoban 3y agoIt probably depends what the limits of physics actually are. If interstellar war is actually practical given the laws of nature, you might be worried about such things. Otherwise, doesn't matter.
- readyplayernull 3y agoWeapons and soldiers would be entering the same time frame, so they would have similar response times.
- sadtoot 3y agopark your army away from the black hole and build up your weapons and drones before the battle. you could build up resources at speeds orders of magnitude greater than the black hole civ
- wwweston 3y agoIf hostiles were conquerors, I’d think they’d send waves of robot-weapons, with extra time to make/improve successive waves. If they were annihilists, I’d think they’d send relativistic projectiles.
- Geee 3y agoIs anyone looking at the stars itself? Isn't modulating the light from a star the easiest way to transmit information afar? This would be the case if you want someone to notice. If I was a digital superintelligence, I would try to conquer the universe by transmitting myself everywhere with maximum power, including instructions to construct a computer which can run me. I could do this by constructing a modulating device around a star. Surely there would be some sort of 'easy detection code' which allows primitive species to first notice the signal and start studying it, and then progressively include more advanced instructions + data.
- ethanpil 3y agoSounds like a great premise for a hard sci-fi novel. let me know when you have a draft, I'll read it!
- frankgrimesjr 3y agoIIRC, modulating light from a star is part of the plot from The Dark Forest.
- Geee 3y agoI'd love to write sci-fi one day. Don't hold your breath though. :)
- Firmwarrior 3y agoRead A Fire Upon the Deep
- andsoitis 3y agoSounds partially like the plot (or the conspiracy theory) from Contact, starring Jodie Foster.
- holografix 3y agoThe book, like in almost all cases, is so much better than then the movie. Eg: she doesn’t travel alone. Think about what that does to the plot.
- joe_the_user 3y agoI just skimmed the paper. Does it say how strong a signal would have to be on a home planet to be detectable by SETI? My understanding is there aren't any earth signals produced by humans that would be detectable by Earth level instruments past Proxima Centauri but perhaps things have changed.
- marsten 3y agoThe upper bound given in the paper is on emitters of one terawatt EIRP (10^12 Watts) and above. EIRP means an isotropic emitter would need to be this powerful to be detected. A beamed transmitter that happened to be pointing in our direction could be somewhat weaker in total power, and still be detectable. It's important to realize that this is at least 100,000 times more powerful than our most powerful Earth-based narrowband emitters. So we would not detect ourselves in this search - not even close. Moreover, we have no good reason to believe that an advanced species would have cause to radiate 1 TW into space. Our own terrestrial emissions are becoming weaker over time, not stronger, as we optimize for total system bandwidth in our communications. So I wouldn't draw too many strong conclusions here about alien life. We are still very much searching for our lost keys directly under the lampposts.
- alphanumeric0 3y agoI've heard someone make this argument before and it makes sense to me. So why does SETI continue to do these sorts of studies?
- galaxyLogic 3y agoWhen we find another civilization, what are the odds that it is more civilized than us? I think that is highly likely because we have had telescopes only a few thousand years. So let's assume that most civilizations we might find are more advanced than us. They have bigger more advanced weapons most likely. So does it make sense to try to tell them our very new civilization exists? Would it help us somehow if they discover us? Perhaps not UNTIL our civilization is capable enough. Other civilizations probably would have similar thoughts and therefore they would not try to contact us, until they feel they have developed enough. Which is probably never. I mean did American Indians really want to be discovered by Europeans?
- mmusc 3y agoThat's the whole premise of The Dark forest hypothesis https://en.wikipedia.org/wiki/Dark_forest_hypothesis https://en.wikipedia.org/wiki/Dark_forest_hypothesis
- dylan604 3y ago>we have had telescopes only a few thousand years. how long?
- gizajob 3y agoYour premise is a little self-referential. Civilizations imply civilized, ours and theirs are both going to think themselves civilized, but might not recognise one another as such. Aboriginal Australians didn't find the colonisers of that continent particularly civilised and the colonisers didn't find them civilised. Our planet could be seen as so uncivilised as to be a worthy candidate for annihilation. Or building a space bypass through our solar system.
- NotSuspicious 3y agoIt always boggles my mind that there is this relatively well-put together effort at looking for extraterrestrial life in the stars that. . . just sort of ignores the fact that UAPs exist and are already here. It's this weird massive epistemic blindspot that tends to come across as smugly pseudointelligent. We should be looking for technosignatures from other bodies in our solar system in addition to what's done here. The signal might be stronger and at the very least it's much closer to where we know these guys are hanging out.
- baq 3y agoEver wondered why a civilization which mastered manned space travel would keep crashing into a planet for 50 years? UAPs are very convenient for top secret military projects, I bet whoever thought of them couldn’t have imagined that the ruse would work so well for so long.
- danparsonson 3y agoThe U in UAP stands for Unidentified. We don't know anything about them.
- tsimionescu 3y agoUAPs that have been studied with any kind of scientific scrutiny have turned out to be ducks and similar advanced forms of non-human life. Beautiful creatures, to be sure, but not exactly what SETI is aiming to find.
- jamilton 3y agoThere are a lot of people trying very hard to investigate UFOs/UAPs. To my knowledge, they haven't been successful. I'd be surprised if they haven't tried surveying the solar system, and the solar system is sufficiently small that I would expect it to be cheap to get results.
- dvh 3y agoI came up with following technosignature: Imagine a star system where there is CO2 rich planet closer than the main habitated planet (think earth as main planet and Venus as CO2 rich inner planet). At some point civilization will try to terraform the CO2 planet by venting CO2 into space, but they don't want to poison their own planet so there will be seasonal gaps in CO2 emissions just when the inner planet crosses in front of main planet. So to find such civilizations you only need to know 2 orbital periods and monitor CO2 or other gas emissions. Any drop during the conjunction is the technosignature.
- kaushalvivek 3y agoRather than venting, the civilisation would probably convert CO2 to a different compound, on the same planet.
- cyberax 3y agoFirst, you can "vent" CO2 outside of the plane of the ecliptic. Second, you do not "vent" CO2 anyway. Why would you do that? It's stupid and wasteful. You just transform it into diamond and bury it inside the crust.
- igrekel 3y agoNow, if we "vent" some enough to the "side", how much can we tilt the ecliptic?
- interfixus 3y agoAny sufficiently advanced technology is indistinguishable from random noise.
- fsiefken 3y agoSo how many stars of spectral type earlier than M8, so type O, B, A, F, G, K, and early M-type stars, are there within a 100 parsec (or 326 light-year) radius of the Sun? How would I go about finding an answer, is there an easily query-able database or astronomy app? GPT4 doesn't know, Wolfram Alpha doesn't know, last time I needed an astronomical answer I bought a ProjectPluto Guest license, but I lost the license.
- tetris11 3y agoIt's not much but the HEASARC has a bright star catalogue[1] that contains the MK classifications you want. https://heasarc.gsfc.nasa.gov/W3Browse/star-catalog/bsc5p.html https://heasarc.gsfc.nasa.gov/W3Browse/star-catalog/bsc5p.ht...
- GoblinSlayer 3y agoIf an average distance between stars is 4 light years, then within 400 light years are about a million stars.
- blackhaz 3y agoSumming up densities for O-K stars in [1] inside the volume of a sphere of r=100 pc, I end up with ~ 91,600 stars. If we include M dwarfs that number rises to ~ 375,000 stars. [1] https://www.pas.rochester.edu/~emamajek/memo_star_dens.html https://www.pas.rochester.edu/~emamajek/memo_star_dens.html
- nologic01 3y agoCould technology, defined as the elaborate (=intelligent) and large scale manipulation of non-biological environments be incompatible with the long term survival of biological life (i.e. it is an unstable evolutionary process)? Its a difficult argument, as all of life manipulates its abiotic surroundings one way or another. Yet the antropocene is clearly at least one qualitative step up. We only have this one data point (our own) so make of that whatever you will. But it doesn't take an ultra-pessimist or doomist psychology to see that on the basis of our behavior the odds that technologically enhanced life self-destructs in short timescales are, indeed, non-zero. If "intelligent" biology is an intrinsically unstable system (can't self-regulate because primal drives for reproduction, dominance etc highjack mechanisms that are too powerful for its own good) this would make the absence of technosignals self-evident.
- vouaobrasil 3y agoSome philosophers in the metaphysics of technology have also proposed this idea. The idea is that the arms race or prisoner's dilemma-type situations make the advance of technology unavoidable (technological determinism) and that its inexorable rise forward eventually has a high probability of extinguishing all life on a planet. (More precisely, determinism states that technological development is a strong force; it can be influenced but it is hard). We already have climate change, advanced AI (that may eventually be able to produce more technology by itself), and a planet of organisms that are counter to growth. Deforestation happens because the long-term costs are not shouldered by the present generation. In some way, I believe the end of times is near, but that humanity has TWO possibilities: (A) The planet is destroyed via advanced technology and most humans die, only to repeat the same mistakes again, OR (B) We reach a critical mass of enlightenment that consists of (1) a cautious approach to growth, (2) a moderation in the use of technology, and (3) a stable, healthy relationship with the biosphere. The eventuality (B) is certainly possible if one by one, we start to adopt a philosophy that economic and technological growth isn't the right path and we slowly give up all this advanced stuff for a slower-paced life centered on local communities, local economies, and less efficiency in return for a more peaceful life.
- mikro2nd 3y ago
- neom 3y agoUnrelated: Is that number of authors common? I don't look at many research papers but in my limited viewing, that seems to be a huge number of authors?
- sulam 3y agoCommon in astronomy, especially broad survey projects that use many observations over many observatories.
- londons_explore 3y agoTL;DR: A large team of scientists have used all the latest gadgetry and science methods to hunt for aliens in the stars. After a lot of effort, they can report that they found nothing.
- m3kw9 3y agoFew things that make chance of detection low 1 Primitive species uses primitive methods, another more advanced species would use a new form of transmission/detection to contact equivalent advanced species. 2 the window of a species transmitting could be in hundreds of years at any point of the billions of years the universe a has existed and we have to also be at that same window.
- YeGoblynQueenne 3y ago>> Jean-Luc Margot, Megan G. Li, Pavlo Pinchuk, Nathan Myhrvold, Lea E. Alcantara, Megan T. Andrakin, Jeth Arunseangroj, Damien S. Baclet, Madison H. Belk, Zerxes R. Bhadha, Nicholas W. Brandis, Robert E. Carey, Harrison P. Cassar, Sai S. Chava, Calvin Chen, James Chen, Kellen T. Cheng, Alessia Cimbri, Benjamin Cloutier, Jordan A. Combitsis, Kelly L. Couvrette, Brandon P. Coy, Kyle W. Davis, Antoine F. Delcayre, Michelle R. Du, Sarah E. Feil, Danning Fu, Travis J. Gilmore, Emery Grahill-Bland, Laura M. Iglesias, Zoe Juneau, Anthony G. Karapetian, George Karfakis, Christopher T. Lambert, Eric A. Lazbin, Jian H. Li, Zhuofu (Chester)Li, Darren J. Lu, Detao Ma, Vedant Mathur, Mary H. Minasyan, Mark T. Nasielski, Janice T. Nguyen, Lorraine M. Nicholson, Divij Ohri, Atharva U. Padhye, Supreethi V. Penmetcha, Yugantar Prakash, Xinyi (Cindy)Qi, Vedant Sahu, Joshua A. Scally, Zefyr Scott, Trevor J. Seddon, Lara-Lynn V. Shohet, Anchal Sinha, Anthony E. Sinigiani, Jiuxu Song, Spencer M. Stice, Andria Uplisashvili, Krishna Vanga, Amaury G. Vazquez, George Vetushko, Valeria Villa, Maria Vincent, Ian J. Waasdorp, Ian B. Wagaman, Amanda Wang, Jade C. Wight, Ella Wong, Natsuko Yamaguchi, Zijin Zhang, Junyang Zhao, Ryan S. Lynch Man...! How do people in those research fields where it's standard to have a few dozen authors a paper choose the order of authors' names?
- ChainOfFools 3y agoWhat's Nathan Myhrvold doing in there, up near the top no less? Not to be a salty sounding skeptic, but basic research funding is awful hard to secure through conventional grant processes (as well as being a huge time sink) and it's absolutely wonderful to have an interested billionaire on your team.
- nvalis 3y agoMy guess is that in this case the first 4 listed are main contributors (in whatever way: authors, funding, ...) , while the following are alphabetically sorted.
- permo-w 3y agofits except Ryan S. Lynch in [-1]