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‘Oumuamua, SETI and the Media

One of the more important things about the interstellar object called ‘Oumuamua is the nature of the debate it has engendered. Harvard astronomer Avi Loeb’s paper examining it as a possible technology has provoked comment throughout the scientific community, as witness Jason Wright’s essay below. Dr. Wright (Penn State) heads the Glimpsing Heat from Alien Techologies (G-HAT) project, which he described in these pages, and is a key player in the rapidly developing field of Dysonian SETI, the study of possible artifacts as opposed to deliberate communications from extraterrestrial civilizations. Here he looks at the debate Loeb’s work has engendered and its implications not only for how we do science but how we teach its values to those just coming into the field. Jason’s essay was originally posted several days ago on his Astrowright blog, which should be a regular stop for Centauri Dreams readers.

by Jason T. Wright

Avi Loeb is the chair of the astronomy department at Harvard, a distinguished and well cited astronomer (he has an h-index of 87), and the chair of the Breakthrough Starshot initiative. He’s a strong proponent of making sure that science doesn’t succumb to groupthink and champion of outré ideas.

He also has been making headlines recently for articles he has co-authored, interviews he has given, and popular media columns he has written about the possibility that fast radio bursts, and now ‘Oumuamua, are artificial in origin. This has created a great deal of buzz in popular culture and a lot of hand-wringing and criticism on social media by scientists who find his actions irresponsible. Many have asked my opinion, so I’m collecting my many thoughts on the topic in this post.

I am happy to defend Avi on these grounds:

  • He is driving us to have an important conversation about what “acceptable” SETI research looks like, and in this conversation I’m mostly on his side. He’s essentially moving the scientific equivalent of the “Overton Window” towards SETI, and that’s a good thing. These are exciting and interesting questions and we should not let the face-on-Mars/Ancient-Aliens/UFOlogy types prevent us from discussing them.
  • He is using tenure and his stature the way we all imagine it’s supposed to be used: as a shield so that he can explore potentially unpopular research avenues without fear of retribution or ostracism. We all imagine that’s what we would do in his position (I hope!) but too often it ends up just being a club to get junior scientists to conform to one’s vision for what “proper” science looks like and what “good” problems are.
  • The papers he and his postdocs are writing are important first steps in making Solar System and other forms of SETI a serious academic discipline.
  • He is being a role model for how scientists can explore outré ideas and spend an appropriate amount of their time on potential breakthroughs.
  • He is putting SETI in the public eye and doing a lot of outreach.

Image: Harvard’s Avi Loeb, at the center of the discussion of ‘Oumuamua. Credit: Harvard University.

Avi wouldn’t be pushing the envelope hard enough if he weren’t getting some pushback, and indeed there is plenty of fair and good-faith criticism that can be made about his approach (not all of which I agree with):

  • The degree of certainty he expresses in ‘Oumuamua being artificial does seem unwarranted to me (though to be fair I’ve always been an ‘Oumuamua-might-be-artificial skeptic.)
  • Given the way we know the press (especially the yellow press) will handle any story about “aliens”, one can argue that the “extraordinary claims require extraordinary evidence” maxim is especially applicable to SETI (I’ve made this argument strongly when discussing my own research in the press.) Avi could hew more closely to this maxim.
  • The tone of his papers and his public comments are quite divergent. The body of the paper on ‘Oumuamua-as-lightsail, for instance, has a brief mention about the potential of the artifice of ‘Oumuamua at the end, but most of it is about the perfectly general problem of thin objects in interstellar space. Snopes highlights this divergence well pointing out that the paper is quite sober and restrained compared to some of the media coverage. (It’s true that the title and abstract of the paper are about ‘Oumuamua specifically, and that it serves as the case study for the whole analysis.) Avi’s public statements are much less conservative and equivocal.
  • He is not just quietly following the evidence; he is using his platform to have a very public and high-visibility discussion about his research. I will concede that Avi is an exception to my earlier (somewhat petulant) protest that SETI scientists are not in it for the attention. That said, I will object to anyone who would claim Avi is only in it for the attention, or that such attention is inherently a bad thing.
  • Many of his papers are de novo explorations of topics like the fate of comets in interstellar space, with little connection to the substantial amounts of work that has already been done on the topic, and his papers would be better and less naive if they had a closer connection to this prior work rather than starting from scratch.

More broadly, let’s look at two threads on Twitter criticizing Avi. I’ll start with this one by Bryan Gaensler:

Bryan makes the rather Popperian argument that if your model is too flexible then it can’t be falsified, so you’re not doing science. The implication is that since we don’t have a good model for aliens, we can always play the “aliens of the gaps” game and so SETI isn’t good science unless it’s looking for unambiguously artificial signals like narrow-band radio waves.

This argument isn’t as tight as it seems. Most interesting new theories start without concrete predictions—General Relativity was so hard to use that even Einstein wasn’t sure what it predicted (he got the deflection of starlight wrong the first time he calculated it; he wrote a paper saying gravitational waves don’t exist). Theories don’t spring fully-formed from theorists’ heads; many important breakthroughs start with something less than quantitative or precise (“maybe we need to modify gravity”; “maybe there is a new subatomic particle involved”) and let the data guide the theories’ details.

This is the normal progression of science. SETI is no different, and so no less scientific.

Then there is this one, by Eric Mamajek, which I mostly agree with:

It’s mostly fine through tweet #9, but then he conflates things in the last tweet using an unwarranted leap of logic.

Up until then he had been criticizing the Holmesian logic of how ‘Oumuamua must be alien because we had ruled out natural explanations. I quite agree with him.

But in the last tweet he jumps to criticizing even bringing up the hypothesis of ETI’s in general, implying that scientists who do are pulling a Giorgio Tsoukalos. (There’s also the assertion at the end such anomalies will “inevitably” turn out to be not just natural, but mundane, which is obviously not strictly true.)

But Tabby and I weren’t pulling a Tsoukalos when we submitted our proposal with Andrew Siemion to NRAO to study Tabby’s Star. We really weren’t. I have clarified the actual events with Eric, so I’m pretty sure that’s not what he meant to imply here, but that is how this tweet reads.

Bryan makes a similar (but softer) implication in his final tweets:

We all would! Indeed, it was Avi Loeb who made the suggestion that Breakthrough Listen point Green Bank at ‘Oumuamua [1] because he understands very well that the proof of alien technology is something like the bullets on Bryan’s list.

But the implications of these tweets aren’t just wrong, they’re harmful to the field of SETI. A very plausible path to SETI success will be that we will see something strange (not “Eureka!” but “That’s funny…” as the old fortune quip goes) and eventually, after lots of follow up, we might find the smoking gun, or perhaps it will just end up being a proof by exclusion. As I wrote in 2014:

Artifact SETI can thus proceed by seeking phenomena that appear outside the range that one would expect natural mechanisms to produce. Such phenomena are inherently scientifically interesting, and worthy of further study by virtue of their extreme nature. The path from the detection of a strange object to the certain discovery of alien life is then one of exclusion of all possible naturalistic origins. While such a path might be quite long, and potentially never-ending, it may be the best we can do.

Communication SETI, on the other hand, shortcuts this path to discovery by seeking signals of such obviously engineered and intelligent origin that no naturalistic explanation could be valid. Together, artifact and communication SETI thus provide us with complementary tools: the most suspicious targets revealed by artifact SETI provide the likeliest targets for communication SETI programs that otherwise must cast an impossibly wide net, and communication SETI might provide conclusive evidence that an extreme but still potentially naturalistic source is in fact the product of extraterrestrial intelligence (Bradbury et al. 2011).

Bryan’s thread and Eric’s final tweet could easily be read to foreclose this sort of research, essentially saying “it’s not worth thinking about the aliens hypothesis until it’s so unavoidable that you’ll get no flak for it” (radio signals à la Contact, the proverbial saucer on the White House lawn, etc.). They certainly make it clear that they won’t hesitate to chastise you on Twitter for going down this road.

But if we want to get to the end of that road, we’ve got to start walking down it at some point, and when the media very reasonably asks what we’re doing so they can report on it to a very understandably curious public, we should be allowed to answer their questions without having our motives (or scientific credibility) questioned by our peers.

In short: your mileage may vary on Avi’s particular style of public communication and conclusions on ‘Oumuamua, but when making your critique please be mindful that you are not slamming the whole endeavor. SETI as a serious science will make hypotheses, explore anomalies, and discuss the possibility of alien technology as the cause, and we need to be able to do so without obloquy from our peers, and without them policing which kinds of SETI we’re “allowed” to work on or talk about in public.

If I seem touchy about this, it’s actually not because I’m smarting from these Twitter threads or anything like that (which I don’t actually disagree with much—in particular I’m friends with Eric and I know I have his respect). As I wrote at the top, I’m glad we’re having this conversation and I hope it continues!

But another purpose of this post is that Avi and I (and other SETI researchers) have advisees that work on SETI and these sorts of messages are not lost on them: these tweets imply that senior people in your field will disapprove of you because of the topic of your research, and they will police what you’re allowed to say to the press, regardless of how good a scientist you are. Keep in mind, “Avi’s” paper on ‘Oumuamua that is being criticized has a postdoc as first author.

So in closing: I pledge to keep the SETI real and well grounded in science, to be responsible in my interactions with the media about it, and to train my students to do the same.

And, I hope my peers will pledge to create a welcoming environment for my advisees as SETI (hopefully!) comes back into the astronomy fold (even when—especially when—they are complaining about Avi).

[Updates: Bryan responds in this thread (click to expand):


[1] = privately, Bryan clarified to me his tweet was referring to his team’s MWA search for signals, not the search by Breakthrough Listen at Avi’s suggestion, as I suggested in my post. My point that Avi appreciates the importance of dispositive evidence stands, but I should have read Bryan’s tweet more carefully and followed link before critiquing his tweet.]

Also, I’ve changed the language about who suggested that GBT observe ‘Oumuamua; Joe Lazio informs me that the observations were made with WVU time following discussions with Breakthrough Listen that preceded Avi’s recommendation. In spite of both errors on my part in the original post, my point that Avi appreciates the importance of dispositive evidence stands.

Also, Avi touches on his motives in this interview:

But the search for intelligent life remains outside the mainstream. I am trying to change that in two ways. First, by speaking out in the way that I did on ‘Oumuamua.


Comments on this entry are closed.

  • ljk January 21, 2019, 14:54

    It is so important for everyone to get past the often sensationalistic headlines the media slaps on to their articles about Oumuamua and especially Dr. Loeb’s comments and work on the object and see what this Harvard professor is trying to accomplish both for the field and the general progress of science – and society in turn.

    This article is also quite important and relevant regarding the future of SETI:

    15th January 2019

    Parasitic SETI and Parasitic Space Science

    Recently there have been signs that NASA may consider a rapprochement with SETI and SETI scientists, after more than twenty years of a de facto NASA ban on funding SETI. It’s not yet clear how far this rapprochement will extend, but NASA did lend its name to the NASA Technosignatures Workshop (NTW18) last September. I wrote on Twitter that the term “technosignatures” may be more palatable than “SETI,” which may sound like an overly-subtle gloss on the situation, but it is still significant. It is conceivable that NASA will consider funding projects that mention “technosignatures” while continuing to pass over any project that mentions “SETI.”

    Full article here:


    To quote:

    There is a kind of subtle irony in SETI science having to operate parasitically on other projects deemed more fundable, or, at least, projects that would not draw the ire of politicians looking for a soft budgetary target to attack. Arguably, whatever public support that there is for space exploration (and however correct or mistaken it may be to connect space exploration with SETI), derives from the hope, perhaps even the titillating hope, of finding something “out there” that would mean that we are not alone.

    I have often said that the excitement over things like exoplanet searches always turns on whether the planets are habitable, and excitement over whether the planet is habitable largely turns on whether we can ever determine whether or not these planets have life, and the excitement over whether or not we can determine if these planets have life largely turns on whether that life could be intelligent, and the excitement over whether or not this life could be intelligent largely turns on whether we might possibly communicate with or travel to these intelligent beings.

    I’ve read a few candid comments to this effect (I can’t remember the source), and I have no doubt that this is the case. In the same way that conservation biology has an easier time raising money to fight for charismatic megafauna but has a much more difficult time raising money based on unattractive or very small animals, so too space science efforts do better when they are related to some “sexy” space science topic like aliens—but this has to be done sotto voce, with a wink and a nudge, because NASA, to be taken seriously, must keep up the appearances of a buttoned-down science prof.

    In a sense, then, it is space science that is parasitic upon SETI and human spaceflight (which appeals as a source of national pride in accomplishment), which, when the latter dominated NASA and NASA’s budget, took the lion’s share of the money and left little for space science. In recent decades, the focus has been more on space science, and so it is SETI (rather than prestige) which is the unspoken background to what is going on in the foreground.

    While I care deeply about space science, and I know how much NASA’s space science programs have transformed our knowledge of the universe, few in the public share my sentiments, and they cannot be expected to share them. But they can share an interest in the “charismatic megafauna” of astrobiology, which are the intelligent aliens that SETI is seeking.

    If NASA can embrace technosignatures as a part of astrobiology, it may find a way to excite the interest of the public while maintaining its scientific respectability. And if that requires a shift in terminology, I suspect that SETI researchers will be ready to make that shift. Of course, any scientific discipline, as it evolves, eventually revises its terminology, as it usually begins with imprecise terms from ordinary language and eventually settles upon more formalized usages that are defined with scientific precision. And there is scientific precision in spades to be found in SETI research papers. What is wanting in SETI (and in technosignatures, for that matter) is the conceptual framework within which these terms of formulated. SETI science is strong, but its concepts are often weak and ambiguous. I have had this on my mind for some time, and I hope to be able to write more about this as I clarify my own thoughts on the matter.

  • Thomas Goodey January 21, 2019, 15:24

    One notes that Loeb hasn’t yet dared to draw the conclusion from his hypothesis, which is:

    If OM really was a discarded solar sail, all crunched up (“squidded”), then it was no longer wanted, its job having been done. It was seen on its way out from perihelion. Therefore the job for which it was deployed was to brake an incoming package, not to accelerate an outgoing package. Since OM was still at hyperbolic velocity even after having done its deceleration task, the package must have performed its own further braking at or near perihelion, perhaps with a reaction engine. This would be a classical Oberth maneuver. Therefore… the package is still here…

    • ljk January 21, 2019, 17:48

      “Therefore… the package is still here…”

      Now there is some food for thought.

      It has been said here in this blog a while back and no doubt elsewhere that if interstellar vessels want to actually stay in our star system rather than just a quick fly through, they will require braking equipment. This equipment may be discarded in the same way that we discard braking equipment when landing probes on Mars, for example, once they have served their purposes. The first physical artifacts from ETI we may one day encounter may be a braking engine or a sail as mentioned above.

      Note that in the case of humanity’s first deep space probes to leave the Sol system, all but one (Pioneer 11) had their final booster stages follow them into the wider Milky Way galaxy. They have just as much of a chance to be found some day as the probes they sent into the void.

      Unless all star exploring ETI use “magical” warp or hyper drives that never detach anything, they may have their own versions of final booster stages trailing their main vessels into the galaxy, purposely following different paths.

      • Harry R Ray January 23, 2019, 11:17

        I have come to a different conclusion, parts of which I laid out in an earlier comment. The following is my revised COMPLETE scenario. I contend that in order for the lightsail to produce the acceleration noted in the literature, IT MUST NOT BE TUMBLING! I agree that it IS discarded, but it is still FULLY FUNCTIONAL(more on this later). It cannot be tumbling because solar radiation pressure would have SPUN-UP a tumbling lightsail, just as outgassing would have(as Roman Rafakov stated in his paper). The reason for the tumbling “effect” is to DELIBERATELY DECEIVE US as to its true nature! This is achieved by CONTINUOUSLY retracting and extending various components of the lightsail. To comply with Loeb’s most recent paper, the lightsail must have been FULLY RETRACTED at its closest approach to Earth and then RE-EXTENDED to near maximum in November to produce the 1 magnitude increase. NOW FOR THE GOOD PART! After discarding the lightsail, the main probe deployed a MAGSAIL to decelerate in order fir it to be captured by the sun’s gravity. Since the main probe would approach Earth, a lander could not be sucsessfully landed on either rhe Earth or the moon on its first pass, so a very close aproach to Earth would have been needed to insert it into an orbit bring it close enough to the sun begin a DAMPENING procedure to make it MORE ALIGNED with Earth’s orbit. In this scenario, it may take YEARS OR EVEN DECADES fir it to achieve an orbit that would make it feasible to land a lander on either Earth or the moon. If the intent was to deceive regarding the lightsail, it should also be so for the main probe as well. I then assume that it is PITCH BLACK! However, there mkight STILL be TWO WAYS to detect it: JWST could detect its infrared signature, but this is a LONG SHOT. I propose that the BEST WAY would be to detect the MAGNETIC FIELD generated by the magsail on the INGRESS portion of a future orbit.

        • ljk January 23, 2019, 11:53

          Is there any evidence that Oumuamua is slowing down? The data shows that the object is speeding up, which I believe is what brought up the whole light sail possibility in the first place.


          As for any hypothetical lander/probe, would “painting” it black be sufficient to hide it in space? Wouldn’t it be giving off some kind of radiation signature? I am presuming if these hypothetical ETI are using light sails that their lander vessel(s) are not paradoxically using some sort of magical high technology instead.

          Also, would such ETI being using a big probe to explore Earth? Wouldn’t something like nanotech make more sense, assuming they do not want to disturb the subjects of their studies? As we have seen with Breakthrough Starshot, the plan is to use tiny StarChips to do the main system exploring.

        • Alex Tolley January 23, 2019, 12:15

          I think Occam’s razor needs to be applied here.

  • Ron S. January 21, 2019, 15:27

    What is being labelled a “theory” is at best a hypothesis, if not a downright WAG. Hypothesis generation if fine, but how should these be presented? I am not concerned with public reaction, which has little staying power, but with those whose opinion can influence the entire field.

    “The tone of his papers and his public comments are quite divergent.”

    That’s a problem. It is not at all uncommon for some to ratchet down their claims in a paper to ensure that it passes review, and ratchet up again during public interactions. I previously made this point about Loeb in this blog that when a reporter pushed him on his extravagant claim he resorted to crying: “it’s peer reviewed!” Yes, the paper did pass, but not the subsequent claims.

    “Keep in mind, “Avi’s” paper on ‘Oumuamua that is being criticized has a postdoc as first author.”

    All the more reason to be circumspect. Loeb has tenure, the first author does not. I see a real risk that his very public claims will damage another person’s career prospects. Is the first author concurring with Loeb’s claims?

    • H. Floyd January 21, 2019, 19:14

      “What is being labelled a theory is at best a hypothesis[.] Hypothesis generation if fine, but how should these be presented? I am not concerned with public reaction . . . but with those whose opinion can influence the entire field.”

      +1. The tedious solid double line separating hypothesis from scientific theory protects the apes at the wheel from the ever-oncoming traffic of their inherited minds. Marvel at the magnificent sights ahead, with sober eyes on a road paved with credibility. This trip is for nothing if we don’t get there before dark.

  • Charley January 21, 2019, 17:03

    “The papers he and his postdocs are writing are important first steps in making Solar System and other forms of SETI a serious academic discipline.”
    … any consideration to the idea that perhaps this is nothing more than a natural ‘gravity assist’ phenomena?

  • David January 21, 2019, 22:55

    I am going to defend Ari and SETI. And ancient aliens. I would also suggest a Philosphy of Science course to look at how you actually do things . First of all dump the concerns of hypothesis and theory and the stuff you learned in high school. You dont do that any way.
    First ancient aliens nothing wrongbwith the idea. Think of the Fermi equation. So what is wrong with it? Very very simple . There is no evidence. Everything posieted as evidence has been well found lacking. The Myan King is being buried not shot into space. My class did a Nazca drawing in one Saturday morning . And we know who built them and why. So its not the idea of ancient aliens that is flawed it is simpky we have no evidence. If you get BS in an academic setting rip into economics the new astrology seriosly google it . Its great . So have ideas and collect evidence. Create models and see what fits. So far we dont have evidence of ETI but no harm in looking. I would also suggest Kuhns book onnthe Coperican revolution. Easier read than Structure of Scientific Revoltions . There is something really interesting there. The earliest data of that time actually came closer to epicycles than Copernican model…..I keep thinking about that with our current cosmological models.

  • Ljk January 21, 2019, 23:27
  • Michael Fidler January 22, 2019, 3:10

    And stones do not fall from the sky! Reputations are at stake!

    All I see are people that are worried about their jobs, not about exploration. Academia entrench in themselves.

    What Loab has brought to the table is the actual possibility of repeatable science in detecting artificial exterrestrial artifacts. Something that in SETI or UFO research has not been possible. So we wait for the next object to fly thru the solar system, and what the scientific community should doing is preparing for that!!!

  • DCM January 22, 2019, 5:41

    The object is a modern UFO complete with cultists.
    When will people appear who claim to have communicated with it?

    • Harry R Ray January 24, 2019, 10:22

      I shudder to think what’s going to happen when the “Ancient Aliens” gang gets a hold of this, AND BELIEVE ME THEY WILL!!!!! I am sure that Dr Loeb will not volunteer to go on their show DIRECTLY, but I am sure they will be able to obtain rights to show some of his interviews on their show and take things out of context to bolster their wacky ideas!

      • Alex Tolley January 24, 2019, 11:36

        The History Channel’s “Ancient Aliens” might be worth monitoring for just this scenario. Rather you than me. ;)

      • DCM January 24, 2019, 17:24

        Maybe this is a followup by the aliens who told Benjamin Franklin lightening was electricity and how he could prove it.

  • Michael Fidler January 22, 2019, 10:06

    So we see the hate develop and the demeaning atitude of the crowd mentality. This is the insulting attitude of the scientific comminuty that the public so despised.

    • ljk January 22, 2019, 12:17

      Gee, maybe we should have an academia that is set up so that alternate ideas can be expressed and explored without ruination to the individual(s) who dare to think outside the box. It is only the year 2019, after all.

      If science and its practitioners cannot rise above politics and pettiness, how can we expect other institutions to follow suit?

  • ljk January 22, 2019, 10:46

    If you want a really good (and even entertaining) perspective on what it really took for science and humanity to accept the fact that Earth orbits the Sun and not everything in the Universe circling our world, check out this great multipart piece on the history of going from the geocentric Cosmos to the heliocentric one:


    In sum: It wasn’t easy, it was not quick, and politics and other human behaviors got in the way as much as they also sometimes helped the process. We may have better tools and more knowledge than they did in 17th Century Europe, but we are no less human. SETI seems to be in that period now.

  • Michael January 22, 2019, 11:26

    We must be careful of falling into a God syndrome, just because we can’t explain it now does not mean it can’t be explained later on.

  • David January 22, 2019, 14:05

    Thanks ljk. It just makes the case for observation. Observations supported the Geocentric until they didnt. Btw some of our Centauri Dreams scientists and engineers came under another attack. It is flat out wrong. A self described tansparency group that once Praised Wikileaks has trashed some of the interstellar work. They claimed it was a easte of money even though much was not even government funded.
    It seems the UAP reserachers consulted some of it because they wanted to see if the UAPs they have the Raytheon pictures of might be ETI. Well had this outfit read the papers they might have found out it is not likely whatever these things are they donr fit anything we have looked at here because of the massive amounts of energy would make tgem hard to well hide.
    I think we have a mysterious phenomenon but I dont think its ETI.
    on to secracy . Yes we have too much and it can backfire and it sure has on us . I see no harm in the DIA simply saying we have some UAP and we have not explained them.

    I end on this here . It should not be arequirement that every observation must fit some explanation. I will apply that to Dark Energy UAPs and passing interstellar objects.

    Now lets look ancient aliens astrolgy and most economic models. They never or almost never make a successful prediction or have any observational evidence.

    • ljk January 22, 2019, 15:13

      Now you see why so many in the SETI community have wanted to avoid UFOs and especially their acolytes like the plague.

      While it is important to always present data, facts, and logic in such situations, the scientists must keep in mind that the behaviors of groups such as with UFOs, the Flat Earth, and those who think the Apollo manned lunar missions were a hoax are not coming at this from either an equal playing field of facts and data or educational levels. Oh, they certainly use science data and its trappings when it fits their needs (even creationists will apply Darwinian evolution when they think it will help their cause, ironically enough), but their ultimate purposes have little to do with fostering real science and knowledge.

      Thus, saying things akin to why don’t the UFO folks realize how much energy it would take to travel at FTL speeds across the galaxy carry far less weight than a typical scientist may think, having been trained and educated otherwise.

      Figure out why so many people do not “naturally” gravitate towards the sciences and related fields when it comes to the unknown and mysterious, and you will begin to figure out how they think and why, and thus hopefully have a better method of reaching these folks.

  • Robert January 22, 2019, 14:21

    It seems that to the SETI establishment, the most embarrassing thing that could happen would be to actually detect a signal.

    • ljk January 22, 2019, 15:02

      You should find this online thesis very interesting:


    • AlexT January 26, 2019, 10:54

      …most embarrassing thing that could happen would be to actually detect a signal

      Signal detecting event – it I what was promised by SETI, but has not detected yet, despite long time listening…
      SETI in troubles, so new methods for ETI detection now entering to scene, like speculation about Oumuamua. It is a race without end.

      • ljk February 5, 2019, 12:13

        So they have been trying a particular method for a while and it is not bringing the results they thought it might. So the SETI folks are now looking at other methods.

        If they stayed with radio indefinitely, you would no doubt accuse them of beating their heads against the wall. So now they are looking at other methods and to you it is just another fruitless chase.

        You do not come up with any real solutions, you just don’t want SETI for whatever reason as your ulterior motive and continue to trash the work of others while you jeer on the sidelines under the guise of claiming to be scientific.

  • Martin Andersen January 22, 2019, 15:29

    This is more of an attack or analysis of the person, than a discussion of the topic.
    Listen to an interesting interview with Avi Loeb here:

  • Alex Tolley January 22, 2019, 16:43

    This is a wider issue than the example in this post. Sagan, after all, was penalized for popularizing his work. One suspects jealousy there. With the ever-proliferating output of content, producers try to poke out of the “noise”. We see university PR departments hype minor research. Almost every discovery “…may one day solve some major problem X”. Newspapers vying for circulation do the same for stories or use other techniques like spreading irrational fear. With the ad-supported internet model, we get clickbait and multipage articles to maximize ad revenue.

    Scientists can no longer stay in their “ivory towers”, but communicating with a public who are trained very differently and generally have a very weak understanding of science, is difficult. Randy Olson’s “Don’t Be Such a Scientist: Talking Substance in an Age of Style” talks about how to communicate scientific ideas effectively, and those lessons include techniques that normally appall scientists. The popular press seems to have got worse over my lifetime, as science journalists and reporters are replaced by those without the requisite background. We see that when articles make ridiculous mistakes.

    I do appreciate that SETI has its own problems, as it still suffers from a “giggle factor”, especially from “serious” scientists in mainstream areas. They also need to fend off association with cultists and other fringe believers. There must be some sensitivity to being caught up with some unwanted association. Even so, SETI reserachers make unsupported claims. Shostak stated in front of a congressional committee that we would discover ET life within 20 years. How was not explained, nor why such a timeline. It seems improbable that traditional radio or optical SETI via messages could be the mechanism given the timeline unless he was hoping that full sky surveys across the full EM spectrum would inevitably turn up evidence.

    I think that Wright is correct in that Loeb is pushing the boundaries in his popular press communications. Maybe he wants to get attention and more funding. If he does and it is successful, he will spawn many imitators, although we see that in other fields too. He may also be playing with fire as it could backfire.

    I suspect the Breakthrough Starshot project has stimulated a lot of attention on sails as THE interstellar propulsion technology, which the ‘Oumuamua light curve has coincidently provided a weak supporting leg. Loeb is standing on the PR shoulders of that project to gain more attention for his ideas.

  • Geoffrey Hillend January 22, 2019, 18:32

    Oumuamua shows a spectral signature of a Trojan or Kuiper belt object and a hyperbolic trajectory. It never changes that trajectory, so it is not under it’s own power but only gravity as already posted, and is too slow to be a ship from another star system, so most likely it is not, but a comet like object. There is no way I can sugar coat this criticism, but a scientist should not have to imagine that something might be an ET spacecraft which has the spectral signature of a rock. Every telescopic object with a hyperbolic trajectory that enters our solar system with the spectral signature of a rock is not an alien spacecraft.

    Be not afraid to challenge convention and be innovative with ideas, but don’t ignore science and the knowledge. Even today’s spacecraft technology is faster than Oumuamua. At least with the UFO’s, I might imagine we could one day visit other star systems in less than a life time.

    • Hamilton1 January 23, 2019, 20:18

      ‘Oumuamua is too slow to be a ship from another star system’

      It could be just a reconnaissance probe dispatched from a much faster mothership.

      • ljk January 24, 2019, 11:47

        Or as the other speculation has gone, it could be an inert vessel that stopped functioning a long time ago and happened to fly through our star system.

        While there are no known star systems that the Pioneer, Voyager, and New Horizons probes (and their final booster stages) will be flying through at least so far as has been calculated, these vessels will have ceased functioning, long, long before they get into interstellar space. That makes them no less artificial, just not terribly useful outside of serving as a form of ambassador/gift to the rest of the galaxy.

        • Hamilton1 January 24, 2019, 17:35

          I think we have to assume that if it’s artificial, it’s still functioning. The chances of any of our probes buzzing an extrasolar planet are essentially zero. We would have had to launch ~1 quadrillion of them for there to be a statistical probability that one would travel as close to a planet as ‘Oumuamua did to Earth.

  • Geoffrey Hillend January 22, 2019, 18:46

    I will admit that I can’t prove that Oumuamua is not an ET spacecraft, but it did not come very close to Earth, the most interesting planet in the solar system. If ET made this long journey to our solar system, why not come closer to Earth.

    • Daniel Högberg January 22, 2019, 22:41

      Our planet is the most interesting planet in the solarsystem to US! This is geocentric thinking. To me (and maybe to them) Jupiter and the jovian moons would be the most fascinating!

      • ljk January 23, 2019, 10:03

        Exactly! On an aesthetic level, I can easily see Saturn attracting more attention with its beautiful ring system. Yes, you can then say well aliens might have different notions of beauty. Certainly Saturn’s magnificent ring system stands out among the worlds in our Sol system, beautiful or otherwise, especially those with their own rings. Interstellar ETI may have also seen similar sights in other star systems.

        The other attraction Saturn has going for it is its magnificent collection of moons. Not only are many of them downright exotic, but they may also be useful for an interstellar visitor in terms of fuel and other resources, especially Titan.

        You may recall that one of the features of the BIS star probe concept Daedalus was the need to mine helium 3 from the atmosphere of Jupiter for fuel. ETI may have to do the same with our Jovian neighbors. Plus Jupiter has its own set of fascinating moons.

        The planetoid and comets may also provide multiple values for visiting ETI, many of which have been discussed elsewhere in this blog.

        Finally, these world also provide something that Earth has way too much of: A severe lack of hostile, noisy, and nosy natives. Not that an ETI with the literal high ground advantage couldn’t take care of such a potential threat with relative ease, but I will give them the benefit of the doubt that they are here to explore, refuel, freshen up, etc., rather than the usual trope of taking over Earth. Not with 400 billion potential solar systems in the Milky Way to choose from.

        • Alex Tolley January 23, 2019, 12:10

          On an aesthetic level, I can easily see Saturn attracting more attention with its beautiful ring system.

          Now that we think Saturn’s rings are recent, maybe ET has sent an inspection probe to see what repairs need to be made to restore the rings to their more pristine glory. ;)

          • ljk January 23, 2019, 16:25

            Or they are the ones who tore apart several moons in the process of dropping a large black Monolith on Iapetus….

  • David January 22, 2019, 22:19

    I wonder if lack of out of the box thinking is what is tanking the economy. See Rise and Fall of American Growth. First chapter is free online worth a read . I think Breakthrough Starshot should be sold as something that could get us some breakthroughs. The only other big things would be cell craft clean meat and aging research.

    • ljk January 23, 2019, 10:12

      We could and should be much further along than we are, both in terms of technology and culturally. Instead our thousands of little tribes prefer to bicker and worse over all sorts of trivial and transient issues that become nothing in the relative blink of an eye. That we have not destroyed ourselves by now I almost chalk up to blind luck.

      We may grow up some day. Or we only be the most recent stepping stone in the evolution of intelligent life on Earth.

  • Michael Fidler January 22, 2019, 22:41

    Well I can actually confirm that I will never be in the Who’s Who’s of America, but I when the Aliens pick me up in their FTL crystal spaceship and take me to Proxima Centuria b, I will start a cult that proves that the naked apes of Earth are intelegent. This will become the fastest growing religion the millions of alien races have seen and the Universal Space Force will land on the Chinese islands in the The South China Sea. ;-)

  • Andrew Palfreyman January 23, 2019, 1:29

    Fortune favours the bold. Kudos to Avi Loeb.

    Soon enough we’ll chase it down and do a thorough recon – perhaps even drag it back here. We know precisely where it is and where it’s going. It is not going to disappear.

    And sure as eggs are eggs something similar will come along, and I hope that this time we’ll be ready to intercept it.

    • ljk January 23, 2019, 10:20

      Is the rumor I have read that Breakthrough Starshot’s first target may be Oumuamua true? Unless of course by the time this vessel is built and ready to go we have other more advantageous interstellar visitors to choose from.

      I am certainly not against the idea, but we could get a mission ready for Oumuamua with current technology and resources far faster than Breakthrough Starshot, which will not be ready for decades assuming it is built at all.

  • ljk January 23, 2019, 10:25


    Self-supervised Anomaly Detection for Narrowband SETI

    Yunfan Gerry Zhang, Ki Hyun Won, Seung Woo Son, Andrew Siemion, Steve Croft

    (Submitted on 15 Jan 2019)

    The Search for Extra-terrestrial Intelligence (SETI) aims to find technological signals of extra-solar origin. Radio frequency SETI is characterized by large unlabeled datasets and complex interference environment. The infinite possibilities of potential signal types require generalizable signal processing techniques with little human supervision.

    We present a generative model of self-supervised deep learning that can be used for anomaly detection and spatial filtering. We develop and evaluate our approach on spectrograms containing narrowband signals collected by Breakthrough Listen at the Green Bank telescope.

    The proposed approach is not meant to replace current narrowband searches but to demonstrate the potential to generalize to other signal types.

    Comments: 5 pages, 3 figures

    Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
    Journal reference: IEEE GlobalSIP 2018

    Cite as: arXiv:1901.04636 [astro-ph.IM]
    (or arXiv:1901.04636v1 [astro-ph.IM] for this version)

    Submission history

    From: Yunfan Zhang G. [view email]

    [v1] Tue, 15 Jan 2019 01:59:30 UTC (1,658 KB)


  • ljk January 23, 2019, 10:28


    Policy options for the radio detectability of Earth

    Jacob Haqq-Misra

    (Submitted on 5 Apr 2018)

    The METI risk problem refers to the uncertain outcome of sending transmissions into space with the intention of messaging to extraterrestrial intelligence (METI).

    Here, I demonstrate that this uncertainty is undecidable by proving that that the METI risk problem reduces to the halting problem. This implies that any proposed moratorium on METI activities cannot be based solely on the requirement for new information.

    I discuss three policy resolutions to deal with this risk ambiguity. Precautionary malevolence assumes that contact with ETI is likely to cause net harm to humanity, which remains consistent with the call for a METI moratorium, while assumed benevolence states that METI is likely to yield net benefits to humanity.

    I also propose a policy of preliminary neutrality, which suggests that humanity should engage in both SETI (searching for extraterrestrial intelligence) and METI until either one achieves its first success.

    Comments: Accepted for publication in Futures

    Subjects: Popular Physics (physics.pop-ph)

    DOI: 10.1016/j.futures.2018.04.002

    Cite as: arXiv:1804.01885 [physics.pop-ph]
    (or arXiv:1804.01885v1 [physics.pop-ph] for this version)

    Submission history

    From: Jacob Haqq-Misra [view email]

    [v1] Thu, 5 Apr 2018 14:53:55 UTC (8 KB)


  • Harry R Ray January 24, 2019, 11:27

    The biggest pushback from the scientific community from a deliberate reconaisance of our solar system is “why now?” Perhaps it is because of a “co-incidence of co-incidences” that will occur over the next century. Within one hundred years, our solar system will be engulfed in a dark matter “hurricane” that will make axions one hundred times easier to detect(should they exist)than at the present. Add on to that that at this point in time, Sag A’s radio jet is pointed almost directly at Earth. Each one of these events, INDIVIDUALLY; is very rare. The odds on them happening simultaneously are ASTRONOMICAL! If `Oumuamua is the MAIN PROBE, and its current trajectory will enable it to be in the ABSOLUTE DIRECT PATH of Sag A’s radio jet at the same time it encounters the dark matter “hurricane”, the odds on this being a RANDOM natural phemomenon become ZERO!

    • Alex Tolley January 24, 2019, 15:09

      You are making a mistake with your probabilities. In reality, there are very many events, some of which are “coincidental” in some way. Picking out a few and claiming that they must be rare/unique and therefore not random is not a good interpretation. This is akin to claiming “bible codes” prove agency, whereas random chance is the cause. We, humans, are evolved to find patterns everywhere, but most are really false positive errors.

      • Harry R Ray January 25, 2019, 10:46

        The best way to resolve this is for someone to do a Baysian analysis of the COMPLETE dataset of the `Oumuamua timeline and trajectory, and then do ANOTHER one(totally SEPARATE, i.e. no INTERSECTING data) for ALL of DERIVED CONCLUSIONS from the TOTAL lightcurve. Such an analysis is possible, but would probably require supercomputers. After both analysese are done, a Baysian Number can be assigned to both separate datasets. If you are correct, the Baysian Number for the timeline-trajectory dataset will be low. If I am correct, it will be high. For this to be CONCLUSIVE in regards to the natural versus non-natural interpretations, BOTH numbers would have to be ABSOLUTE WHOPPERS! Case in point: Teachey and Kipping derived a Baysian Number of 40,000 favoring the exomoon interpretation over the second planet interpretation vis a vis the transit timing variations of Kepler 1625b, but even this was not high enough to VERIFY the exomoon.

        • Ron S. January 25, 2019, 14:36

          Mathematics is not magic. You cannot swing a hammer at mirages and expect to build a house.

  • Gary Wilson January 24, 2019, 14:21

    A very interesting and thought provoking article. Thank you Dr. Wright. Surely the best way forward involves keeping the lines of communication open to everyone who is interesting in studying the possibilities of ETI through whatever means in a serious, and scientifically rigorous way. Personally, I feel the ideas surrounding Oumuamua have gotten beyond anything that is testable and although it is perfectly acceptable to use this as a test case for the next object to enter the system I see no point in continuing to add even more claims to what the object might be. As has been said let’s prepare for the next visitor, not make unsupportable and unverifiable claims about the previous one.

    • ljk January 24, 2019, 15:04

      If we could get an automated probe to Oumuamua – and we could with today’s resources and technology – then these ideas would be testable.

      • Gary Wilson January 24, 2019, 16:26

        I like the idea ljk but I don’t think anybody (i.e. a government space agency) has indicated any interest. It would take very fast action now. I saw some estimates that it could be done but only if it got underway immediately and a launch occurred very soon. The US government shutdown surely precludes any action by NASA?

        • ljk January 25, 2019, 11:04

          Have you sent an inquiry/request to Elon Musk or Jeff Besos? How about Yuri Milner?

          • Gary Wilson January 25, 2019, 13:27

            Haha, no I haven’t ljk. Have you? I’m just trying to point out that it doesn’t look like we are going to send a probe after Oumuamua. I hope I’m wrong. It might turn out to reveal something very interesting. We would at least get to study it more thoroughly which is a no lose proposition.

            • ljk January 25, 2019, 14:59

              Yes I have. That is why I am suggesting if more people join the chorus they may actually pay attention and turn this into a reality.

  • Rob Flores January 24, 2019, 20:59

    Since Astronomy projects rely partly on federal funding it’s easy to
    see why the non-seti branch of the discipline will disavow or even ridicule some outlying claims of the seti branch.

    Even astrobiologist at Nasa-Jpl scientists have felt compelled to walk back
    some predictions that I though were reasonable. For example C. MaCay and his view of free hydrogen cycle that seems to be occuring on
    Titan. Just what is consuming the H2, that falls planetward reducing its abundance, could it be acetyline using lifeform?. He had predicted this, and “took it back” a notch or two, when the hydrogen was indeed depleted at Titan’s surface.
    IMO there was nothing wrong with this type of prediction, only he
    needed to qualify that there was significant possibility that some time
    of biotic life was present, certainly not virtual certainty.
    This walk back is a good guideline for extra-solar artifacts claims. The emphasis should be that even when most known procesees don’t explain observed behaviour/character you don’t give the extra-solar explanation the majority probability of it being true. This will be true until we have a 100yr+ database of extra-solar objects entering out neck of the woods .

    • ljk January 25, 2019, 11:25

      I cannot help but think of Alfred Wegener, a German meteorologist who proposed in 1912 that Earth’s continents actually move en masse across the planet. His idea was rejected and ridiculed by geologists and other scientists until the 1960s, because clearly objects as big as continents do not move!


      The evidence was there, but the prevailing paradigms and the usual human flaws and limitations delayed this discovery for decades. The same is no doubt occurring with the subject of extraterrestrial life in all its potential forms.

  • Alex Tolley January 25, 2019, 11:37

    This will be true until we have a 100yr+ database of extra-solar objects entering out neck of the woods .

    Or a decent sample size, depending on frequency of observation.

    However, as Geoffrey Hillend stated upthread, the spectral signature suggests a natural object, not a fabricated solar sail. If it is a sail, it isn’t very reflective, and appears to be carbonized or covered in carbon “gunk”. [ interstellar bugs on the windshield? ;) ] If a camouflaged probe, why draw such attention to itself by its apparently elongated form?

    Also noted is its low velocity, much slower than our own Parker probe to the sun. Almost every interstellar probe idea we have suggests fractional lightspeed. Surely technologically ET could manage something of that order.

    The most reasonable answer is that it is a natural object. Any anomalous acceleration is due to some low emission of volatiles.

    Rather than spend resources chasing this object, I would prefer that we spend resources on a better plan for the detection and observations of other interstellar objects passing through our system.

    • Gary Wilson January 25, 2019, 13:32

      That makes a lot of sense Alex. I would love to find out more about Oumuamua but not at the expense of another project more certain to yield results. Wishful thinking aside, Oumuamua is gone and we’re not going to chase it.

    • AlexT January 26, 2019, 11:27

      Appreciate your argumentation, agree 100%.

  • ljk January 25, 2019, 15:05

    When a Harvard Professor Talks About Aliens

    News about extraterrestrial life sounds better coming from an expert at a high-prestige institution.

    Marina Koren

    Jan 23, 2019

    Astrophysicists usually don’t get chased by reporters, but that’s what happened to Avi Loeb last November.

    They bombarded Loeb’s phone lines. They showed up at his office with television crews. One of them even followed him home and confronted him at the front door, demanding Loeb answer a question.

    “Do you believe that extraterrestrial intelligence exists?”

    Full article here:


  • Harry R Ray January 28, 2019, 10:54

    FINALLY!!!!! A natural “cometary” explanation that MAY circumvent the Rafikov Connundrum! ArXiv 1901.08704: “1I/`Oumuamua As Debris of Dwarf Interstellar Comet That Disintegrated Before Perihelion.” by Zdenek Sekannia. I see only two problems with this(one minor and one very VERY major), assuming that radiation pressure does NOT “spin-up” a tumbling object as it accelerates. The minor problem is that the odds of one of our telescopes capturing the pre-perihelion disintegration of the parent body(and perhaps even the ingress)is very high, but not astronomically so, so I can live with a non-detection being just doe to bad luck. The very VERY major problem is the one magnitude increase in brightness of `Oumuamua witnessed between October and November. If this is some kind of natural “thin film”, it would lack enough ice to completely “ice over” during that period, so I still prefer the non-tumbling retractable lightsail as the only viable solution for `Oumuamua’s total lightcurve.

    • ljk January 28, 2019, 14:28

      The link to the paper you mention:


      And here is this paper on a related subject:

      The fate of planetesimal discs in young open clusters: implications for 1I/’Oumuamua, the Kuiper belt, the Oort cloud and more

      Thomas Oliver Hands, Walter Dehnen, Amery Gration, Joachim Stadel, Ben Moore

      (Submitted on 8 Jan 2019)


      As with Tabby’s Star, Oumuamua will keep being a comet or pile of dust – until it isn’t. :^)

      • Harry R Ray January 29, 2019, 10:31

        DON’T THINK SO! As for a comet, the Rafikov Connundrum COMPLETELY ELIMINATES this scenario REGARDLESS of whether ANY outgassing was detected or not. As for the pile of dust, it can EITHER expand create a one magnitude increase in brightness as it gets farther and farther away from the Sun, OR maintain its RATE OF ROTATION despite tumbling if it remains reasonably compact, but it ABSOLUTELY POSITIVELY CANNOT DO BOTH AT THE SAME TIME, unless it is “magic dust, which is what none other than Tabetha Boyajian HERSELF refers to the objects blocking the light of Boyajian’s Star! Depending on these two scenarios is bordering on FAKE NEWS to deflect any serious cintemplation of a non-natural solution by the general scientific community!

        • ljk January 29, 2019, 11:16

          The masses are afraid of aliens because of all the science fiction stories they have read and seen about creatures from other worlds coming to invade Earth and have us for dinner or turn us into slaves, etc.

          The professional science community are afraid of aliens not only because of the ridicule and rejection by their peers, but also because aliens will mess up their carefully laid out ideas for how the Universe works. Microbes are okay because they are not considered intelligent and therefore cannot announce their own ideas and plans for how things go.

          As Dr. Loeb recently noted, astronomers and cosmologists have no issues with the ideas of dark matter and dark energy controlling the Universe, even though they still do not know what these things are made of or how they operate. But aliens – oh no, not that uncontrollable possibility.

          I feel like we are just coming out of the equivalent era of thinking that the entire Cosmos revolves around Earth and finally starting to accept the heliocentric Universe. And it is the 21st Century CE.

          • Harry R Ray January 30, 2019, 11:29

            An “empty trashbag” object designated as A10bMLz has just been discovered orbiting Earth in an extremely eliptical orbit(minima: 600 km, maxima: 538621 km). The object is several meters in width but weighs less than 1 kg. REMIND YOU OF ANYTHING!!!!! According to Northolt Branch Observatories in London. the object is a light piece of material left over from a rocket launch, most likely a bit of Aluminum foil. OBVIOUSLY, IT CANNOT POSSIBLY BE OF EXTRATERRESTRIAL ORIGIN! It is essential that Breakthrough should do two things IMMEDIATELY: ONE, inquire all space agencies as to which launches could put an object in that kind of orbit(the prime candidates are OBVIOUSLY TESS and the recent Chinese lunar farside mission)and whether protective coverings on these launches match the specs of A10bMLz, and: TWO, arrange for telescope time to obtain a SPECTRA at its next minima. After that, they should compare the ORIENTATION of the orbit to see if it is COMPATIBLE with `Oumuamua’s trajectory, allowing it to be inserted into its present orbit during `Oumuamua’s pass by Earth in 2017. Unlikely as that may be, in the long term, this object should be CONSTANTLY MONITORED for non-gravitational acceleration due to solar radiation pressure! Also, a detailed lightcurve of this object should be obtained to see whether it is tumbling or not.

            • ljk January 31, 2019, 14:29

              I would think there are a number of cameras, both civilian and military, that could image this object up close.

              I know when the first Space Shuttle Columbia flew on its inaugural flight in 1981, they were worried about the handful of tiles that had fallen off. A military ground camera that could supposedly count the bolts on a Soyuz was employed to see the Shuttle had sustained any further damage, especially in areas where the two astronauts could not see.

              Now if they could do this in 1981, I am sure there are even better cameras now.

              • Harry R Ray February 1, 2019, 10:38

                ljk, google A10bMLz and click on “Pseudo-MPEC for A10bMLz-Project Pluto. Apparently both the orbit for and the size of this object is still VERY UNDEFINED! Until a better fit for both of these parameters is determined, a lot of luck would be needed to obtain a very narrow field long exposure image from a super spycam properly slewed to keep it in the exact center of the field. This would NOT prevent high precision wide field spectroscopy at minima. If the spectra turns out to be paint, case closed. This happened before with spent Saturn 5 upper stages. Radar imaging may be possible now, but I am not sure. Finally, it is uncertain whether the orbit is even prograde or not. If it turns out to be RETROGRADE, It should become Breakthrough Initiatives TOP PRIORITY!

                • SpiderImAlright February 2, 2019, 19:36

                  FWIW the observatory’s Facebook says it’s retrograde (i=121 degrees): https://www.facebook.com/NBObservatories/videos/293401511372535/

                • Harry R Ray February 3, 2019, 15:09

                  Bad news and good news for A10bMLz. First the bad news. The latest updated information predicts that it will never get closer than 334,000 miles from Earth, and its orbit(if you could CALL it that – more on this below)is rather(but not perfectly circular)with the minima at 334,000 miles from Earth, and the maxima at 372,000 miles. So, unfortunately NO detailed images or spectra are possible. Now for the good news. Solar radiation pressure seems to be utterly OVERPOWERING Newtownian orbital mechanics, causing it to LITTERALLY zig-zag through space, going from retrograde to prograde in motion in aperiodic cycles, which gives Dr Loeb et al a chance to TEST their “discarded lightsail” hypothesis. In other words, when `Oumuamua was EXACTLY the same distance from the Sun as Earth, if it were a tumbling defunct lightsail. it should have been ALSO have been zig-zagging. The OVERALL effect should have been far less apparent because of `Oumuamua’s high initial speed, but it would not have been NEGLIGIBLE! Farther out, when `Oumuamua’s non-gravitational acceleration became apparent, the solar radiation pressure was so much less than at Earth’s distance that the “zig-zag”effect should have dampened DOWN, but not entirelly OUT, leaving it with a more predictable trajectory. Finally, and MOST important, spending BILLIONS of years in space wandering the galaxy, may have NATURALLY caused it to wander to a LSR point due to radiation pressure equaling out from all directions in the galaxy. Paul Gilster, could you ask Dr Loeb if he is aware of this object and if he CAN test his “derilict lightsail” hypothesis via continued observations of A10bMLz. Also, The Planetary Society may also be very interested as well, due to their upcoming lightsail mission. RSVP. Thanks.

                  • ljk February 5, 2019, 12:18

                    I know there are several agencies that have maneuverable spysats in Earth orbit, but whether any of them will be employed to investigate this object is another matter.

                    Can HST be able to image the object, or is it too close? Hubble did image the lunar surface, despite earlier statements that the Moon would be too close for such an action.

                    • Harry R Ray February 6, 2019, 11:00

                      I FINALLY FOUND A VIDEO OF A10bMLz IN MOTION at https://curiosmos.com/A10bMLz! Click on “MIND-BLOWN”, scroll down to Mystery Object in Retrograde Orbit Around Earth id Puzzling Astronomers.” and WATCH IT VERY CAREFULLY! After doing so myself, I IIMMEDIATELY checked the RESOLUTION POWER of the telescope from which the observations “video was derived and came to a startling conclusion! Based on the latest informationthat the object NEVER gets any closer to Earth than `325,000 miles, A10bMLz must be SIGNIFIGANTLY LARGER than the “several meters in diameter” origianally stated for this object! What is starting to concern me is that there has been NO update on this object since February 1(not on Pseudo-MPEC for A10bMLz-Project Pluto, the #A10bMLz hashtag, https://curiosmos.com, or anywhere else. NOTHING!). Is this because a loss of interest due to the fact that a true orbiy may never be able to be computed for this object , or some other reason? Due to the current situation, I now believe that it is IMPERATIVE that Breakthrough Initiatives get involved in this IMMEDIATELY, and reserve telescope time on the largest ground-based optical and infrared telescopes possible to observe this object on a CONTINUAL BASIS!

            • Hamilton1 February 1, 2019, 9:02

              Another strange object being monitored Harry –


              • Harry R Ray February 1, 2019, 11:09

                This one is so new that it isn’t up on Google yet. Therefore, the only pertinent information I found came from YE Quanzhi’s tweet itself: “Weird object ZTFO2Rm found by @ztfsurvey last night. Current nominal orbit has a q = 0.15 au, a = 0.66 au. H 22.5 suggests a size of perhaps 100-m. But most intreguingly, it seems to have rotational period of 10 sec or so. Did someone lose a spacecraft/booster out there?” I’m waiting for this one to be posted on Pseudo-MPEC for ZTFO2Rm-Project Pluto before I make a detailed comment, however, a ~100m object rotating once every 10 seconds would generate some SERIOUS artificial gravity at the two ends! My take FOR NOW is that it probably has something to do with space junk generated by the Parker Solar Probe launch.

                • Harry R Ray February 3, 2019, 15:41

                  Here’s the most recent updated information on ZTFO2Rm: Jonathan Mc Dowell twetted this on Jan 31: Further observations have shown the object in a 0.21 X 1.o AU orbit, very similar to the Parker third stage, but with a different inclination and node.” !?!!!??!!!!?!!????? It is still not up on Google, although I for the life of me cannot figure out why not.

  • ljk January 28, 2019, 11:47

    Advanced Extraterrestrials as an Approximation to God

    Our first encounter with E.T. technology could be as baffling to us as a smartphone would have been to a Neandertal.

    By Abraham Loeb on January 26, 2019

    Despite the impression one gets from textbooks, our current knowledge of the universe represents a small island in a vast ocean of ignorance. The scientific enterprise is all about expanding the landmass of this island. And it is fun to engage in the activity of gaining knowledge; knowing everything in advance would have been much more boring. Still, it would be shocking to learn all at once of the discoveries of an alien civilization that been doing scientific and technological exploration for billions of years, in contrast to our mere few centuries.

    The eminent science fiction writer Arthur C. Clarke codified this idea in the third of his three laws : “Any sufficiently advanced technology is indistinguishable from magic.” Put another way, members of such a civilization would appear to us as a pretty good approximation to God.

    Full article here:


  • ljk January 28, 2019, 14:24

    It’s time to start taking the search for E.T. seriously, astronomers say

    Some scientists are pushing for NASA to make looking for alien technology an official goal

    By Lisa Grossman

    6:00am, January 28, 2019


    The time to have taken SETI seriously should have started when we had enough astronomical knowledge and the technology to start conducting scientific searches for them.

  • ljk January 31, 2019, 14:27


    A Critical Review on the Assumptions of SETI

    Kelvin F Long

    (Submitted on 11 Jan 2019)

    The Search for Extraterrestrial Intelligence (SETI) makes certain assumptions which guide all current search programs. To illustrate some, this includes (1) that interstellar flight is not possible (2) that the motivations of interstellar cultures are based largely on anthropomorphic understandings of homo sapiens (3) that the Fermi Paradox and the Drake equation are the starting point (axioms) of all reasoning (4) that definitions of ‘life’ are based largely on our understanding of homeostasis (5) that radio waves are the most likely method of interstellar communications (6) that unknown single event source signatures detected in space are not amenable to scrutiny due to the demands of the scientific method to be reproducible (7) that such anomalous signatures are either astronomical or communications based in type with no consideration for emissions from advanced industrialisation or propulsion and power technology.

    These assumptions, and others, have guided the SETI community towards a constrained level of thinking that is equivalent to philosophical dogma.

    In this paper, we unpack these assumptions, and others, and argue that the potential for life and intelligent life in the Cosmos may be much greater than the SETI community currently appears to conclude. It is also argued that more progress in our underanding of our place in the Cosmos can be made, if the separate disciplines of astronomy, interstellar spacecraft design, SETI, biology and philosophy can work together in a complementary way.

    Presented at the 47th IAA Symposium on the Search for Extraterrestrial Intelligence. SETI and Society.

    Comments: 14 pages, 7 figures, submitted to Acta Astonautica, 19th December 2018, presented at the 47th IAA Symposium on SETI, Bremen

    Subjects: Popular Physics (physics.pop-ph)

    Cite as: arXiv:1901.10551 [physics.pop-ph]
    (or arXiv:1901.10551v1 [physics.pop-ph] for this version)

    Submission history

    From: Kelvin F Long [view email]

    [v1] Fri, 11 Jan 2019 17:22:47 UTC (458 KB)


    • ljk January 31, 2019, 14:37

      Supplement your reading of this paper with this online document:


      SETI definitely needs to expand its horizons. It was hampered in the past by many things, not the least of which were lousy funding, peer and public ridicule, and a relatively few practitioners who stuck to just a few ideas, methods, and technologies. At last the thaw seems to be on the horizon.

  • ljk February 5, 2019, 12:24

    Harvard’s top astronomer says an alien ship may be among us — and he doesn’t care what his colleagues think

    Avi Selk

    February 5, 2019

    CAMBRIDGE, Mass. —Before he started the whole alien spaceship thing last year, the chairman of Harvard University’s astronomy department was known for public lectures on modesty. Personal modesty, which Avi Loeb said he learned growing up on a farm. And what Loeb calls “cosmic modesty” — the idea that it’s arrogant to assume we are alone in the universe, or even a particularly special species.

    Full article here:


    To quote:

    And while he’s not saying it’s definitely aliens, he is saying he can’t think of anything other than aliens that fits the data. And he’s saying that all over international news.

    “Many people expected once there would be this publicity, I would back down,” Loeb says. “If someone shows me evidence to the contrary, I will immediately back down.”

    In the meantime, he’s doubling down, hosting a Reddit AMA on “how the discovery of alien life in space will transform our life,” and constantly emailing his “friends and colleagues” with updates on all the reporters who are speaking to him.

    In a matter of months, Loeb has become a one-man alternative to the dirge of terrestrial news.

    “It changes your perception on reality, just knowing that we’re not alone,” he says. “We are fighting on borders, on resources. . . . It would make us feel part of planet Earth as a civilization rather than individual countries voting on Brexit.”

  • Harry R Ray February 6, 2019, 12:29

    BREAKING NEWS: Dr Loeb did a recent interview with the Chicagi Tribune in which he now BELIEVES that `Oumuamua IS(as opposed to just “might be”)a ONE KILOMETER LONG and one centimeter thick OBLOID lightsail. AND: He has been working on an equation that will PROVE(!!!?!???!!??)that `Oumuamua is part of an alien spaceship! This is a FAR FAR CRY from his assertion that we will have to wait for the next interstellar object to be detected to come to a definite conclusion! As much as I desperately want this to be true, I am CURRENTLY taking this one with an EXTREME GRAIN OF SALT. Comments on this from other Centauri Dreams readers would be very welcome.

    • ljk February 6, 2019, 17:51

      This Chicago Tribune piece is the same as the article I linked to just above via The Washington Post:


      Dr. Loeb is “biting the bullet” when it comes to alien life in regards to our perceptions of it, especially in academia. He has the knowledge, experience, and the clout (and tenure) to bring about this change, which is vital if we ever want to grow up about the subject and as a result actually get out there and find it.

      SETI has been hobbled for far too long, even since the modern era of the field began in 1960. Yuri Milner’s cash infusion, while very nice, can only last so long and I have not heard of another one since the initial donation in 2015. SETI needs to really ramp up, using different methods and tactics. Time to get past the radio paradigm, but not to abandon it since it is still a viable method of interstellar communication.

      While I think Dr. Loeb does consider the possibility of Oumuamua to be an artificial light sail with growing seriousness, I think he is using it largely as a jumping off point for the much larger and important issues of how humanity views the concept of beings from other worlds and how we have gone about them.

      After all these decades (centuries if you want to count the ancient Greeks with their first dalliance with the concept), alien beings are still mostly seen as monsters and invaders. Either that or they are hoped to be almost-divine saviors. Or analogies to various human types.

      The professional community, which can do the most good in terms of actually finding extraterrestrial life, intelligent or otherwise, are the ones playing it way too safe. They worry about being ridiculed by their peers and the public and therefore losing credibility and their careers. The UFO crowd has certainly taken its toll on keeping science from getting into the subject very far. Then there are those who hold too tightly to the notion that since aliens have not been found, even though so relatively little has been done in regards to searching for them on multiple fronts, they therefore do not exist. That is only true in the most technical sense. Of course one could go stand at the shore of any ocean, stare at it for a few minutes, then declare that creatures called fish do not exist in those waters because they did not see any, or that no fish jumped out of the water to meet them.

      So good luck Dr. Loeb, you are a smart and brave man. Future exobiology efforts will thank you. As for everyone else, look at the forest and not just the few trees the media and everyone else is focusing on.

      Here is a different new article on the subject from Newsweek:


    • Harry R Ray February 7, 2019, 11:14

      I was in a bit of a rush posting the above comment, so I was unable to get into any of my concerns SPECIFICALLY. Here are some of them now. My first specific concern is his revised size for `Oumuamua. He has increased it from the previous MAXIMUM value of 800 meters to 1,000 meters. This flies in the face of the recent Spitzer Space Telescope NON-DETECTION, constraining the maximum size way below 800 meters. Dr Loeb argues that a loophole out of this would be for `Oumuamua to be “obloid” in shape. The definition of “obloid” is “oblong at all three axes”. However, to be a lightsail, `Oumuamua must be exceedingly thin, essentially converting it into a two dimensional object, with no THIRD axis, so `Oumuamua cannot be obloid in a literal sense. My other specific concern is OBVIOUSLY the equation that will prove `Oumuamua to be of non-natural origin. I am not against the concept of this. I, myself proposed such an equation on this website. The difference boils down to working on it NOW. My equation was derived from the fact of an 8+ sigma detection of a five microns per second acceleration for `Oumuamua in the early part of the observation run(this acceleration STOPPED in the later part of the observation run). Since this sigma was SO HIGH, I proposed that this acceleration might not be UNIFORM throughout its existence, and that its NON-UNIFORMITY may be measurable in the existing data set. However, the maximum non-uniformity would be expressible in milimicrons per second squared. These extremely small acceleration rate differentials would be extremely hard to extract from the very limited data set, perhaps BEYOND the ability of unaided human detection. I proposed that a machine learning algorithm be derived to detect them. Then(AND ONLY THEN)if derived, the timelines of these acceleration rate differentials can be compared with timelines for `Oumuamua’s flux variations. If the two timelines matched PERFECTLY(i.e., MAXIMUM acceleration rate at MAXIMUM brightness)this would be a proof of a FULLY OPERATIONAL LIGHTSAIL! If this IS the equation Loeb et al IS working on, they must have already created the machine learning algorithm which has produced the data to work on. I’m just not buying that it could have been done SO QUICKLY! EVEN IF THIS IS THE CASE, the best proof that can be hoped for would be at the four sigma level, due to the paucity of data to work with. THIS IS NOT EXTRORDINARY PROOF BY A LONG SHOT. When I proposed this equation, I had no intention of saying that it would be the ULTIMATE proof required, bot only that it would be SUFFICIENT proof to MANDATE a space mission to `Oumuamua to OBTAIN the ultimate proof! If this is NOT the equation that Loeb et al are working on, I cannot immagine that whatever they come up with would be anywhere near the Sagan Threshold, either. As a final note, BOY, I HOPE THAT I AM WRONG! Good luck, Loeb et al!! Let’s ALL keep our fingers crossed!!!!!

  • Hamilton1 February 8, 2019, 10:14

    The silence over on the minor planet mailing list is deafening. The last posts described the object ZTFO2Rm as being of ‘high interest’ but not a squeak since. It strikes me that, in a situation like this, a handful of experts with access to major telescopes will be the first to know. It wouldn’t surprise me if they’re having private discussions among themselves rather than informing the public, and to be honest I wouldn’t blame them.

    • Harry R Ray February 10, 2019, 14:37

      With a booster used in accordance with the Parker Solar Probe out(see previous comment above)as the culprit, this leaves a Beppo-Columbo launch booster as the only man-made explanation. The situation is even more concerning for A10bMLz, because its erratic orbit is a POTENTIAL HAZARD to the ISS and other spacecraft. I am SURE that the military is tracking it, because if it DOES turn out to be a lightsail of some kind, it might be the result of a secret launch by a nation that has some kind of HOSTILE INTENT for its use!

    • ljk February 14, 2019, 15:14

      We need more Dr. Loebs, which is exactly what he is trying to do by having the science community consider the possibility that Oumuamua is artificial. I wonder how many will take that brave step – which should not be so brave in the early Twenty-First Century!

  • ljk February 12, 2019, 10:43

    It is just amazing what comets can suddenly do when astronomers are determined to have Oumuamua be anything rather than an alien artifact!


    Just ask Tabby’s Star with its incredible morphing cloud of dust particles that can do just about anything so long as it isn’t due to a Dyson Shell.

  • Hamilton1 February 13, 2019, 7:38

    Here’s a well-written article summing up what we know:


    It also has some tidbits I hadn’t seen before, such as Dr Meech describing Dr Loeb’s speculations as “wild and crazy”.

    • ljk February 14, 2019, 15:16

      Of course if Oumuamua does turn out to be an alien artifact, you may rest assure that Dr. Meech and/or others will be declaring that they knew it was an alien probe all along! :^)

  • ljk February 14, 2019, 15:13


    Project Lyra: Catching 1I/’Oumuamua – Mission Opportunities After 2024

    Adam Hibberd, Andreas M. Hein, T. Marshall Eubanks

    (Submitted on 13 Feb 2019)

    In October 2017, the first interstellar object within our solar system was discovered. Today designated 1I/’Oumuamua, it shows characteristics that have never before been observed in a celestial body. Due to these characteristics, an in-situ investigation of 1I would be of extraordinary scientific value.

    Previous studies have demonstrated that a mission to 1I/’Oumuamua is feasible, using current and near-term technologies. However, the anticipated launch date of 2020-2021 is too soon to be realistic.

    In this paper, we demonstrate that a mission to 1I/’Oumuamua is feasible at an even later point in time, providing sufficient time for developing a spacecraft. Using the OITS trajectory simulation tool, various scenarios are analyzed, including a powered Jupiter flyby and Solar Oberth manoeuvre, a Jupiter powered flyby, and more complex flyby schemes including a Mars and Venus flyby.

    With a powered Jupiter flyby and Solar Oberth manoeuvre, we identify a trajectory to 1I/’Oumuamua with a launch date in 2033, a total velocity increment of 18.6 km/s, and arrival at 1I/’Oumuamua in 2049.

    With an additional deep space manoeuvre before the powered Jupiter flyby, a trajectory with a launch date in 2030, a total velocity increment of 16.2 km/s, and an arrival at 1I/’Oumuamua in 2047 were identified.

    Both launch dates would provide over a decade for spacecraft development, in contrast to the previously identified 2020-2021 launch dates.

    We conclude that a mission to 1I/’Oumuamua is feasible, using existing and near-term technologies and there is sufficient time for developing such a mission.

    Subjects: Space Physics (physics.space-ph)

    Cite as: arXiv:1902.04935 [physics.space-ph]
    (or arXiv:1902.04935v1 [physics.space-ph] for this version)

    Submission history

    From: Andreas Hein M. [view email]

    [v1] Wed, 13 Feb 2019 14:49:42 UTC (1,149 KB)


    • Andreas Hein February 17, 2019, 11:03

      Dear ljk,
      Thank you very much for sharing our paper!

      • ljk February 19, 2019, 14:25

        You are most welcome, Andreas. Thank you for writing it and pushing the urgency to get a probe to that interstellar visitor!

  • ljk February 19, 2019, 14:27

    No, ‘Oumuamua is not an alien spaceship. It might be even weirder.

    Phil Plait

    February 18, 2019


  • ljk February 22, 2019, 13:01

    Dr. Loeb wrote this very recent article for Scientific American:


    Be Kind to Extraterrestrials

    We need to tread lightly if we encounter alien ecosystems

    By Abraham Loeb on February 15, 2019

    In his celebrated book On Walden Pond (!), Henry David Thoreau wrote: “We need the tonic of wildness…. At the same time that we are earnest to explore and learn all things, we require that all things be mysterious and unexplorable, that land and sea be indefinitely wild, unsurveyed and unfathomed by us because unfathomable. We can never have enough of nature.”

    Thoreau raises a fundamental question in space exploration. Should we allow ourselves to terraform planets in an effort to make them habitable and seed objects in space with life as we know it, or should we leave nature out there to its own devices, intact and pure?

    On the one hand, it would be prudent not to keep all our eggs in one basket; we might choose to spread terrestrial life to other worlds in an effort to reduce the risk of it being eliminated by catastrophes on Earth. But at the same time, one might worry that by doing so we could unleash unforeseen forces that would modify natural ecosystems in ways that could get out of hand. Moreover, artificial seeding of Earth life would muddy the waters in extraterrestrial “Walden-like” ponds. It would deprive us from the opportunity to find out if other life-forms may have existed before our arrival.

    I cannot help but love the fact that he called Thoreau’s landmark book On Walden Pond – and that the SA editor et al never caught the error!

  • ljk March 20, 2019, 15:57

    This week Oumuamua is a comet again. Last month it was a fractal snowflake, an idea which many scientists flocked to mainly because it wasn’t the dreaded possibility of being an alien vessel.

    Next week or next month it will be something else, and this speculation will continue so long as we do not get a deep space probe to Oumuamua.


    • ljk March 20, 2019, 16:05

      Some relevant quotes from the above SA article on everyone’s favorite interstellar visitor:

      “We found that if the cometary jet continuously tracks the sun’s direction, ‘Oumuamua rocks back and forth like a pendulum instead of spinning up,” says Seligman. That motion, in turn, would independently peg ‘Oumuamua at some 250 meters long—consistent with earlier size estimates derived from the object’s brightness.

      “I cannot say that we have ruled out a more sensationalist claim,” Seligman says, noting even so that their “more physically motivated outgassing model” would eliminate the “need to rely on less likely explanations.”

      That comes as a relief [note that word, relief] for some astronomers, such as Micheli and Meech, who balk at invoking “aliens” for any astronomical curiosity. “The [study’s] overall reasoning seems sounds, and the results are a really good match to the observed characteristics of ‘Oumuamua,” Micheli says.

      Others are less accepting. Implicit in the “comet” hypothesis, says Loeb, is the assumption that ‘Oumuamua should be a fairly typical object—or that our solar system and its retinue of comets should somehow be an outlier.

      Yet Seligman, Laughlin and Batygin’s model reinforces ‘Oumumua’s distinctiveness from native objects around our sun.

      “It does not look like at least 99.999 percent of the solar system’s comets,” Loeb says, suggesting that our a priori chances of having detected it in the first place with present-day telescopes are no better than a million to one.

      “Note that one in a million is a small probability,” he adds. “When I thought my wife is that special, I married her.” All of which could mean that either we are extremely lucky to have discovered ‘Oumuamua—or that there are deep flaws in our interpretation of it as a comet.

  • Hamilton1 April 12, 2019, 16:06

    Jonathan Katz has submitted an article questioning the accuracy of the non-grav findings, although the thrust of his argument seems to be that they are unlikely because, well, they are unlikely…


  • ljk May 7, 2019, 11:30


    Oumuamua and Scout ET Probes

    John Gertz

    (Submitted on 9 Apr 2019)

    Numerous advantages may accrue to ET from the use of probes for the conveyance of information relative to the alternative of beaming information electromagnetically from its home star system.

    However, probes would benefit from a trans-galactic communications network to transmit information back to their progenitor civilization(s) and throughout the Galaxy.

    A model for such trans-galactic communications has previously been proposed, comprised of probes linked together by relay nodes. The current paper refines that model, specifying two types of probes or nodes, both part of a communications lattice.

    The first type of cellular probe (CP) is statically associated with individual stars, and the second type is a scout CP that traverses the galaxy surveying successive star systems rather than permanently residing within any one of them. CPs would communicate with adjacent CPs and, ultimately, through the network of CPs, with their progenitor civilization(s). The question of whether Oumuamua is such a flyby scout CP is considered. Search strategies for CPs are suggested.

    Comments: 10 pages, submitted for publication

    Subjects: Popular Physics (physics.pop-ph)

    Cite as: arXiv:1904.04914 [physics.pop-ph]
    (or arXiv:1904.04914v1 [physics.pop-ph] for this version)

    Submission history

    From: John Gertz [view email]

    [v1] Tue, 9 Apr 2019 21:11:10 UTC (703 KB)


  • ljk May 7, 2019, 11:34


    Outgassing As Trigger of 1I/`Oumuamua’s Nongravitational Acceleration: Could This Hypothesis Work at All?

    Zdenek Sekanina

    (Submitted on 2 May 2019 (v1), last revised 6 May 2019 (this version, v2))

    The question of what triggered the nongravitational acceleration of 1I/`Oumuamua continues to attract researchers’ attention. The absence of any signs of activity notwithstanding, the prevailing notion is that the acceleration of the stellar, cigar-like object was prompted by outgassing.

    However, the Spitzer Space Telescope’s failure to detect `Oumuamua not only ruled out the CO_2 and/or CO driven activity (Trilling et al. 2018), but made the cigar shape incompatible with the optical observations.

    Choice of water ice as the source of outgassing is shown to be flawed as well: (i) the water sublimation law is demonstrably inconsistent with the observed variations in the nongravitational acceleration derived by Micheli et al. (2018), the point that should have been assertively highlighted; and (ii) an upper limit of the production rate of water is estimated at as low as 4 x 10^(23) molecules s^(-1), requiring that, at most, only a small area of the surface be active, in which case the conservation of momentum law is satisfied only when `Oumuamua’s bulk density is extremely low, <0.001 g cm^(-3), reminiscent of the formerly proposed scenario with `Oumuamua as a fragment of a dwarf interstellar comet disintegrating near perihelion, with the acceleration driven by solar radiation pressure (Sekanina 2019a) and no need for activity at all.

    This conclusion is possible thanks to the high quality of astrometry and Micheli et al.'s orbital analysis, whose results were confirmed by the computations of other authors.

    Comments: 11 pages. 5 tables, 1 figure

    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

    Cite as: arXiv:1905.00935 [astro-ph.EP]
    (or arXiv:1905.00935v2 [astro-ph.EP] for this version)

    Submission history

    From: Zdenek Sekanina [view email]

    [v1] Thu, 2 May 2019 19:00:59 UTC (239 KB)
    [v2] Mon, 6 May 2019 17:48:52 UTC (239 KB)