[Warning: This post is not, strictly, a research post. It is a response to events in the astronomical community in the recent past.] Word on the street (I can't find out, because it is not open) is that some argument broke out on the Facebook(tm) astronomy group about loose discussion on the internets about #aliens, and things like the Boyajian star or the 'Oumuamua asteroid. Since I am partially responsible for this loose talk, here is my position:
First, I want to separate informal discussion (like on twitter or blogs) from formal discussion in scientific papers (like what might be submitted to arXiv) from press releases. These are three different things, and I think we need to treat them differently. Second, I am going to assert that it is reasonable and normal for astronomers to discuss in scientific papers (sometimes) the possibility that there is alien life or alien technology with visible impact on observations. Third, I am going to presume that the non-expert public deserves our complete respect and cooperation. If you disagree with any of these things, my argument might not appeal to you.
On the second assumption (aliens are worthy of discussion), you can ask yourself: Was it a reasonable use of telescope time to look at 'Oumuamua in the radio, to search for technological radio transmissions? If you think that this was a reasonable thing to do with our resources, then you agree with the second assumption. Similarly if you think SETI is worth doing. If you don't think these uses of telescopes are reasonable—and it is understandable and justifiable not to—then you might think all talk of aliens is illegitimate. Fine. But I think that most of us think that it is legitimate to study SETI and related matters. I certainly do.
Now if we accept the second assumption, and if we accept the third assumption (and I really don't have any time for you if you don't accept the third assumption), then I think it is legitimate (and perhaps even ethically required) that we have our discussions about aliens out in the open, visible to the public! The argument (that we shouldn't be talking about such things) appears to be: “Some people (and in particular some news outlets) go ape-shit when there is talk of aliens, so we all need to stop talking about aliens!” But now let's move this into another context: Imagine someone in a role in which they serve the public and are partially responsible for X saying: “Some people (and in particular some news outlets) go ape-shit when there is talk of X, so we all need to stop talking about X!” Obviously that would be a completely unethical position for any public servant to take. And it wouldn't just be fodder for conspiracy theorists, it would actually be evidence of a conspiracy.
Imagine we, as a community, decided to only discuss alien technology in private, and never in public. Would that help or hurt with the wild speculation or ape-shit reactions? In the long run, I think it would hurt us, and hurt the public, and be unethical to boot. Informal discussion of all matters of importance to astronomers are legitimately held in the open. We are public servants, ultimately.
Now, I have two caveats to this. The first is that it is possible for papers and press releases and news articles to be irresponsible about their discussion of aliens. For example, the reportage claiming (example here)—and it may originate in the paper itself—that the reddening observed in the Boyajian Star rules out alien megastructures was debatably irresponsible in two ways. For one, it implied that the megastructure hypothesis was a leading hypothesis, which it was not, and for two, it implied that the megastructure hypothesis was specific enough to be ruled out by reddening, which it wasn't. Indeed, the chatter on Twitter(tm) led to questions about whether aliens could ever be ruled out by observations, and that is an interesting question, which relates to the second assumption (aliens are worthy of discussion) given above. Either way, the paper and resulting press implied that the observational result constrained aliens, which it did not; the posterior probability of aliens (extremely low to begin with) is almost completely unchanged by the observations in that paper. To imply otherwise is to imply that alien technology is a mature scientific hypothesis, which it isn't.
Note, in the above paragraph, that I hold papers and press releases to a higher standard than loose, informal discussion! That is my first assumption, above. You might disagree with it, but note that it would be essentially completely chilling to all informal, open discussion of science if we required refereed-publication-quality backing for anything we say, anywhere. It would effectively re-create the conspiracy that I reject above.
I don't mean to be too critical here, the Boyajian-star paper was overall extremely responsible and careful and sensible. As are many other papers about planet results, even ones that end up getting illustrated with an artist's impression of a rocky planet with ocean shores and/or raging surf. If I have a complaint about exoplanet science as a community (and I count myself a member of this community; I am not casting blame elsewhere), it is about the paper-to-press interface, where artist's conceptions and small signals are amplified into luscious and misleading story-time by perfectly sensible reporters. We (as a community, and as a set of funded projects) are complicit in this.
The second caveat to what I have written above is that I (for one) and many others talk on Twitter(tm) with tongue in cheek and with sarcasm, irony, and exaggeration. It takes knowledge of the medium, of scientists, and of the individuals involved to decode it properly. When I tweeted that it was “likely” that 'Oumuamua was an alien spaceship, I was obviously (to me) exaggerating, for the purposes of having a fun and interesting discussion.
And indeed, the asteroid looks different in color, shape, and spin rate (and maybe therefore composition and tensile strength) from other asteroids in our own Solar System. But it might have been irresponsible to use my exaggeration and humor when it comes to aliens, because aliens do set off some people, especially those who might not know the conventions of scientists and twitter. I take that criticism, and I'll try to be more careful.
One last point: The underlying idea of those who say we should keep alien discussion behind closed doors (or cut it off completely) is at least partly that the public can't handle it. I find that attitude disturbing and wrong: In my experience, ordinary people are very wise readers of the news, with good sense and responsibility, and they are just as good at reading arguments on Twitter(tm). The fact that there are some exceptions—or that the Daily Mail is an irresponsible news outlet—does not change the truth of my third assumption (people deserve our respect). We should just ignore and deprecate irresponsible news, and continue to have our discussions out in the open!
In the long run, astronomy will benefit from open-ness, honesty, and carefully circumscribed reporting of goals and results. We won't benefit from hiding our legitimate scientific discussions from the public for fear that they will be mis-interpreted.