If there's no plausible model that involves aliens and explains the observations, it's not science. "Advanced aliens did it in a way we don't understand" is basically a "Goddidit" argument.
We've got something funny here, which may be (probably is?) nothing new, or may be exciting.
Now, speculation of this type can be the starting point to developing a testable hypothesis, so its not completely outside the scientific process, but it's far sorry of even a hypothesis.
> "its not completely outside the scientific process"
Here you unfairly (imo) diminish the role of wonder and speculation in science, which isn't something at the fringes of it, but part of the very soul and essence of it.
Ironically, this same mistake has been made time and time again throughout history when science has made great strides. Someone points out that "that's funny", and are immediately shot down for coming up with ridiculous ideas that are not supported by the current theories.
This might not describe OP, but it's a pretty common phenomenon that often shows up in discussions where the boundaries of our current scientific knowledge are close. E.g. AI, the un-observable part of the universe, experiments that seem to break physics (e.g. the RF resonant cavity thruster), what is consciousness, etc.
Many of us yearn for novel, exciting discoveries with extraordinary explanations. The desire for novelty is a fundamental part of the human condition, and alien intelligence is one of the most thrilling, evocative, thought-provoking ideas that exist. However, the very fundamental point of the scientific method is to explicitly work against this bias - to ensure we're pursuing the truth and not our pet ideas.
As I brought up in another comment, it is wrong to single out "aliens" in the vast space of hypotheses just because that concept happens to be especially accessible and fascinating to laypeople. There are a plenty of possible explanations that are astrophysically novel and interesting and don't involve such a huge multiplication of entities as the aliens hypothesis does.
A 1% probability of aliens seems pretty significant to me. Obviously it's more likely that it's not aliens, and no one disagrees with that. But the fact that it's even a possibility is very interesting and makes it worthy of investigation.
Anyway there isn't anything inherently unlikely about aliens. You make it like it's incredibly unlikely that aliens exist, so any hypothesis that includes them must be incredibly unlikely. A lot of people have higher prior probabilities on the existence of aliens.
Anyway, I'll give the megastructure conjecture much more weight the second someone in the research community suggests it, preferably with some sort of a testable hypothesis. As far as I know it has been purely layperson speculation and as such not much more plausible than the ramblings of UFO believers or free energy cranks.
Well... almost.
It was originally suggested (as a highly unlikely but testable hypothesis) by astronomer Jason Wright. Then the press completely distorted his original point beyond recognition.
Methods for using Kepler data to identify artificial megastructures is the subject of research by several astronomers, including Luc Arnold (French National Centre for Scientific Research), Jason Wright (Penn State), and Geoff Marcy (UC Berkeley).
Here's a representative paper: http://arxiv.org/abs/astro-ph/0503580
Luc Arnold wrote a paper arguing that swarms of artificial structures would have certain unusual signature variations in their light curves. Jason Wright later pointed out that KIC 12557548 had similar predicted variations.
"Now, I don’t know what this is. Maybe it really is an evaporating planet (the best guess, I’d say). ... I’d bet my house on it not being aliens. But given that he went way out on a limb and predicted almost exactly this sort of thing, don’t you think Luc Arnold at least deserved a citation?"
This line, "I'd bet my house on it not being aliens," somehow got picked up by the media as "Astronomers have found super-advanced aliens," because that's how the press works.
So is it all lay speculation? Well, if you just mean credible astronomers aren't seriously arguing for this as a likely possibility, then yes. But if you mean there's no testable way to analyze Kepler data to distinguish between artificial and natural satellites... well... work in progress.
Neither of those things should increase the probability at all. Just because a researcher believes it doesn't make it more likely to be true. Neither does the fact that it's testable.
Conversely, you shouldn't lower the probability because those things aren't true.
So given that aliens might exist, and this might be the most likely way for us to detect them, it's certainly possible that it really is aliens this time.
Of course we don't know for certain. Not by a long shot. It is absolutely speculation, but it's reasonable speculation. We probably need a lot more data before we can say anything more specific about this. Maybe we do find a natural explanation after all. But it's not reasonable to ignore this possibility because some people don't want to discuss it.
And the person who proposed this is a real astronomer. Of course he didn't say it's definitively aliens. He said it's a real possibility. That doesn't mean a lot (because it's technically true of any star or exoplanet), but it's the most likely case we've got. And that's worth some attention.
But it is falsifiable, for example we could falsify it by visiting the star and observing that there is no life in its solar system and no artificial satellites orbiting the star.
Neither does anything in the way of real explanation, but if you believe that advanced alien civilizations are likely to exist (which is a fairly defensible argument based on things we DO know) or have existed (depending on how far away what we're observing is), the likelihood is quite different.
Not that I'm saying it's aliens.
The attitude has always baffled me in fact. We constantly say that alien life is likely due to the size of the universe yet we can't use them as an explanation for observed phenomenon.
With SETI, we explicitly make the assumption that any prospective aliens are using communications technology that can be intercepted by us.
And they probably are not. :-)
Detecting alien megastructures, though, there might be something to that.
A hundred years, actually. I made the same mistake reading the article and had to do a double take.
I think my argument still stands, though--even a hundred years for something of this scale is beyond any science we can reasonably hypothesize about. Doesn't mean we can't speculate, just that it's not terribly constructive speculation.
This isn't goddidit. That argument is used to end a debate, to say that the how is unknowable. A claim that aliens are doing something is the opposite, a call for more careful and complete scientific scrutiny.
If you assert that no intelligent extraterrestrial entities are capable of harnessing, redirecting, or otherwise manipulating the light from a star, then you have a burden of proof of your own to meet.
It comes down to the amount of surprise we should experience at finding evidence of any ET civilization. Arguably, given the sheer number of other worlds that we now know to exist, it's surprising that we haven't found any such evidence.
At the same time, given the vast distances involved, it would be surprising if any evidence that we might find didn't consist of something truly unusual and spectacular on a stellar scale... something like a Dyson structure that only one in a million civilizations might be capable of creating. With our current observational tech, we'd never notice anything less.
In the OP, Sharlin used the term "outlandish." That's a value judgement, not a term of art. It's a judgment we're not qualified to make.
It may be true, but it is definitely a hypothesis sitting on the bottom of the list of sensible possibilities. Any rational analysis pretty much has to put "our understanding of stellar dynamics is missing something" multiple orders of magnitude more likely, given our current state of information.
Occam's Razor isn't a nuclear weapon. You still have to decide which entities are necessary and which are superfluous, presumably through some insight into the underlying premises.
In this case we simply don't have the perspective we need to decide what's "outlandish" (to use Sharlin's term) and what isn't. What's inherently outlandish about aliens? We're aliens, too, from the perspective of every other civilization that might exist.
See my other post -- some very credible authorities would say it's surprising that we haven't found evidence of any ET civilizations, given the number of possible habitats for them. What's almost certain is that the only such civilizations we could observe are the few who can deliberately alter the appearance of a star. Not only is it scientifically inappropriate to reject "Aliens did it!" as a hypothesis or to assign it an arbitrary (un)likelihood, but IMO we shouldn't even be surprised if that turns out to be the case. Alien civilizations are, or should be, no big deal.
Show me a coherent information signal coming from this star and I'll change my tune in a heartbeat, but "the brightness of this star is behaving a bit oddly" just isn't that spectacular of a signal.
OTOH, "aliens did it by unknown means" is experimentally undistinguishable from "it happened by unknown mechanisms" more generally, and untestable.