Tuesday, September 6, 2016

Almost certainly wrong: an alien megastructure speculation about KIC 8462852

Update: 20 September 2016 - with the Gaia DR1, we didn't really know which way the 300 micro arcsecond systematics would push, us, but now there is some evidence that the parallax measurements are systematically underestimated. Another nail in the coffin.

Update: 14 September 2016 - it would seem that today's Gaia data release invalidates this, as the the star is no further from us than what Boyajian, et. al., estimated from its brightness, and possibly a fair bit closer.  So what we are seeing is a real dimming, and possibly not very much.

OK, what follows is highly speculative, but as far as I can tell, is at least internally consistent and doesn't require any exotic new physics. I've got some facts in here, but if all you care about is the facts, this isn't for you.

As I pointed out recently, to find ET technological civilizations, we're going to have to be wrong a lot - unless they are trying to make it easy for us, which they very well may not be. So, I am a long term optimist but short term pessimist. Unfortunately, being persistently wrong is very painful for some people, many of which might be the most qualified to try and set out the theoretical parameters for ET technology.

So, let me have a crack at it for the case of the star KIC 8462852, commonly referred to on this blog as "Tabby's Star," and I could well be proven wrong in a few days with the first Gaia data release. I will stick to known physics exploited with unknown technology, and perhaps it may take a bit longer to prove me wrong.

The conjectured megastructure is actually a swarm (conceivably millions) of light sails flying close to the star, using light pressure in clever ways to maintain their positions (I won't detail this yet, because my model of "near field" stellar sailing isn't very good). The megastructure is a shell of reflectors, perhaps within one or two stellar radii (a few million kilometers) of the star's atmosphere. These sails are steered in a coordinated way such that they concentrate the star's light in a particular direction by a high magnification, for the purpose of accelerating (or possibly deaccelerating) a very large light sail and its payload up to interstellar speeds - perhaps a few percent of the speed of light. It would concentrate the star's light by several orders of magnitude.

Thursday, September 1, 2016

Moving this blog

I've really had all I can take from Blogger, so will be moving this blog soon to a new platform. I will keep this site up, but it will lose its domain name, although there will be a link to it form the new site.

I don't yet know what will happen to RSS feeds - please stay tuned, I will let you know everything I know as soon as I know it.

Sunday, August 28, 2016

The Possible SETI Target HD 164595 - more messing around with Aladin

Last Update:  9 September 2016

There been a lot of kerfuffle lately about a possible SETI detection more than a year ago at the RATAN-600 radio telescope in Russia. Some would say far too much kerfuffle, since it was only seen once and may well admit to alternative explanations. SETI scientists like  Eric Korpela are unimpressed.

Saturday, August 20, 2016

The Gaia data release and Tabby's Star - the ELI5

Updated 6 September 2016: the bookshelf analogy was a bit muddled - I think I've fixed it.

On the 14th of September 2016 we are expecting the first data release from Gaia, and it could well
Exploded view of the Gaia Probe
turn out to reinforce, constrain, or rule out some favorite conjectures about the weird behavior of a star romantically named KIC 8462852, aka Tabby's Star - behavior that was discovered by exploring the data from the Kepler Space Telescope.

Now, this is going to get pretty elementary, so if you feel you're already up to speed on the topics in the last paragraph, you may want to skip this.

Saturday, August 6, 2016

Aliens, Perhaps, but Not the Aliens of the Gaps

Update (8 August 2016): Audio Interview with Ben Montet.

With the publication of Montet and Simon's arresting new preprint showing even more anomalous dimming behavior by Tabby's Star,  a lot of reasonable people are asking whether it's time to declare this stellar weirdness the work of an ET civilization, or whether it may be soon. While I am emotionally inclined to go this way, and intuitively sense that this may be the ultimate conclusion reached, I am not a believer. There is a fundamental error we still must avoid.

Light curve for KIC 8462852 from Montet and Simon
It is not crazy or deluded to think that this could be the work of ET. Not at all. We know that technological civilizations exist in our galaxy, we just don't know how many. It is easy to get into pointless arguments about whether there is just one, or the universe is swarming with creatures in some ways analogous to dexterous, talking monkeys like ourselves. These arguments are usually based upon probability guesses with very weak, or even non existent empirical support.

The truth is that nobody really knows how common ET civilizations are, or how long they flourish, and the so far null result of our (so far) very poorly funded SETI enterprise isn't much help in resolving it one way or the other, as has been argued by such persons as Jill Tarter for many years now.