Tabby's star is dimming at an incredible rate
sciencealert.com
sciencealert.com
> The biggest axe against it being an alien megastructure project is the fact its an F-type star. F-types only live a couple billion years, depending on mass.
> But the drop in the radiant flux... a sustained drop. That could be something far more interesting. If you could do stellar engineering... you could draw the material off an F-type star while altering its core. You could reduce the mass to a G or K star, greatly increasing its lifespan... and gaining trillions upon trillions of tons of raw material with which to build an alien megastructure...
http://www.popularmechanics.com/space/deep-space/a10885/the-...
Of course if this was happening we'd see some unusual proper motion from KIC 8462852. Which we're not. (Did someone check?)
Of course there would be all sorts of secondary effects, lowering the density in the core could slow down the rate of fusion, increased temp would increase it, but no garuntee that the effects would cancel. Also depending on how far out your mirror is the core might not ever notice the change. The outer layers could heat up and destroy your mirror before the increased temperature reaches the core.
By estimating how much starlifting would explain the observed luminosity drop, and then backing out the expected increase in the star's life against its flux decrease one could estimate how efficient the "aliens'" energy-harvesting technology is (coupled to a financial discount rate).
[1] https://en.wikipedia.org/wiki/KIC_8462852
[2] http://astronomy.swin.edu.au/cosmos/M/Main+Sequence+Lifetime
https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper...
https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...
They also contain links to the resulting paper itself
> Is this the last remaining explanation after Montet/Simon?
> The dimming comes from the shadow of a spaceship traveling on an (almost) straight line from KIC8462852 to Earth. The slow continuous dimming results from the increase of the apparent size of the approaching ship while Earth/Kepler is in the penumbra. The irregular dips happen when Kepler accidentally passes the antumbra. A rough estimation by simple geometry would suggest that the alien spaceship is quite big (> 100 km diameter), significantly slower than light velocity (< 0.05 c) and has now almost reached its goal (< 2 ly away), arriving at Earth within the next 100 years after a journey of several 10,000 years. (cf. http://archimedes.soup.io/post/632873371/) The c200 days of "rapid decreased flux" between Kepler-day 1100 and 1300 (first half of 2012) which Monet/Simon reported, followed by a series of large dips after day 1500, would suggest a course correction with the space ship now on its final homing trajectory. -- Comments?
-- https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...
Why even assume it's a spaceship and not an asteroid or a rogue planet?
But yes, that's exactly the theory, that the starship is somewhere between us and them, and it sometimes dips into the focal point of light.
The object[s] would have to be lined up. That's why an artificial object intentionally traveling to Earth is in some sense more plausible than an asteroid, which could be headed in any direction.
Specifity bias. It "feels" more probable to have object going here because someone send it here, than to just have object going here.
A ship can sail a straight line from Falmouth to Boston, but that motion can be described as an arc because of the curvature of the Earth. Add in the motion of Earth's orbit, and the shape of that motion changes again. Add in the Solar System's motion relative to the Galactic Centre, and it's yet another shape.
It's all a matter of perspective :-)
You indeed can change a curve into a straight line by manipulating the frame of reference, but it would need to be very contrived - basically you follow the object movement and add constant translation and some linear movement on top of that (one example - camera is in on a kite tied to the ship, and the rope is progressively loosened).
> That doesn't even make sense when you're flying within the Solar System. Stuff moves, so you have to fly towards where it's going to be, not where it is.
> The star is far enough away to be treated as a point source, with its light forming an apparent cone with the Earth's diameter. It doesn't intuitively make sense, at least to me, that the ship would stay within that cone as it corrects for the motion of our Solar System (and its own) within our galaxy. Remember that this dimming effect has been observable for several decades.
Then again, aliens don't have any obligation to make sense to us.
[1] : https://www.reddit.com/r/Astronomy/comments/4waozn/new_paper...
The corollary: if there are aliens around KIC 8462852 they don't care that what they're doing is visible for 1500 light years around them.
A while back I had a plan for a science fiction setting: an intergalactic ship is approach Earth. The people who sent it thought big, and as a result the ship has at its core an enclosed star (a miniature Dyson Sphere) as a gravitational anchor and power source, and round it is orbiting a vast swarm of asteroids and habitats with a few million times the living space of Earth, inside which civilisations endlessly rise and fall.
The plot centred around this thing going to make a class pass by Sol in a few years at 0.01c, with the gravitational effects pretty much dooming the Earth; so the current lead civilisation sends some ships on ahead to evacuate the Earth. (Big ships. I did the maths.)
The story never gelled, but I think it's plausible that my ship would produce these effects.
BTW, if this turns out to be true, I want credit.
is kinda similar
Terre en fuite (Fleeing Earth) (1960) by François Bordes (pen name Francis Carsac), though, there is still no translation in english of that gem, where Earth and Venus was converted to spaceships for running away from exploding Sun!
You cool if we blame you too? :)
a) Tabby's Star is roughly 1500 light years away from us; we only began emitting radio signals ~150 years ago (at most -- assuming propagation from early telegraph wires; not actually very likely) and it'd take ~3000 years for our signals to reach the vicinity of Tabby's Star and indications of a reaction getting back to us,
b) "Military" is a category error on this scale; the energy budget required to generate the sort of luminosity changes we're seeing around Tabby's Star by deliberately occulting it are mind-blowing compared to anything we've ever achieved. Might as well speculate about an ant-hill (us) wondering about the military intentions of an M1 Abrams tank driving across the Iraqi desert (hypothetical alien actors at Tabby's star) -- either they aren't going to drive over us, or we just encountered an Outside Context Problem.
B) sure.
can it be easily ruled out?
At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").
However, I wonder if there is a way to save the idea without requiring a ridiculously large spacecraft? Suppose instead of one ginormous ship, it is a fleet of big ships each big enough to cause irregular dimming if that ship happens to get between Earth and KIC8462852. If the fleet is spread out, it could then be that one ship or another ends up between Earth and KIC8462852 at several times during one Earth orbit around the Sun.
That would give us the irregular dimming throughout the year.
For the slow continuous dimming, perhaps that is something going on with the star itself. That could be what made the inhabitants of the system decide to build a fleet of big ships and leave their weirdly behaving and very scary star.
Wiki:
The leading hypothesis, based on a lack of observed infrared light, is that of a swarm of cold, dusty comet fragments in a highly eccentric orbit.[12][13][14] Many small masses in "tight formation" orbiting the star have also been proposed.[9] The changes in brightness could be signs of activity associated with intelligent extraterrestrial life building a Dyson swarm.[9][15][16][17] The SETI Institute's initial radio reconnaissance of KIC 8462852, however, found no evidence of technology-related radio signals from the star.
SETI is only useful for catching civilizations in the ~100 Earth year-equivalent span between their development of wireless tech and information theory. There's nothing to listen to but white noise after that.
<quote>
Shannon’s channel capacity criteria for noisy channels Given a communication channel with bandwidth of B Hz. and a signal-to-noise ratio of S/N, where S is the signal power and N is the noise power, Shannon’s formulae for the maximum channel capacity C of such a channel is
C = B log (1 + S/N)
(log is to base 2)
For example, for a channel with bandwidth of 3 KHz and with a S/N value of 1000, like that of a typical telephone line, the maximum channel capacity is
C = 3000 * log (1 + 1000) = 30000 bps (approx.)
http://computernetworkingsimplified.com/physical-layer/relat...
On SETI's use of the Hydrogen line:
<quote>
The hydrogen line (1420.40575 MHz) is the precession frequency of neutral hydrogen atoms, the most abundant substance in space. It happens to fall in the quietest part of the radio spectrum, what's known as the Microwave Window. Although there may not seem to be a lot of loose hydrogen atoms about (there's perhaps one per cubic centimeter of interstellar space), the interstellar medium contains a lot of cubic centimeters. So these individual atoms chirping away at 1420 MHz make a powerful chorus, which is readily detected by even small radio telescopes.
</quote>
http://www.setileague.org/askdr/hydrogen.htm
At 1420 MHz, even with an S/N of 1/1000, you'd have about 2,048 kbaud channel, if I'm doing my maths right. Given that an intentional signal could be highly directional, this seems possible.
There's no reason to think that something else would abandon using EM as a transfer of communication.
Most long-distance communication travels over wires too--everyone uses fiber backhaul. Phones and computers use EM (cellular, WiFi, Bluetooth) but the range is very short, so the signal power is far too low to report us to the universe.
On top of that, most entertainment and communications signals today are digital, and many are encrypted. It's going to sound like noise to a receiver that doesn't know the encoding and/or have the encryption key.
The most powerful space-facing EM emissions we make today, as a species, is probably RADAR, not a form of communications.
Since I don't think its coming from manned satellites where the content is generated, I'm pretty sure there is a space-facing signal involved in satellite TV as well as a ground-facing signal.
Sure some of the uplink will make it past the satellite, but that's a fairly low-power beam that would need to intersect an alien antenna to be heard.
It would be interesting if this turned out to be like the OnOff star from A Deepness in the Sky.
I'm pretty sure that if human's resources were suddenly all turned towards getting the hell out of here, we could certainly pull it off for a good part of the population in a few hundred years. Whether we'd eventually survive, after decades or centuries in space (before we manage to find and arrive at a new planet, if any), is something I'm less certain about, but I'd still estimate the odds to be fairly okay, especially with 1000+ years to prepare.
No. That time has already passed. If we see signs that the star will go nova "in one year", we have one year, not 1481.
The popular idea that we see "the past" in the sky is not really the best way to think about it. It is far more accurate to say that there is no such thing as "the" present, and what we see in the sky really is our present. The view that we're seeing "the past" is ironically perhaps less sophisticated than the more naive idea that it is simply our present we are seeing in the sky. (And at the moment, there aren't any other "presents" that we much care about.)
The thing that really saves us is that even supernovas that far away can't really hurt us because of the inverse square law. A quick Google search shows one site estimating that a supernova would have to be 50 ly or closer or so: http://www.howitworksdaily.com/could-a-supernova-destroy-ear... Something would have to be beamed specifically at us, and the only natural phenomena I know that can do that are black holes and pulsars, neither of which seem to be what is at that star, and probably still wouldn't be powerful enough to hurt us at that distance.
You sound way more expert on this than me (I had no idea lightyears had a notation, ly, nor that supernovas are dangerous to us as far as 50ly away), so I'll assume what you say is accurate, but I still see no imminent threat.
I'm also not suggesting we'd have the full 1481 years, since we don't see what's presently there but what was there, but as long as the phenomenon doesn't travel at the speed of light (and it doesn't, or we would be experiencing it already, since we can observe the effect) we still have time.
Eta Corina is a double star containing at least one hypergiant that's going to go supernova any epoch now, so it gets studied a lot. It's 7500 light years away and I believe it's judged not to be a threat, although there may be ozone layer damage and it's probably not healthy to be an unshielded astronaut.
However supernovae appear to emit gamma ray bursts along their axes. These can travel very large distances. Eta Corina's isn't point our way, but Tabby's Star? Who knows. 1500 light years is basically point blank range for a GRB, so if one is coming our way that would be very bad news. Like, worse than mass extinction grade bad news.
Inverse square applies here; moving 100 times farther away makes the effect 10,000 times less.
(I have to say it "applies here" because people sometimes overapply the law. It only applies when something is spreading out in an even sphere. However, that applies to supernovae, or at least close enough.)
You're right that I neglected gamma ray bursts. But it also doesn't seem like this star could be building up to that, since it requires conditions not evident there. (I'm just following up on my point, not implying that you claimed otherwise.)
Oh, bah. Yes, of course. My upbringing in Flatland is obviously showing.
Elimination of of all life not like me. Or simply eliminate life that might singularity and become a threat. Even if, who's to say one aliens pursuit of knowledge latest experiment dose not require and earth sized amount of raw materials.
But why do you assume they would be interested in observing the patterns that actually have been produced, instead of running high-precision evolutionary emulators that can generate patterns that could be produced at a much higher rate, and maybe even some automated filters to condense it down to "interesting" stuff? It's still knowledge, and there's no innate value scale for knowledge which says that things that have "actually happened" are more valuable.
In fact, how's that for Fermi paradox? Civilizations that are sufficiently technologically advanced to communicate, much less travel, across the stars, are also sufficiently technologically advanced to simulate the things they are interested about and get answers faster that way.
Basically, the end result of any civilization is creating, maintaining and expanding a simulation of the universe. Which, of course, goes recursive...
A counterargument to that would go along the the similar lines as to why we don't, and can't, resolve wars by e.g. playing chess (or StarCraft). Even if all nations mutually agreed that the shall will be won bloodlessly by some other kind of competition, the first nation to nuke its enemies would be a winner. In conflict situations, you want to seek as much advantage from the "most real" reality as you can get. So, in your recursion example, you'd travel up the call stack...
But I think it's a mistake to try to characterize any civilization by a single motivation. People on Earth do things for many different reasons and I think we should expect the same of alien civilizations even if single motivations tax our imaginations less. The questions is if any of the motivations driving a stellar civilization would be enough to prompt the establishment of colonies. I don't think you can say that the answer will be 'no' reliably for every civilization that might arise and it only takes on to colonize a galaxy in short order (by cosmic standards). Hence sophisticated life is probably very rare.
Then, once you have the attributes of that emulator, you'd have to calculate how long it would take that emulator to deliver the same information that can be harvested today on Earth with simple observations. And even if it completed, how would you confirm it is indeed the same information without traveling here to check?
The energy budget would be immense of course, but heat management might be the limiting issue on how fast it can run. It's hard to dump heat into space.
I'm not intending to argue one or another about hypothetical god-like alien civilizations. It's just a pet peeve when programmers make open-ended claims about simulations or emulations without considering physical constraints. We tend to think of electronic computers as powerful, but their information handling capabilities are quite slow and diffuse compared to what biology has produced on Earth so far.
That's making a lot of assumptions about alien psychology, believing they're going to have the same goals as us. Why not
1. Propagation of your species, forever
2. Expansion of your territory until the entire Universe is yours
3. Endless pursuit of pleasure
4. Propagating religious beliefs, or something we'd recognize as such.
5. Escaping this Universe, which will eventually end.
https://en.wikipedia.org/wiki/Near-Earth_supernova
Unexplained dimmings do give rise to the question of "Is it about to explode" but we have a good sense of how often large explosions occur in galaxies because they're so obvious and so I suppose I shouldn't be concerned about natural phenomenon. And given the potential expansion rates of being who could create megastructures like this our priors on that explanation have to be pretty low.
He specifically referred to something traveling at half of the speed of light, in which case it would arrive in >=1480 years not one.
"They" may have watched the Romans build roads and sussed out their mining activities from atmospheric spectroscopy. Or much earlier, signs of agriculture.
In which case they could be here...right about...just a sec, somebody's at the door....
Curiosity killed the cat, but I'd rather learn about the aliens (if they are indeed arriving on our doorstep soon) than know they're too far away for either of us to make it in time.
Why would it be so unlikely that a big comet swarm happens to be between us and Tabby's star, a distance of 1500 light years!
Comets seem like a pretty good explanation, I haven't heard an argument against them.
If you can create a credible reason why there might be a swarm of comets like this say as remnants from a collision between a large body with just the right orbit* then that's just 1 event which is more plausible.
*And I don't mean me saying it, actually create a model that would result in it based on you know math.
Science is done by people, and it is often very challenging or impossible to rigorously quantify exactly how unlikely something is. This is especially true in observational science. Furthermore, in communicating results to the public it isn't necessarily helpful to speak with quantitative rigor because the audience doesn't care. If someone says this has a 1 in a 10000 chance of being due to aliens, the headlines will scream "Scientists say alien life could be found!"
It also doesn't explain the long-term dimming of the star. The alien megastructure kinda does. It's not a perfect explanation either, but from what I understand, slightly more convincing than the giant comet swarm.
Though I'd love to have someone that's actually knowledgeable on the subject to weigh in and tell me how wrong I have this.
A black hole is also too small to explain the drop in brightness. That would require something planet-sized, but a black hole is only about the size of a city.
more information https://disownedsky.blogspot.com/2016/02/tabbys-star-for-per...
This doesn't necessarily rule out aliens. It could be a post-singularity society of virtual aliens living in a quantum computer, leaching energy directly from the sun and periodically expelling waste material through relativistic jets. Of course.
* If it is some structure being built at/around the star, has anyone done the math on the rate of such a structure occluding the star from us to match the observed rate of change?
* On a similar line of reasoning, what if the star were either being drained as a power source or caught in some kind of SG1 (that stargate TV series) level disaster?
To be clear, I don't think that they're likely, but I'd rather they were eliminated for an obvious actual flaw instead of simply being unlikely.
> a “perilous approach to science”—one > that could lead to an “alien in the > gaps” fallacy, and unfalsifiable > hypotheses.
But on the other hand, if we always strain to find a non-alien answer to everything we are in danger of making them up and distoring our ideas of what can happen naturally.
https://en.wikipedia.org/wiki/Accretion_disk
Two planets collide, forming a huge mess, that mess continues to collide with itself in a chain reaction. If the rings of saturn surrounded a star, what would that star look like when viewed edge on? Do the rings precess? What can we say about the size of the object in the ring and how will the ring structure evolve over time?
Tabby's star is a bit larger than the sun (1.4 solar masses) but you get the idea. You would need something much larger than Jupiter to visibly impact it.
So it must be aliens. That can explain anything.
> The name refers to the fact that it does not emit or interact with electromagnetic radiation, such as light, and is thus invisible to the entire electromagnetic spectrum.
I think aliens would be a little bit more exciting... Might just be me though.
Imagine the 60s-90s and advertising just overwhelm with sexualised figures. We don't notice, because we just silently pass by.
I don't see any way of turning back the tide of hyperbolic titles on articles. Better to just ignore them and move on.
Buzzfeed headlines worked on me the first few times, now I know not to go there.
And 'alien megastructures' isn't even the most ridiculous idea: https://www.reddit.com/r/KIC8462852/comments/4w7qfi/ben_mont...
Incredibly implausible idea for the sheer improbability, but fun to imagine nevertheless.
Going from e.g. Earth to Mars does not consist of aiming for Mars and firing your rockets. It consists of hitting a parabolic transfer orbit and then doing another burn to place yourself in Mars' orbit -- or just heading right in if you've got the heat shields and retropropulsion for that. Basically you do orbital mechanics like Wayne Gretzky: you don't go to where the planet is, but where it's going to be.
Would interstellar flight be that different? Wouldn't you be executing a "transfer orbit" about the galactic center? Or is the effect of galactic-scale gravitational pull negligible there and you just end up basically going straight from A to B?
Edit: turns out this came from an actual subreddit dedicated to this star!
https://www.reddit.com/r/KIC8462852/
Subscribed!
Similar how transfer from earth to mars works via a solar orbit.
So, yes, you have to include orbital mechanics, not just straight lines.
At 2 light years for instance, that spacecraft would trace an apparent ellipse 3.3" in diameter, while Tabby's star (1,480 ly) would be stationary (0.004" parallax). In comparison, the star's apparent disk is just 30 μas wide (0.00003").
Perhaps one mathematical solution to the problem is to score pages based on the average time spent for each article. My hypothesis is that clickbait articles will score very low because the article will attract a lot of clicks from people who are not interested in the actual content but only the headline.
In theory, you could do this by deploying a tracker across the web similar to a Google analytics that performs the measurement. But in practice, of course, this isn't possible.
You might be able to approximate the score by building a browser extension that makes the measurement. A browser extension might also a good way to output results. It could, for instance, colour-code links (on mouseover) to help you spot click-bait before you click it!
We just need something like that for the web.
There are several libraries that extract article text reasonably well. I believe browser extensions are written mainly in HTML/JS/CSS. Would the following node library suffice? https://github.com/ageitgey/node-unfluff
There's just the question of retrieval speed. I suspect simple HTML retrieval is an order of magnitude faster than normal page rendering due to ads, javascript, etc. So the client-only solution you've proposed might indeed be sufficient!