 So last time exploring the unknown Tabby star at the Kepler space observatory, and that was a probe photo Sensitive probe that looked at a small patch of sky Only roughly about 150,000 stars. What it does is detect over long periods of years up to a long period of time up to years because we're trying to detect actual periodic orbits of exoplanets around stars Other than our own of course And one star that we particularly found fascinating was in 2011 Discovered by Tabitha Where's her name? Tabitha and her Molly Crue Astronomers discovered this brightness Roughly every 750 certainly in line what takes 365 So I kind of teased you last time you discovered about Tabby star. I kind of just mentioned it He left you hanging so we're going to pick you up Pull you in from that cliff the only place you're going to fall is to sleep Astronomer Tabitha Boyajan Tabby's star. So we missed it in 2015. We observed it again in 2017 And just what it could be we're going to speculate Do it all bad scientists do and speculate But We're going to use all this. We're going to make it an informed speculation and the first question we're going to ask is what natural phenomena might explain this Before we jump to aliens megastructures and Dyson swarms That uh artificial alien constructions artifacts architecture Absorbed so much of the actual sunlight between its star and our planet that uh We can actually detect from And we're but nonetheless the nearest stars alphas and chari And that would have been that's four light years takes light four years to To get there and that we did not talk about that last time. I'm sure we'll we'll get to that It's a pretty big article. There's lots of information about it So we know it's too big to be a planet. It actually doesn't have to be very massive to block that much sunlight Any more than your curtains have to be heavier than a bowling ball Just because there are blackout plants curtains gas and ice therefore were Some of them first speculations about this Very interesting very small but very bright A lot of light a lot of gas Just happens to be Do some quick calculations. They you know, they could have a huge huge uh plume Has been released once upon getting close enough in proximity to the sun and heating up or alternatively maybe a Collision of planets actually sprayed debris everywhere And I remember we've only seen this twice. So for an instance For instance a big comet coming in from deep space Could have been spotted as it approached and 750 days later as it left And it could have been a whole wave of comet were perturbed in some some way by a large body sweeping around The outer solar system, but this little bit of the article is written It's been observed Again, so we know it actually is a periodical orbit So tabby star does have a red dwarf Star about 800 AU from it and for relative comparison Pluto is about 120th of that distance at 40 AU In Alpha Centauri, which is four light years Is over 300 times further away At around 250,000 So really it has a red dwarf star Only 20 times further away from it It's star tabby star as Pluto is from us so That's a very plausible source of the sort of disruption That can cause a big deluge of comets And debris spread out by the star um Stays decently clumped on timelines of you know couples of years and again the first div mass to 15 percent In the second 22 percent of these stars brightness total brightness So an expanding wave of debris receding away from the star and becoming more diffuse Would uh Would account for the observed phenomena just like that from two planets colliding possibly Now such collision ought to be incredibly rare so that it would be weird to look out and actually see one um and again remember I told you it's already incredibly rare that we Want to have two and and you know we like to think of it as a roughly two-dimensional plane um the galactic plane that all the stars lie on and roughly it is but The orbits of the planets around the stars such as ours actually Aren't like I said in the last episode Most of our planets including us are actually tilted about Over 45 degrees so about 60 degrees about something like that relative to the plane Galactic plane I love saying that galactic expanse of space opera which we We may be a bit player that we uh characters yet Not that so it's incredibly rare already that we happen to be lined up with the orbital I gotta stop saying that guys I say that way too. It's incredibly rare and drake I'm sure would attest to that it should be rare and it's It would be weird to look out and see one that Perfect of two planets colliding Given that we've been observing this for a few years and we're talking about time scales that are Over millions and millions of years I guess we really don't know how rare it is though honestly could happen Once every billion years or so we expect the debris to hang around for decades. I guess So watching the 150,000 stars and seeing one is it's pretty improbable probably more probable though Of course, they looked for further evidence of either of those Knowing that any big debris field ought to be scattered Or scattering light And it ought to be admitting as uh As much light as it absorbed when it's scattered and reflected plus what it absorbs Would equal it would equal when it blocked even comets which are quite reflective Still do absorbed quite a bit of light, but that's just a little tangent Let's get back to it Because um, especially in regard to Dyson spheres in the concept of a city Like a Ecumenopolis light gets absorbed light absorbed sorry gets emitted as heat In this case as infrared radiation in the general zone of about 10 micron wavelengths Which corresponds to roughly Earth like whatever hits an object in space It doesn't bounce away until it reaches a temperature Where it's radiating away as much as it absorbs Kind of an equilibrium the peak frequency for distribution of wavelengths around it that we can actually observe and or look for With quite advanced So needless to say those wavelengths associated to the temperature liquid water can exist at interest us greatly when looking at places where biological life We'd expect the debris to be glowing with all that light and quite brightly as these things go Need a planetary collision when since there's a lot of energy converted into heat In that sort of collision You also wouldn't expect an older star to have as many big collisions around it. You also wouldn't expect An older star to have as many big collisions around it Those get of course less common As time passes and debris clumps together and either gets into a stable orbit or just simply falls into the sun Given that it doesn't be get injected Into deep space first Fert folks doubt the comet barrage options because of how much would be needed but i'm inclined to reject that because It really would need to be a huge amount in this case and I agree it isn't terribly Isn't really satisfactory answer So this is interesting about how much ice we don't know how much there is hanging out in deep space Near near earth like in the oar estimates estimates in the oar cloud often routinely And largely exceeds earth's own mass And an awful lot of that is that mass is actually ice So it doesn't seem strange to me to think that This larger star might have even more than us In its own oar cloud and that having a red dwarf cause a massive disruption in the uh Yeah, think about the orbital dynamics Of that system You know stars are Generally our star is about 99 Of the entire mass of our solar system So it's definitely not unheard of um or to imagine that a star that's only An au of course is the Distance it's very arbitrary distance, but it's what a lot of astronomers use to measure sub Lightyear, I guess maybe inter um planetary systems Distances Because it's the distance between our sun and earth Us and in the sun Or I guess about eight light minutes But you can imagine A star the fact that jupiter Isn't even one percent of what our sun is In terms of mass Having another star 800 au Only 20 times the distance from us to pluto away from it Would certainly perturb a lot of the orbits So very complex Phenomena really but you know, I don't know they they're thinking that so maybe um An icy dwarf like pluto or a series is it would maybe be dragging a slew of comets around with it being perturbed by that other red dwarf in near proximity, but It doesn't look terribly plausible And you know a really big asteroid belt could work between the internet rides block more light per unit mass than Planets do actually I guess maybe because they have more surface area So when earth's worth of asteroids mass Would block a lot more light than a single earth size planet But you'd kind of expect something like that to be decently symmetric in not a well asymmetric blob and um That would cause You know a ring doesn't have an I need speech lessons that extra syllable the whole period Because it's symmetric and evenly Blocks would have a partial ring now You know a bit of a swarm of asteroids that moved in a pack. We see that with the Trojan asteroid fields Which I did an episode on Probably a year ago in the Trojans. That's really it's a really fascinating Phenomena because Somehow you guys can see this you guys can see right here body system of gravitationally interacting bodies There's always these fields called the Grange points And for some reason which I don't quite understand, but it's proven Mathematically and observationally Um empirically, I guess It's another word for that It's been proven that there's like these gravitational wells At roughly the exact opposite 180 degrees And like 30 degrees Of yeah, so basically jupiter Is corralling A ton of asteroids in three clumps Called the Trojans Yeah, I don't know where I was going with that other than the fact that That could be something that Could account for light absorption But yeah, I'd encourage you guys to look that up sometime Wikipedia It's it's cool. You know, it's not something and it's different. It's not the asteroid belt It's actually a clump of asteroids that are in jupiters. I guess same orbital or orbital distance You should play a drinking game every time I say orbital, you know, these asteroids move in a pack due to these Um due to these gravitational forces And we we see that with The trojan asteroid fields For instance, and uh for that matter a real big planet like jupiter Could have a really huge Swarm of a junk around it Sort of like Saturn's rings and it could be tilted like Uranus. So rings were, you know, perpendicular to the Blocked a lot of light So, you know area of light absorption to be that much more So what's left um after all these? Possibilities, you know similar to the aftermath of planetary collisions to planets gliding It could simply be a planet that hasn't yet Finished coalescing congealing also called a proto planet It's not an ideal solution either particularly since the star would have to uh presumably be a lot younger Than it appears but I guess dating stars is actually not that easy and he says that we often Do it by looking at the stars near it That it's moving with gravitationally linked to Someway, but that's not always the same thing by the way stars often form From the same nebula and stick together through their movement Through the galaxy, but many spin-off and packs of stars often plow through other packs Some stars are in our night sky have been with us since the sun was born actually and Others are just briefly passing by stars. I guess dating them is Seeing how many other stars near it Look So, um some newer developments though now But if it's younger it might be a prototype a proto planet that's causing it now you can have planets form in a new stars Systems that aren't new And after all of two ram together You'd expect some of that to coalesce back into it and what's interesting is actually the star They they've been looking at old photographic plates Like from when Hubble didn't Again the catalog name we're calling it the wtf or tabby star um, it's just a convention and This thing was found over actually a century ago. So it had a different name Long before the Kepler space observatory was launched But they've dug up over a thousand old shots of it and The the field it was in and they've noticed it's faded um since 1890 as much as 20 percent so You know, there's a lot of room for error, but nonetheless that's tells us that uh, it's probably not a new phenomena. So it's at least A hundred years now that we've been observing it Dipping. So we've gotten through most of the dry stuff. Now, let's get into the juicy alien Speculation now folks often suggest that aliens might use entirely encrypted signals Or not use radio at all or maybe use lasers that are hyper focused And wouldn't allow for eavesdroppers Unless they were directly You know in the path of a signal Signals a laser signals trajectory is actually A form of communication among aliens, but if this is an artificial structure It's not particularly subtle and covert You know as he used His metaphor was an elephant blundering down Town of a metropolis Encryption always has a cost so you wouldn't want to encrypt everything Unless you had a reason to and your reason If it was hiding a civilization By building a giant structure around a star That noticeably Eclipses it It's not really the best way to go about doing that It would be like a sniper for recon force sneaking out in the jungle and camouflage, but Stopping every few minutes to fire flares And sing the national anthem through megaphones. All right, so if this was a megastructure a dyson sphere Can be well, it could be a swarm or a sphere It's essentially a spherical Something that spheres Spherically encapsulates the entire sun in order to actually absorb its energy And um, if you imagine that how much energy I think I said it in the firmy paradox episode but Our planet just our little planet Which is like a dot if you had a sphere If you had a sphere with the radius of our planet's orbit Our planet would be like one one actually gets Enough light to power our entire civilization For a thousand years every day We just don't harness it's it's It's really amazing to think about that So a civilization would obviously going back to the Kardashev scale would be a type one No, sorry a type two Civilization one that's able to harness the energy output of an entire star So a Dyson sphere doesn't need to be a rigid shell though It actually shouldn't be and was wasn't really meant to be when Freeman Dyson came up with the idea It could be an early stage Dyson swarm um, that's Maybe one percent complete so That's just a series of I guess you could think of them as as asteroids or artificial planets that specifically engineered and designed to Harness light in block, you know by the simple fact That they're not translucent they would block and um in that their purpose if it is Their purpose is to absorb the energy from the sun it it would of course dim the star and a Dyson swarm Is you know on paper The most efficient way to harness all the energy would be to make a sphere around the entire sun their star And so it could be you know barely complete and you might be able to do it in stages by Making rings each ring And then adding and it's easier to do it that way since those swarm objects Have virtually no escape velocity and so you need almost no thrust To move from one place on the ring to a neighbor Moving that same ring of orbitals in a Dyson swarm Could be accomplished with a space suit and a fire extinguisher You'd imagine um, you'd expect the home planet to basically be They would expand and probably Exponentially drop off in number and density You know that would at first at least during the phases of construction So that would drop off as the structure Begins nears completion, but it's asymmetrical Dimming of the star Would would be in effect until the thing is at least 50% done you'd imagine right if this is what's going on That's probably What it would be star And similarly you could mine a planet in a similar similar fashion you'd expect to see a big swarm Of orbital and megastructures You were strip mining and a lot of debris too because you can armor them up and Surround them with ice and rock now considering the star appears to have dimmed in the century. We've been observing it too You could have a fairly symmetric distribution of overall except Where some planets are that are being stripped down for additional construction material But here's the big problem. There's no reason to do this around the star We're not seeing indicators of some sprawling interstellar empire In this region and again kepler was staring at that batch of sky So a lot of those stars were near or further, but it's neighbors We're all in that sample and of course we didn't observe any other dimming. So Unless this just happens to be the very first megastructure ever built then It's uh, not looking likely it stretches Credulity that any intelligent life evolved around a star whose maximum lifetime is only three billion years And again, while it's probably pretty near the end of that It might be younger too and which would make even more unlikely So this isn't someone's home solar system There's no sprawling empire here with other stars exhibiting then this gets us into motives Why would you pick a short-lived star when probably on the old side and as you're One place to start setting up megastructures You might mine inferior veins Of ore or form not so fertile land, but not until you'd already gone for the low-hanging fruit and there are tons of nearby stars that You know would of course be younger and um more stable for long-term endeavors such as this No, maybe they just got there a century or so ago Relatively speaking It's 1500 Oh, there we go 1500 light years away. So what we're seeing now in terms of dimming In the last century is really does seem a stretch to think that this is either a um someone's home solar system and they evolved Very fast compared to us Be this whole place they've decided to do this or see One of the first they did in the only one we can so far see I don't think he mentions this in the rest of the article, but of course along that same line of thought I just made me think that If they take a hundred or so years to construct or maybe even a thousand or ten thousand Perhaps they already have multiple megastructures and Dyson spheres around other stars that are so complete in uniform in their mass intensity that There would be no way for us to detect any observable dimming of the star because even if it as a whole was blocking A percentage of the star's light even a significant percentage It would be uniform so Due to its this is a megastructure and it's just the one currently being built mostly Because even with yeah, even if they were full-blown Kardashev to us harnessing Civilization plausible that they could be this close to us it again would be quite the coincidence After all if one civilization developed 1500 light years from us Then if we drew a bubble of space 3000 light years out With double the radius and therefore eight times the volume and eight times the stars on average You'd expect eight more planets to a birth technological civilization It would be strange on her hit start Especially since this solar system if it was their home A tabby star Would imply three billion years is enough to become technological compared to our 4.6 billion in summary I don't see much odds for this being a megastructure You know a because it seems pretty likely that it's a natural celestial phenomena And b because it just doesn't fit The bill for what a megastructure would theoretically Look like and appear to us We didn't solve any riddles of the smash And that calculator but a lot of it has always helped. 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