Using Earth to See Across the Universe: The Terrascope with Dr. David Kipping

the greatest discoveries in science often sprung from outside of the box thinking it could be said that both newton and einstein came up with their ideas initially simply by taking a fresh look at how we describe our universe what's currently important is that fresh ideas get looked at and debated that's innovation and it's all around us currently from spacex revolutionizing the aerospace industry to murmurs of private efforts to harness fusion but what else might we do my guest today has come up with an idea for a new type of telescope not using mirrors or lenses per se but the earth itself perhaps eventually giving us an entirely new way to view our universe welcome to event horizon with john michael gaudier [Music] dr kipping is the assistant professor of astronomy at columbia university where he researches extrasolar planets and moons dr kipping also leads the cool world lab at columbia which includes a youtube channel and a website where you can learn about their research dr kipping's other areas of research interests also include study and characterization of transiting exoplanets exoplanet atmospheres bayesian inference population statistics and understanding stellar hosts he is also the principal investigator of the hunt for the exo moons with kepler hek project welcome everyone to event horizon with me john michael gautier if you enjoy what you hear fall into the event horizon hit the like button and become an active subscriber by ringing the bell david kipping welcome back to the program thank you so much for having me jon it's a real pleasure to be back now david you have a new paper out and i found the idea very compelling to say the least the pteroscope give us an overview the idea is very simply to build one of the largest telescopes we can imagine which is to use the earth as the telescope now normally when we build telescopes we use mirrors or even before that we use glass lenses which bend light to a focus here we're going to use the earth's atmosphere to bend light to a focus point and that of course offers the opportunity of huge gains by having essentially an earth-sized telescope how do we do that what mechanism is it obviously there's always been the idea of gravitational lensing for a telescope where you might use a star or something like that but this is different explain the differences between the terrascope and a standard gravitational lensing which i guess isn't standard because we haven't done it what is the difference what's going on here that's that's very different from previous ideas the difference is what's doing the bending so with gravitational lens especially like the focal mission which had been proposed to the european space agency in 1993 by claudia mcconney the idea there was to put a detector at beyond the orbit of 550 astronomical units just for the viewers that's one astronomical unit represents the distance the earth orbits the sun so this is really far out on the very very outer edges of the solar system about the sort of distance that planet nine might be this is so way beyond even the orbit of pluto and if you put a detector there then light from a distant source you can imagine a light beam sort of skimming the surface of the sun and it will bend by a very small angle but because it deflects by that small angle all the way around the rim of the sun then like a spherical lens the light will bend to a point and come to a focus at this special distance in fact it comes to a focus at every distance beyond that as well because you can imagine a ray which doesn't quite skim the surface of the star has a little bit of a higher altitude if you like away from the sun and then that light will bend a little bit less because it's not so deep in the gravitational well of the sun and come to a focus there for a little bit further out so actually what you get is a focal line starting at 550 au and then working out to infinity essentially and here with the pteroscope we have a very similar setup except that it is not gravity that is doing the bending it is the earth's atmosphere through refraction whenever light moves from one medium to another it will bend and that's essentially just because the effective speed of light is changing as it goes through different mediums you see the same thing if you look in a swimming pool and you look into the water objects will appear shifted from away from their true position and that's refraction another more familiar example might be looking at a sunset if you see a sunset the sun is actually about half a degree lower than it really appears and that's actually why even though the sun can be below the horizon we can still see it because light kind of curves its way around the earth and makes its way to your eye now that same effect is going to be used here to create a telescope if i get half a degree bend on the horizon from a sunset then as that light ray then not only goes from space to my eye but then remove my eye it will just keep going and eventually leave back out into space i will get another half a degree bend giving us one degree bend in total and that ray will therefore come to a focus at about sort of two-thirds the distance between the earth and the moon now that's the inner focus point and again just like the gravitational lens you can have higher altitude rays which deflect a little bit less because the atmosphere is less dense as you go up in the column and therefore the focus sort of moves out so you get a focal line in exactly the same way and there are some advantages actually to putting a telescope further away than the inner focus that we could sort of touch on later if you like your thesis dealt with a similar phenomenon the green flash which i've personally seen actually on a cruise ship lucky in tell us about that yeah the green flash i mean this this goes back to my i say my thesis this is my master's thesis it's not my phd thesis but my master's thesis this is 13 years ago and i talked about this in my uh cool worlds video about this a little bit more but the i you know i was asked by an advisor to sort of think about this problem and i'm sure he gave this project out every year and every year students probably just gave exactly the same answer about probably even copy and pasted some of their answers and the idea is to to just explain that okay there's two effects happening there's bending through the earth's atmosphere refraction and there's um there's scattering so a green flash it's this little flash of light that you see during the sunset now as i said the sun actually when it's setting on the horizon it's actually truly half a degree further down than your eyes are telling you it's actually below the horizon but green light and even blue light bend more than red light do so actually even though all the red light is bending and trying to make its way to you eventually the bend angle just isn't enough and the sun has set too far down below the horizon but the green and the blue light can still bend enough to make its way to your eye unless the sun would have this sort of green or blue uh hue to it now the problem is you can't really see the blue light because the earth's atmosphere is very good at scattering blue light that's why the earth's sky looks blue um so the only thing you really see is the green and that was the problem i was working on it's a classic problem it's been well understood i think probably since sir cassini's time in you know the the 18th century um but uh when i was working on that i came across the idea hey maybe if you're in space um you would also be able to see a green flash maybe an astronaut could see a green flash as the sun sort of dips below the you know the edge the rim of the earth and if they were actually further out than that then they might even see a green ring all the way around the earth and uh that was at that point just an intellectual curiosity i showed it to my advisor he was like yeah that's cool nobody's ever thought of that before but i'm not sure as any point and i was like yeah yeah i guess so yeah and i kind of um left it at that but the idea always stuck with me and then when i heard about the idea of the gravitational lens as a telescope many years later i kind of connected the dots and thought maybe maybe we could use the earth instead of the sun now the atmosphere of the earth though is notoriously dodgy it it's always moving so if you have clouds for example at a certain altitude it's going to mess this up so you have to move out to a certain distance to where you might have enough stability in the atmosphere in in order to pull this off what altitudes are we talking about what distance from earth do you have to put the the end point of your telescope yeah the short answer that is um as far out as you can is the better and probably the the most practical far out distance you could consider would be the most distant stable orbit around the earth and that's the hill sphere the hill sphere is the region of dynamical stability for satellites it's about four times further out than the earth moon distance so pulling a satellite there the rays would um i mean if the ray traveled so close to the earth that it basically skimmed the surface then it would bend too much to reach that detector and that would be far too much of a bend it would actually miss your detector so you want to go higher up in altitude and it turns out if you do the math which i show in the paper it's about 13.7 kilometers this somewhat depends on the climatic zone that you're in so for instance over the arctic it's a little bit deeper in the atmosphere versus over a warmer climate like over africa say um it's a little bit higher altitude but it's it's more or less around about 14 kilometers and that's enough that you are above the vast majority of clouds which uh tend to be sort of in the troposphere there are still a very small amount of high altitude cirrus cloud uh that will remove about eight percent of your signal so small enough that it's not really a show-stopper in any way at all and of course there'll be a small amount of losses just by virtue of passing through a gas um you're passing through quite a lot of gas unless there's going to be some losses there as well through absorption of light into the atmosphere but both of those effects end up being uh moderately small you sort of lose about 20 of your light overall as a result of this and thus you end up with a just give you some numbers like if you put a one meter detector for example a one meter telescope it's kind of typical size space telescope out at this distance you could expect to get a amplification which is to say the light from a star would appear this many times brighter of 50 000 so 50 000 sort of the ballpark number which is equivalent to turning your one meter telescope into something like a 150 even a 200 meter class telescope so therefore you know it could be a very cost effective way of building effectively a very large telescope yeah that's one thing that strikes me here is this sounds cheap if you put a bunch of one meter space telescopes which not really a big deal to mass manufacture or something like that you could put them at different altitudes and angles yeah and basically turn earth into a gigantic telescope amplifier and look at certain things that you would not see even if you built a you know very very large telescope here on earth now you study exomoons exoplanets things like that what benefit here is there it it you know what would we be able to do with that amplified aperture of a telescope you know could we see an exoplanet atmosphere yeah so um there's always two things you might consider doing with any telescope whatever the science is but we'll focus it on exoplanets just as a pointed example and that's obviously my familiar area the two things you might do are one try and resolve very small things on say the surface of the exoplanet maybe you could resolve continents or you might even be able to resolve cities if you had extremely high precision the other thing you can do is to make that it's almost like a magnifying glass in a in a way in terms of how much brighter an object can appear like burning an ant right with a magnifying glass on a hot day you're just focusing like you're getting much more flux many more photons than you normally would and that allows you therefore to make very precise measurements of how a brightness of an object changes or for instance to detect things which are extremely faint planets which are much further out than conventional telescopes can see or even you know going further afield galaxies on the other side of the universe which are too faint to be detected with conventional telescopes those are the sorts of things you might be able to do in my paper i kind of threw the idea of resolving small things magnification to use the correct term under the bus to be honest i just sort of left that aside and the reason is because it kind of comes back to the point you raised earlier the earth's atmosphere is messy it it's not a clean gas cylinder or sphere even it's it has all these movements in it has shears it has turbulence and layers and that's going to distort your image and so i i just sort of left that aside i said i'm not going to worry about trying to reconstruct an image it may be possible with some fancy algorithms and some corrective adaptive optics techniques for instance but the simplest thing to focus on is just how much brighter does this light appear and yes the light might be a blob at the end of the day but it's way way brighter than it would have normally been now with that level of precision to come back to your your question and then sort of seems like i'm skirting around it so to come back to your question what could you do for an exoplanet with this huge amplification well um a one meter telescope that's kind of like kepler kepler was a one meter telescope and it obviously did not use atmospheric lensing and it was able to achieve about tens of parts per million photometry so that's 10 to the power of -5 and that means that it was able to detect planets about as small as the earth not much smaller with that kind of sensitivity now here i'm going to increase the the power of that telescope essentially by the factor of 50 000 and so it should be able to find planets which are around 200 times smaller than the earth using that kind of scaling so you know you would be looking at objects which might not even be round quite frankly at that sort of size scale they might be sort of asteroids or potato shaped things in that distant solar system of course that raises the prospect of detecting small moons comets things like this you could even actually detect topography on the surface of these exoplanets for for small stars it should be possible to see how non-spherical the planet is as it rotates around the silhouette of that planet slightly changes and we could actually infer that when we talk about the kind of precision that a 50 000 times better than kepler telescope might be able to achieve so uh there's a lot of interesting things you could do biosignatures of course is another sort of obvious point that a lot of people would probably like to focus on the idea of detecting the signatures of life in another planet and just the idea of seeing plants at this level of detail would reveal all sorts of interesting you'll be able to measure properties of the planet like it's a blatant for instance extremely precisely so it would really open the door to learning a great deal more about planets so the vegetative red edge which is something that's talked about a lot with biosignatures these this idea where plants become reflective in infrared light what advantages does this idea offer us as far as detecting that well that's a good question i'm i'm not actually sure what the wavelength of the red edge is uh do you know whereabouts that occurs off the top of your head i can sort of have a quick look see if i can find it here you no i'm not sure i'm not sure i have to admit that uh okay it looks like it's happening okay so i've just sort of looked it up quickly it looks like that happens in in the visible wavelength i guess well actually you know not too far after uh the green bump due to chlorophyll okay that that would be tricky with the terrascope the terrascope prefers if possible to use infrared light and that's just because optical light is somewhat scattered in the earth's atmosphere through a process called rally scattering blue light is almost completely lost as a result of that red light it's uh it still gets through but you lose some some degree of flux through it so you would definitely get a very large amplification of that effect it would probably be a better buyer signature to look for than ozone say ozone is basically completely off with the terrascope and that's because the earth's atmosphere has way too much ozone in it already so you can't really use the telescope to look for ozone on another planet because our own atmosphere is just full of the stuff and thus that wavelength is completely washed out yeah exactly it's completely blocked essentially it's basically uv light uv light is completely absorbed by ozone in the upper atmosphere so you wouldn't really be able to use it for ozone detection things like methane as a biosignature um or maybe even o2 you might have a chance for because that's that doesn't tend to have such a pronounced signature in the earth's atmosphere especially the upper atmosphere and the the red edge would be another good one so um but when we think about biosignatures it's becoming ever broader we're trying to be uh non-anthropocentric and trying to think about by signatures that we don't necessarily have on our own earth things that alien biology might produce uh aside from the things of course that we see in our own earth and that's that's uh the library of biosignatures is sort of ever growing and we have to take a break everybody check out david's channel cool worlds on youtube which is just amazing we'll be back in a moment if you like hearing about cutting edge research in space and astronomy then consider swinging on by our channel called cool worlds i lead a research group at columbia university where we discover and characterize new planets outside of the solar system and we like to share our work through videos on our channel futurism fans will also enjoy our hard science takes on topics like artificial gravity alien megastructures the kardashev scale and more real science videos by real scientists so thank you again for tuning in today and i hope to see some of you over there at our channel cool worlds and we're back with dr david kipping of columbia university david it seems to me that one issue with us would be that the earth's atmosphere could color you know the information that we receive from the telescopes the if we set them out in far orbit of earth so how does this affect spectroscopy if we for example say we look for the techno signature of cfcs well we're going to see them in earth's atmosphere so how does this color things yeah so what you the ideal wavelength of light for for the terrascope are the wavelengths which the earth's atmosphere does not like to absorb and those are well known they're called atmospheric windows for instance there's there's one at about one micron which is 1000 nanometers a little bit outside of our range of perception but the earth's atmosphere is pretty much transparent that to that wavelength range and there's about you know five or six of these in the infrared and these windows which can be quite broad sort of plus or minus a few microns in the in the far infrared are your ideal regions in which to apply this technique so you know when we look at think about the infrared i mean you have to think about what kind of science does the infrared give you well infrared is heat mostly so that means that you're able to potentially detect say the one idea of using infrared for exoplanet studies in the far future might be actually to touch the heat island effect that cities have so cities anyone who's living in a city probably knows this certainly i know in new york it's like three degrees celsius hotter in new york city than it is everywhere else in the in in new york state right now and that's just because of this the heat gets trapped by the concrete it gets trapped by just having so many air conditioners on and all this kind of stuff and so we we think that one possible techno signature might be that you'd get these heat islands which as the planet rotates into view you'd see these heat islands sort of pop up like hot spots and that would tell you that there's potentially a city there which is responsible for that and this telescope because it has great sensitivity in the infrared this would be the sort of thing it could um be quite sensitive to um the infrared of course we we use it for spectroscopy in terms of chemistry as well um water for instance one of the most basic things you might look for in exoplanet atmosphere water vapor has features all over the infrared spectrum it doesn't just have like one sharp spike actually it's litters all the way across the infrared spectrum and all of those infrared windows it has specific specific features that you could look for so certainly there are regions that you're not going to be able to detect and the one example i gave earlier is probably the most pointed one to say and that's ozone ozone is the earth's atmosphere just absorbs too much of that for you to be able to see it but you know when we think about the sort of lists of molecules that we've been detecting on exoplanets and planning to detect in the future things like methane carbon dioxide carbon monoxide ethane carbohydrates those all um have many specific features which all go across the infrared wavelength range and should be detectable with the terrascope system now that's interesting so the heat island effect that's that that would seem to me to be a new techno signature because i've heard of detecting like city lights like sodium lights or something like that at a distance yeah actually detecting the heat of a city how could you differentiate that between geology you know say you're looking at some lava flow plane that's that's emitting infrared you know absorbing and emitting infrared how can you sort of differentiate between that and an actual city yeah well i think if you had a lava plane i mean that's gonna be really hot you're talking about 3000 kelvin sort of temperature um for the sort of melting of iron and rock and stuff so that that would have you'd see a very different infrared signature to something that was say 300 kelvin and thus maybe 5 kelvin hotter than the background so it would be a smaller contrast in terms of the absolute difference but presumably probably a larger diffuse area um cities tend to be quite large potentially you know you know when we think about the growth of cities they could actually become much larger than even the cities we have on earth and so you're looking for a diffuse low contrast hot spot versus if it was geology i think you'd probably expect something much much hotter and likely much more concentrated but who knows i mean when we look when we when we're doing this work for alien geology we really don't know what to expect so this i kind of agree with you that this is probably not going to be a completely unambiguous techno signature but it's one and there's many techno signatures which probably fall into that bracket yet it has uh clearly if you if you had this in conjunction with some other information um such as you also had for some evidence some weak evidence that the lights were on on the night side you would probably then have a fairly compelling argument by building all this evidence together that there was somebody living on that world if you have people on the night side you're looking for city lights basically night night time lights is there any hope that this method could detect that or is it just too far outside of infrared or for that for for that matter i mean say you have a city that's rotating out of the lit side of the planet and radiating in infrared you know residual heat could you see that yeah i think so i mean probably the best strategy for doing that would be to collect what we call a phase curve so a phase curve happens when you look at an exoplanet not just when it passes in front of the star which is a transit but you monitor it all the way around on its orbit now if you think about the earth it takes 365 days to grow in the sun and if you look at maybe a five-day window when it's you know presumably not transiting just some arbitrary point in time then you'd have this you'd have five rotations of the earth and that would mean that every rotation you're getting um the you know different continents come into view you might have an ocean side as kind of we do on the earth like the pacific is more or less that hemisphere is more it's just completely ocean and thus you wouldn't really expect to have any uh emission really on that side and then when the continents come into view suddenly maybe you get more brightness as people turn on their lights for instance so i think if you look to the phase curve um you know i i don't want to say that i've run the numbers in this because i haven't but i would expect that that would be the best method to attempt to detect these types of signatures and obviously if you had parts per billion photometry that the terrascope could offer you then it would be very exciting to try and look for those types of signatures to build a terrascope and it would seem to me that this this this could be done with multiple spacecraft so you're out i think you said four times the distance of the moon and you're you're putting these these things in orbit you could build multiple terrascopes say a hundred of them and look at all different types of of objects from many different angles because you don't just uh you're not just limited to one telescope as you would be with with with a standard instrument yeah so i mean you're kind of solving there with that suggestion one of the big limitations of the pteroscope i'd say probably the largest limitation here is that you only get to observe what happens to be behind the earth at that incident in time i mean imagine drawing a straight line from your detector all the way to the earth and then out to infinity and something has to be within that line um basically not quite doesn't have to be exactly on top of that line it has to be within about an earth diameter offset in either direction and you'd get this very pronounced lensing effect but if it's any further than that then you don't see it and those things which are out of the plane of your orbit are basically invisible so there's a big limitation you don't get to look at anything you want it's the same limitation that affected of course the gravitational lens idea there it's even more pronounced though because um there not only are you limited to looking at whatever's in your plane you're pretty much limited to looking at one object that happens to be behind the sun and that's because the the telescope is orbiting the sun so slowly it takes tens of thousands of years to orbit the sun when you're at this kind of distance that you're more or less static you're basically not moving and so you you have one object that's behind the sun and it basically lives there all the time and you get to look at that one object at least with the terrascope you're in orbit of the earth and thus the stars that you're looking at are constantly changing and the earth is an orbit of the sun and that gives you some variations as well but you're still limited to one plane so one solution would therefore be to have a fleet of small telescopes you might even consider using cubesats for instance for this cubesats nice and cheap we're getting better and better at building those they can cost as low as just ten thousand dollars for some of the cheapest ones this would probably cost a bit more than that because of course you're developing new technology and you're pushing it to a further orbit than most cubesats go into they're mostly going to low earth orbit this would be a very high earth orbit to go to the hill sphere but you know still it'd be a relatively cheap concept compared to say the james webb space telescope which comes at 10 billion dollars and you could have this let's say a typical cubesat might have an 85 millimeter lens that's basically like a dslr the sort of camera actually we use for our youtube channel it's basically the same kind of camera uh you'd have a camera like that something on this cubesat and it would have the collecting area effectively of about a 50 meter telescope um by being using the earth as a lens so if you had many of those you could potentially have many 50 meter telescopes looking at all different objects and perhaps if you once you've built that first one the the cost the technology costs is going to obviously be greatly reduced for each next one since you don't have to reinvent the wheel every time now you have a template to go from so potentially a fleet you know might be the best way to go so you could mass manufacture these cubesats so that can take advantage of this perspective and with the heavy launch systems that are promised from blue origin and spacex we could basically build one heck of a telescope right yeah that that would be my dream future uh but uh we'll see i mean i don't wanna i'm not exactly knocking on the door of elon musk and uh nasa just yet i although i of course would love to see this come to fruition and see this telescope fly one day hopefully sooner rather than later i mean i'm just one person i wrote this paper and there's really nothing else really on this concept and i would love to see some of my colleagues you know take a skeptical view to this i'd love to see more detailed modeling of the turbulence for instance in the atmospheres i'd love to see some kind of demonstration before we build a fleet that might be a bit premature to build a giant fleet and then oh hold on a second there was this hiccup that we hadn't thought of so you know there's a road ahead i mean it may be that a terrascope fleet is in the is on the cards for the future or it may be that there's something here um that is going to prevent us from getting all the way or that it might take longer to develop this technology than we've currently anticipated but certainly at this point in the journey this is more or less the first step one might say i'm very excited about it and i really hope that uh it can be useful and if it if it does work it would greatly increase our capabilities and our view of the universe and that really excites me as an astronomer it's very exciting and i it it it helps to hammer at home that you know this is sort of a this is just a seed idea and a lot of work it needs to be or a lot of thought needs to be put into it but it could give us really great benefits over our standard way of doing things in other words you may not need to send things like james webb out and spend all this money when you might be able to do this on the cheap and use the earth as a telescope and but it's again very early in the game right yeah i mean you kind of remind me there of avila webb who i know you've interviewed on your channel before as well and when i was at harvard uh he he used to tell me something that really stuck with me and that was sort of the stocks and bonds approach to research and that's that you know there's these things that we know will work those are your bonds they'll give a slow rate of return such as building a slightly larger telescope and you know to lean on the analogy in this case a little bit more and just keep developing and pushing further on existing proven techniques and then there's your stocks and they could be extremely high risk stocks maybe you invest in in five percent of your equity in something that really could go burst or could really explode and become the next big thing and i try and adopt that philosophy i really like that philosophy and avi certainly obviously not only promotes that philosophy but lives it if you look at his research and i i try to do the same thing a little bit in my approach as well so of course i'm not going to say let's abandon conventional telescopes guys this is this is the only thing we need to do but i would say hey when you know maybe we should be investing a small fraction of our resources to pursue this because if it works out then it's kind of it's kind of a game-changing idea a very cheap lottery ticket so to speak yeah exactly yeah and i i agree with you i i think sometimes things can get too rigid within science you know within the academic system and dr loeb certainly tries to say well wait a minute maybe we need to think outside the box and i wish i wish it was easier for scientists to think outside the box sometimes admittedly and i'm glad that you do it now to flip this around to flip this around using this as a transmitter say we wanted to create a beacon that other species if they're out there could see could we do that yeah uh so this is this is an idea that i didn't get to talk about in the paper because there was a there was a lot of new stuff in the paper as it was so i didn't want to push things too much but one of the things that really excites me about this is that you could potentially use the earth as an antenna as well as a detector and it's just it's just the same effect in reverse and this is not that novel i mean people had already suggested the same thing again for the gravitational lens so if you put a transmitter at 550 au then it produces somewhat spherical waves that come off it and they just basically isotropically go off in all directions but then a very large cross-section of those waves intercepts the sun and are focused into a collimated beam which then uh diffracts far less than this this spherical wave going outwards and so essentially you get a gain or an amplification you know in your in your antenna which is equivalent to the same amplification that you had as a receiver going the other way around so just like the same light rays in reverse and so you could potentially do the same thing for the telescope you could have a antenna rather than the detector with an amplification of 50 000. now what would that mean what would that do um so this is this is uh really pushing things a little bit with this idea but some of the things i've been thinking about is well you could potentially uh have a very high speed interplanetary network essentially you know you could have a probe like juno orbiting jupiter or cassini which is now done with but used to be around saturn and these missions obviously collect images high resolution data and they're very limited in what they can send back just because they're so far away and their their antennas only have a specific gain and a certain power level but what if they could use the planet they're orbiting jupiter as an antenna or jupiter's atmosphere as an antenna or saturn as an antenna and then they could beam back very high fidelity data back to us and we could even maybe even use the earth as the receiver as well so they could use jupiter as the transmitter and we could use the earth back as a terrascope as the receiver and you'd get you know you can almost imagine doing sort of kind of uh uh extremely like 4k 8k live feeds or something from from jupiter with that kind of stuff or telepresence or something it'd just be so ridiculous the data bandwidth you could pull off so that'd be kind of fun and then the other angle i've been sort of thinking about with this is um you know what about extraterrestrial civilizations should they exist maybe they might also use such a system and that raises the prospect that when you see a planet transiting at that very moment in time that's the perfect moment for this for them to send us a signal using their own planet's atmosphere as a lens and we could even enhance that signal using our own planet earth again as a receiver so it raises another possible techno signature to to think about that maybe we should also be scanning transits in the radio or something when this is happening we shouldn't just be limiting ourselves to optical observations we should be thinking about the sorts of frequencies that communication might be attempted at because um especially the frequencies that the earth the earth's atmosphere would be amenable for lensing to those frequencies would be really good frequencies to scan and see if there was any kind of communication buried within those transit signatures mind blown so you could have a live io cam where you're watching io's volcanoes erupt in real time insofar as you can at that distance yeah it's possible it's possible it depends depends exactly on the configuration and obviously there'd be a significant time delay of course i mean light takes you know probably i think it's something like half an hour more or less to get to jupiter so you know there's going to be a time delay but apart from the time delay it would essentially be a live streaming video it would it would at least be video just video of ios volcanoes just just popping off and and going crazy now when we come back we're gonna have to take a break but when we come back we're gonna get into the seti options here and go deeper into that i am joined today by dr david kibbing of columbia university who has an amazing idea the pteroscope and we'll explore that further when we come back and i'm joined today by dr david kipping david seti and this is this this idea of the terrascope seti likes the 14 20 megahertz hydrogen line you know as far as radio is this of any use in radio astronomy or is just we're so far away from infrared that it's useless i'd say the answer is maybe um the the reason is because of the ionosphere of the earth so this is this layer where atoms essentially become ionized through interactions with sort of high energy radiation from the sun for instance in cosmic rays and as a result of that they can become quite opaque to certain wavelengths and even reflective to certain wavelengths of light and it's the ionosphere has some quite complicated physics going on when it comes to radio waves there can be both a help and a hindrance so i think if you were serious about using the pteroscope as a radio transmitter you'd have to model the ionosphere which i definitely did not do in this paper i really took a deliberate effort to sort of shut off before i even hit the radio however having said that um the amplification is basically flat so the amplification basically changes quite a lot as you go from blue light to red light and that's because the earth's atmosphere bends blue light more than it bends red light but once you get beyond about one micron which is just beyond our visible red light detectability for our eyes um it's pretty flat the earth's atmosphere really doesn't bend radio waves dramatically different to how it bends infrared light with the exception of the sort of the interaction with the ionosphere so that would be sort of the the last piece of the puzzle to fill in before you could before you can make a definitive claim about what it could do in the radio and uh again that's one of the sorts of areas i'm hoping this paper might spark interest in so essentially you need other scientists to read the paper think on the idea and expand upon it yeah i mean that's how science works best right it's science isn't a one-man army like no one person should try and solve everything and sometimes i get there sometimes i get people send me you know einstein was wrong here's the theory of everything like like these scripts sent to my office and it's you know it's almost never that science really proceeds that way it's a collaborative thing and yeah i like the idea of thinking of science as a conversation that each of us are sort of sat in the cocktail party holding our drinks and chatting away and each paper we write is almost like just chirping in and adding our own perspective into that conversation and then someone else will come and build upon that idea and have a different thought and we're all trying to kind of inspire each other and keep the conversation moving in a forward progressive sense um so that's i like that analogy for science i also kind of picked that up during my time at harvard but i mean when it comes to techno signatures and seti you know radio isn't the only game in town of course so even even if the ionosphere really does become a problem of course you've got mars has an atmosphere so and it doesn't have ionosphere like the earth does or at least not an atmosphere quite the same same way as we have it would interact quite differently in jupiter and saturn you have all these different atmospheres in our own solar system so the game doesn't end with with the earth we can imagine using this effect in for different worlds and we could imagine if other civilizations are using this technology then we may be able to detect their transmitters for instance one of the requirements of the terrascope is to block out the disk of the earth um the disk of the earth is basically a pain in the butt it's just you know this bright thing which is in your image there might be digital ways to remove that but probably the simplest way to remove it would be just to fly a big disc which blocks out most of the earth and then you just have the atmosphere left over you might even be able to use the moon you know the moon would basically serve that purpose for you at certain choices of angle is basically a big black thing in the sky for all intents and purposes so you need something to block out the light and uh depending on how big you make your terrascope that thing could be quite large um if you went for a really large terrascope it could be quite a large disk maybe even hundreds of kilometers across and that's again something that you would be able to detect as that as that whole system planet plus terrascope shade transit in front of an alien star we would see that and it would be located a very specific region you'd be able to calculate whether given the atmosphere of that planet whether the location of that second signature was consistent with the lensing focal point that you would expect for that atmosphere so you could even potentially uh expect you know one of the things we think about is whenever we think of a good technology uh one of the first things we always ask is well maybe someone else has thought of this and if someone else has thought of this maybe it's detectable in our in our observations um another aspect that this gives rise to as well is um satellites just more generally there's a a lot of satellites around the earth live in one particular orbit called a geostationary orbit there's a very very crowded ring around the earth and it's been suggested by one of my colleagues hector savaros that we might be able to detect the these satellites themselves these small satellites just because there's so many of them as they transit in front of a star but the problem is that this the signal is very small just because these satellites are probably going to be very small and yet here again the terrascope could offer an opportunity because if you can detect parts per billion photometry then you would have the sensitivity potentially to detect artificial satellites orbiting exoplanets as well as natural satellites which would presumably be much larger so uh when we think about techno signatures it's not just radio there's a there's a bunch of stuff that having high precision uh powerful telescopes could enable us to look for so to throw out crazy on on that theme if a civilization decided well we're gonna put a bunch of very large telescopes out in orbit of a planet maybe they chose a gas giant or something that's that's within their um their their star system and they decided to build essentially a dyson swarm around it of telescopes and say these aren't small say they're not cubesats say they're big that could potentially be a techno signature right yeah exactly you would you know it's it's a nice analogy to the dyson swarm but instead of being circumstellar it's circumplanetary and uh if you saw something like that then um especially you know if they're all located at the same distance from the planet um that'd be very suspicious right because natural satellites you could they can't really share orbits um they become unstable if they share orbits so these things would be likely thin material and thus not have much mass and therefore would be more easily stabilized in in these orbits and yet because they're thin and big then they would have the a large signature a large amount of light would be blocked from the parent star as they pass in front thus giving us an opportunity to detect them so um this you know people have thought about even doing a similar idea a similar kind of techno signature might be a sort of a geoengineering solution obviously we're very concerned about climate change at the moment on our own planet and one possible solution proposed it's kind of a radical solution would be to fly a giant sun shade which would block out light from the sun and help cool the planet down by a small percent and that's again the sort of effect that if if another civilization built something like that it's going to be hard for it to avoid our telescopes especially when we talk about telescopes with a power of hundreds of meters in diameter those telescopes would be able to detect those types of artificial structures in space so i'm really i mean when we get to hundreds of meters size telescopes there's all sorts of wonderful techno signatures that we could start looking for that you know really are not detectable right now with current telescopes how sad would it be if we saw the signature of a sun shade and we also saw the signature of cfcs in an atmosphere and of an exoplanet we would be looking at a civilization in in its death throes perhaps but it might also you know it might also give us some hope that you know perhaps that sunshade actually uh you know it's kind of unlikely you caught the sun shade and then sort of you know it'd have to be stabilized continuously and there have to be some kind of system to keep it in place so that sort of suggests if if you see a sun shade that there's somebody still at home controlling it and uh maybe that maybe that would give us some hope that that's not the end because you know there's this idea of these sort of transition points that civilizations have to go through and one possible great filter that we are about to face might be climate change and so if we could see civilizations who are just a little bit further ahead the nurse have sort of found solutions that might be helping them to cool their plant down maybe that might give us some hope that we're not about to approach the end um to flip it around though you could see a planet that looks like it should be a venus you know a hell world and somebody's put a sun shade in orbit of it and started adding you know whatever whatever atmospheric chemicals you need to to terraform it so you could just as easily see a civilization in its death rows or you could see one that's terraforming another world and that that gives you the opposite um viewpoint where maybe things are possible that we had never imagined yeah and i'm kind of hoping that that's what we find out there if we ever see evidence of an alien civilization which is a big if but if we do i'm hoping it's something like that yeah or even it might be mars and you know mars is cold it's not hot so it actually be you know there's the opposite problem you're trying to add heat into the system that's actually in many ways more straightforward to add heat than it is to take away heat so you might imagine the mirror is being positioned in a different configuration to that end instead so you know all of these ideas and i think the terrascaping is included in this are examples of geoengineering or maybe even more generally you might call it astro engineering and that's kind of obviously what dyson freeman dyson was very interested in when he proposed his swarms and his spheres all of this work for me has been part of a philosophy that i think you know we there's only so far we can build physical structures only so far we can build but the universe offers these tricks these loopholes that we might be able to exploit to sort of achieve huge feats unimaginable feats by conventional standards by using planets or by using gravity to help us along the way and this uh you know presumably this isn't just us that might realize this the ultimate in technology is probably to not fight nature but to work with nature and uh that's why thinking about these ideas like the terrascope can actually help us to have it have some clues as to where other civilizations might end up because surely you can't do better than an earth size or sun sized telescope that's almost the unimaginable limit for us that brings up a question now the original idea the original seed idea was using the sun as a telescope do you think we have any hope because that's obviously our biggest lens that we have in this star system is there any hope of using the sun as a telescope sure i mean that that idea has been um thrown about since and i think the first paper and that was 1979 by von eschlerman who first proposed that it comes with an enormous number of problems we've already spoken about one of them and that's just that you only really get to look at one object that whatever happens to be behind the sun and the orbital speed is so slow that it's kind of almost static in nature so you'd have to have a very large number of them even if you do that though and you're willing to book the cost it takes current speeds with our rocketry it takes over 100 years to fly to that distance and this is more than four times further out about four times further out in the voyager 2 probe that means it's really out there and it's taken voyager 2 like 30 years to get to that distance so you have to be very patient to fly to that distance and politicians usually aren't patient when it comes to choosing their missions and then and then finally once you get out there there's an awful lot of debugging to be done um how do you block out the sun's corona so even if you block out the sun which you know i think we could straightforwardly imagine ways of doing that um anyone who's seen a solar eclipse knows that you still see something even during a solar eclipse there's this you can see the corona it's beautiful sort of filtering around the outside of the moon and that light could completely overwhelm the light from the star that you're trying to observe so the corona is also a very finickity thing to deal with and obviously the nice thing of the terrascope is there is no corona you don't have to to worry about that um effect i mean i guess there might be a small amount of aurora that you might have to worry about at certain wavelength the aurora could be a problem but it's much much smaller than the corona is of the sun which completely can screw you over so a gravitational lens um it's a really interesting idea it has many challenges associated with it but for me it's always been the end point of telescope design i don't see where you go beyond that you could image um structures a few kilometers across on an exoplanet which is 100 light years away with a telescope like that it's just absolutely ludicrous the ability that you would have with a telescope of that of that size um there's not really anywhere else and apart from like building artificial black holes or something like this i mean you really can't go any any bigger than the sun so um i think it's important that we keep thinking about it and uh not only that we think about it but we think about the ways in which other civilizations might also exploit it and use it and even starshot you know which is planning to fly to alpha centauri have seriously considered the idea of using this as a as a way of transmitting information back to earth maybe they could fly past proxima centauri wait uh maybe if you know it wouldn't be that long at 0.2c the sort of speed they're planning on flying at and maybe even use the alpha centauri stars themselves as a means of sending the signal back as a transmitter back to earth so you know when we keep an open mind to the gravitational lens and the atmospheric lens as i mentioned before it gives us these opportunities to think about signatures we might look for in technological uh hacks if you like for our future missions that's fascinating i hadn't thought of that so you could because we're dealing with very tiny little spacecraft with with project starshot you could use the star itself i.e proxima centauri or alpha centauri wherever we're going to actually transmit back to earth yeah and you could do with just you know a few watts detector would be sufficient if you had a few what detector on board that spaceship and you use the the star as a lens um then the signal should be detectable across many light years and thus that could be an easy way to to get the signal back or maybe even if we decided that this was the end for our civilization and a very grim perspective we might just choose to create a beacon that might just live out on that outer edge of the solar system sending out our own knowledge and whatever we learn about ourselves across the universe using the sun as a beacon to transmit that information so i i kind of have a pessimistic view sometimes as views of my channel know and you know those beacons uh are one thing we have actually seriously talked about for our own civilization and uh again the sort of thing that we might keep an eye out for when we do our searches across the sky for other civilizations that would be amazing if we if we detect a civilization sending out all of its accumulated knowledge somehow you know the wikipedia wikipedia or galactic encyclopedia galactica is was said in the past that would be amazing that would be i mean imagine what the effect on human civilization would be if we detected an alien encyclopedia yeah it would be uh transformative and of course you can imagine just centuries of study just to try and translate and pass the information within such a thing yeah yeah if you if you could ever even decipher it but just the idea of it is is alluring i think absolutely yeah all right david it was great to talk to you again we'll give you links to the cool world's uh youtube channel below and we'll also link to the paper and thanks for joining us hey thank you so much for having me this is a lot of fun always enjoyed chatting with you jim always a pleasure david talk to you again soon bye now the idea of using earth as a telescope is an alluring one should it prove possible it could open up entirely new avenues of scientific research the dramatic dropping of launch costs along with the budding cubesat industry could make such a telescope viable that would allow for dramatic increases in capability to do things like seti or studying exoplanets at a level of detail that might be impractical or impossible otherwise i look forward to seeing the terrascope someday become a reality john who left that car on our driveway it's mine i got a new car anna and it's real nice it's called a chevy malibu and it gets great gas mileage judging by the amount of money debited from your account it's precisely two miles per gallon what oh it's not a malibu john the stickers they're peeling off it's a 1977 vladivostok motor john you've been had how much did this car cost 400 rubles and that didn't tip you off tip what off

Channel: Event Horizon

Views: 107,562

Rating: 4.8526702 out of 5

Keywords: Using Earth to See Across the Universe, The Terrascope with Dr. David Kipping, The Terrascope, Dr. David Kipping, Event Horizon John Michael Godier, Event Horizon, Can we see the end of the universe?, Earth sized telescope, Earth Telescope, Telescope, Kipping terrascope, Terrascope, David kipping, Cool Worlds, deep astronomy universe, astronomy (field), science, space, nasa, david kipping cool worlds, exoplanets, universe, SETI, Earth as an Atmospheric Lens, futurism, asmr

Id: OjXN-SmHvC0

Length: 59min 4sec (3544 seconds)

Published: Thu Aug 15 2019