{"version":"1.0.0","segments":[{"startTime":5.575,"endTime":6.325,"body":"Where to start?"},{"startTime":7.485,"endTime":12.518,"body":"I suppose it's something that happens to everyone who watches the sky, who pays attention"},{"startTime":12.518,"endTime":13.525,"body":"to the universe."},{"startTime":13.525,"endTime":18.405,"body":"Eventually, we all at some point see a UFO."},{"startTime":19.105,"endTime":24.27,"body":"Uh, for me, it was about 10 years ago, I was standing on a Sussex"},{"startTime":24.27,"endTime":29.436,"body":"beach, uh, watching the sun go down, looking at a crescent moon, hoping to see"},{"startTime":29.436,"endTime":30.125,"body":"the planet."},{"startTime":30.275,"endTime":30.765,"body":"Mercury."},{"startTime":31.185,"endTime":34.525,"body":"Uh, mercury is the hardest of the naked eye planets to see."},{"startTime":34.605,"endTime":35.845,"body":"I like to check it's still there."},{"startTime":36.245,"endTime":41.473,"body":"Occasionally, uh, there's enough of the, uh, I spy train spotter astronomer in me that"},{"startTime":41.473,"endTime":43.565,"body":"it's good to see these things."},{"startTime":44.105,"endTime":45.805,"body":"Um, and so I was staring at the moon."},{"startTime":45.805,"endTime":49.195,"body":"I knew mercury was a few degrees away, and there was a point of light"},{"startTime":49.195,"endTime":50.325,"body":"in about the right place."},{"startTime":52.905,"endTime":56.115,"body":"Will we ever be able to see beyond the current observable universe?"},{"startTime":56.615,"endTime":56.835,"body":"Oh,"},{"startTime":56.835,"endTime":57.875,"body":"It's much worse than that."},{"startTime":57.975,"endTime":59.835,"body":"The observable universe is shrinking."},{"startTime":60.295,"endTime":64.61,"body":"If you want to know what are my odds of winning the lottery, you come"},{"startTime":64.61,"endTime":65.474,"body":"straight to probability."},{"startTime":65.585,"endTime":69.755,"body":"Yeah, because probability is all about how likely or not events are to happen."},{"startTime":70.275,"endTime":74.814,"body":"I think the chance of there being an undiscovered second species, very like humans out"},{"startTime":74.814,"endTime":77.235,"body":"there in the world today is pretty slender."},{"startTime":77.265,"endTime":77.755,"body":"However,"},{"startTime":78.375,"endTime":80.195,"body":"And these are the pictures if you haven't seen them."},{"startTime":80.315,"endTime":81.515,"body":"I mean, New York was orange."},{"startTime":81.815,"endTime":82.795,"body":"The air was orange."},{"startTime":83.025,"endTime":86.875,"body":"They said one day out in that air was like smoking a pack of cigarettes."},{"startTime":87.015,"endTime":90.035,"body":"It had the same effect on the lungs as smoking a number of cigarettes."},{"startTime":90.035,"endTime":93.035,"body":"So people would never smoke in their life, were suddenly going to suffer some of"},{"startTime":93.035,"endTime":93.835,"body":"the same health effects."},{"startTime":94.815,"endTime":99.677,"body":"Any further questions is a brand new podcast from Gresham College, a place where we"},{"startTime":99.677,"endTime":104.54,"body":"ask our speakers all of your questions that went unanswered following their lecture guests have"},{"startTime":104.54,"endTime":108.755,"body":"included Ronald Hutton, Robin May, Chris Lin tot, Sarah Hart and Maggie snowing."},{"startTime":109.175,"endTime":109.995,"body":"Any further questions?"},{"startTime":110.335,"endTime":113.355,"body":"All episodes are available wherever you listen to your podcasts,"},{"startTime":120.075,"endTime":122.255,"body":"But it was brighter than Mercury should have been."},{"startTime":123.115,"endTime":127.962,"body":"And as I watched it began to move in the sky and it moved in"},{"startTime":127.962,"endTime":129.255,"body":"a really surprising way."},{"startTime":129.275,"endTime":134.415,"body":"It moved, um, sharply across the sky."},{"startTime":134.415,"endTime":139.386,"body":"It was fast, and then it took a right turn and it zigzagged its way"},{"startTime":139.386,"endTime":144.357,"body":"across the sky looking for all the world like it was under intelligent control that"},{"startTime":144.357,"endTime":146.015,"body":"somebody was steering this thing."},{"startTime":146.445,"endTime":147.215,"body":"It's not a plane."},{"startTime":147.395,"endTime":149.095,"body":"Planes flash and don't really move like that."},{"startTime":149.095,"endTime":149.815,"body":"It's not a satellite."},{"startTime":149.815,"endTime":155.095,"body":"If you go out, uh, at night, uh, in the first few moments of twilight"},{"startTime":155.095,"endTime":158.615,"body":"these days, we're blessed with thousands of Elon Musk's satellites."},{"startTime":158.615,"endTime":162.015,"body":"We're used to seeing those, but they move smoothly across the sky."},{"startTime":162.015,"endTime":163.375,"body":"This thing was not doing that."},{"startTime":164.595,"endTime":169.26,"body":"And somewhere in the back of my head, as I watch this thing, you're just"},{"startTime":169.26,"endTime":173.615,"body":"thinking, well, could it be it certainly to me, an unidentified and flying object."},{"startTime":173.715,"endTime":178.163,"body":"But luckily it passed overhead and I could see it was nothing more than a"},{"startTime":178.163,"endTime":182.611,"body":"Chinese lanter, a paper, uh, lantern with a candle underneath that had been blown by"},{"startTime":182.611,"endTime":183.205,"body":"the wind."},{"startTime":183.205,"endTime":186.485,"body":"But if it hadn't come overhead, I would've been convinced."},{"startTime":186.645,"endTime":190.965,"body":"I think that I'd seen something unnatural in the sky."},{"startTime":191.505,"endTime":192.885,"body":"And it's a very human thing."},{"startTime":192.885,"endTime":198.56,"body":"Ever since we've been looking at the sky, almost every culture that has an astronomical"},{"startTime":198.56,"endTime":201.965,"body":"tradition talks about thinking about life amongst the stars."},{"startTime":202.145,"endTime":207.804,"body":"And so whenever we look and see anything, um, it's natural, um, to question whether"},{"startTime":207.804,"endTime":210.445,"body":"it might be a sign of intelligence."},{"startTime":210.445,"endTime":214.645,"body":"And in the lectures that I've already given this year, um, I've mentioned several examples."},{"startTime":214.765,"endTime":220.131,"body":"I talked about, um, maps like this made in the 19th century of the planet"},{"startTime":220.131,"endTime":225.498,"body":"Mars, where people conscientiously use the largest telescopes available in the world to record a"},{"startTime":225.498,"endTime":230.864,"body":"set of canals that the intelligent martians were building, uh, to move water from the"},{"startTime":230.864,"endTime":234.085,"body":"poles down to the dusty deserts of the equator."},{"startTime":234.265,"endTime":238.483,"body":"No such straight lines, no such canals exist, but people saw what they wanted to"},{"startTime":238.483,"endTime":238.765,"body":"see."},{"startTime":239.825,"endTime":244.43,"body":"In more recent times, we've sent robots to Mars robot geologists that have explored the"},{"startTime":244.43,"endTime":249.036,"body":"surface, and the internet has had great joy with pictures like this one from the"},{"startTime":249.036,"endTime":253.642,"body":"Spirit Rover, which shows depending on your point of view, either a rock, um, or"},{"startTime":253.642,"endTime":255.485,"body":"a tiny little Bigfoot on Mars."},{"startTime":256.225,"endTime":259.813,"body":"Um, you know, you, you can raise the objection that Bigfoot's quite large, but of"},{"startTime":259.813,"endTime":262.205,"body":"course, Martian big feet might be a slight big feet."},{"startTime":262.315,"endTime":265.285,"body":"Yeah, we'll go with big feet, might be slightly different size."},{"startTime":265.505,"endTime":268.3,"body":"And so, you know, it's hard to look at that and not see a figure,"},{"startTime":268.3,"endTime":269.605,"body":"but I promise it's just a rock."},{"startTime":270.585,"endTime":272.445,"body":"People do this professionally as well."},{"startTime":272.585,"endTime":277.478,"body":"Almost every phenomenon that has been found in 20th and 21st century astrophysics has been"},{"startTime":277.478,"endTime":282.045,"body":"accompanied by a set of people who think that possibly this might be aliens."},{"startTime":282.045,"endTime":286.685,"body":"My favorite example involves the detection of what are called gamma ray bursts."},{"startTime":287.035,"endTime":291.645,"body":"This is a high, an image of the sky in high energy radiation."},{"startTime":292.025,"endTime":295.485,"body":"And the.in the center is a sudden burst of gamma rays."},{"startTime":295.495,"endTime":300.623,"body":"These are seen coming from the distant universe, and so they appear all over the"},{"startTime":300.623,"endTime":300.965,"body":"sky."},{"startTime":300.995,"endTime":306.812,"body":"They were detected first by satellites, which had been sent into orbit to monitor for"},{"startTime":306.812,"endTime":312.629,"body":"nuclear weapons testing, but instead discovered a cosmic phenomenon of gamma ray bursts all over"},{"startTime":312.629,"endTime":313.405,"body":"the sky."},{"startTime":313.955,"endTime":316.925,"body":"What could be causing these dramatic high energy exposures?"},{"startTime":316.925,"endTime":322.205,"body":"Well, clearly they are the signs of spaceships accelerating faster than the speed of light."},{"startTime":322.205,"endTime":326.952,"body":"Because if you watch Star Trek, when the enterprise goes into warp speed, there's that"},{"startTime":326.952,"endTime":329.485,"body":"blue flash, which of course looks like this."},{"startTime":330.265,"endTime":334.525,"body":"Uh, you do need a bit of imagination to get from here to here, but"},{"startTime":334.525,"endTime":338.785,"body":"still, and there were papers published in the literature that speculated and talked about how"},{"startTime":338.785,"endTime":340.205,"body":"we might test this idea."},{"startTime":340.765,"endTime":344.965,"body":"I gave a whole lecture to this thing to more, more, this is the artist"},{"startTime":344.965,"endTime":349.165,"body":"impression, the first asteroid to come through the solar system, which is a fascinat interstellar"},{"startTime":349.165,"endTime":351.125,"body":"asteroid to come through the solar system."},{"startTime":351.125,"endTime":356.421,"body":"This is a fascinating and interesting object in its own right, but it looked to"},{"startTime":356.421,"endTime":361.365,"body":"several people, to many people, like something that could be an alien reconnaissance spacecraft."},{"startTime":361.385,"endTime":362.805,"body":"And we've even fooled ourselves."},{"startTime":362.945,"endTime":367.506,"body":"I'm a big fan of this thing, um, this moving object which was found, uh,"},{"startTime":367.506,"endTime":372.067,"body":"about 20 years ago in a suspicious orbit around the earth, the kind of orbit"},{"startTime":372.067,"endTime":376.628,"body":"that you'd expect, uh, surveillance craft sent by some distance civilization to keep an eye"},{"startTime":376.628,"endTime":380.885,"body":"on us and perhaps to find out whether we've grown up yet or not."},{"startTime":381.385,"endTime":385.641,"body":"Um, this thing which is in the catalog as J 0 0 2 E three"},{"startTime":385.641,"endTime":389.898,"body":"turns out to be the third stage, the upper stage of the Apollo 12 rocket"},{"startTime":389.898,"endTime":391.885,"body":"that took the astronauts to the moon."},{"startTime":392.345,"endTime":397.784,"body":"Uh, we'd lost track of it since the, uh, early seventies and had rediscovered it"},{"startTime":397.784,"endTime":400.685,"body":"and classified it as a potentially alien visitor."},{"startTime":401.225,"endTime":407.423,"body":"And so I do want to start by acknowledging that this habit of thinking about"},{"startTime":407.423,"endTime":412.795,"body":"intelligence in the cosmos is both common and I think actually quite productive."},{"startTime":412.815,"endTime":417.955,"body":"It makes sense when we find something new to question whether there's intelligence out there."},{"startTime":418.175,"endTime":423.133,"body":"But, and I don't wanna disappoint those of you who've queued for a a while,"},{"startTime":423.133,"endTime":428.091,"body":"uh, I am going to say that we have no definitive evidence that that shows"},{"startTime":428.091,"endTime":430.075,"body":"us that there's intelligence out there."},{"startTime":430.075,"endTime":431.155,"body":"We're still looking."},{"startTime":431.935,"endTime":436.646,"body":"And so what we're actually dealing with is an absence of signs of aliens in"},{"startTime":436.646,"endTime":437.275,"body":"the cosmos."},{"startTime":437.455,"endTime":438.635,"body":"And that's confusing."},{"startTime":439.415,"endTime":444.74,"body":"And it's become more confusing recently because we've got very good at finding homes for"},{"startTime":444.74,"endTime":446.515,"body":"aliens out amongst the stars."},{"startTime":446.615,"endTime":449.555,"body":"We now know that planets are common."},{"startTime":449.985,"endTime":455.506,"body":"They're so common that the discovery of new exoplanets planets around other stars is now"},{"startTime":455.506,"endTime":455.875,"body":"commonplace."},{"startTime":456.455,"endTime":459.595,"body":"So in the last week, we found four more."},{"startTime":460.095,"endTime":461.155,"body":"Uh, I can tell you about them."},{"startTime":461.155,"endTime":462.115,"body":"They've got great names."},{"startTime":462.625,"endTime":464.075,"body":"I'll deal with the second three first."},{"startTime":464.655,"endTime":469.852,"body":"Um, you'll all be familiar, I'm sure with KMT 2023 B BLG 0 4 1"},{"startTime":469.852,"endTime":475.049,"body":"16 lb, uh, which is a new Jupiter mass planet around, uh, a nearby star"},{"startTime":475.049,"endTime":476.435,"body":"in the Milky Way."},{"startTime":476.455,"endTime":479.315,"body":"And its, uh, other two companions found by the same survey."},{"startTime":479.855,"endTime":485.037,"body":"Uh, the first thing to say about this is that we better hope there aren't"},{"startTime":485.037,"endTime":489.875,"body":"aliens from KMT 2023 BLG 0 4 16 lb, um, who care about branding."},{"startTime":490.375,"endTime":492.275,"body":"Uh, it's a bit of a mouthful."},{"startTime":492.275,"endTime":496.755,"body":"And I imagine they call their planets something like Earth rather than this catalog number."},{"startTime":497.395,"endTime":501.028,"body":"Actually, it's a sign of how common discovering planets is that we now give them"},{"startTime":501.028,"endTime":501.755,"body":"just catalog numbers."},{"startTime":502.215,"endTime":506.808,"body":"Um, the one I was excited about this week was HIP 3 9 0 1"},{"startTime":506.808,"endTime":507.115,"body":"7."},{"startTime":507.735,"endTime":510.915,"body":"Um, and I'm excited about this one because we can actually see it."},{"startTime":511.455,"endTime":517.658,"body":"So these images at the bottom from a telescope in Hawaii, um, show, well, they"},{"startTime":517.658,"endTime":521.794,"body":"don't, they almost exactly don't show a nearby bright star."},{"startTime":521.825,"endTime":527.652,"body":"They're images with, uh, an instrument called a coronagraph, which hides the light from the"},{"startTime":527.652,"endTime":529.595,"body":"start, creates a fake eclipse."},{"startTime":530.015,"endTime":532.728,"body":"And so the little yellow blobs in the middle have been added back in to"},{"startTime":532.728,"endTime":533.995,"body":"show you where the star would be."},{"startTime":534.415,"endTime":538.638,"body":"Um, but what you can see next to them with the arrow pointing to it"},{"startTime":538.638,"endTime":539.765,"body":"is a large planet."},{"startTime":539.795,"endTime":541.965,"body":"It's about 20 times the mass of Jupiter."},{"startTime":541.965,"endTime":545.375,"body":"It's about as big as a planet can get before it starts to feel a"},{"startTime":545.375,"endTime":546.285,"body":"bit like a star."},{"startTime":547.025,"endTime":552.093,"body":"But we can actually see this thing, uh, against, uh, the glare of the planet"},{"startTime":552.093,"endTime":553.445,"body":"using these special instruments."},{"startTime":554.185,"endTime":560.466,"body":"And these are always special because I think there's something really exciting about seeing another"},{"startTime":560.466,"endTime":560.885,"body":"world."},{"startTime":561.385,"endTime":564.325,"body":"My favorite example, HR 8 7 9 9."},{"startTime":564.745,"endTime":569.628,"body":"Uh, this, these are images from, uh, a similar instrument this time on the European"},{"startTime":569.628,"endTime":570.605,"body":"very large telescope."},{"startTime":571.265,"endTime":574.845,"body":"Um, for those who don't know, astronomers are terrible at naming things."},{"startTime":574.865,"endTime":578.36,"body":"You sort of got that from the exoplanets, but the very large telescope does what"},{"startTime":578.36,"endTime":579.525,"body":"it says on the tin."},{"startTime":579.905,"endTime":584.15,"body":"Um, we're building the extremely large telescope, which we'll do it genuinely, which will do"},{"startTime":584.15,"endTime":585.565,"body":"a better job of this."},{"startTime":585.625,"endTime":590.989,"body":"We were unsuccessful in getting funding for a project called owl, which was the overwhelmingly"},{"startTime":590.989,"endTime":594.565,"body":"large telescope, but we're getting to extremely, and that's good."},{"startTime":594.565,"endTime":596.325,"body":"Anyway, this is from the very large telescope."},{"startTime":596.665,"endTime":599.485,"body":"And again, the light from the star has been removed."},{"startTime":600.465,"endTime":604.205,"body":"And what you can see here are four planets around this star."},{"startTime":604.345,"endTime":608.722,"body":"And what's nice about this is it's been studied for many years, so we can"},{"startTime":608.722,"endTime":610.765,"body":"animate and show you in real images."},{"startTime":610.875,"endTime":614.405,"body":"This isn't a computer simulation planets in orbit around a star."},{"startTime":614.985,"endTime":619.178,"body":"And what I like about this is that in almost every talk I've ever given"},{"startTime":619.178,"endTime":623.372,"body":"and every TV program I've worked on, and every time you've encountered astronomers talking about"},{"startTime":623.372,"endTime":627.566,"body":"the solar system, you've seen and computer generated animated version of this with planets whizzing"},{"startTime":627.566,"endTime":628.405,"body":"around a star."},{"startTime":628.705,"endTime":629.885,"body":"But this is real data."},{"startTime":630.785,"endTime":633.365,"body":"Um, and I think it's beautiful, exciting."},{"startTime":633.365,"endTime":634.845,"body":"Then the system's interesting."},{"startTime":635.235,"endTime":638.085,"body":"It's sort of like a blown up version of our solar system."},{"startTime":638.385,"endTime":642.814,"body":"So, um, there are four outer planets here, just like we have Jupiter, Saturn, neuros,"},{"startTime":642.814,"endTime":643.405,"body":"and Neptune."},{"startTime":643.705,"endTime":647.201,"body":"Um, these are all about two to three times the size, or at least the"},{"startTime":647.201,"endTime":649.765,"body":"mass of the ones that we have in our source system."},{"startTime":650.105,"endTime":652.685,"body":"And the orbits are about two to three times larger as well."},{"startTime":652.685,"endTime":658.226,"body":"So that outmost planet on the left, making its stately way around its star, um,"},{"startTime":658.226,"endTime":663.767,"body":"orbits in about 460 years for a complete orbit, uh, the innermost one whizzes round"},{"startTime":663.767,"endTime":665.245,"body":"in just 45 years."},{"startTime":665.905,"endTime":669.805,"body":"And so we can see some of these planets."},{"startTime":669.805,"endTime":670.805,"body":"We believe that they're real."},{"startTime":671.425,"endTime":673.965,"body":"Um, most of the time we can't do that."},{"startTime":674.625,"endTime":679.556,"body":"Not because the planet's a faint, but because the glare from the star is too"},{"startTime":679.556,"endTime":679.885,"body":"bright."},{"startTime":679.885,"endTime":684.129,"body":"It's like watching that Chinese lantern with its candle that I saw drift in front"},{"startTime":684.129,"endTime":687.525,"body":"of a stadium floodlight and be able to pick out the candle."},{"startTime":687.675,"endTime":688.925,"body":"It's just too difficult."},{"startTime":689.305,"endTime":694.365,"body":"And so what we have to do is use indirect methods of detecting planets."},{"startTime":694.945,"endTime":700.032,"body":"And unlike so much of modern astronomy and so much of the astronomy that I"},{"startTime":700.032,"endTime":703.085,"body":"love, this is about making simple measurements really precisely."},{"startTime":703.665,"endTime":706.325,"body":"And so I can show you an example using our own star."},{"startTime":706.785,"endTime":711.895,"body":"Um, twice a century last time in 2012, uh, next time about a hundred years,"},{"startTime":711.895,"endTime":716.325,"body":"hence, um, Venus passes in front of the sun as seen from Earth."},{"startTime":716.795,"endTime":719.605,"body":"This is a video of the last such event seen from Oxford."},{"startTime":719.945,"endTime":722.765,"body":"Uh, there's Venus transiting across the face of the sun."},{"startTime":723.225,"endTime":725.725,"body":"Um, these transits used to be really useful."},{"startTime":725.725,"endTime":728.765,"body":"People used them to scope out the size of the solar system."},{"startTime":728.765,"endTime":734.019,"body":"And in the 18th and 19th centuries expeditions were organized to go and observe these"},{"startTime":734.019,"endTime":739.273,"body":"cooks voyage to, to what turned out to be Australia, um, was organized to see"},{"startTime":739.273,"endTime":741.725,"body":"such a transit of Venus from Tahiti."},{"startTime":741.895,"endTime":745.685,"body":"These days they're, they're curiosities, but we can do a simple experiment."},{"startTime":745.685,"endTime":749.036,"body":"So on the right is sort of the, if you've got the nice video on"},{"startTime":749.036,"endTime":752.165,"body":"the left, on the right, we've got the lamb physicists' view of the event."},{"startTime":752.315,"endTime":756.786,"body":"This is, uh, the result of holding a light meter out in the parks in"},{"startTime":756.786,"endTime":757.085,"body":"Oxford."},{"startTime":757.265,"endTime":759.605,"body":"And what you can see, a love astronomy."},{"startTime":759.605,"endTime":760.525,"body":"It's such a simple thing."},{"startTime":760.525,"endTime":764.445,"body":"When Venus is in front of the sun, the sun appears slightly dimmer."},{"startTime":764.945,"endTime":768.592,"body":"If you block a lot, if you block part of a light source out, it"},{"startTime":768.592,"endTime":769.565,"body":"gets slightly dimmer, right?"},{"startTime":769.565,"endTime":770.605,"body":"It's not rocket science."},{"startTime":771.105,"endTime":774.685,"body":"Um, and it's not by much, it's by less than a 10th of 1%."},{"startTime":775.565,"endTime":777.125,"body":"'cause Venus doesn't block much of the sun."},{"startTime":777.585,"endTime":781.524,"body":"But if we were in such a position as to observe such a transit, such"},{"startTime":781.524,"endTime":785.463,"body":"a dip every time Venus got in front of the sun, then you'd be able"},{"startTime":785.463,"endTime":787.565,"body":"to deduce that there was a planet there."},{"startTime":787.975,"endTime":791.33,"body":"You'd be able to work out the size of the planet from how quickly the"},{"startTime":791.33,"endTime":794.686,"body":"dip happens, and you'd be able to work out the orbital period, how long it"},{"startTime":794.686,"endTime":795.805,"body":"takes Venus to go round."},{"startTime":796.105,"endTime":797.245,"body":"Of course, you'd have to be lucky."},{"startTime":797.305,"endTime":801.867,"body":"You have to be exactly in line with the orbit of Venus so that you"},{"startTime":801.867,"endTime":804.605,"body":"get this every time twice every century or so."},{"startTime":804.605,"endTime":808.685,"body":"Doesn't really cut it, but we do get lucky occasionally."},{"startTime":808.685,"endTime":812.923,"body":"There is, for example, a nearby star called T Garden Star, which is about 12"},{"startTime":812.923,"endTime":817.161,"body":"light years away, and it has at least two planets which happen to orbit in"},{"startTime":817.161,"endTime":821.399,"body":"a plane such that they go in front of the star as we are looking"},{"startTime":821.399,"endTime":821.965,"body":"at it."},{"startTime":822.145,"endTime":826.91,"body":"What's fun about T Garden Star, and here's a visualization of it, is that from"},{"startTime":826.91,"endTime":830.405,"body":"their planets, they see us going in front of the sun."},{"startTime":831.105,"endTime":834.788,"body":"So if they're using the same technology that we are using, there are aliens on,"},{"startTime":834.788,"endTime":835.525,"body":"on this star."},{"startTime":835.795,"endTime":838.885,"body":"They will have found our solar system by now."},{"startTime":838.885,"endTime":843.599,"body":"And so if I had to bet on where the nearest aliens who know about"},{"startTime":843.599,"endTime":845.485,"body":"us are, it's tea garden star."},{"startTime":846.585,"endTime":849.573,"body":"Now, what's nice about this transit method, there are lots of other ways of finding"},{"startTime":849.573,"endTime":851.565,"body":"planets too that I'm not gonna go into this evening."},{"startTime":851.565,"endTime":855.431,"body":"But what's nice about this transit method is that you can look at lots of"},{"startTime":855.431,"endTime":856.205,"body":"stars at once."},{"startTime":857.265,"endTime":859.965,"body":"And if you do that, you just have to wait and be lucky and hope"},{"startTime":859.965,"endTime":861.045,"body":"that some of them will blink."},{"startTime":861.265,"endTime":863.965,"body":"So we've had dedicated space missions that have done this."},{"startTime":864.025,"endTime":869.457,"body":"The most famous of them was a NASA satellite called Keppler that stared at one"},{"startTime":869.457,"endTime":874.165,"body":"patch of sky, just in the constellation of nus just above the horizon."},{"startTime":874.265,"endTime":878.938,"body":"If we went outside at the end of this lecture, looked at one patch of"},{"startTime":878.938,"endTime":883.611,"body":"sky for three years, monitoring the brightness of a couple of hundred thousand stars with"},{"startTime":883.611,"endTime":888.285,"body":"a precision that's enough to detect a tiny planet going in front of the star."},{"startTime":888.945,"endTime":893.888,"body":"And because of the results from Kepper and others, what we found is a remarkable"},{"startTime":893.888,"endTime":896.525,"body":"diversity of worlds out in the Milky Way."},{"startTime":896.985,"endTime":899.365,"body":"So one way of thinking about this is to make a a graph."},{"startTime":899.825,"endTime":904.445,"body":"Um, each.here is a Kepler planet, um, or one found by another means."},{"startTime":904.745,"endTime":908.382,"body":"Um, on the Y axis, you've got the size of the higher up you are,"},{"startTime":908.382,"endTime":910.565,"body":"the more the larger or more massive you are."},{"startTime":910.565,"endTime":913.931,"body":"Jupiter's at the top, Neptune's in the middle, earth's at the bottom, and then there's"},{"startTime":913.931,"endTime":914.605,"body":"the orbital period."},{"startTime":914.705,"endTime":918.845,"body":"So planets over here are whizzing around their star in just a matter of days."},{"startTime":919.435,"endTime":921.245,"body":"Further out, they're going more slowly."},{"startTime":921.305,"endTime":925.067,"body":"And of course, you could work out where the earth was on this diagram, it"},{"startTime":925.067,"endTime":927.325,"body":"would be about 365 days and one earth mass."},{"startTime":927.345,"endTime":928.925,"body":"So we're down here in the bottom right."},{"startTime":929.905,"endTime":933.525,"body":"But what's clear from this diagram already is that we have all sorts of planets."},{"startTime":933.525,"endTime":935.085,"body":"We have things that we didn't expect."},{"startTime":935.145,"endTime":937.965,"body":"We have, for example, in the top left hot Jupiter."},{"startTime":938.415,"endTime":940.005,"body":"These are great, they're easy to find."},{"startTime":940.025,"endTime":944.429,"body":"It turns out these are as big as Jupiter, but they all bit, they're star"},{"startTime":944.429,"endTime":946.485,"body":"in just a few days or weeks."},{"startTime":947.265,"endTime":949.165,"body":"We don't have such a thing in our solar system."},{"startTime":949.165,"endTime":952.365,"body":"The planets that cluster close to the sun are small, rocky things."},{"startTime":952.615,"endTime":956.428,"body":"There are solar systems out there where there's a hot Jupiter or a Saturn, uh,"},{"startTime":956.428,"endTime":957.445,"body":"whizzing around the star."},{"startTime":957.505,"endTime":958.725,"body":"We didn't expect that."},{"startTime":959.145,"endTime":965.125,"body":"In the bottom left, there's uh, an exotic set of worlds called the Lava Worlds."},{"startTime":966.015,"endTime":971.97,"body":"These are rocky planets who are so close to their suns that their surface must"},{"startTime":971.97,"endTime":972.765,"body":"be molten."},{"startTime":972.765,"endTime":974.885,"body":"They're at temperatures of maybe a thousand degrees."},{"startTime":975.705,"endTime":976.925,"body":"We didn't expect these either."},{"startTime":976.985,"endTime":977.605,"body":"How did they form?"},{"startTime":977.665,"endTime":978.445,"body":"How did they get there?"},{"startTime":978.465,"endTime":979.005,"body":"Are they stable?"},{"startTime":979.005,"endTime":980.485,"body":"Will they keep existing?"},{"startTime":980.485,"endTime":983.725,"body":"We don't know the answers to any of those questions at the minute."},{"startTime":983.765,"endTime":987.894,"body":"I was just talking to somebody this afternoon who's doing laboratory experiments where they're heating"},{"startTime":987.894,"endTime":992.023,"body":"up rock and trying to observe it to try and work out what these things"},{"startTime":992.023,"endTime":993.125,"body":"are are made of."},{"startTime":993.825,"endTime":997.165,"body":"In between, we found plenty of earth size planets, rocky planets."},{"startTime":997.385,"endTime":998.445,"body":"We found some Neptunes."},{"startTime":998.445,"endTime":1004.005,"body":"And actually the most common type of planet lies in between those two categories."},{"startTime":1004.035,"endTime":1007.005,"body":"It's a type that we don't have in our solar system."},{"startTime":1007.355,"endTime":1011.805,"body":"It's either a super earth or a puny Neptune, whichever you like."},{"startTime":1011.885,"endTime":1015.358,"body":"I guess Super earth is the better branding, uh, but two to three times the"},{"startTime":1015.358,"endTime":1016.285,"body":"size of the earth."},{"startTime":1016.825,"endTime":1020.605,"body":"Um, and possibly, but most likely gaius."},{"startTime":1020.625,"endTime":1023.205,"body":"But we don't have anything like that in our solar system."},{"startTime":1023.865,"endTime":1025.885,"body":"So we found this variety of worlds."},{"startTime":1027.105,"endTime":1031.095,"body":"But particularly if I show you not this schematic diagram, I'm gonna plot the, the"},{"startTime":1031.095,"endTime":1035.086,"body":"real data, same axes, but this is all the planets that we found as of,"},{"startTime":1035.086,"endTime":1035.885,"body":"uh, last week."},{"startTime":1036.385,"endTime":1037.964,"body":"So there are four missing."},{"startTime":1038.165,"endTime":1039.365,"body":"I didn't add them in, sorry."},{"startTime":1039.743,"endTime":1041.723,"body":"Um, we'll do that for you at home."},{"startTime":1042.185,"endTime":1045.569,"body":"Um, but you can go to the, actually if you go to NASA's exoplanet archive"},{"startTime":1045.569,"endTime":1048.953,"body":"that every week they tell you what we've discovered and they'll give you updated versions"},{"startTime":1048.953,"endTime":1049.405,"body":"of this."},{"startTime":1049.425,"endTime":1052.085,"body":"So you can just keep updating this talk week after week."},{"startTime":1052.425,"endTime":1058.104,"body":"But what won't change, at least in the near future, is that there's this bottom"},{"startTime":1058.104,"endTime":1060.755,"body":"right of this diagram that isn't populated."},{"startTime":1060.935,"endTime":1062.835,"body":"All the plants we found are up in the top left."},{"startTime":1062.835,"endTime":1067.085,"body":"They're either very close to their stars or they're very massive."},{"startTime":1069.105,"endTime":1074.165,"body":"And that's shouldn't be too surprising because those are the easy ones to find."},{"startTime":1074.945,"endTime":1078.911,"body":"If you are a massive planet and you get in front of your star, then"},{"startTime":1078.911,"endTime":1082.085,"body":"you create a big dip, it's easy to see that that's happening."},{"startTime":1082.195,"endTime":1086.245,"body":"Smaller planets, it's harder to see if you whiz around the planet."},{"startTime":1086.305,"endTime":1090.222,"body":"If you whiz around your star every few days, then I don't need to look"},{"startTime":1090.222,"endTime":1094.139,"body":"at that star for very long to see many dips to get good evidence that"},{"startTime":1094.139,"endTime":1095.445,"body":"there's really a planet there."},{"startTime":1095.745,"endTime":1099.448,"body":"But if I want a planet in an earth-like orbit, then I have to wait"},{"startTime":1099.448,"endTime":1102.165,"body":"year after year after year to get even a single dip."},{"startTime":1102.625,"endTime":1107.95,"body":"And so Kepler, for example, which stared at that patch of sky for three years,"},{"startTime":1107.95,"endTime":1112.565,"body":"if it was very lucky looking at Earth, would've only had three dips."},{"startTime":1112.565,"endTime":1116.84,"body":"And it's very hard to pick out the signal from a small planet in that"},{"startTime":1116.84,"endTime":1117.125,"body":"region."},{"startTime":1117.265,"endTime":1121.085,"body":"So we are not yet at the point where we're finding planets like our own."},{"startTime":1122.545,"endTime":1126.261,"body":"We believe that they're there, but we haven't yet managed to find lots of them"},{"startTime":1126.261,"endTime":1127.005,"body":"via these methods."},{"startTime":1127.505,"endTime":1131.265,"body":"Now we do have some tools in our armory to try and, and fix this"},{"startTime":1131.265,"endTime":1134.525,"body":"one, which is quite surprising is that we can ask for your help."},{"startTime":1135.425,"endTime":1139.556,"body":"So, uh, my team and a project called Zooniverse that I I ran into very"},{"startTime":1139.556,"endTime":1141.485,"body":"recently built a project called Planet Hunters."},{"startTime":1141.635,"endTime":1143.245,"body":"This is led by Nora Eisner."},{"startTime":1143.245,"endTime":1148.399,"body":"He's currently at the Flatiron Institute in New York, um, where we take data not"},{"startTime":1148.399,"endTime":1153.554,"body":"from Keppler these days, but from NASA's latest planet Hunter Tess, which looks at bright"},{"startTime":1153.554,"endTime":1158.365,"body":"stars and puts it online and invites you to look at graphs for fun."},{"startTime":1159.185,"endTime":1162.751,"body":"But if you're willing to do that and you are one of the people who"},{"startTime":1162.751,"endTime":1165.605,"body":"spots a dip, you could be the discoverer of a new planet."},{"startTime":1166.065,"endTime":1169.33,"body":"And about once a month we get to send an email out to people that"},{"startTime":1169.33,"endTime":1171.725,"body":"says, we think you found a planet, which is really exciting."},{"startTime":1172.105,"endTime":1176.669,"body":"And planet hunters is good at finding our volunteers are good at finding longer period"},{"startTime":1176.669,"endTime":1181.233,"body":"of planets, planets that take longer to go around their their star because they're the"},{"startTime":1181.233,"endTime":1184.885,"body":"kind of planet that you see when you inspect the data visually."},{"startTime":1184.885,"endTime":1187.885,"body":"When you look at the graph, you see that dip and you're able to pick"},{"startTime":1187.885,"endTime":1188.285,"body":"it out."},{"startTime":1188.285,"endTime":1192.205,"body":"Whereas our automated algorithms rely on repeated transits."},{"startTime":1192.285,"endTime":1194.325,"body":"I can say more about that in the questions if you like."},{"startTime":1195.065,"endTime":1198.165,"body":"Planet hunters have found some unexpected things as well."},{"startTime":1198.305,"endTime":1203.69,"body":"My favorite system is the K 2 1 3 8 system, which was found by"},{"startTime":1203.69,"endTime":1205.485,"body":"volunteers on the zoo universe."},{"startTime":1205.975,"endTime":1210.135,"body":"There are five planets in the system, B, C, D, E, and F and luckily"},{"startTime":1210.135,"endTime":1211.245,"body":"they're in that order."},{"startTime":1211.425,"endTime":1212.445,"body":"So that makes things nice."},{"startTime":1213.095,"endTime":1214.045,"body":"Thank you for laughing."},{"startTime":1214.465,"endTime":1218.32,"body":"Um, but what's really exciting about this, well, the first thing to say about the"},{"startTime":1218.32,"endTime":1219.605,"body":"system is that it's crammed."},{"startTime":1219.605,"endTime":1222.005,"body":"So mercury on this diagram would be out here."},{"startTime":1222.585,"endTime":1226.005,"body":"So these are five planets that are very close to their parents' star."},{"startTime":1226.585,"endTime":1231.15,"body":"Um, the best analogy in our solar system is something like the moons of Jupiter,"},{"startTime":1231.15,"endTime":1235.716,"body":"which are crammed close to Jupiter rather than a solar system that we're used to"},{"startTime":1235.716,"endTime":1236.325,"body":"thinking of."},{"startTime":1236.705,"endTime":1240.685,"body":"But the other thing is that there's a relationship between the orbits of these planets."},{"startTime":1240.785,"endTime":1243.685,"body":"So for every three times, B goes round."},{"startTime":1244.765,"endTime":1247.085,"body":"C completes two orbits for every three orbits."},{"startTime":1247.205,"endTime":1250.245,"body":"C completes D completes two orbits for every three orbits."},{"startTime":1250.285,"endTime":1253.885,"body":"D completes E goes round twi twice for every three times E goes round."},{"startTime":1253.885,"endTime":1255.725,"body":"The star F goes round twice."},{"startTime":1255.725,"endTime":1259.525,"body":"There's a three to two, three to two, three to two, three to two relationship."},{"startTime":1260.315,"endTime":1261.245,"body":"This has consequences."},{"startTime":1261.545,"endTime":1264.925,"body":"One is that we can have some fun making music with this."},{"startTime":1264.985,"endTime":1270.645,"body":"So my friend Matt Russo in Toronto, uh, likes to turn planetary systems into music."},{"startTime":1270.745,"endTime":1275.221,"body":"And so every time a planet completes an orbit, it chimes and the pitch of"},{"startTime":1275.221,"endTime":1278.205,"body":"the chime is related to the size of the orbit."},{"startTime":1281.025,"endTime":1283.005,"body":"And all I want you to hear is that that's musical."},{"startTime":1283.305,"endTime":1284.645,"body":"It sounds nice to us."},{"startTime":1284.755,"endTime":1286.845,"body":"I'll defer to Milt for reasons why."},{"startTime":1287.505,"endTime":1291.793,"body":"Um, but it's musical because of this three to two, three to two, three to"},{"startTime":1291.793,"endTime":1292.365,"body":"two ratio."},{"startTime":1294.555,"endTime":1298.725,"body":"That ratio also tells us that these planets have formed and migrated together."},{"startTime":1298.835,"endTime":1300.885,"body":"They, we don't think they formed this close to the star."},{"startTime":1300.885,"endTime":1303.685,"body":"They must have formed further out and moved inwards."},{"startTime":1304.385,"endTime":1308.12,"body":"And we think that they must have done so together otherwise why have they ended"},{"startTime":1308.12,"endTime":1309.365,"body":"up in, in this ratio?"},{"startTime":1309.425,"endTime":1311.245,"body":"So people are still studying the system."},{"startTime":1311.345,"endTime":1312.285,"body":"It was unexpected."},{"startTime":1312.665,"endTime":1317.81,"body":"And the complex pattern of dips that resulted were identified by the planet hunters volunteers,"},{"startTime":1317.81,"endTime":1319.525,"body":"sorry, by the zuniverse volunteers."},{"startTime":1320.865,"endTime":1325.755,"body":"But really the, the system I want to talk about tonight is very different."},{"startTime":1325.855,"endTime":1327.915,"body":"It was also found by planet hunters."},{"startTime":1328.025,"endTime":1332.635,"body":"It's um, a star called KIC 8 4 6 2 8 5 2."},{"startTime":1333.085,"endTime":1334.435,"body":"Those as you'll hear in a second."},{"startTime":1334.555,"endTime":1337.892,"body":"I know you know it, uh, uh, you'll hear in a second game, some other"},{"startTime":1337.892,"endTime":1338.115,"body":"names."},{"startTime":1338.695,"endTime":1342.795,"body":"Um, and it was observed for the whole three years of the Kepler mission."},{"startTime":1343.335,"endTime":1346.515,"body":"So this is, this is the most exciting graph of the night."},{"startTime":1346.535,"endTime":1349.816,"body":"By the way, this is on one of those astronomy lectures where you get beautiful"},{"startTime":1349.816,"endTime":1350.035,"body":"pictures."},{"startTime":1350.385,"endTime":1352.755,"body":"It's mostly graphs this evening, but that's okay."},{"startTime":1353.095,"endTime":1357.242,"body":"Um, this is the brightness of that star over time and look at the whole"},{"startTime":1357.242,"endTime":1357.795,"body":"three years."},{"startTime":1358.295,"endTime":1362.972,"body":"And you can see that just after Kepler started observing KIC 8 4 6 2,"},{"startTime":1362.972,"endTime":1365.155,"body":"8 5 2, there was a dip."},{"startTime":1366.275,"endTime":1367.345,"body":"Quite a big one actually."},{"startTime":1367.725,"endTime":1369.305,"body":"So maybe that's a large planet."},{"startTime":1370.695,"endTime":1372.745,"body":"It's particularly exciting that the dip reappears."},{"startTime":1374.405,"endTime":1378.105,"body":"But then there's no third dip, not the same depth anyway."},{"startTime":1378.725,"endTime":1381.865,"body":"And so whatever's causing those dips, it's not a planet."},{"startTime":1382.175,"endTime":1386.489,"body":"Planets don't go round once and then twice and then take a break or go"},{"startTime":1386.489,"endTime":1387.065,"body":"on holiday."},{"startTime":1387.245,"endTime":1388.425,"body":"That's not how this works."},{"startTime":1388.885,"endTime":1391.025,"body":"And so maybe this is some behavior of the star."},{"startTime":1391.025,"endTime":1394.025,"body":"Maybe these are big star spots, just like the sun has sun spots."},{"startTime":1394.045,"endTime":1394.465,"body":"Who knows?"},{"startTime":1394.715,"endTime":1395.265,"body":"We're not sure."},{"startTime":1395.365,"endTime":1401.335,"body":"No one was paying a huge amount of attention until about a year later the"},{"startTime":1401.335,"endTime":1403.325,"body":"start of this it dimed."},{"startTime":1403.345,"endTime":1404.445,"body":"See it is a good graph."},{"startTime":1405.265,"endTime":1409.682,"body":"It dim by about 20% for about five days and then came all the way"},{"startTime":1409.682,"endTime":1413.805,"body":"back up to full brightness and then it carried on like nothing had happened."},{"startTime":1414.545,"endTime":1416.165,"body":"And stars don't do this."},{"startTime":1417.065,"endTime":1421.681,"body":"No other star in the 200,000 that were in the main Kepler catalog ever did"},{"startTime":1421.681,"endTime":1422.605,"body":"anything like this."},{"startTime":1422.625,"endTime":1427.525,"body":"In the three years that we studied it, the volunteers on planet hunters found this."},{"startTime":1427.715,"endTime":1431.133,"body":"They kept an eye on it and they were the first to notice when about"},{"startTime":1431.133,"endTime":1434.325,"body":"a year and a half later, the star did this, which makes no sense."},{"startTime":1434.325,"endTime":1438.205,"body":"Like somebody's got hold of a dimmer switch and has started fiddling with this thing."},{"startTime":1438.665,"endTime":1443.933,"body":"Um, this earned the star, the nickname, the WTF star \u003claugh\u003e, which I think makes"},{"startTime":1443.933,"endTime":1444.285,"body":"sense."},{"startTime":1444.785,"endTime":1449.653,"body":"Um, but the volunteers, particularly Darryl lacoe, who led a lot of this work, started"},{"startTime":1449.653,"endTime":1451.925,"body":"thinking about what might be causing this."},{"startTime":1451.925,"endTime":1454.885,"body":"It's clearly not an ordinary planet getting in front of the star."},{"startTime":1455.025,"endTime":1459.666,"body":"The theory that Darryl came up with was presented here on a post on, on"},{"startTime":1459.666,"endTime":1464.308,"body":"the forums in, uh, the Planet Hunter's website was that maybe there's a planet with"},{"startTime":1464.308,"endTime":1466.165,"body":"a disc of material around it."},{"startTime":1466.215,"endTime":1472.333,"body":"Maybe think Saturn's rings, but larger may be made out of dust grains, astronomical dust"},{"startTime":1472.333,"endTime":1476.005,"body":"being carbon and silicon grains, uh, around the planet."},{"startTime":1476.005,"endTime":1479.705,"body":"Then when that moves over the star, uh, it would create these complex dips at"},{"startTime":1479.705,"endTime":1481.925,"body":"the kind that we're seeing is a good idea."},{"startTime":1482.465,"endTime":1487.762,"body":"Um, I love, my favorite thing about this though is not that the theory's good,"},{"startTime":1487.762,"endTime":1493.06,"body":"it was, but I love Darryl's last sentence, which is the true situation is probably"},{"startTime":1493.06,"endTime":1498.005,"body":"nothing like this, but it seemed a good opportunity to rampantly speculate in paint."},{"startTime":1498.585,"endTime":1502.005,"body":"And there's a man who's understood what doing science is really about."},{"startTime":1502.645,"endTime":1503.805,"body":"I think that's really exciting."},{"startTime":1504.025,"endTime":1506.125,"body":"So we have a mystery."},{"startTime":1506.145,"endTime":1510.495,"body":"We have this bizarre behavior and we have a theory from Darrell that maybe this"},{"startTime":1510.495,"endTime":1513.685,"body":"star is, um, orbited by a planet with a dust disc."},{"startTime":1514.275,"endTime":1521.559,"body":"Dust, sand, grains, carbon silicon grains should go, they should get warm in the stars"},{"startTime":1521.559,"endTime":1522.045,"body":"light."},{"startTime":1522.235,"endTime":1524.765,"body":"They should glow in infrared light."},{"startTime":1525.105,"endTime":1529.797,"body":"So if this theory is right, there's enough dust to block 20% of the stars"},{"startTime":1529.797,"endTime":1532.925,"body":"light, we should see it shine brightly in the infrared."},{"startTime":1533.225,"endTime":1537.518,"body":"So we looked and the stars perfectly normal in the infrared, there's no excess at"},{"startTime":1537.518,"endTime":1537.805,"body":"all."},{"startTime":1538.345,"endTime":1540.845,"body":"So there's no large dust disc."},{"startTime":1541.705,"endTime":1545.365,"body":"We started to rack our brains to work out what else could be going on."},{"startTime":1545.905,"endTime":1547.845,"body":"We got a bit desperate, if I'm honest."},{"startTime":1548.465,"endTime":1554.015,"body":"Um, this is all work led by, uh, my colleague Tabby Boin, who's now at"},{"startTime":1554.015,"endTime":1555.125,"body":"LSU Louisiana State."},{"startTime":1555.545,"endTime":1559.165,"body":"But we were trying everything we thought for a long while."},{"startTime":1559.165,"endTime":1562.39,"body":"This must be something that's gone wrong with the camera or the data or the"},{"startTime":1562.39,"endTime":1562.605,"body":"software."},{"startTime":1562.945,"endTime":1564.525,"body":"We looked at neighboring stars."},{"startTime":1565.875,"endTime":1569.405,"body":"None of them showed anything like this behavior we got as far."},{"startTime":1569.405,"endTime":1573.46,"body":"There was an awful week where we tried to work out which pixel of the"},{"startTime":1573.46,"endTime":1577.245,"body":"camera the Starlight had been falling on every time it, this observation was made."},{"startTime":1577.405,"endTime":1580.965,"body":"'cause we thought maybe there was a dead pixel somewhere that was causing this problem."},{"startTime":1581.025,"endTime":1585.322,"body":"It wasn't that we eventually gave up and we sent a paper to the journal"},{"startTime":1585.322,"endTime":1589.619,"body":"describing the WTF star and saying that we thought it was interesting, but we didn't"},{"startTime":1589.619,"endTime":1590.765,"body":"know what it was."},{"startTime":1592.585,"endTime":1596.599,"body":"We got a response from the journal with a positive report saying that they would"},{"startTime":1596.599,"endTime":1598.205,"body":"publish it, but with two comments."},{"startTime":1599.505,"endTime":1604.947,"body":"The first one was that the editor politely pointed out that all acronyms have to"},{"startTime":1604.947,"endTime":1607.125,"body":"be spelt out in full \u003claugh\u003e."},{"startTime":1608.905,"endTime":1611.805,"body":"So WTF stands for Where's the Flux \u003claugh\u003e."},{"startTime":1612.145,"endTime":1615.731,"body":"Um, and I should point out lots of these people are citizen scientists and volunteers"},{"startTime":1615.731,"endTime":1617.645,"body":"who, who led a lot of this work."},{"startTime":1617.825,"endTime":1618.565,"body":"So we solved that one."},{"startTime":1618.565,"endTime":1622.788,"body":"But the second problem was bigger, which was that the editor said that we couldn't"},{"startTime":1622.788,"endTime":1625.885,"body":"publish a paper that just said we'd found a weird star."},{"startTime":1627.105,"endTime":1628.445,"body":"We needed an explanation."},{"startTime":1629.585,"endTime":1633.149,"body":"So we tried to make one up and we eventually came up with the idea"},{"startTime":1633.149,"endTime":1635.525,"body":"that we were gonna blame the whole thing on comets."},{"startTime":1636.345,"endTime":1637.605,"body":"Now comets are well understood."},{"startTime":1637.605,"endTime":1641.685,"body":"These are icy bodies that go on elliptical orbits in our solar system."},{"startTime":1641.685,"endTime":1643.525,"body":"Presumably other solar systems have them as well."},{"startTime":1643.525,"endTime":1648.925,"body":"In fact, we have actually seen some exo comets since and comets misbehaved."},{"startTime":1648.925,"endTime":1654.209,"body":"There's a famous example, uh, of what's called Bala's Comet, which was very famous in"},{"startTime":1654.209,"endTime":1658.085,"body":"the 19th century because it's orbit crossed that of the earth."},{"startTime":1658.785,"endTime":1662.561,"body":"And there was a panic in the early 19th century, mostly led by articles in"},{"startTime":1662.561,"endTime":1666.337,"body":"the New York Times for some reason that when the earth passed through the comets"},{"startTime":1666.337,"endTime":1670.113,"body":"orbit, there would be a miasma on Earth and we'd all get sick from Comet"},{"startTime":1670.113,"endTime":1670.365,"body":"gas."},{"startTime":1670.835,"endTime":1671.645,"body":"This doesn't happen."},{"startTime":1671.895,"endTime":1675.285,"body":"We're safe from comets, but bah itself suffered."},{"startTime":1675.755,"endTime":1680.729,"body":"This is a drawing of it made in its 1846 apparition when it appeared in"},{"startTime":1680.729,"endTime":1684.045,"body":"the inner solar system and then split into two pieces."},{"startTime":1684.535,"endTime":1688.245,"body":"These are icy bodies that get heated up every time they come near the sun."},{"startTime":1688.385,"endTime":1694.645,"body":"So they eventually disintegrate biela after 1846, didn't reappear when it was next expected."},{"startTime":1694.745,"endTime":1699.687,"body":"We got instead a meteor shower of bits of comet burning up in the atmosphere"},{"startTime":1699.687,"endTime":1701.005,"body":"so comets can disintegrate."},{"startTime":1701.585,"endTime":1705.947,"body":"So we thought, okay, so what's happened around the WTF star, also known as Bogen"},{"startTime":1705.947,"endTime":1710.31,"body":"Star by this point, said, okay, there's a comet and the comet has split up"},{"startTime":1710.31,"endTime":1711.765,"body":"into lots of little bits."},{"startTime":1712.065,"endTime":1715.925,"body":"Here's an unconvincing press release image to convince you that this is plausible."},{"startTime":1716.305,"endTime":1720.223,"body":"Um, and then what happens is you can arrange these comet bits to cause these"},{"startTime":1720.223,"endTime":1720.485,"body":"dips."},{"startTime":1720.905,"endTime":1723.43,"body":"So we have a medium sized bit and then a medium sized bit, then a"},{"startTime":1723.43,"endTime":1725.956,"body":"gap, then a big bit, and then there's a whole host of them at the"},{"startTime":1725.956,"endTime":1726.125,"body":"end."},{"startTime":1726.745,"endTime":1728.725,"body":"And we can explain our observations."},{"startTime":1730.685,"endTime":1732.005,"body":"I dunno, does that sound convincing?"},{"startTime":1733.305,"endTime":1734.645,"body":"So somebody said yes."},{"startTime":1734.705,"endTime":1735.365,"body":"So that's good."},{"startTime":1735.765,"endTime":1736.845,"body":"I shall stop the talk here."},{"startTime":1737.185,"endTime":1742.175,"body":"Um, what's nice about this idea, I one feature of this theory of course, is"},{"startTime":1742.175,"endTime":1747.165,"body":"that I can explain any pattern at all just by rearranging my bits of comet."},{"startTime":1747.785,"endTime":1752.025,"body":"But at least it's the next expression when comets don't glow blind because they're icy,"},{"startTime":1752.025,"endTime":1754.005,"body":"they don't glow brightly in the infrared."},{"startTime":1754.005,"endTime":1758.538,"body":"So we can get away with adding comets to the system without violating what we"},{"startTime":1758.538,"endTime":1759.445,"body":"knew from observations."},{"startTime":1760.145,"endTime":1764.61,"body":"So we published this paper, we said it's probably comets and roughly every astronomer in"},{"startTime":1764.61,"endTime":1769.076,"body":"the world who works on comets wrote to us, uh, pointed out that we do"},{"startTime":1769.076,"endTime":1770.565,"body":"actually know something about comets."},{"startTime":1770.565,"endTime":1772.325,"body":"We have in fact landed on a comet."},{"startTime":1772.385,"endTime":1777.091,"body":"Here's the filet probe from the European Space Agency, which bounced along the surface of"},{"startTime":1777.091,"endTime":1781.485,"body":"Comet Cher Madoff Geka as part of the Rosetta mission a few years ago."},{"startTime":1781.945,"endTime":1783.925,"body":"Um, Phil a didn't come to a good end."},{"startTime":1783.945,"endTime":1786.005,"body":"It sort of ended up on its side as you can see."},{"startTime":1786.025,"endTime":1789.645,"body":"But the orbiter, the Rosetta Orbiter told us a lot about the nucleus."},{"startTime":1790.025,"endTime":1794.702,"body":"Uh, and one of the things we found out was that chair Garmen, a fairly"},{"startTime":1794.702,"endTime":1796.885,"body":"typical comment is about four kilometers across."},{"startTime":1796.885,"endTime":1799.765,"body":"Here's a graphic of it, menacing London for scale."},{"startTime":1800.345,"endTime":1803.365,"body":"Um, not a real photo I should say."},{"startTime":1803.745,"endTime":1806.405,"body":"Um, but comets are a few kilometers across."},{"startTime":1806.945,"endTime":1809.325,"body":"To block out 20% of the stars light."},{"startTime":1809.585,"endTime":1814.527,"body":"One piece of our putative comet would have to be 10,000 times larger than the"},{"startTime":1814.527,"endTime":1815.845,"body":"largest comet ever seen."},{"startTime":1816.825,"endTime":1820.485,"body":"Ice also breaks up when you expose it to heat."},{"startTime":1820.505,"endTime":1826.205,"body":"So we needed the largest comet ever suspected to have just broken up just before"},{"startTime":1826.205,"endTime":1829.245,"body":"we started looking at it with a spacecraft."},{"startTime":1829.825,"endTime":1835.278,"body":"And because only one in 200,000 stars showed this behavior, this needed to be a"},{"startTime":1835.278,"endTime":1840.005,"body":"rare event that we just happened to capture, it sounded really, um, implausible."},{"startTime":1840.425,"endTime":1844.445,"body":"And we were never hugely committed to our comment theory anyway, he says now."},{"startTime":1844.825,"endTime":1848.393,"body":"Um, and so what happened was other people started putting forward their own ideas about"},{"startTime":1848.393,"endTime":1851.725,"body":"what this star was up to and the paper that got the most attention."},{"startTime":1851.945,"endTime":1856.525,"body":"And I wouldn't normally in a lecture show a paper title and abstract."},{"startTime":1856.525,"endTime":1860.365,"body":"It's a bit lazy as a speaker, but to show you, it's a real paper"},{"startTime":1860.365,"endTime":1861.645,"body":"published in the Astrophysical Journal."},{"startTime":1861.995,"endTime":1867.308,"body":"This is a paper from Jason Wright at Penn State and friends, and the title"},{"startTime":1867.308,"endTime":1871.205,"body":"is The Ghat Search for Extraterrestrial Civilizations With Large Energy Supplies."},{"startTime":1871.415,"endTime":1877.626,"body":"Paper Four, I'm gonna assume you've all read papers one to three, um, the signatures"},{"startTime":1877.626,"endTime":1880.525,"body":"and information content of transiting Mega Structures."},{"startTime":1881.665,"endTime":1885.834,"body":"Now, I find out about this paper when my phone rang in the office on"},{"startTime":1885.834,"endTime":1890.003,"body":"a Monday morning, I picked it up and a voice at the other end said,"},{"startTime":1890.003,"endTime":1891.115,"body":"hello, I'm a journalist."},{"startTime":1891.395,"endTime":1892.715,"body":"I hear you found aliens."},{"startTime":1894.095,"endTime":1896.795,"body":"Now I'm not good on Monday mornings, especially not before coffee."},{"startTime":1896.815,"endTime":1899.656,"body":"And genuinely, I said, I don't know, I'll check my email and I'll get back"},{"startTime":1899.656,"endTime":1900.035,"body":"to you."},{"startTime":1900.035,"endTime":1904.075,"body":"And I hung up and I sort of stood there going, what, what's happened now?"},{"startTime":1904.075,"endTime":1905.875,"body":"And what had happened was this paper had been released."},{"startTime":1905.875,"endTime":1907.155,"body":"And the argument is quite simple."},{"startTime":1908.015,"endTime":1916.194,"body":"The argument is that we've long expected sensible alien civilizations to need carbon, carbon free"},{"startTime":1916.194,"endTime":1917.285,"body":"electricity, right?"},{"startTime":1917.285,"endTime":1921.075,"body":"You need as much power as possible, and the source of power is the star"},{"startTime":1921.075,"endTime":1922.845,"body":"at the center of your solar system."},{"startTime":1923.065,"endTime":1926.775,"body":"But it's a waste allowing that starlight to have to hit the earth or, or"},{"startTime":1926.775,"endTime":1927.765,"body":"whichever planet you're from."},{"startTime":1928.105,"endTime":1932.365,"body":"And so what you do is you build an orbiting swarm of solar panels."},{"startTime":1932.995,"endTime":1937.536,"body":"This is sometimes called a Dyson swarm or a Dyson sphere after the astronomer who"},{"startTime":1937.536,"endTime":1938.445,"body":"publicized the idea."},{"startTime":1938.465,"endTime":1944.309,"body":"It actually goes back to the 1930s, uh, with the slightly crazy sci-fi philosopher Ola"},{"startTime":1944.309,"endTime":1949.765,"body":"Stapleton in his book Star Maker talked about a vision of orbiting solar panels."},{"startTime":1950.265,"endTime":1955.535,"body":"And so Jason and Co are proposing that this star harbors such a civilization that"},{"startTime":1955.535,"endTime":1960.805,"body":"there are orbiting solar panels, and that's what's blocking out the light from the star."},{"startTime":1961.625,"endTime":1964.514,"body":"So where we see a dip, it's because one of these panels has gone in"},{"startTime":1964.514,"endTime":1965.285,"body":"front of the star."},{"startTime":1966.225,"endTime":1969.565,"body":"So do we think this is a good hypothesis?"},{"startTime":1970.665,"endTime":1971.685,"body":"It was certainly popular."},{"startTime":1972.145,"endTime":1973.565,"body":"Um, it got written up all over the place."},{"startTime":1973.665,"endTime":1977.317,"body":"I'm gonna show you the independent because they were the only people who used the"},{"startTime":1977.317,"endTime":1977.805,"body":"word may."},{"startTime":1978.725,"endTime":1984.765,"body":"Everyone else confidently, almost everyone else confidently reported that, uh, we had found aliens."},{"startTime":1985.105,"endTime":1991.073,"body":"Um, one paper who shall remain nameless, uh, said astronom, something like astronomers in coverup"},{"startTime":1991.073,"endTime":1996.645,"body":"of alien discovery, which given that the papers were all online seemed particularly unfair."},{"startTime":1997.305,"endTime":1999.285,"body":"Um, but is this a good idea?"},{"startTime":1999.755,"endTime":2003.805,"body":"Well, it suffers from the same problem as the comet hypothesis."},{"startTime":2005.325,"endTime":2009.085,"body":"I can arrange my alien solar panels however I like, right?"},{"startTime":2009.205,"endTime":2015.314,"body":"I can explain any pattern with this idea, but yet it is an explanation that"},{"startTime":2015.314,"endTime":2018.165,"body":"works for, for what we were seeing."},{"startTime":2018.785,"endTime":2023.459,"body":"And so I think that the fair way to put it was that the best"},{"startTime":2023.459,"endTime":2028.133,"body":"evidence we had for alien life in the universe was this star and its strange"},{"startTime":2028.133,"endTime":2028.445,"body":"behavior."},{"startTime":2030.515,"endTime":2035.345,"body":"Given that that was true, we felt it important to try and test this idea."},{"startTime":2036.725,"endTime":2038.465,"body":"We did that by keeping an eye on the star."},{"startTime":2038.845,"endTime":2043.545,"body":"But while we were doing that, other people were interested enough to start looking at"},{"startTime":2043.545,"endTime":2045.425,"body":"the star's behavior in the archives."},{"startTime":2045.565,"endTime":2051.621,"body":"And there's a remarkable project at the Harvard College Library, which has taken these glass"},{"startTime":2051.621,"endTime":2052.025,"body":"plates."},{"startTime":2053.005,"endTime":2057.56,"body":"Old style photography was to take in astronomy, was to take these large glass plates,"},{"startTime":2057.56,"endTime":2062.116,"body":"put them at the focus point of the telescope, usually ride along with them as"},{"startTime":2062.116,"endTime":2066.065,"body":"the telescope moved around the sky, swapping them out every hour or so."},{"startTime":2066.605,"endTime":2068.905,"body":"And these are pictures of the sky."},{"startTime":2069.565,"endTime":2073.221,"body":"Um, take 'em for most of the 20th century by lots of the world's largest"},{"startTime":2073.221,"endTime":2073.465,"body":"observatories."},{"startTime":2073.465,"endTime":2079.164,"body":"And at Harvard, they've been scanned and digitized, and the brightness of objects in those"},{"startTime":2079.164,"endTime":2081.824,"body":"plates has been carefully measured and calibrated."},{"startTime":2082.885,"endTime":2088.745,"body":"And when they looked at data for this particular star, they discovered something really unusual."},{"startTime":2088.745,"endTime":2090.185,"body":"This is also an exciting graph."},{"startTime":2090.215,"endTime":2091.905,"body":"This is brightness over time."},{"startTime":2092.205,"endTime":2093.824,"body":"The blue points are the thing that matter."},{"startTime":2094.205,"endTime":2096.985,"body":"And this is from 1890 to 1990."},{"startTime":2097.165,"endTime":2099.145,"body":"So this is a hundred years worth of data."},{"startTime":2099.925,"endTime":2103.865,"body":"And what we see is that the star is fading over time."},{"startTime":2104.085,"endTime":2107.625,"body":"It actually drops by about 30% over the course of a century."},{"startTime":2108.605,"endTime":2110.185,"body":"So now we've got two mysteries."},{"startTime":2110.845,"endTime":2114.927,"body":"What's causing the star to fade over time and why does it have these sudden"},{"startTime":2114.927,"endTime":2117.105,"body":"dips when we look at them more recently?"},{"startTime":2119.055,"endTime":2122.465,"body":"Obviously the aliens are constructing more solar panels."},{"startTime":2123.245,"endTime":2125.265,"body":"We can actually predict when they'll finish."},{"startTime":2125.295,"endTime":2130.225,"body":"It's in about 5,000 years time when they will have completely, um, covered the star."},{"startTime":2130.225,"endTime":2133.655,"body":"And you can speculate if you're in a, that sort of mood on how long"},{"startTime":2133.655,"endTime":2137.086,"body":"it must be between general elections on this alien planet if they can, can get"},{"startTime":2137.086,"endTime":2138.23,"body":"this sort of thing done."},{"startTime":2138.785,"endTime":2143.605,"body":"Um, scarily close to things I'm not allowed to say 'cause of my BBC contract."},{"startTime":2143.625,"endTime":2144.525,"body":"So let's move on."},{"startTime":2144.985,"endTime":2147.005,"body":"Um, so there's now two mysteries."},{"startTime":2147.645,"endTime":2153.026,"body":"I think this is a bit of a hole in the alien theory because the"},{"startTime":2153.026,"endTime":2158.408,"body":"idea that we'd catch this grand infrastructure project just at the point where it's being"},{"startTime":2158.408,"endTime":2159.485,"body":"built seems implausible."},{"startTime":2159.635,"endTime":2163.241,"body":"It's like the fact that we needed the comet to have just broken up, but"},{"startTime":2163.241,"endTime":2164.925,"body":"we kept an eye on the star."},{"startTime":2164.925,"endTime":2166.885,"body":"We used robotic telescopes around the world."},{"startTime":2166.885,"endTime":2169.565,"body":"This one's on the island of Maui, uh, in Hawaii."},{"startTime":2170.185,"endTime":2176.045,"body":"And in 2017, suddenly the star dipped again in brightness."},{"startTime":2176.145,"endTime":2178.485,"body":"And this time we caught it and we were ready."},{"startTime":2178.865,"endTime":2183.765,"body":"And we used advanced technology to alert the astronomers of the world to this event."},{"startTime":2184.565,"endTime":2189.205,"body":"\u003claugh\u003e, this is Tabby telling the world that Boian star is dipping."},{"startTime":2189.205,"endTime":2189.965,"body":"This is not a drill."},{"startTime":2190.545,"endTime":2193.325,"body":"Uh, astro tweets on telescopes in the next 48 hours."},{"startTime":2193.555,"endTime":2196.525,"body":"Spectra, please, genuinely, this is how science is done."},{"startTime":2197.225,"endTime":2202.445,"body":"Uh, we had about 200 telescopes, amateur and professional respond to this call for observations."},{"startTime":2203.225,"endTime":2207.715,"body":"Um, and they produced between them a critical piece of information, which we didn't know"},{"startTime":2207.715,"endTime":2212.206,"body":"before, which is that we had telescopes with cameras that were set up to detect"},{"startTime":2212.206,"endTime":2212.805,"body":"red light."},{"startTime":2213.025,"endTime":2216.005,"body":"And we had telescopes with cameras that were set up to detect blue light."},{"startTime":2216.585,"endTime":2222.643,"body":"And both sets saw this dip in brightness, but the blue light dipped more than"},{"startTime":2222.643,"endTime":2223.855,"body":"the red light."},{"startTime":2224.915,"endTime":2228.59,"body":"So in other words, how much of a dip there was depended on the color"},{"startTime":2228.59,"endTime":2229.815,"body":"that you were looking at."},{"startTime":2230.635,"endTime":2232.735,"body":"And that means that this is whatever's blocking the light."},{"startTime":2232.765,"endTime":2238.615,"body":"It's not a solid object because a solid object would block all wavelengths equally."},{"startTime":2239.115,"endTime":2241.895,"body":"So we're back to sort of ideas about a cloud of dust."},{"startTime":2241.895,"endTime":2246.495,"body":"And we can rule out, sadly, solar panels from an alien civilization."},{"startTime":2247.835,"endTime":2251.36,"body":"You could have solar panels from an alien civilization with Christmas lights on the back"},{"startTime":2251.36,"endTime":2254.415,"body":"if you want, but you have to make the Christmas lights really bright."},{"startTime":2254.675,"endTime":2256.655,"body":"And then you have several other questions to answer."},{"startTime":2257.995,"endTime":2259.215,"body":"So what explains all of this?"},{"startTime":2259.215,"endTime":2263.135,"body":"What are our best ideas as to what's going on with this star?"},{"startTime":2263.405,"endTime":2268.922,"body":"Well, it's still a topic of some debate and people are still, uh, watching, but"},{"startTime":2268.922,"endTime":2274.439,"body":"I have a a, a favorite theory which explains both the long-term dimming and the"},{"startTime":2274.439,"endTime":2275.175,"body":"sudden dips."},{"startTime":2275.675,"endTime":2278.375,"body":"And it's actually quite a disquieting and, and upsetting one."},{"startTime":2278.435,"endTime":2284.735,"body":"So we think our solar system as stable, we are used to the idea that"},{"startTime":2284.735,"endTime":2287.255,"body":"the planets are in their orbits."},{"startTime":2287.255,"endTime":2291.015,"body":"They've been there, well not quite forever, but for 4 billion years."},{"startTime":2291.015,"endTime":2294.498,"body":"And we expect, you know, there's a cheerful future of astronomy thing where I tell"},{"startTime":2294.498,"endTime":2297.981,"body":"you that in 4 billion years time, the sun will blow up to a red"},{"startTime":2297.981,"endTime":2299.375,"body":"giant and will engulf the earth."},{"startTime":2299.395,"endTime":2301.335,"body":"But that's 4 billion years time, right?"},{"startTime":2301.335,"endTime":2308.068,"body":"We don't have to worry about that now, except that we've recently learned that stars"},{"startTime":2308.068,"endTime":2309.415,"body":"eat planets sometimes."},{"startTime":2309.425,"endTime":2314.997,"body":"There was a result a month ago that showed with this unconvincing, uh, press illustration,"},{"startTime":2314.997,"endTime":2320.57,"body":"which is a theme of the talk that one in a dozen stars shows evidence"},{"startTime":2320.57,"endTime":2321.685,"body":"of planetary ingestion."},{"startTime":2322.065,"endTime":2323.845,"body":"So this is actually quite a clever experiment."},{"startTime":2323.845,"endTime":2326.765,"body":"They looked at pairs of stars that were born together."},{"startTime":2326.865,"endTime":2330.727,"body":"So these are double stars in orbit around each other, and we assume that they"},{"startTime":2330.727,"endTime":2333.045,"body":"formed in the same conditions outta the same material."},{"startTime":2333.785,"endTime":2336.445,"body":"So these stars should be made of the same stuff."},{"startTime":2337.225,"endTime":2340.144,"body":"And then what the team did was they looked to see if there were any"},{"startTime":2340.144,"endTime":2342.285,"body":"differences in the makeup of the atmospheres of the two stars."},{"startTime":2342.425,"endTime":2346.994,"body":"And they found that in about one in 12 cases, one of the stars essentially"},{"startTime":2346.994,"endTime":2351.564,"body":"had planets smeared all over its face that had heavy meth heavy elements in the"},{"startTime":2351.564,"endTime":2355.525,"body":"atmosphere that looked rather like the remnants of having eaten a rocky planet."},{"startTime":2356.985,"endTime":2358.045,"body":"So this happens."},{"startTime":2359.545,"endTime":2362.245,"body":"How does this help us with Bogen star, with the WGF star?"},{"startTime":2362.275,"endTime":2367.703,"body":"Well, it turns out the theory says that when a star consumes a planet, the"},{"startTime":2367.703,"endTime":2371.685,"body":"star gets brighter for about a thousand years and fade slowly."},{"startTime":2372.865,"endTime":2376.125,"body":"So we could be catching our star in the act of fading."},{"startTime":2376.545,"endTime":2380.942,"body":"And if the planet was disrupted, as the young convincing illustration shows, uh, before being"},{"startTime":2380.942,"endTime":2385.339,"body":"swallowed by the star, there could be rubble left in orbit around the star and"},{"startTime":2385.339,"endTime":2387.685,"body":"the rubble could be causing the sudden dips."},{"startTime":2387.685,"endTime":2391.685,"body":"So we can explain both things with this one, uh, explanation."},{"startTime":2391.985,"endTime":2397.142,"body":"Now there's a catch, which is, and I only, we were only working on this"},{"startTime":2397.142,"endTime":2399.205,"body":"yesterday, so this might be wrong."},{"startTime":2399.585,"endTime":2404.12,"body":"Uh, but this is a, this is a study of double stars here that were"},{"startTime":2404.12,"endTime":2404.725,"body":"born together."},{"startTime":2404.725,"endTime":2405.685,"body":"That's how you do the night."},{"startTime":2405.685,"endTime":2406.565,"body":"It's a twin study."},{"startTime":2406.565,"endTime":2409.685,"body":"Basically you're trying to see whether one's eaten something that the other one hasn't."},{"startTime":2410.145,"endTime":2415.188,"body":"But there's a reason to believe that double stars would be more likely to consume"},{"startTime":2415.188,"endTime":2415.525,"body":"planets."},{"startTime":2416.825,"endTime":2420.663,"body":"If you've got a two stars in orbit around each other as they travel around"},{"startTime":2420.663,"endTime":2424.501,"body":"the galaxy, it's quite plausible that their orbits would be disrupted by an encounter with"},{"startTime":2424.501,"endTime":2426.805,"body":"another star or pass it through a spiral arm."},{"startTime":2427.065,"endTime":2430.73,"body":"And if you send one star on a suddenly unstable orbit, then the planets around"},{"startTime":2430.73,"endTime":2432.685,"body":"both of them are going to get disrupted."},{"startTime":2433.425,"endTime":2437.572,"body":"So around a single star like a sun, our planets might be okay around a"},{"startTime":2437.572,"endTime":2438.125,"body":"double star."},{"startTime":2438.125,"endTime":2439.125,"body":"This kind of thing should happen."},{"startTime":2439.225,"endTime":2444.79,"body":"So I predict that Bogen star, the WTF star should be a double, but I"},{"startTime":2444.79,"endTime":2446.645,"body":"don't think we've ever looked."},{"startTime":2447.665,"endTime":2450.845,"body":"So we now need to go and do that and I'll get back to you."},{"startTime":2451.505,"endTime":2457.01,"body":"Um, but this planet eating is quite a good explanation and it leaves us, sadly"},{"startTime":2457.01,"endTime":2458.845,"body":"with a lack of aliens."},{"startTime":2459.185,"endTime":2461.605,"body":"Um, in fact, I was gonna update the title of the torque."},{"startTime":2461.605,"endTime":2466.325,"body":"We started with his aliens, but uh, the astronomy creed is, it's never aliens."},{"startTime":2466.345,"endTime":2469.525,"body":"But you know, Gresham said that wouldn't be quite so exciting, \u003claugh\u003e."},{"startTime":2469.525,"endTime":2475.027,"body":"Um, and also it's a bit too pessimistic I think because this search for this"},{"startTime":2475.027,"endTime":2478.695,"body":"WTF star caused a lot of attention to be paid."},{"startTime":2478.875,"endTime":2481.335,"body":"And we found other stars that misbehave."},{"startTime":2481.805,"endTime":2482.935,"body":"This is the current favorite."},{"startTime":2482.965,"endTime":2487.948,"body":"This is two years of data for a star called HD 1 3 9 1"},{"startTime":2487.948,"endTime":2492.931,"body":"3 9, which has 80 separate dips at surpri at seemingly random times over the"},{"startTime":2492.931,"endTime":2494.925,"body":"two years it was originally studied."},{"startTime":2495.435,"endTime":2496.925,"body":"This isn't a planetary system."},{"startTime":2497.025,"endTime":2499.125,"body":"You can't, I think somebody worked out."},{"startTime":2499.125,"endTime":2503.1,"body":"You need about 30 planets crammed in all in exactly the right orbits to course"},{"startTime":2503.1,"endTime":2503.365,"body":"this."},{"startTime":2503.365,"endTime":2504.925,"body":"That's not what's going on here."},{"startTime":2504.925,"endTime":2506.205,"body":"You wouldn't have a stable system."},{"startTime":2506.545,"endTime":2511.565,"body":"And we don't know to date why this is happening."},{"startTime":2512.235,"endTime":2516.885,"body":"It's a wonderful quote from Andrew Vandenberg, uh, who's, uh, exoplanet astronomer and and rival"},{"startTime":2516.885,"endTime":2521.535,"body":"of the planet hunters team, but a friendly one who, who drew attention to this"},{"startTime":2521.535,"endTime":2521.845,"body":"star."},{"startTime":2522.305,"endTime":2525.565,"body":"He said he was quoted in new scientists talking about this discovery."},{"startTime":2526.185,"endTime":2530.045,"body":"Uh, he'd had the phone call that said, maybe you've discovered aliens."},{"startTime":2530.165,"endTime":2535.493,"body":"And he said, well, in astronomy we have a long history of not understanding something,"},{"startTime":2535.493,"endTime":2539.045,"body":"thinking it's aliens, and later on finding it's something else."},{"startTime":2539.185,"endTime":2541.325,"body":"So the odds are pretty good that it's another one of those."},{"startTime":2542.025,"endTime":2545.96,"body":"But we're in the process here where the best explanation we've got is yes, alien"},{"startTime":2545.96,"endTime":2546.485,"body":"solar panels."},{"startTime":2546.485,"endTime":2547.885,"body":"We have done some follow up."},{"startTime":2548.185,"endTime":2552.897,"body":"The Green Bank telescope in West Virginia has listened in to see if there are"},{"startTime":2552.897,"endTime":2555.725,"body":"any signals coming from a civilization around the star."},{"startTime":2555.945,"endTime":2556.405,"body":"No luck."},{"startTime":2557.105,"endTime":2561.722,"body":"Um, more mysteriously the European Space Agencies chaos Op satellite recently took a look, look"},{"startTime":2561.722,"endTime":2565.725,"body":"at the star for a few weeks and showed no dips at all."},{"startTime":2566.385,"endTime":2569.165,"body":"It seems to be behaving exactly like a normal star."},{"startTime":2570.025,"endTime":2572.045,"body":"Now it's possible we didn't look for long enough."},{"startTime":2572.045,"endTime":2574.725,"body":"There's about one in 20 chance that we were just unlucky."},{"startTime":2575.385,"endTime":2579.605,"body":"Um, but it may be that the star has changed behavior."},{"startTime":2579.905,"endTime":2582.165,"body":"So we might be learning something about how stars behave."},{"startTime":2582.625,"endTime":2590.387,"body":"We may uh, perhaps be finding unusual signals that will in the long term turn"},{"startTime":2590.387,"endTime":2595.045,"body":"into something important in understanding intelligence in the universe."},{"startTime":2595.425,"endTime":2600.237,"body":"And the broader message here, I think, is that we're used to thinking about discovering"},{"startTime":2600.237,"endTime":2603.125,"body":"life in the universe as one of two things."},{"startTime":2603.225,"endTime":2608.331,"body":"Either we detect biology, uh, there are people who are working hard on understanding the"},{"startTime":2608.331,"endTime":2613.437,"body":"atmospheres of these planets around other stars, such that when we look at them with"},{"startTime":2613.437,"endTime":2618.543,"body":"that extremely large telescope that we're building, maybe we'll be able to see in the"},{"startTime":2618.543,"endTime":2620.245,"body":"atmosphere that there's oxygen there."},{"startTime":2620.635,"endTime":2625.533,"body":"That on earth would be produced by life or perhaps carbon dioxide from a technological"},{"startTime":2625.533,"endTime":2630.432,"body":"civilization or one of the many other chemicals that might be what we call a"},{"startTime":2630.432,"endTime":2633.045,"body":"biomarker, a chemical that's produced mostly by life."},{"startTime":2633.795,"endTime":2639.118,"body":"It's challenging 'cause you have to understand the chemistry of the atmosphere extremely well or"},{"startTime":2639.118,"endTime":2644.442,"body":"we're used to thinking about the kind of thing the GBT was doing, which is"},{"startTime":2644.442,"endTime":2649.766,"body":"radio astronomy, the search rate extra intelligence by expecting to see a deliberately beamed signal"},{"startTime":2649.766,"endTime":2655.09,"body":"into space, a message either for us or intercepted, uh, on its way to somewhere"},{"startTime":2655.09,"endTime":2655.445,"body":"else."},{"startTime":2656.145,"endTime":2657.605,"body":"And we can still do both of those things."},{"startTime":2657.865,"endTime":2662.742,"body":"But I think what we've learned from studying Stein the WTF stars, that we can"},{"startTime":2662.742,"endTime":2666.645,"body":"think much more broadly about how to find life in the universe."},{"startTime":2667.305,"endTime":2671.867,"body":"We can start to think of looking for what are called techno signatures, the effect"},{"startTime":2671.867,"endTime":2674.605,"body":"that life and intelligence civilizations have on their surroundings."},{"startTime":2675.285,"endTime":2678.685,"body":"I want to give you a silly example, A sensible example and a speculative example."},{"startTime":2679.305,"endTime":2681.405,"body":"The silly example is this."},{"startTime":2682.795,"endTime":2690.046,"body":"This is, uh, the Tesla Roadster launched into space by, um, space billionaire and world's"},{"startTime":2690.046,"endTime":2695.365,"body":"largest ego, Elon Musk, um, to show off his SpaceX capabilities."},{"startTime":2695.435,"endTime":2697.885,"body":"This car is now heading out into the outer solar system."},{"startTime":2698.265,"endTime":2700.005,"body":"Um, it was reported as going to Mars."},{"startTime":2700.005,"endTime":2701.645,"body":"It's not, it's just shooting out into space."},{"startTime":2702.145,"endTime":2705.005,"body":"Um, this I guess is a techno signature."},{"startTime":2705.005,"endTime":2709.559,"body":"If you were an alien studying the solar system in the far future finding this"},{"startTime":2709.559,"endTime":2714.114,"body":"would presumably give you some idea that there was at least some sign of intelligence"},{"startTime":2714.114,"endTime":2718.365,"body":"on, on one of the planets, uh, that you might want to steer clear."},{"startTime":2718.825,"endTime":2721.205,"body":"Um, we can turn that around."},{"startTime":2721.575,"endTime":2725.285,"body":"Would we recognize this car as something unusual?"},{"startTime":2725.955,"endTime":2730.982,"body":"Well it turns out we've done this experiment and the answer's yes, there's a telescope"},{"startTime":2730.982,"endTime":2735.005,"body":"called Wise that spends its time monitoring the sky, looking for asteroids."},{"startTime":2735.705,"endTime":2737.805,"body":"And it has a camera that has the ability."},{"startTime":2737.805,"endTime":2740.947,"body":"When you find an asteroid, it tells us what color it's, and there are a"},{"startTime":2740.947,"endTime":2742.205,"body":"couple of waves of measuring color."},{"startTime":2742.265,"endTime":2746.703,"body":"One roughly measures how red it is and one roughly measures how blue it's, and"},{"startTime":2746.703,"endTime":2751.141,"body":"you can make a plot of all asteroids using this wise data and put these"},{"startTime":2751.141,"endTime":2752.325,"body":"things on the axi."},{"startTime":2752.325,"endTime":2757.225,"body":"So every.here is an asteroid and where it is on this diagram tells you what"},{"startTime":2757.225,"endTime":2758.205,"body":"color it is."},{"startTime":2758.425,"endTime":2761.046,"body":"And what you can see is there are three main types of asteroid and then"},{"startTime":2761.046,"endTime":2762.445,"body":"the red dot the bottom is the car."},{"startTime":2763.355,"endTime":2766.565,"body":"It's a different color from everything else in the solar system."},{"startTime":2767.025,"endTime":2771.725,"body":"So we would notice that we had a space roadster heading our way."},{"startTime":2771.725,"endTime":2775.61,"body":"We're thinking about doing this on a grand scale just to check that there are"},{"startTime":2775.61,"endTime":2777.165,"body":"alien spacecraft in the solar system."},{"startTime":2777.165,"endTime":2778.445,"body":"We haven't found any yet."},{"startTime":2780.405,"endTime":2782.825,"body":"We can think more broadly about this as we look into space."},{"startTime":2783.285,"endTime":2788.13,"body":"I'm a big fan of a study by Duncan Forgan and colleagues that used I"},{"startTime":2788.13,"endTime":2789.745,"body":"think some quite ingenious logic."},{"startTime":2789.775,"endTime":2794.834,"body":"They said a bit like Jason's prediction that alien civilizations would build solar panels orbiting"},{"startTime":2794.834,"endTime":2799.893,"body":"their star Duncan and co said, well look, one of the things you do as"},{"startTime":2799.893,"endTime":2804.952,"body":"you moved into space, as you became a space fairing civilization is probably if you've"},{"startTime":2804.952,"endTime":2810.011,"body":"got a handy asteroid belt as we do between Mars and Jupiter, we'd mine the"},{"startTime":2810.011,"endTime":2815.07,"body":"asteroid belt for raw materials, for rocket parts for ram minerals that we can't get"},{"startTime":2815.07,"endTime":2815.745,"body":"on earth."},{"startTime":2815.745,"endTime":2817.025,"body":"This is something that's been talked about."},{"startTime":2817.205,"endTime":2821.545,"body":"Now there's a whole fascinating side conversation to have about the economics, but people have"},{"startTime":2821.545,"endTime":2825.886,"body":"talked about going and getting rare earth minerals or platinum or even ice from the"},{"startTime":2825.886,"endTime":2826.465,"body":"asteroid belt."},{"startTime":2827.245,"endTime":2832.715,"body":"And the logic is that where you have mining, you create dust inevitably."},{"startTime":2833.215,"endTime":2838.045,"body":"And so what we should do is look for star systems that have a suspicious"},{"startTime":2838.045,"endTime":2842.875,"body":"glow in the infrared coming from an excess of small dust grains in the system."},{"startTime":2843.435,"endTime":2847.715,"body":"'cause that's a sign that there's been active mining and there was nothing very suspicious."},{"startTime":2847.815,"endTime":2849.64,"body":"But people have started to look, look for these things."},{"startTime":2849.64,"endTime":2852.02,"body":"Maybe we can detect the side effects of alien mining."},{"startTime":2852.905,"endTime":2854.965,"body":"And I said, I'd give you a speculative example as well."},{"startTime":2855.045,"endTime":2860.271,"body":"I was at a conference about the future of looking for extraterrestrial intelligence and it"},{"startTime":2860.271,"endTime":2865.497,"body":"was a very sober and serious discussion about machine learning and anomaly detection of the"},{"startTime":2865.497,"endTime":2868.285,"body":"techniques that one would use to do this."},{"startTime":2868.865,"endTime":2873.258,"body":"And I nipped to the loo and came back a few minutes later and the"},{"startTime":2873.258,"endTime":2877.651,"body":"conversation had changed and people were talking about whether alien intelligences would be pleased by"},{"startTime":2877.651,"endTime":2882.045,"body":"the notion of making stars in different bits of the galaxy, flash in different patterns."},{"startTime":2882.665,"endTime":2884.565,"body":"Sounds crazy, but we could check for that."},{"startTime":2884.745,"endTime":2890.034,"body":"We could look for unusual patterns amongst the stars and maybe that's how we'll discover"},{"startTime":2890.034,"endTime":2891.445,"body":"there's life out there."},{"startTime":2892.225,"endTime":2893.485,"body":"We have a new data set coming."},{"startTime":2893.505,"endTime":2898.107,"body":"We have a telescope called the Vera Rubin Observatory, which is as big as the"},{"startTime":2898.107,"endTime":2902.71,"body":"biggest telescopes today, but which will scan the whole sky every three nights producing 30"},{"startTime":2902.71,"endTime":2904.245,"body":"terabytes of data a night."},{"startTime":2904.785,"endTime":2907.805,"body":"Uh, and about 10 million alerts a night that something has changed."},{"startTime":2908.265,"endTime":2911.965,"body":"And in there we hope will be all sorts of things."},{"startTime":2911.965,"endTime":2914.765,"body":"There'll be stars misbehaving, perhaps flashing in unison."},{"startTime":2915.175,"endTime":2919.734,"body":"We'll have a catalog of a few million objects in our solar system that we"},{"startTime":2919.734,"endTime":2924.293,"body":"can search for unusual or orbits or perhaps even the odd shiny metallic thing that"},{"startTime":2924.293,"endTime":2925.205,"body":"shouldn't be there."},{"startTime":2925.465,"endTime":2927.245,"body":"Or detect more in stellar visitors."},{"startTime":2927.625,"endTime":2930.005,"body":"And we'll look in detail at distant galaxies."},{"startTime":2930.105,"endTime":2936.233,"body":"And what's becoming clear is that as well as searching that data and using it"},{"startTime":2936.233,"endTime":2942.362,"body":"to do conventional astronomy, it's worth spending some time thinking about the most profound question"},{"startTime":2942.362,"endTime":2944.405,"body":"of all, is it aliens?"},{"startTime":2944.575,"endTime":2945.325,"body":"Thank you very much."},{"startTime":2958.815,"endTime":2959.565,"body":"Thank you so much."},{"startTime":2959.805,"endTime":2960.125,"body":"Chris."},{"startTime":2960.885,"endTime":2965.985,"body":"I should announce that Chris will be signing his latest book, our Accidental Universe outside"},{"startTime":2965.985,"endTime":2967.005,"body":"after this talk."},{"startTime":2967.065,"endTime":2970.205,"body":"Yes, it's, it's, this is the first Gresham lecture since this book has been out."},{"startTime":2970.205,"endTime":2972.325,"body":"So I promise this is the last time I'll advertise it."},{"startTime":2972.625,"endTime":2975.546,"body":"Uh, but if you'd like to hear more stories like this, then please come and"},{"startTime":2975.546,"endTime":2976.325,"body":"get a book, right?"},{"startTime":2976.325,"endTime":2977.525,"body":"That's the advertising done."},{"startTime":2977.865,"endTime":2979.965,"body":"So we have lots of questions."},{"startTime":2980.075,"endTime":2983.845,"body":"I'll start with the more, um, sensible ones and we'll get to all of them."},{"startTime":2983.985,"endTime":2984.205,"body":"Um,"},{"startTime":2984.305,"endTime":2985.605,"body":"So I've just seen your T-shirt."},{"startTime":2985.785,"endTime":2986.165,"body":"Oh yes."},{"startTime":2986.205,"endTime":2987.605,"body":"I forgot to have a go at Pluto."},{"startTime":2987.735,"endTime":2988.085,"body":"Sorry."},{"startTime":2988.195,"endTime":2988.485,"body":"Yeah."},{"startTime":2991.315,"endTime":2994.405,"body":"Okay, so \u003claugh\u003e, um, let's go with this one."},{"startTime":2994.745,"endTime":2998.325,"body":"Are the fluctuations of the, oh careful how I say this."},{"startTime":2998.525,"endTime":3002.925,"body":"WTF star similar to the dimming of Beetlejuice a couple"},{"startTime":3002.925,"endTime":3003.325,"body":"Years ago?"},{"startTime":3003.325,"endTime":3004.205,"body":"Oh yeah, no, that's a great question."},{"startTime":3004.205,"endTime":3004.485,"body":"Yeah."},{"startTime":3004.485,"endTime":3009.711,"body":"People will remember perhaps in 2020, actually the end of 2019 into 2020, uh, Beetlejuice"},{"startTime":3009.711,"endTime":3014.937,"body":"bettger, the, the bright star on the top left of Orion, which is a familiar"},{"startTime":3014.937,"endTime":3017.725,"body":"presence in the wind sky dimmed quite dramatically."},{"startTime":3018.205,"endTime":3021.645,"body":"I found it, you may remember 2020 was an odd year."},{"startTime":3022.065,"endTime":3025.868,"body":"Uh, I felt it, I found it really unsettling that Orion looked different if you"},{"startTime":3025.868,"endTime":3029.165,"body":"went out and looked up, it didn't look like it was supposed to."},{"startTime":3029.505,"endTime":3034.565,"body":"Now what happened there was, uh, beetle Beetlejuice is a giant red giant star."},{"startTime":3035.185,"endTime":3037.485,"body":"It produces dust in its atmosphere."},{"startTime":3038.065,"endTime":3040.725,"body":"And so we could see that happening with the VLT."},{"startTime":3040.785,"endTime":3043.845,"body":"So that was, that took months to play out."},{"startTime":3043.845,"endTime":3045.645,"body":"Whereas these are much more rapid changes."},{"startTime":3045.785,"endTime":3049.16,"body":"So they must have a different, and this isn't a red giant, so they must"},{"startTime":3049.16,"endTime":3050.285,"body":"have a different, um, origin."},{"startTime":3050.385,"endTime":3051.205,"body":"But it's a good question."},{"startTime":3052.065,"endTime":3056.405,"body":"Uh, is the James Webb telescope going to help in finding exoplanets?"},{"startTime":3056.405,"endTime":3056.685,"body":"Chris,"},{"startTime":3057.075,"endTime":3057.485,"body":"Tell us."},{"startTime":3057.515,"endTime":3063.17,"body":"Yeah, so the JWST, which is our new infrared telescope, um, probably won't discover exor"},{"startTime":3063.17,"endTime":3063.925,"body":"planets actually."},{"startTime":3064.265,"endTime":3068.125,"body":"Um, on, apparently I'm doing all my plugs on next month's sky at night."},{"startTime":3068.635,"endTime":3073.09,"body":"I've just recorded an interview with Beth Biller, who, who's using JWST to do some"},{"startTime":3073.09,"endTime":3073.685,"body":"direct imaging."},{"startTime":3073.745,"endTime":3076.685,"body":"So you will actually see the planets, but it won't be discovery."},{"startTime":3077.235,"endTime":3080.894,"body":"What it does is follow up and tell us about the planet's atmospheres and we"},{"startTime":3080.894,"endTime":3084.553,"body":"heading towards a world in which you could look at an atmosphere and say something"},{"startTime":3084.553,"endTime":3085.285,"body":"about its chemistry."},{"startTime":3085.625,"endTime":3089.525,"body":"But for jwst only for planets that are close to their style will need bigger"},{"startTime":3089.525,"endTime":3090.565,"body":"telescopes to do better."},{"startTime":3092.195,"endTime":3094.605,"body":"Okay, I won't respond 'cause there's so many questions here."},{"startTime":3094.625,"endTime":3095.765,"body":"So we'll just get through, we'll"},{"startTime":3095.765,"endTime":3096.365,"body":"Do rapid bio mode."},{"startTime":3096.365,"endTime":3096.645,"body":"Okay."},{"startTime":3096.665,"endTime":3102.149,"body":"Are there any correlations between the types of exoplanets and the type age predis predisposition"},{"startTime":3102.149,"endTime":3105.805,"body":"to eat planets of the, of the stars they orbit?"},{"startTime":3105.905,"endTime":3106.125,"body":"Yes."},{"startTime":3106.185,"endTime":3107.365,"body":"We don't know yet."},{"startTime":3107.685,"endTime":3111.922,"body":"'cause we've, we've really only, this is the, the, the double star study I talked"},{"startTime":3111.922,"endTime":3116.16,"body":"about was the, the first systematic study I've seen on whether planets eat, whether stars"},{"startTime":3116.16,"endTime":3116.725,"body":"eat planets."},{"startTime":3116.965,"endTime":3119.765,"body":"Commonly it was something we need to, to look into more."},{"startTime":3120.305,"endTime":3121.965,"body":"Um, I find it quite disturbing."},{"startTime":3121.965,"endTime":3126.53,"body":"There have been these hints for a while that the solar system may have been"},{"startTime":3126.53,"endTime":3128.965,"body":"unusually stable, but other planetary systems are unstable."},{"startTime":3128.965,"endTime":3133.498,"body":"Maybe atonal music and all sorts of things if we're, if we're visualizing their or"},{"startTime":3133.498,"endTime":3134.405,"body":"sonifying their orbits."},{"startTime":3134.405,"endTime":3136.725,"body":"So, um, don't know what the space,"},{"startTime":3137.745,"endTime":3141.005,"body":"How do the stars actually eat the planets, how do they catch them?"},{"startTime":3141.305,"endTime":3145.485,"body":"Is it usually only one of the twin stars that is a planet muncher?"},{"startTime":3145.705,"endTime":3145.965,"body":"The nature?"},{"startTime":3145.965,"endTime":3147.445,"body":"Yeah, this is a, this, this is a great question."},{"startTime":3147.505,"endTime":3150.699,"body":"So yeah, the, there weren't any in the study where both seem to have eaten"},{"startTime":3150.699,"endTime":3151.125,"body":"a planet."},{"startTime":3151.545,"endTime":3155.873,"body":"Um, so in these systems, the uh, stars are far enough apart that they likely"},{"startTime":3155.873,"endTime":3157.605,"body":"both have their own solar systems."},{"startTime":3158.135,"endTime":3162.745,"body":"There are worlds we've discovered which have two stars close together and planets going around"},{"startTime":3162.745,"endTime":3165.205,"body":"both of them, but they're a separate story."},{"startTime":3165.705,"endTime":3170.51,"body":"So what's happening we think is that either some gravitational interaction between the planets causes"},{"startTime":3170.51,"endTime":3175.316,"body":"one or more of them to fall into the star or some disruption to the"},{"startTime":3175.316,"endTime":3180.122,"body":"whole system maybe causes one of the stars to swing by on its orbit and"},{"startTime":3180.122,"endTime":3182.045,"body":"disrupt the planetary system of another."},{"startTime":3182.505,"endTime":3186.694,"body":"So the dynamics of this are quite comp predicting exactly what's gonna happen is quite"},{"startTime":3186.694,"endTime":3190.605,"body":"complicated, but showing that this kind of thing could happen, um, seems quite easy."},{"startTime":3190.705,"endTime":3193.205,"body":"So things are much more fragile than they seem"},{"startTime":3193.705,"endTime":3196.405,"body":"Is, does it have something to do with the stability?"},{"startTime":3196.625,"endTime":3198.805,"body":"You know, the three over two nature of"},{"startTime":3198.805,"endTime":3198.925,"body":"It?"},{"startTime":3198.945,"endTime":3199.365,"body":"Oh yeah."},{"startTime":3199.365,"endTime":3202.815,"body":"So the three over two, it's interesting, the three over two ratio may be more"},{"startTime":3202.815,"endTime":3203.045,"body":"stable."},{"startTime":3203.265,"endTime":3205.845,"body":"So that particular, because they've settled into a relationship"},{"startTime":3205.845,"endTime":3207.445,"body":"With each other, you get punished for making a bad"},{"startTime":3207.865,"endTime":3208.325,"body":"Courts, right?"},{"startTime":3208.325,"endTime":3211.525,"body":"So, so they're not going to disrupt each other 'cause they're in this nice pattern."},{"startTime":3211.875,"endTime":3217.421,"body":"Whereas we think early in the solar systems history, I mentioned this in a previous"},{"startTime":3217.421,"endTime":3222.967,"body":"talk, we think Jupiter and Saturn got into a resonance where their mutual gravitational interaction"},{"startTime":3222.967,"endTime":3225.925,"body":"meant that they were suddenly, uh, dramatically moved."},{"startTime":3225.925,"endTime":3228.925,"body":"So Jupiter seems to have come inward Saturn seems to have gone outwards."},{"startTime":3229.565,"endTime":3233.128,"body":"Uranus and Neptune may have swapped places, but we thought that was something that happened"},{"startTime":3233.128,"endTime":3236.692,"body":"to a young solar system, and then everything was supposed to settle down into a"},{"startTime":3236.692,"endTime":3237.405,"body":"nice middle age."},{"startTime":3237.625,"endTime":3239.125,"body":"It seems to be that may not be the case."},{"startTime":3239.665,"endTime":3244.2,"body":"Is it possible that the changes in brightness are due to solar, mass, ejections, or"},{"startTime":3244.2,"endTime":3244.805,"body":"solar flares?"},{"startTime":3244.835,"endTime":3246.045,"body":"Yeah, this is a great question."},{"startTime":3246.145,"endTime":3247.925,"body":"So we see the sun change brightness."},{"startTime":3247.985,"endTime":3251.501,"body":"So the sun has sun spots, which calls it to dim though not in this"},{"startTime":3251.501,"endTime":3252.205,"body":"sort of way."},{"startTime":3252.625,"endTime":3256.308,"body":"And we have solar flares or, or Corona, mass ejections, which send material out into"},{"startTime":3256.308,"endTime":3257.045,"body":"the solar system."},{"startTime":3257.145,"endTime":3261.821,"body":"We do see with Kepler and with tests these satellites, we do see flares, but"},{"startTime":3261.821,"endTime":3262.445,"body":"they're brightenings."},{"startTime":3262.625,"endTime":3263.685,"body":"Things get brighter."},{"startTime":3264.265,"endTime":3266.485,"body":"And this particular star doesn't seem to ever do that."},{"startTime":3266.585,"endTime":3269.165,"body":"It only dims and then comes back to its previous brightness."},{"startTime":3269.195,"endTime":3270.525,"body":"Well, we have a hypothesis here."},{"startTime":3270.755,"endTime":3276.605,"body":"Suppose W2 air, WTF planet aliens required high energy, blue light, right?"},{"startTime":3276.705,"endTime":3281.085,"body":"So build a Dyson sphere to capture blue light to minimize the mass the sphere's."},{"startTime":3281.085,"endTime":3282.285,"body":"Translucent sails,"},{"startTime":3282.395,"endTime":3283.005,"body":"Obviously."},{"startTime":3283.005,"endTime":3283.205,"body":"Yes."},{"startTime":3283.205,"endTime":3287.278,"body":"The trouble is we have thought about this and obviously you can make alien technology"},{"startTime":3287.278,"endTime":3288.365,"body":"do whatever you like."},{"startTime":3288.625,"endTime":3293.828,"body":"So with the caveat that magic alien technology is not allowed, anything that's absorbing starlight"},{"startTime":3293.828,"endTime":3298.685,"body":"should heat up things that are hot grow in the infrared or the red."},{"startTime":3298.985,"endTime":3302.478,"body":"So we think even if you had some magic technology that could only absorb the"},{"startTime":3302.478,"endTime":3305.972,"body":"blue light, you would radiate away in the red as well, and we'd still see"},{"startTime":3305.972,"endTime":3306.205,"body":"it."},{"startTime":3306.465,"endTime":3310.285,"body":"So we think that we can get away with, with arguing against that."},{"startTime":3310.385,"endTime":3310.605,"body":"But,"},{"startTime":3310.945,"endTime":3315.792,"body":"But the challenge with, um, extraterrestrials is that we don't have any to have an"},{"startTime":3315.792,"endTime":3317.085,"body":"hamms razor to work"},{"startTime":3317.235,"endTime":3317.525,"body":"With."},{"startTime":3317.525,"endTime":3317.885,"body":"That's right."},{"startTime":3317.885,"endTime":3318.085,"body":"Yeah."},{"startTime":3318.185,"endTime":3322.026,"body":"And I gave a, a version of this talk to, um, some of the schools"},{"startTime":3322.026,"endTime":3325.867,"body":"groups that we work with, with, um, Gresham this, this afternoon, and one of them"},{"startTime":3325.867,"endTime":3329.708,"body":"said, look, why are you assuming that aliens do things that we would think were"},{"startTime":3329.708,"endTime":3329.965,"body":"sensible?"},{"startTime":3330.425,"endTime":3331.605,"body":"And that's a really good question."},{"startTime":3331.925,"endTime":3333.285,"body":"I I don't have a good answer to that."},{"startTime":3333.505,"endTime":3337.36,"body":"So yeah, so that's why I, I mean that quite seriously magical alien and technology"},{"startTime":3337.36,"endTime":3338.645,"body":"can do everything you want."},{"startTime":3338.785,"endTime":3343.941,"body":"So you can explain the apparent lack of aliens by cloaking devices, which work perfectly"},{"startTime":3343.941,"endTime":3344.285,"body":"Great."},{"startTime":3344.435,"endTime":3344.725,"body":"Good."},{"startTime":3344.795,"endTime":3345.085,"body":"Done."},{"startTime":3345.425,"endTime":3346.565,"body":"We can now all go to the pub."},{"startTime":3346.985,"endTime":3350.967,"body":"Um, so, so we can only really work within the realms of the physics that,"},{"startTime":3350.967,"endTime":3354.95,"body":"that we are thinking about, but I still think that gets you a reasonable way"},{"startTime":3354.95,"endTime":3357.605,"body":"into thinking about what techno signatures you should look for."},{"startTime":3358.235,"endTime":3364.274,"body":"What I want to ask you is for 20 years ago or 20 years ago,"},{"startTime":3364.274,"endTime":3370.313,"body":"uh, we, uh, there were more UFOs seen by people and also, uh, there's been"},{"startTime":3370.313,"endTime":3376.352,"body":"a close shave of where a UFO has landed and it's been seen by a"},{"startTime":3376.352,"endTime":3382.391,"body":"police officer in the United States, and somebody got off and then went back into"},{"startTime":3382.391,"endTime":3384.405,"body":"this dislike object that disappeared."},{"startTime":3384.785,"endTime":3389.743,"body":"Are you rejecting these sort of things as complete fallacies, or is there some truth"},{"startTime":3389.743,"endTime":3390.405,"body":"in that?"},{"startTime":3390.635,"endTime":3395.177,"body":"Yeah, I think it, it depends on, on, um, my mood, frankly, \u003claugh\u003e, um, I"},{"startTime":3395.177,"endTime":3399.719,"body":"mean, one answer is that I'm an astronomer, so I, I want to point out"},{"startTime":3399.719,"endTime":3404.262,"body":"before I say anything else, but I have expertise in images of space and how"},{"startTime":3404.262,"endTime":3406.685,"body":"telescopes and cameras built to do that work."},{"startTime":3407.185,"endTime":3412.63,"body":"And so I can say with certainty that we don't see any evidence of such"},{"startTime":3412.63,"endTime":3414.445,"body":"technology, um, beyond the atmosphere."},{"startTime":3414.905,"endTime":3418.184,"body":"Um, if, uh, you know, one can invent cloaking devices and all sorts of technology,"},{"startTime":3418.184,"endTime":3421.245,"body":"but if there were things zipping around the solar system, we would've seen them."},{"startTime":3421.945,"endTime":3426.502,"body":"Now, as for the reports, and these days, they tend to go under the, the"},{"startTime":3426.502,"endTime":3429.845,"body":"phrase UAP because it's considered a more, uh, unidentified aerial phenomenon."},{"startTime":3429.925,"endTime":3431.725,"body":"I believe it's a polite version of UFO."},{"startTime":3432.265,"endTime":3435.765,"body":"Um, there are lots of reports which have been much in the news recently."},{"startTime":3436.345,"endTime":3439.885,"body":"Um, I'm now expert on airborne cameras and so on."},{"startTime":3439.885,"endTime":3444.66,"body":"But to me, given the surveillance technology that we have, given the images we have"},{"startTime":3444.66,"endTime":3449.436,"body":"of both earth and space, and indeed on the ground, um, I would be deeply"},{"startTime":3449.436,"endTime":3454.211,"body":"suspicious of a phenomenon where the only ways it turns up are in blurry pictures"},{"startTime":3454.211,"endTime":3455.485,"body":"or the occasional recollections."},{"startTime":3455.485,"endTime":3459.797,"body":"So I would think that if such things were common, we would have much better"},{"startTime":3459.797,"endTime":3460.085,"body":"evidence."},{"startTime":3460.585,"endTime":3462.565,"body":"And so that's the plight way of saying that."},{"startTime":3462.565,"endTime":3467.365,"body":"I don't give much credence to such reports, but I certainly understand, as I started"},{"startTime":3467.365,"endTime":3472.165,"body":"by saying the desire to want to have aliens here and to talk to them."},{"startTime":3472.285,"endTime":3474.005,"body":"I think that's a very natural and human thing."},{"startTime":3474.005,"endTime":3478.538,"body":"It's not surprising that when people see the unusual or the unexpected or they experience"},{"startTime":3478.538,"endTime":3482.165,"body":"the unusual unexpected, that that's the, the reach that they go to."},{"startTime":3482.225,"endTime":3484.805,"body":"And hopefully that's a polite and sensible answer."},{"startTime":3485.065,"endTime":3486.045,"body":"But thank you for the question."},{"startTime":3487.115,"endTime":3492.207,"body":"However, from Chloe age 11, if there were aliens, what do you think they would"},{"startTime":3492.207,"endTime":3494.245,"body":"look like or be like \u003claugh\u003e?"},{"startTime":3494.315,"endTime":3497.205,"body":"Well, one, this is a really good question, so I've got two answers."},{"startTime":3497.945,"endTime":3501.165,"body":"Um, one is I have no idea, right?"},{"startTime":3501.225,"endTime":3504.896,"body":"We can't imagine, look at the variety of life on earth if you look at"},{"startTime":3504.896,"endTime":3506.365,"body":"creatures from the deep city, but"},{"startTime":3506.365,"endTime":3507.085,"body":"It's carbon based."},{"startTime":3507.235,"endTime":3507.525,"body":"Yeah,"},{"startTime":3507.525,"endTime":3507.725,"body":"Yeah."},{"startTime":3507.905,"endTime":3511.033,"body":"But, but you know, even within the constraints of life on earth where everything is"},{"startTime":3511.033,"endTime":3512.285,"body":"DNA based, everything is carbon based."},{"startTime":3512.285,"endTime":3514.885,"body":"So we share a chemistry, look at the variety that we have."},{"startTime":3515.265,"endTime":3516.125,"body":"So that's one answer."},{"startTime":3516.145,"endTime":3516.885,"body":"So who knows?"},{"startTime":3518.225,"endTime":3523.96,"body":"And certainly I think we could be guilty of limiting our imaginations by Star Trek"},{"startTime":3523.96,"endTime":3524.725,"body":"budgets, right?"},{"startTime":3524.755,"endTime":3530.012,"body":"There's a reason that all aliens in science fiction are about six foot tall and"},{"startTime":3530.012,"endTime":3531.765,"body":"humanoid because it's cheaper, right?"},{"startTime":3532.265,"endTime":3536.165,"body":"Um, so, so I, I wouldn't want to say for sure however you could make"},{"startTime":3536.165,"endTime":3536.685,"body":"an argument."},{"startTime":3536.985,"endTime":3541.091,"body":"And it's due to, there's an argument due to a guy called Simon Conway Morris,"},{"startTime":3541.091,"endTime":3544.925,"body":"who's a paleontologist, who says, look, we are a good solution to intelligent life."},{"startTime":3544.925,"endTime":3550.413,"body":"Being about this tall, having bipedal, uh, limbs, having two eyes, um, is a good"},{"startTime":3550.413,"endTime":3554.805,"body":"way of encountering the kind of planet that we find ourselves on."},{"startTime":3554.865,"endTime":3558.993,"body":"So he argues based on looking at evolution on earth, that if they're intelligent aliens,"},{"startTime":3558.993,"endTime":3560.645,"body":"they will look roughly like us."},{"startTime":3561.545,"endTime":3565.645,"body":"So the answer is go wild and speculate or they'll look exactly like us."},{"startTime":3565.745,"endTime":3568.605,"body":"And I think either end of that extreme is a good answer, but"},{"startTime":3569.015,"endTime":3569.365,"body":"Great."},{"startTime":3569.625,"endTime":3570.925,"body":"Is there another question in the room?"},{"startTime":3572.565,"endTime":3577.261,"body":"I, we are often saying these days that we're at a point where the person,"},{"startTime":3577.261,"endTime":3581.645,"body":"the first person who's going to set foot on Mars is alive right now."},{"startTime":3582.305,"endTime":3588.277,"body":"Um, are we, do you think we'll ever realistically get to the point where we"},{"startTime":3588.277,"endTime":3594.25,"body":"are, uh, going to be able to definitively visit or communicate with one of these"},{"startTime":3594.25,"endTime":3595.445,"body":"exo pla planets?"},{"startTime":3595.745,"endTime":3601.302,"body":"Or do you think we just have to be satisfied with just knowing all the"},{"startTime":3601.302,"endTime":3603.525,"body":"questions but not having the answers?"},{"startTime":3604.065,"endTime":3606.525,"body":"Or do we just wait for them to contact us"},{"startTime":3606.535,"endTime":3606.885,"body":"First?"},{"startTime":3606.885,"endTime":3607.085,"body":"Yes."},{"startTime":3607.085,"endTime":3608.285,"body":"There, there is the waiting option."},{"startTime":3608.365,"endTime":3612.299,"body":"I have a friend who I think as a joke, but I'm not really sure,"},{"startTime":3612.299,"endTime":3616.234,"body":"runs the Wet Institute, which argues that because the aliens are clearly more intelligent than"},{"startTime":3616.234,"endTime":3619.645,"body":"us, instead of searching for them set, we should just wait for them."},{"startTime":3619.665,"endTime":3620.485,"body":"So that's Watty."},{"startTime":3620.865,"endTime":3623.725,"body":"And you know, there are days when that appeals No, but you are, you're right."},{"startTime":3623.745,"endTime":3626.085,"body":"We, we think we've got this cosmic speed limit."},{"startTime":3626.305,"endTime":3630.525,"body":"So then even T Garden Star, um, is 12 light years away."},{"startTime":3630.525,"endTime":3632.085,"body":"So even if there were aliens there, they knew about us."},{"startTime":3632.085,"endTime":3635.779,"body":"We knew about their, when we were exchanging radio messages, you have to wait 12"},{"startTime":3635.779,"endTime":3636.765,"body":"years for a reply."},{"startTime":3637.425,"endTime":3640.365,"body":"Um, even the nearest stars, if you'd like, is away travel."},{"startTime":3640.365,"endTime":3644.407,"body":"Even at 99% of the speed of light is gonna take you, uh, years and"},{"startTime":3644.407,"endTime":3645.485,"body":"years to get there."},{"startTime":3645.985,"endTime":3650.805,"body":"So there's a boring physicist answer, which is conversation will be very slow."},{"startTime":3651.605,"endTime":3656.177,"body":"I still think it would be fascinating to know that there was a world there"},{"startTime":3656.177,"endTime":3660.445,"body":"with life on, but we may have to restrict ourselves to very slow conversation."},{"startTime":3662.155,"endTime":3666.782,"body":"However, every time a physicist has predicted what we'll be able to do in 200"},{"startTime":3666.782,"endTime":3668.325,"body":"years time, we've been wrong."},{"startTime":3668.985,"endTime":3672.875,"body":"And so I'm looking forward to the invention of the limb to drive in the"},{"startTime":3672.875,"endTime":3676.766,"body":"next 50 years, which will take us at interstellar speeds and then we can explore"},{"startTime":3676.766,"endTime":3677.285,"body":"the galaxy."},{"startTime":3677.425,"endTime":3681.675,"body":"But if we can do that, I want to know why we don't see people"},{"startTime":3681.675,"endTime":3682.525,"body":"doing it already."},{"startTime":3683.025,"endTime":3686.645,"body":"Why are we not watching the Starship zip around, uh, space?"},{"startTime":3686.645,"endTime":3687.445,"body":"Maybe they're hard to see."},{"startTime":3687.445,"endTime":3689.485,"body":"Maybe it's physically just very difficult."},{"startTime":3689.505,"endTime":3693.926,"body":"So I fear that Einstein's right and we have a cosmic speed limit, but I"},{"startTime":3693.926,"endTime":3696.285,"body":"hope that we'll be able to beat it."},{"startTime":3697.115,"endTime":3697.405,"body":"Okay."},{"startTime":3697.405,"endTime":3700.125,"body":"Let's go back to a very solid technical question."},{"startTime":3700.465,"endTime":3705.193,"body":"In measuring the light dip from a planetary transit, how do you, how do you"},{"startTime":3705.193,"endTime":3707.085,"body":"adjust for changes in cloud cover?"},{"startTime":3707.265,"endTime":3708.245,"body":"Oh, well, this is a great question."},{"startTime":3708.245,"endTime":3709.685,"body":"So that's one reason I probably didn't."},{"startTime":3709.685,"endTime":3710.285,"body":"It's clear enough."},{"startTime":3710.345,"endTime":3714.405,"body":"Kepler and Tess are in space precisely 'cause it's a lot easier."},{"startTime":3715.125,"endTime":3717.045,"body":"'cause then you don't have to worry about the earth."},{"startTime":3717.145,"endTime":3717.365,"body":"Now."},{"startTime":3717.625,"endTime":3719.285,"body":"You can do it from the ground."},{"startTime":3719.285,"endTime":3723.525,"body":"There are projects, uh, that have discovered transiting planets from the ground."},{"startTime":3724.025,"endTime":3727.667,"body":"But what you have to do is observe for long enough that you see transit"},{"startTime":3727.667,"endTime":3729.125,"body":"after transit, after transit, after transit."},{"startTime":3729.385,"endTime":3734.012,"body":"So you can build up evidence that something's happening despite what's happening with cloud cover"},{"startTime":3734.012,"endTime":3738.639,"body":"or, or even just changing it, changing conditions above your heads, even from clear night"},{"startTime":3738.639,"endTime":3739.565,"body":"to clear night."},{"startTime":3739.665,"endTime":3743.325,"body":"So going into space is the best way, and that's what we've started to do."},{"startTime":3743.875,"endTime":3748.225,"body":"Have we looked from a long way away at what we look like using these"},{"startTime":3748.225,"endTime":3748.805,"body":"various methods?"},{"startTime":3749.155,"endTime":3750.685,"body":"Yeah, people have simulated it."},{"startTime":3750.745,"endTime":3752.965,"body":"We haven't, uh, actually, actually done so."},{"startTime":3752.985,"endTime":3757.038,"body":"So as I said, so t Garden Star, uh, people have looked at what they'd"},{"startTime":3757.038,"endTime":3761.091,"body":"be able to discover and we think that, um, mercury, Venus, earth and Mars would"},{"startTime":3761.091,"endTime":3765.144,"body":"be obvious and Jutter and Saturn would be harder 'cause they take, take longer to"},{"startTime":3765.144,"endTime":3765.685,"body":"go round."},{"startTime":3766.225,"endTime":3770.6,"body":"Um, some of my, the nicest things with this has been where we've used spacecraft"},{"startTime":3770.6,"endTime":3774.685,"body":"that are flying past the earth to study the earth in exactly this way."},{"startTime":3774.865,"endTime":3780.006,"body":"So, uh, the most famous example of this was, um, the Ulysses spacecraft, which went"},{"startTime":3780.006,"endTime":3784.805,"body":"past, uh, on its way into an orbit that studied the sun from above."},{"startTime":3785.345,"endTime":3788.473,"body":"Um, and they didn't have a camera on board, but they looked at what they"},{"startTime":3788.473,"endTime":3789.725,"body":"could detect at the Earth's atmosphere."},{"startTime":3789.725,"endTime":3793.391,"body":"And the conclusion of the study was that they'd found life on earth, but they"},{"startTime":3793.391,"endTime":3796.325,"body":"weren't sure whether it was intelligent, which I think is rather nice."},{"startTime":3797.995,"endTime":3798.285,"body":"Okay."},{"startTime":3798.285,"endTime":3801.585,"body":"We'll do one last one from online and then may be one last from the"},{"startTime":3801.585,"endTime":3801.805,"body":"floor."},{"startTime":3801.805,"endTime":3802.085,"body":"Okay."},{"startTime":3802.385,"endTime":3806.98,"body":"Um, is it possible the orbit partner of the Star is a small black hole"},{"startTime":3806.98,"endTime":3809.125,"body":"occasionally eating away at the Star's mass?"},{"startTime":3809.515,"endTime":3809.805,"body":"Yeah."},{"startTime":3810.225,"endTime":3811.925,"body":"Um, black holes seem to get invo."},{"startTime":3811.925,"endTime":3815.045,"body":"They're almost like aliens in almost any astronomical mystery."},{"startTime":3815.045,"endTime":3816.565,"body":"You can invoke a black hole."},{"startTime":3816.945,"endTime":3822.102,"body":"Um, I think you would see the e if it was close enough to disrupt"},{"startTime":3822.102,"endTime":3825.885,"body":"a planetary system, I think you'd see, uh, the star wobble."},{"startTime":3826.065,"endTime":3827.445,"body":"And we, we've got spectrum of it."},{"startTime":3827.445,"endTime":3829.525,"body":"We don't see it moving around the black hole."},{"startTime":3829.525,"endTime":3831.165,"body":"So I think we can rule that out."},{"startTime":3831.545,"endTime":3834.295,"body":"Of course, you could have a very small black hole, but then it's probably not"},{"startTime":3834.295,"endTime":3834.845,"body":"a useful one."},{"startTime":3835.265,"endTime":3838.878,"body":"So yeah, I think we can rule that out 'cause the star doesn't appear to"},{"startTime":3838.878,"endTime":3840.805,"body":"be an orbit around a, a massive thing."},{"startTime":3841.735,"endTime":3842.085,"body":"Great."},{"startTime":3842.235,"endTime":3842.525,"body":"Okay."},{"startTime":3842.525,"endTime":3844.645,"body":"So the last of the evening, let's see what it is."},{"startTime":3847.545,"endTime":3848.165,"body":"Uh, yes."},{"startTime":3848.425,"endTime":3854.989,"body":"Um, this book probably suffer the same fate as the, um, the, uh, comets, but,"},{"startTime":3854.989,"endTime":3861.553,"body":"uh, if one imagined just a, a massive rubble, maybe a solar system that's, uh,"},{"startTime":3861.553,"endTime":3868.118,"body":"exploded and cooled down, and this is transiting sort of across between us and that"},{"startTime":3868.118,"endTime":3874.245,"body":"planet, would that not, uh, accommodate the, uh, these various dips in the brightness?"},{"startTime":3874.315,"endTime":3874.605,"body":"Yeah."},{"startTime":3874.605,"endTime":3874.885,"body":"Yeah."},{"startTime":3874.885,"endTime":3878.947,"body":"That was something that this, that's a really good idea and it's something that people"},{"startTime":3878.947,"endTime":3883.01,"body":"consider both in orbit around the distance star, like the star, but also maybe in"},{"startTime":3883.01,"endTime":3884.365,"body":"between us and the stars."},{"startTime":3884.465,"endTime":3886.485,"body":"So you've sort of got rubble just in the way."},{"startTime":3886.945,"endTime":3890.405,"body":"Um, if it's around the star, it should be heated and light."},{"startTime":3890.405,"endTime":3891.965,"body":"The comets, it would glow in the infrared."},{"startTime":3891.965,"endTime":3893.525,"body":"So I'm afraid we can rule that out."},{"startTime":3893.745,"endTime":3897.565,"body":"But it's a really good, and we actually see such things around other stars."},{"startTime":3897.565,"endTime":3902.338,"body":"They're called debris discs, and they seem to be, the outcome of some periods of"},{"startTime":3902.338,"endTime":3904.885,"body":"planet formation leaves rubble all over the place."},{"startTime":3904.945,"endTime":3906.245,"body":"So we've actually seen that."},{"startTime":3906.465,"endTime":3908.485,"body":"But in this case, I don't think that's what's going on."},{"startTime":3908.625,"endTime":3912.525,"body":"But, but yeah, no, you've invented something that exists in the universe, which I think"},{"startTime":3912.525,"endTime":3914.605,"body":"is all we can ask for as astronomists."},{"startTime":3914.665,"endTime":3915.565,"body":"So, so thank you."},{"startTime":3915.725,"endTime":3916.845,"body":"I think that's really, really good."},{"startTime":3917.975,"endTime":3921.045,"body":"Thank you so much to Professor Chris for a wonderful lecture."},{"startTime":3921.045,"endTime":3921.405,"body":"Thank you."},{"startTime":3921.405,"endTime":3921.645,"body":"Thank."}]}