{"version":"1.0.0","segments":[{"startTime":5.315,"endTime":5.805,"body":"Good evening."},{"startTime":6.115,"endTime":9.485,"body":"It's a delight to be here and to talk to you all."},{"startTime":9.745,"endTime":13.925,"body":"Um, our story tonight is about what happens when astronomers get ambitious."},{"startTime":14.035,"endTime":19.275,"body":"When we look beyond, uh, the visible spectrum that we are used to seeing and"},{"startTime":19.275,"endTime":19.625,"body":"that we're used to looking up at the night sky, uh, and utilizing and start"},{"startTime":19.625,"endTime":19.974,"body":"to think about, um, wavelengths that aren't accessible to our eyes, to use technology to"},{"startTime":19.974,"endTime":30.805,"body":"explore the universe."},{"startTime":31.425,"endTime":33.485,"body":"Um, and really it's a story of perseverance."},{"startTime":33.485,"endTime":38.435,"body":"It's a story of some, uh, amazing characters who've taken place part in the development"},{"startTime":38.435,"endTime":41.405,"body":"of radio astronomy over the last century or so."},{"startTime":41.785,"endTime":44.645,"body":"Um, but it's also a story of remarkable discoveries."},{"startTime":45.265,"endTime":48.635,"body":"Um, and I thought I'd start off by talking about one that was reasonably close"},{"startTime":48.635,"endTime":49.085,"body":"to home."},{"startTime":49.085,"endTime":54.298,"body":"This is an artist's impression, um, just to have something on the screen of a"},{"startTime":54.298,"endTime":59.165,"body":"possible planet around our nearest star, or rather the nearest star to the sun."},{"startTime":59.625,"endTime":64.306,"body":"So Proximus Centura is just a matter of a few light years away, and we"},{"startTime":64.306,"endTime":64.618,"body":"now know that this nearest star to us has at least one, actually at least"},{"startTime":64.618,"endTime":71.485,"body":"two, and possibly more planets going around it."},{"startTime":71.485,"endTime":74.205,"body":"And the one that features in this artist's impression."},{"startTime":74.835,"endTime":78.085,"body":"Proxima B, which is a properly sci-fi kind of name."},{"startTime":78.325,"endTime":78.925,"body":"I think prox."},{"startTime":78.985,"endTime":83.045,"body":"And normally I'm, I'm not into astronomers naming things, but proximal B sounds good."},{"startTime":83.385,"endTime":85.885,"body":"Um, goes round the star every 11 days."},{"startTime":86.425,"endTime":90.156,"body":"So it's pretty close to its star, certainly much closer than Mercury is to the"},{"startTime":90.156,"endTime":90.405,"body":"sun."},{"startTime":90.985,"endTime":96.637,"body":"But because Proxima Ura itself is a faint red dwarf, Proxima B may have the"},{"startTime":96.637,"endTime":100.405,"body":"right kind of climate to support our kind of life."},{"startTime":100.435,"endTime":105.243,"body":"It's in what we call the habitable zone, clustered up against the pale red dot"},{"startTime":105.243,"endTime":106.205,"body":"of its star."},{"startTime":107.105,"endTime":111.499,"body":"And so this is a place that we can think about looking for life in"},{"startTime":111.499,"endTime":112.085,"body":"the universe."},{"startTime":112.145,"endTime":113.405,"body":"And that has been done."},{"startTime":113.405,"endTime":117.405,"body":"It's been done many times, but most recently by this magnificent dish."},{"startTime":117.435,"endTime":120.325,"body":"This is the Mur Young Parks Telescope."},{"startTime":120.395,"endTime":125.74,"body":"It's most famous as the dish in the film, um, which relayed the TV pictures"},{"startTime":125.74,"endTime":131.085,"body":"from Apollo 11, uh, and the first walk on the moon to the waiting world."},{"startTime":131.425,"endTime":136.685,"body":"But it's a high class, uh, research facility, not just a communications dish."},{"startTime":137.145,"endTime":142.293,"body":"Uh, and in 2019, it spent, uh, a couple of months spending most of its"},{"startTime":142.293,"endTime":142.637,"body":"time looking at Proximus Centura, looking for signals that might betray the p presence, not"},{"startTime":142.637,"endTime":142.98,"body":"just of life, but of intelligence, uh, on, uh, this near on a planet going"},{"startTime":142.98,"endTime":153.965,"body":"around this nearby star."},{"startTime":154.885,"endTime":159.885,"body":"A year later in 2020, the team who were doing this from a project called"},{"startTime":159.885,"endTime":160.218,"body":"Breakthrough Listen Now, colleagues of mine in Oxford, but then based in Berkeley, um, realized"},{"startTime":160.218,"endTime":160.551,"body":"that they thought they had something, that there was a signal in these observations that"},{"startTime":160.551,"endTime":173.885,"body":"seem to be coming from a planet orbiting, uh, our nearest star."},{"startTime":174.385,"endTime":175.525,"body":"Uh, and this leaked."},{"startTime":175.905,"endTime":180.373,"body":"Uh, so anyone who, who likes the conspiracy theories, I've always told people that astronomers"},{"startTime":180.373,"endTime":181.565,"body":"can't keep a secret."},{"startTime":181.935,"endTime":182.925,"body":"Turns out this is true."},{"startTime":183.325,"endTime":184.965,"body":"Ian sample at The Guardian got hold of this."},{"startTime":184.965,"endTime":190.965,"body":"And on the 18th of December, 2020 published a reasonably cautious article that says, scientists"},{"startTime":190.965,"endTime":194.565,"body":"Looking for Aliens investigate radio Beam from nearby Star."},{"startTime":194.565,"endTime":199.418,"body":"And it went on to explain that while the signal will, they said, will probably"},{"startTime":199.418,"endTime":199.742,"body":"turn out to be something other than life, um, this was the kind of thing,"},{"startTime":199.742,"endTime":200.066,"body":"a narrow band signal at a particular frequency that moved as if it was on"},{"startTime":200.066,"endTime":200.389,"body":"a planet, uh, that those who've spent years looking for alien intelligent life out there,"},{"startTime":200.389,"endTime":200.713,"body":"uh, might have hoped to have found, to find it on the next star is,"},{"startTime":200.713,"endTime":219.805,"body":"is really exciting."},{"startTime":219.825,"endTime":225.315,"body":"If there's an intelligent civilization next door, then surely we live in a properly Star"},{"startTime":225.315,"endTime":230.805,"body":"Trek universe with intelligent species on most planets, or at least most m class planets."},{"startTime":231.065,"endTime":234.685,"body":"Uh, and then we can go on and explore the galaxy with our new neighbors."},{"startTime":234.905,"endTime":240.056,"body":"So this was hugely exciting and it builds on this long tradition of using radio"},{"startTime":240.056,"endTime":240.399,"body":"telescopes for exactly this, for the search for extra terrestrial intelligence that goes all the"},{"startTime":240.399,"endTime":246.925,"body":"way back to the 1960s."},{"startTime":247.665,"endTime":252.947,"body":"Uh, when scientists, uh, green Bank in West Virginia, uh, undertook what they called Project"},{"startTime":252.947,"endTime":253.3,"body":"Osmo using spare time and spare resources because they didn't want to be seen to"},{"startTime":253.3,"endTime":253.652,"body":"be spending government money listening for aliens on pointing their telescopes at the sky, looking"},{"startTime":253.652,"endTime":254.004,"body":"for repeating signals in the radio that they thought might be, uh, setting might be"},{"startTime":254.004,"endTime":270.205,"body":"signs of extraterrestrial intelligence."},{"startTime":270.205,"endTime":272.685,"body":"And of course, this is a staple of science fiction."},{"startTime":272.785,"endTime":273.885,"body":"You know how this works."},{"startTime":273.945,"endTime":276.485,"body":"You know how radio astronomers go about this work?"},{"startTime":276.765,"endTime":278.485,"body":"'cause you've seen films, films like Contact."},{"startTime":279.225,"endTime":283.245,"body":"Uh, here is, uh, Jody Foster as radio astronomer listening in."},{"startTime":283.665,"endTime":288.215,"body":"Uh, you can tell she's serious 'cause the headphones are upside down, uh, to data"},{"startTime":288.215,"endTime":292.765,"body":"from the very larger array just before in the film, a a signal comes in."},{"startTime":293.545,"endTime":299.245,"body":"But it's worth thinking about why radio is the astronomers tool for choice for this."},{"startTime":299.245,"endTime":305.165,"body":"There are advantages in looking, uh, or using the radio rather than the optical."},{"startTime":305.225,"endTime":309.285,"body":"One of them, of course, is that you can observe even when it's cloudy."},{"startTime":309.625,"endTime":314.445,"body":"And for an astronomer based in Britain, this is an essential feature of radio astronomy."},{"startTime":314.445,"endTime":316.325,"body":"So have we got the live feed running?"},{"startTime":316.425,"endTime":317.765,"body":"If we could just turn up the sound."},{"startTime":318.635,"endTime":323.165,"body":"This is noise from a a, a very simple antenna acting as a radio telescope."},{"startTime":323.985,"endTime":329.825,"body":"And what you are listening to is a frequency is associated with a TV station"},{"startTime":329.825,"endTime":330.215,"body":"that's over the horizon from this antenna, which is broadcasting live on the internet on"},{"startTime":330.215,"endTime":336.445,"body":"live meteors.com."},{"startTime":336.945,"endTime":342.162,"body":"And what we're listening for is the moment when a meteor, a shooting star hits"},{"startTime":342.162,"endTime":342.51,"body":"the upper atmosphere, just for that moment, it will ionize, it'll excite atoms in the"},{"startTime":342.51,"endTime":342.858,"body":"earth's atmosphere, and then the signal from the distant TV station will bounce off that"},{"startTime":342.858,"endTime":354.685,"body":"and be received by the antenna."},{"startTime":355.185,"endTime":357.085,"body":"So we should at some point hear a ping."},{"startTime":357.165,"endTime":359.525,"body":"Now, there isn't a meteor shower going on at the minute."},{"startTime":359.985,"endTime":364.601,"body":"If I did this in the middle of August, we'd get maybe, uh, as many"},{"startTime":364.601,"endTime":364.908,"body":"as 80 an hour we're listening for sporadic meteors that maybe happen once every few"},{"startTime":364.908,"endTime":369.525,"body":"minutes."},{"startTime":370.105,"endTime":372.485,"body":"Um, and I was hoping that by filling we'd hear something."},{"startTime":372.785,"endTime":375.765,"body":"But what I might do is just ask the text to let that play."},{"startTime":375.825,"endTime":377.045,"body":"Oh, there we go."},{"startTime":377.045,"endTime":377.845,"body":"That was just a gap."},{"startTime":379.065,"endTime":381.245,"body":"You know, atmospheric conditions interfere."},{"startTime":381.995,"endTime":385.321,"body":"This was gonna be great when it pinged early, but you could tell I haven't"},{"startTime":385.321,"endTime":385.765,"body":"faked it."},{"startTime":385.985,"endTime":389.078,"body":"We might just let that play if that's not disturbing people, let's just let that"},{"startTime":389.078,"endTime":389.285,"body":"play."},{"startTime":389.285,"endTime":392.21,"body":"And if you hear anything, my hearing's not the best, please just put a hand"},{"startTime":392.21,"endTime":392.405,"body":"up."},{"startTime":392.905,"endTime":395.285,"body":"Uh, and then we'll have a moment of meteor observation."},{"startTime":395.345,"endTime":399.166,"body":"So yes, you can observe during the day and you can observe when it's cloudy,"},{"startTime":399.166,"endTime":401.205,"body":"and you can observe in these interesting ways."},{"startTime":401.985,"endTime":406.365,"body":"Um, but there's a more fundamental reason to switch to radio astronomy as well."},{"startTime":406.905,"endTime":410.31,"body":"Um, that is, I can see the sound people at the back going, this is"},{"startTime":410.31,"endTime":411.445,"body":"gonna ruin this lecture \u003claugh\u003e."},{"startTime":412.425,"endTime":414.605,"body":"Um, I'm gonna keep going till we get a meteor there."},{"startTime":415.065,"endTime":418.645,"body":"Um, there's a more fundamental reason to, oh, there you go."},{"startTime":418.785,"endTime":419.325,"body":"Did you hear that?"},{"startTime":419.555,"endTime":419.845,"body":"Yeah."},{"startTime":419.845,"endTime":420.205,"body":"There you go."},{"startTime":420.275,"endTime":420.565,"body":"Good."},{"startTime":420.845,"endTime":421.045,"body":"Excellent."},{"startTime":421.065,"endTime":422.085,"body":"One meteor detected."},{"startTime":423.155,"endTime":424.085,"body":"Kill that for now."},{"startTime":425.665,"endTime":429.769,"body":"Um, I recommend live meteors.com even when you're trying to get to sleep, it's quite"},{"startTime":429.769,"endTime":431.685,"body":"restful in a strange kind of way."},{"startTime":431.795,"endTime":432.085,"body":"Good."},{"startTime":432.415,"endTime":436.365,"body":"We've made an astronomical observation live from the stage that makes me very happy."},{"startTime":436.865,"endTime":441.59,"body":"Um, there's a fundamental reason not just observing in cloud during the day that makes"},{"startTime":441.59,"endTime":443.165,"body":"you switch to radio astronomy."},{"startTime":443.385,"endTime":447.715,"body":"And it's a consequence of the fact that we are looking at, at wavelengths that"},{"startTime":447.715,"endTime":452.045,"body":"are much longer than the visible light we're used to seeing with the visible light."},{"startTime":452.045,"endTime":454.405,"body":"You're at, um, nanometers."},{"startTime":454.465,"endTime":456.485,"body":"So, so very small wavelengths."},{"startTime":456.785,"endTime":462.77,"body":"The radio waves we use for astronomy range from about 10 centimeters up to tens"},{"startTime":462.77,"endTime":464.765,"body":"or even hundreds of kilometers."},{"startTime":465.105,"endTime":468.245,"body":"So these are very long wavelength radiation."},{"startTime":468.825,"endTime":473.725,"body":"And what that means is that they pass through the galaxy relatively unimpeded."},{"startTime":474.505,"endTime":478.568,"body":"And so if you look for example, towards the center of the galaxy, using a"},{"startTime":478.568,"endTime":478.838,"body":"normal telescope, one with a mirror and an eyepiece or a camera that's used to"},{"startTime":478.838,"endTime":479.109,"body":"working in the optical, you get beautiful shots like this one from my friend Will"},{"startTime":479.109,"endTime":486.965,"body":"Gator."},{"startTime":487.705,"endTime":493.611,"body":"But what you're seeing here is dust blocking our view towards the center of the"},{"startTime":493.611,"endTime":494.005,"body":"galaxy."},{"startTime":494.065,"endTime":499.15,"body":"So this dark material actually obscures our view of, of much of our, of the"},{"startTime":499.15,"endTime":500.845,"body":"system that we live in."},{"startTime":501.105,"endTime":503.325,"body":"We get to only see our local neighborhood."},{"startTime":503.865,"endTime":508.355,"body":"And this, for those of you who are here for my first lecture, uh, earlier"},{"startTime":508.355,"endTime":508.655,"body":"in the year, this was why William Herschel's great project of mapping the Milky Way"},{"startTime":508.655,"endTime":514.044,"body":"by counting stars fails."},{"startTime":514.585,"endTime":519.57,"body":"It fails because all he does is measure how much dust there is in the"},{"startTime":519.57,"endTime":521.565,"body":"galaxy, absorbing and scattering visible light."},{"startTime":521.865,"endTime":526.552,"body":"But with radio waves, you can see right through this dust, you can see all"},{"startTime":526.552,"endTime":529.365,"body":"the way, uh, to the center of the galaxy."},{"startTime":529.625,"endTime":534.481,"body":"And so we have a very different view of our surroundings once we switch to"},{"startTime":534.481,"endTime":534.805,"body":"radio."},{"startTime":535.385,"endTime":540.136,"body":"And this was something that was apparent even in the early days of radio astronomy,"},{"startTime":540.136,"endTime":540.453,"body":"um, radio astronomy, sort of, I was gonna say it happened by accident, that's probably"},{"startTime":540.453,"endTime":545.205,"body":"unfair."},{"startTime":545.665,"endTime":550.432,"body":"But what is true is that it was developed by people who were not astronomers,"},{"startTime":550.432,"endTime":550.75,"body":"who people with expertise in the new technology of radio communication that was growing up,"},{"startTime":550.75,"endTime":551.068,"body":"uh, after the first World War in the twenties, and particularly into the thirties and"},{"startTime":551.068,"endTime":560.285,"body":"forties."},{"startTime":561.465,"endTime":565.948,"body":"The man with the distinction of being the first radio astronomer ever, I think is"},{"startTime":565.948,"endTime":566.845,"body":"is this chap."},{"startTime":566.845,"endTime":568.045,"body":"This is Carl Jansky."},{"startTime":568.825,"endTime":573.405,"body":"Um, he was working at Bell Labs in New Jersey in, uh, the United States."},{"startTime":574.145,"endTime":581.201,"body":"Um, and his task was to identify where background static was coming from, um, the"},{"startTime":581.201,"endTime":584.965,"body":"kind of noise that interferes with radio communication."},{"startTime":585.785,"endTime":590.603,"body":"Um, and so to research this question, he built the, the rather magnificently jury rigged"},{"startTime":590.603,"endTime":590.925,"body":"instrument."},{"startTime":591.105,"endTime":593.805,"body":"You can see here, this was known as his merry-go-round."},{"startTime":594.185,"endTime":599.779,"body":"So this is a set of simple antennae on, uh, bicycle wheels, um, that he"},{"startTime":599.779,"endTime":600.525,"body":"could rotate."},{"startTime":601.345,"endTime":604.285,"body":"And the point here is that you then have a directional instrument."},{"startTime":604.345,"endTime":608.64,"body":"So you can tell if the noise is coming from over here or over here"},{"startTime":608.64,"endTime":610.645,"body":"or over here and using this instrument."},{"startTime":610.745,"endTime":615.671,"body":"And after lots of painstaking study, uh, Jansky realized that most of the noise of"},{"startTime":615.671,"endTime":619.285,"body":"the frequencies at which he was working, um, came from thunderstorms."},{"startTime":619.665,"endTime":622.445,"body":"So he was observing thunderstorms in the earth atmosphere."},{"startTime":623.065,"endTime":628.947,"body":"Um, and then the story gets interesting 'cause there's a long sequence of many of"},{"startTime":628.947,"endTime":629.34,"body":"the observations I'll be telling you about tonight where somebody isn't content with doing half"},{"startTime":629.34,"endTime":635.615,"body":"a job."},{"startTime":636.255,"endTime":640.481,"body":"I think Jankis bosses would've been very happy if he'd written up his results and"},{"startTime":640.481,"endTime":642.735,"body":"said, most of the noise comes from thunderstorms."},{"startTime":642.735,"endTime":644.055,"body":"Can't do anything about thunderstorms."},{"startTime":644.615,"endTime":645.895,"body":"I guess you can monitor the activity."},{"startTime":646.115,"endTime":647.815,"body":"Job done, move on to next project."},{"startTime":648.275,"endTime":652.951,"body":"But he realized there was this other source of noise there that seemed to always"},{"startTime":652.951,"endTime":653.575,"body":"be there."},{"startTime":654.315,"endTime":659.097,"body":"And initially he thought that it was coming from the direction of the sun in"},{"startTime":659.097,"endTime":659.735,"body":"the sky."},{"startTime":660.645,"endTime":662.015,"body":"This was a remarkable discovery."},{"startTime":662.115,"endTime":665.215,"body":"No one had predicted that radio waves would come from the sun."},{"startTime":665.215,"endTime":668.495,"body":"And so jansky began to study this extra noise."},{"startTime":670.765,"endTime":676.507,"body":"Perhaps, unfortunately, or perhaps fortunately, over time, what happened was the whatever was causing this"},{"startTime":676.507,"endTime":680.335,"body":"extra noise drifted away from the sun in the sky."},{"startTime":680.835,"endTime":684.861,"body":"So as the months rolled on, it turned out this wasn't the sun that was"},{"startTime":684.861,"endTime":685.935,"body":"causing the, the noise."},{"startTime":686.555,"endTime":691.785,"body":"Um, but he did realize that it repeated, it appeared in the same part of"},{"startTime":691.785,"endTime":694.575,"body":"the sky every 23 hours and 56 minutes."},{"startTime":695.435,"endTime":699.895,"body":"Now, that's the side day, that's the time it takes for the earth to rotate."},{"startTime":700.205,"endTime":703.575,"body":"Once 24 hours is the solar day."},{"startTime":703.575,"endTime":706.101,"body":"It's how long it takes to get back with the sun in the same position"},{"startTime":706.101,"endTime":706.775,"body":"relative to the earth."},{"startTime":706.795,"endTime":711.353,"body":"If you pointed a star and wait a day, the earth will rotate you and"},{"startTime":711.353,"endTime":715.0,"body":"you'll be back pointing at, at it 23 hours, 56 minutes later."},{"startTime":715.0,"endTime":719.085,"body":"That's why stars set four minutes earlier each day."},{"startTime":719.085,"endTime":720.805,"body":"It's why we get the changing of the constellations."},{"startTime":721.105,"endTime":727.092,"body":"So this observation, the fact that this noise was 23 hours, 56 minutes, uh, in"},{"startTime":727.092,"endTime":730.685,"body":"repetition, meant that it was coming from the universe."},{"startTime":731.745,"endTime":736.805,"body":"And Jansky called it star noise, which is apparently the thread this evening."},{"startTime":736.805,"endTime":738.925,"body":"Is astronomers doing a good job of naming things?"},{"startTime":739.125,"endTime":740.085,"body":"I like star noise."},{"startTime":740.245,"endTime":742.565,"body":"I think we should have stuck with calling this star noise."},{"startTime":743.305,"endTime":744.925,"body":"Um, and so he wrote up these results."},{"startTime":744.925,"endTime":749.267,"body":"He got some publicity, and he was essentially told by his bosses that he should"},{"startTime":749.267,"endTime":751.005,"body":"go back to doing proper work."},{"startTime":751.625,"endTime":754.845,"body":"Um, and went back and, and never quite developed."},{"startTime":754.985,"endTime":760.085,"body":"So he died early in 1950 before the great burgeoning of radio astronomy."},{"startTime":760.085,"endTime":762.885,"body":"But we now recognize him as the, the first radio astronomer."},{"startTime":763.465,"endTime":766.405,"body":"He did get his star noise played on NBC radio."},{"startTime":767.545,"endTime":771.729,"body":"One of the people listening was the second great pioneer of radio astronomy and a"},{"startTime":771.729,"endTime":772.845,"body":"hero of mine, groat."},{"startTime":773.005,"endTime":777.962,"body":"Reba Reba was a, an engineer who worked in suburban Illinois, lived in Wheaton, commuted"},{"startTime":777.962,"endTime":779.285,"body":"to work in Chicago."},{"startTime":779.945,"endTime":784.045,"body":"Um, and as soon as he heard star noise on the radio, he wrote to"},{"startTime":784.045,"endTime":785.685,"body":"Bell Labs asking for a job."},{"startTime":786.435,"endTime":790.685,"body":"They presumably went, we've already got one of these people distracted by the universe."},{"startTime":791.225,"endTime":792.885,"body":"And so gave him very short shift."},{"startTime":793.545,"endTime":798.541,"body":"He then, um, wrote to pretty much every astronomer in the United States to Yerkes"},{"startTime":798.541,"endTime":798.875,"body":"to Harvard, to the new observatories in California, and said, I want to work on"},{"startTime":798.875,"endTime":804.205,"body":"radio astronomy."},{"startTime":804.865,"endTime":810.076,"body":"And he basically got a set of reactions, which were what no one wanted to"},{"startTime":810.076,"endTime":814.245,"body":"know about this guy with his vacuum tubes and his, his radios."},{"startTime":814.245,"endTime":815.285,"body":"This isn't astronomy."},{"startTime":815.485,"endTime":819.005,"body":"Astronomy is about making maps with telescopes, uh, and so on."},{"startTime":819.025,"endTime":823.556,"body":"And so he concluded in his writings at his time that the astronomers were afraid"},{"startTime":823.556,"endTime":824.765,"body":"of this new science."},{"startTime":825.505,"endTime":829.026,"body":"And in a very great Reba sentence, he said, it was clear that nobody was"},{"startTime":829.026,"endTime":829.965,"body":"going to do anything."},{"startTime":830.065,"endTime":832.085,"body":"So maybe I thought I should do something."},{"startTime":832.105,"endTime":833.205,"body":"And this is what he did."},{"startTime":833.625,"endTime":836.325,"body":"He built the world's first proper radio telescope."},{"startTime":836.325,"endTime":840.485,"body":"This is only four years after Jankis publication of his star noise."},{"startTime":840.825,"endTime":842.885,"body":"So this is a fully steerable dish."},{"startTime":843.305,"endTime":846.765,"body":"Uh, it's about 30 foot across, so that's nearly 10 meters across."},{"startTime":847.425,"endTime":853.282,"body":"Um, and he could swing this around the sky and make maps observing with it"},{"startTime":853.282,"endTime":854.845,"body":"wasn't without its difficulties."},{"startTime":855.065,"endTime":856.125,"body":"He still had to go to work."},{"startTime":856.625,"endTime":860.69,"body":"So he'd go to work, he'd come back, he'd sleep for an hour, and then"},{"startTime":860.69,"endTime":862.045,"body":"he'd observe him at night."},{"startTime":863.235,"endTime":867.045,"body":"This confused me when I found this out 'cause we've just said you can observe"},{"startTime":867.045,"endTime":867.299,"body":"during the day if you're a radio astronomer, but the starter motors of cars at"},{"startTime":867.299,"endTime":872.125,"body":"the time emit radio waves."},{"startTime":872.505,"endTime":874.725,"body":"And so during the day, he just detected traffic."},{"startTime":875.265,"endTime":878.469,"body":"Um, and so he would observe at night, get a couple more hours, sleep, go"},{"startTime":878.469,"endTime":879.965,"body":"back to work and repeat the process."},{"startTime":880.705,"endTime":885.871,"body":"Um, the only hindrance to this very valuable scientific practice was that his mother who"},{"startTime":885.871,"endTime":890.005,"body":"lived with him, um, used to hang her washing on the dish."},{"startTime":890.145,"endTime":894.245,"body":"And so that often had to be removed before observations could, could proceed."},{"startTime":896.325,"endTime":902.261,"body":"Reba got remarkable results out of this telescope, spending his weekends reducing the observations and"},{"startTime":902.261,"endTime":903.845,"body":"turning them into maps."},{"startTime":904.745,"endTime":908.245,"body":"Um, these, uh, this is a map of the radio sky."},{"startTime":908.385,"endTime":912.165,"body":"So this is, you can imagine this is the celestial globe, two sides."},{"startTime":912.555,"endTime":918.232,"body":"This is the intensity of radio waves in a map that he produced after six"},{"startTime":918.232,"endTime":920.125,"body":"years of effort in 1939."},{"startTime":920.905,"endTime":925.064,"body":"And what it really shows you is that there are places in the sky where"},{"startTime":925.064,"endTime":927.005,"body":"there are bright sources of radio waves."},{"startTime":927.005,"endTime":930.852,"body":"The brightest of them at the top of this map is, uh, towards the constellation"},{"startTime":930.852,"endTime":931.365,"body":"of Sagittarius."},{"startTime":931.735,"endTime":935.66,"body":"There are others in Nus, in Cassie p in the North Canis major and puppets"},{"startTime":935.66,"endTime":936.445,"body":"in the South."},{"startTime":936.465,"endTime":938.605,"body":"But he managed to find that there are different sources."},{"startTime":938.745,"endTime":943.205,"body":"So it's not a uniform glow of radio waves that we're, we are bathed in."},{"startTime":943.205,"endTime":948.085,"body":"It's, uh, a universe where there are things that emit radio waves."},{"startTime":949.145,"endTime":954.29,"body":"He wrote to Otto Str, uh, who was a professional astronomer, who ran the main"},{"startTime":954.29,"endTime":954.633,"body":"journal at the time, said in a deeply technical paper that explained the observations, showed"},{"startTime":954.633,"endTime":954.976,"body":"these maps, and noted for the first time that our galaxy, the Milky Way, seemed"},{"startTime":954.976,"endTime":969.725,"body":"to have spiral arms, that the structure of the galaxy is revealed in these maps."},{"startTime":969.725,"endTime":971.605,"body":"We hadn't been able to see that before."},{"startTime":972.185,"endTime":976.368,"body":"Um, str and the other astronomers didn't know what, still didn't know what to make"},{"startTime":976.368,"endTime":977.205,"body":"of, of Reba."},{"startTime":977.585,"endTime":981.085,"body":"Um, they didn't publish his paper, but nor did they reject it."},{"startTime":981.085,"endTime":983.205,"body":"They sort of viewed it as a curiosity."},{"startTime":984.105,"endTime":989.641,"body":"And I think uniquely in the history of scientific, of astronomical publishing, they sent a"},{"startTime":989.641,"endTime":990.011,"body":"delegation of proper astronomers to Wheaton outside Chicago to inspect this man and his telescope"},{"startTime":990.011,"endTime":990.38,"body":"and see what he was talking about after the, he seemed to have passed the"},{"startTime":990.38,"endTime":1001.085,"body":"inspection."},{"startTime":1001.085,"endTime":1004.805,"body":"They published the paper, uh, many years after it'd been submitted."},{"startTime":1004.945,"endTime":1009.838,"body":"And, and Reba complained that it, that his data had been sat on until it"},{"startTime":1009.838,"endTime":1014.405,"body":"got moldy, starting a lifetime of really not getting on with the scientific establishment."},{"startTime":1014.785,"endTime":1021.614,"body":"Uh, but he'd shown that radio astronomy, not just radio monitoring of a background noise"},{"startTime":1021.614,"endTime":1022.525,"body":"was possible."},{"startTime":1023.505,"endTime":1026.204,"body":"Um, I could fill the rest of the lecture with Reba."},{"startTime":1026.204,"endTime":1030.501,"body":"He ends up in the fifties, employed as an astronomer, but he proposes a telescope"},{"startTime":1030.501,"endTime":1030.787,"body":"that's bigger than anything we've got today, which the US government doesn't want to pay"},{"startTime":1030.787,"endTime":1035.085,"body":"for."},{"startTime":1035.505,"endTime":1040.855,"body":"Uh, he then decides that the solution is to look for radio waves bouncing off"},{"startTime":1040.855,"endTime":1041.925,"body":"ocean, uh, waves."},{"startTime":1041.925,"endTime":1046.24,"body":"So you use the ocean as a radio telescope essentially, uh, that takes him to"},{"startTime":1046.24,"endTime":1049.405,"body":"Hawaii while in Hawaii, decides he doesn't want to come home."},{"startTime":1049.425,"endTime":1052.205,"body":"So he quits his job and stays in Hawaii for about 20 years."},{"startTime":1052.585,"endTime":1057.414,"body":"He ends up in Tasmania where he publishes a well sighted paper, uh, that explains"},{"startTime":1057.414,"endTime":1057.735,"body":"that Tasmanian parrots are right clawed in the same way that some of us are"},{"startTime":1057.735,"endTime":1062.565,"body":"right-handed."},{"startTime":1062.985,"endTime":1066.96,"body":"Uh, he also studies the genetics of beans, builds his own electric car, and has"},{"startTime":1066.96,"endTime":1070.405,"body":"a house that's mostly made of aluminum to keep the energy use down."},{"startTime":1070.475,"endTime":1072.125,"body":"It's very advanced for the seventies."},{"startTime":1072.665,"endTime":1079.628,"body":"Um, he also built more radio telescopes, um, and was frustrated that he couldn't prove"},{"startTime":1079.628,"endTime":1081.485,"body":"his theories of cosmology."},{"startTime":1081.585,"endTime":1083.605,"body":"He didn't believe in the Big bang, correct."},{"startTime":1084.185,"endTime":1089.816,"body":"Um, he acknowledged that other astronomers didn't agree with him, but he put that down"},{"startTime":1089.816,"endTime":1092.445,"body":"to what he described as narrow-minded incompetence."},{"startTime":1093.065,"endTime":1097.445,"body":"Um, and thought that the problem was the earth's upper atmosphere."},{"startTime":1097.445,"endTime":1102.905,"body":"We had a demonstration earlier that the Earth's upper upper atmosphere can change properties of"},{"startTime":1102.905,"endTime":1104.725,"body":"radio waves passing through it."},{"startTime":1104.725,"endTime":1107.085,"body":"That's how we heard the ping of the meteor."},{"startTime":1107.945,"endTime":1115.102,"body":"Um, and so Reba requested a intercontinental ballistic missile to be launched above his house"},{"startTime":1115.102,"endTime":1117.965,"body":"thinking that its exhaust would change."},{"startTime":1118.115,"endTime":1121.865,"body":"This is all true, by the way, uh, that it would change the ionosphere and"},{"startTime":1121.865,"endTime":1123.365,"body":"enable him to make his observations."},{"startTime":1123.425,"endTime":1124.805,"body":"Now, that didn't work."},{"startTime":1124.865,"endTime":1130.125,"body":"He wasn't allowed to use an ICBM, but he did have enough clout at the"},{"startTime":1130.125,"endTime":1130.476,"body":"age of 70 that NASA fired the engines of a space shutter while it passed"},{"startTime":1130.476,"endTime":1139.245,"body":"over his observatory in an effort to change the upper atmosphere."},{"startTime":1139.385,"endTime":1144.147,"body":"And, you know, I think aspiring to that sort of influence after a career spent"},{"startTime":1144.147,"endTime":1144.465,"body":"studying parrots, making inventions and inventing a branch of science, I think this is, this"},{"startTime":1144.465,"endTime":1152.085,"body":"is, there's a reason that he's a hero of mine."},{"startTime":1153.315,"endTime":1156.445,"body":"However, he left questions behind us."},{"startTime":1156.445,"endTime":1157.685,"body":"He left the astronomical mainstream."},{"startTime":1157.685,"endTime":1160.965,"body":"Mainly, what on earth are these things that are emitting radio waves?"},{"startTime":1160.965,"endTime":1166.045,"body":"And in particular, what is this bright thing in the constellation of Sagittarius?"},{"startTime":1166.545,"endTime":1169.485,"body":"Now we've seen Sagittarius already when I showed you this picture."},{"startTime":1170.265,"endTime":1172.925,"body":"Uh, this is an image of the middle of our galaxy."},{"startTime":1172.925,"endTime":1174.805,"body":"We're looking towards the center of the Milky Way."},{"startTime":1174.805,"endTime":1179.89,"body":"And the constellation of Sagittarius is right there looking a little like a celestial teapot"},{"startTime":1179.89,"endTime":1181.925,"body":"for those who know their constellations."},{"startTime":1182.425,"endTime":1189.043,"body":"But working out what this thing was, had to wait until sharper images could be"},{"startTime":1189.043,"endTime":1189.485,"body":"obtained."},{"startTime":1190.105,"endTime":1194.605,"body":"The trouble is that how sharp an image produced by a telescope is depends on"},{"startTime":1194.605,"endTime":1195.205,"body":"two things."},{"startTime":1195.385,"endTime":1196.925,"body":"One is the size of the telescope."},{"startTime":1197.565,"endTime":1201.399,"body":"A bigger telescope will give you a sharper image, but it also depends on the"},{"startTime":1201.399,"endTime":1203.445,"body":"wavelength of the light that you're looking at."},{"startTime":1203.785,"endTime":1208.365,"body":"And because radio waves have this long wavelength, you get blurry images."},{"startTime":1208.465,"endTime":1213.949,"body":"That's why in the 1930s when we were taking beautiful pictures of nebuli in the"},{"startTime":1213.949,"endTime":1214.315,"body":"radio with sketching squiggles on a map, the solution is to have a very big"},{"startTime":1214.315,"endTime":1220.165,"body":"telescope indeed."},{"startTime":1220.785,"endTime":1223.645,"body":"But building very, very big telescopes is very difficult."},{"startTime":1224.065,"endTime":1227.925,"body":"And so by the seventies, what people have learned to do is what's called interferometry."},{"startTime":1228.465,"endTime":1231.605,"body":"Um, combining light from many telescopes."},{"startTime":1231.605,"endTime":1233.845,"body":"This is the very large array in New Mexico."},{"startTime":1234.625,"endTime":1238.605,"body":"And though these are all individual dishes, they act as one telescope."},{"startTime":1239.145,"endTime":1244.413,"body":"So you feed the, the, uh, signal they receive either directly at the time through"},{"startTime":1244.413,"endTime":1247.925,"body":"cables or later in the computer into a central system."},{"startTime":1247.945,"endTime":1252.895,"body":"And you get to some extent an image that's as sharp as if the dish"},{"startTime":1252.895,"endTime":1255.205,"body":"was as big as the whole array."},{"startTime":1255.785,"endTime":1261.899,"body":"And these days, we can combine dishes from across continents to produce virtual telescopes that"},{"startTime":1261.899,"endTime":1262.306,"body":"the size of the earth using, uh, an early version of this interferometer in the"},{"startTime":1262.306,"endTime":1262.714,"body":"1970s, um, it was a astronomers were able to show that that thing at the"},{"startTime":1262.714,"endTime":1276.165,"body":"century of Sagittarius is small."},{"startTime":1277.075,"endTime":1278.405,"body":"It's less than a parex."},{"startTime":1278.405,"endTime":1280.645,"body":"So that's less than about three light years across."},{"startTime":1281.225,"endTime":1286.215,"body":"So even though whatever it is is bright enough that we see it from the,"},{"startTime":1286.215,"endTime":1291.205,"body":"uh, center of the galaxy, more than 20,000 light years away, it's a small object."},{"startTime":1291.785,"endTime":1296.727,"body":"And it was called at that point, Sagittarius a star for shadowing GCSE grates by"},{"startTime":1296.727,"endTime":1298.045,"body":"a couple of decades."},{"startTime":1298.705,"endTime":1301.885,"body":"Uh, the star is a chemical notation for being excited."},{"startTime":1302.025,"endTime":1306.125,"body":"And the astronomers in question thought it was exciting that they had this compact source."},{"startTime":1306.865,"endTime":1308.645,"body":"Now, the Galactic Center is complicated."},{"startTime":1308.795,"endTime":1314.12,"body":"Here is a modern radio image from the Meca telescope in South Africa via my"},{"startTime":1314.12,"endTime":1316.605,"body":"colleague Ian Hayward and Co in Oxford."},{"startTime":1316.945,"endTime":1319.805,"body":"Um, if you can see, there's all sorts of stuff going on here."},{"startTime":1319.905,"endTime":1324.455,"body":"The, the compact source is the bright thing at the bottom that's sag a star,"},{"startTime":1324.455,"endTime":1325.365,"body":"Sagittarius a star."},{"startTime":1325.745,"endTime":1326.965,"body":"You see there's a sort of bubble."},{"startTime":1327.065,"endTime":1328.445,"body":"You're looking at gas here."},{"startTime":1328.445,"endTime":1332.685,"body":"And so there's a bubble of gas just above, uh, that bright object."},{"startTime":1332.985,"endTime":1337.273,"body":"And then there's these mysterious arcs that sweep across this image from bottom left to"},{"startTime":1337.273,"endTime":1337.845,"body":"top right."},{"startTime":1337.845,"endTime":1344.595,"body":"They're filaments of material and we don't understand yet what the cause of these structures"},{"startTime":1344.595,"endTime":1345.045,"body":"are."},{"startTime":1345.065,"endTime":1346.525,"body":"We need to look more, more closely."},{"startTime":1346.665,"endTime":1348.805,"body":"We need to see if they change over time."},{"startTime":1348.865,"endTime":1351.525,"body":"We need to investigate them at different wavelengths."},{"startTime":1351.525,"endTime":1357.051,"body":"But we do now know what lurks at the center of that blob at the"},{"startTime":1357.051,"endTime":1358.525,"body":"bottom of the image."},{"startTime":1359.105,"endTime":1363.605,"body":"And we know this not just because of radio, but because we followed up with"},{"startTime":1363.605,"endTime":1364.205,"body":"other wavelengths."},{"startTime":1364.205,"endTime":1368.591,"body":"Having identified that the center of the galaxy is interesting, we can look in the"},{"startTime":1368.591,"endTime":1372.685,"body":"infrared and using the infrared because we get a sharper image of the center."},{"startTime":1373.735,"endTime":1375.485,"body":"We've been able to watch over time."},{"startTime":1376.415,"endTime":1378.965,"body":"Stars move near this object."},{"startTime":1379.665,"endTime":1384.211,"body":"So this is a movie from a group led by Andrea Gates in, uh, California,"},{"startTime":1384.211,"endTime":1384.515,"body":"um, from a telescope called cac, which is on monarchy on the big island of,"},{"startTime":1384.515,"endTime":1389.365,"body":"of Hawaii."},{"startTime":1389.865,"endTime":1392.005,"body":"And the year is in the top right here."},{"startTime":1392.005,"endTime":1393.125,"body":"So this is 1995."},{"startTime":1393.125,"endTime":1397.148,"body":"Oh, I'm going to run almost 20 years worth of observations at the center of"},{"startTime":1397.148,"endTime":1397.685,"body":"our galaxy."},{"startTime":1398.305,"endTime":1403.877,"body":"Um, this is an incredibly small patch of sky, uh, much less than a a"},{"startTime":1403.877,"endTime":1405.735,"body":"thousandth of a degree across."},{"startTime":1406.235,"endTime":1409.815,"body":"So we're using all sorts of technology to get this incredibly sharp view."},{"startTime":1410.235,"endTime":1415.495,"body":"But what you can see over time is the, the stars move."},{"startTime":1417.125,"endTime":1422.015,"body":"They also move in orbit around some object that's at the center."},{"startTime":1423.085,"endTime":1426.285,"body":"Um, it's marked by the open star shape here, which I've added."},{"startTime":1426.545,"endTime":1428.805,"body":"That's not what stars look like \u003claugh\u003e."},{"startTime":1428.805,"endTime":1433.525,"body":"Um, but it coincides with the position of S Jy star."},{"startTime":1433.585,"endTime":1435.725,"body":"So the radio source is right at the middle."},{"startTime":1436.265,"endTime":1441.303,"body":"And because we know about stars and because we know how massive these stars are,"},{"startTime":1441.303,"endTime":1441.639,"body":"particularly this one that's coming down now with the yellow trail, that's, uh, S two,"},{"startTime":1441.639,"endTime":1451.045,"body":"which we've observed complete a whole orbit, um, takes about 16 years to do."},{"startTime":1451.045,"endTime":1455.276,"body":"So we're able to measure the mass of the thing at the center, so sort"},{"startTime":1455.276,"endTime":1456.405,"body":"of basic physics problem."},{"startTime":1456.785,"endTime":1462.635,"body":"And at the center, whatever SJ star is, it weighs 4 million times the mass"},{"startTime":1462.635,"endTime":1463.805,"body":"of the sun."},{"startTime":1464.545,"endTime":1467.95,"body":"And all of that mass is in a volume that's smaller than that of our"},{"startTime":1467.95,"endTime":1468.405,"body":"solar system."},{"startTime":1469.185,"endTime":1473.877,"body":"And theory tells us that if you put that much stuff in that smaller space,"},{"startTime":1473.877,"endTime":1477.005,"body":"then it collapses to form what's called a black hole."},{"startTime":1477.545,"endTime":1482.445,"body":"So an object whose gravity is so immense that not even light can escape."},{"startTime":1483.305,"endTime":1488.893,"body":"And in Avie or a fe of radio astronomy, uh, organization called the Event Horizon"},{"startTime":1488.893,"endTime":1489.265,"body":"Telescope used telescopes from all over the world over many years to release a couple"},{"startTime":1489.265,"endTime":1499.325,"body":"of years ago an image in the radio of that very central object."},{"startTime":1500.065,"endTime":1504.565,"body":"And here it is, it's sort of an orange donut, uh, at the center of"},{"startTime":1504.565,"endTime":1505.165,"body":"our galaxy."},{"startTime":1505.185,"endTime":1507.165,"body":"So this is s Jy star more or less."},{"startTime":1507.505,"endTime":1512.725,"body":"And what you are seeing here around the edge is very lucky light that escaped"},{"startTime":1512.725,"endTime":1516.205,"body":"from just outside the event horizon of this black hole."},{"startTime":1516.205,"endTime":1518.245,"body":"The event horizon is the point of no return."},{"startTime":1518.785,"endTime":1522.811,"body":"And you can see the structure, the blobs are due partly due to the gravity"},{"startTime":1522.811,"endTime":1525.765,"body":"distorting the light, and partly due to structure in the disc."},{"startTime":1526.265,"endTime":1530.145,"body":"Um, and in the center, this dark patch in the middle is what you can"},{"startTime":1530.145,"endTime":1530.404,"body":"think of as the shadow of the large black hole at the center of our"},{"startTime":1530.404,"endTime":1534.285,"body":"galaxy."},{"startTime":1534.985,"endTime":1537.085,"body":"So more than night, where are we set?"},{"startTime":1537.085,"endTime":1537.605,"body":"39."},{"startTime":1538.025,"endTime":1543.477,"body":"So more than, um, 80 years after Reba and Jansky discovered that there was a"},{"startTime":1543.477,"endTime":1543.841,"body":"source in Sagittarius that was emitting radios, we could see the hot gas falling into"},{"startTime":1543.841,"endTime":1552.565,"body":"the black hole, which is responsible from those radio waves."},{"startTime":1552.565,"endTime":1557.836,"body":"And if that's not exciting enough, when this image was released, if you were in"},{"startTime":1557.836,"endTime":1562.405,"body":"the States, dunking Donuts would give you a free specially made glazed donut."},{"startTime":1563.105,"endTime":1568.381,"body":"Um, unfortunately only on that particular day and only in the us which made me"},{"startTime":1568.381,"endTime":1569.085,"body":"extremely upset."},{"startTime":1569.545,"endTime":1574.658,"body":"Uh, so I call upon the donut makers of Britain to celebrate the center of"},{"startTime":1574.658,"endTime":1577.045,"body":"our galaxy, uh, and this iconic image."},{"startTime":1577.585,"endTime":1581.044,"body":"If Gresham achieves nothing else this year, I think if we can get free donuts"},{"startTime":1581.044,"endTime":1581.275,"body":"for everyone who's in the audience and those of you online, I think we'll have"},{"startTime":1581.275,"endTime":1584.965,"body":"done well."},{"startTime":1586.465,"endTime":1588.685,"body":"So I've told one story about radio astronomy."},{"startTime":1588.685,"endTime":1593.579,"body":"I've told you about going from crude instruments that were designed to track noise, to"},{"startTime":1593.579,"endTime":1593.906,"body":"steerable dishes, to interferometers that can give us very sharp images of objects like the"},{"startTime":1593.906,"endTime":1601.085,"body":"black hole at the center of our galaxy."},{"startTime":1601.385,"endTime":1607.55,"body":"But there's another parallel story that happens that's really important and it mirrors what's happening"},{"startTime":1607.55,"endTime":1609.605,"body":"elsewhere in astronomy as well."},{"startTime":1612.025,"endTime":1616.765,"body":"And that story is about the discovery of things that change in the sky."},{"startTime":1617.955,"endTime":1620.525,"body":"Fundamentally, there are only two kinds of astronomy."},{"startTime":1620.585,"endTime":1623.565,"body":"We map things and we watch them move, right?"},{"startTime":1623.785,"endTime":1625.485,"body":"That's essentially, we're still a visual."},{"startTime":1626.385,"endTime":1629.405,"body":"I'm slipping up still observational science, right?"},{"startTime":1629.405,"endTime":1630.365,"body":"Those are the things we could do."},{"startTime":1630.365,"endTime":1633.085,"body":"So I've talked about mapping, trying to take pictures of objects."},{"startTime":1633.745,"endTime":1635.965,"body":"We can also watch things change in brightness."},{"startTime":1636.465,"endTime":1638.645,"body":"And sometimes that can be really, really important."},{"startTime":1639.235,"endTime":1645.296,"body":"When in the 1950s and early 1960s, astronomers, particularly in Australia, particularly in Cambridge in"},{"startTime":1645.296,"endTime":1648.125,"body":"the uk, had mapped the radio sky."},{"startTime":1648.155,"endTime":1652.762,"body":"We'd got to the point where there were a few hundred heading towards a few"},{"startTime":1652.762,"endTime":1654.605,"body":"thousand sources, uh, in the sky."},{"startTime":1655.105,"endTime":1659.668,"body":"So we got a sky full of what were called radio stars of, of objects"},{"startTime":1659.668,"endTime":1660.885,"body":"that we could observe."},{"startTime":1660.985,"endTime":1663.885,"body":"But there was a school of thought that said, those must be nearby."},{"startTime":1664.745,"endTime":1667.586,"body":"And there was a school of thought that said, these things must be in the"},{"startTime":1667.586,"endTime":1667.965,"body":"distant universe."},{"startTime":1668.825,"endTime":1672.413,"body":"And one of the ways to resolve that is to take a closer look at"},{"startTime":1672.413,"endTime":1675.045,"body":"them and determine whether they really are point sources like stars."},{"startTime":1675.905,"endTime":1680.205,"body":"In which case you might assume that they're distant, or if they're closer, then you"},{"startTime":1680.205,"endTime":1681.925,"body":"might be able to see structure."},{"startTime":1681.975,"endTime":1685.623,"body":"Maybe they'll be shaped like a nebula or like a disc or something like that,"},{"startTime":1685.623,"endTime":1685.866,"body":"in which case they're close enough for you to see them as more than points"},{"startTime":1685.866,"endTime":1690.245,"body":"they must be nearby."},{"startTime":1691.145,"endTime":1696.061,"body":"And we can use an old way of distinguishing these things, which is to see"},{"startTime":1696.061,"endTime":1697.045,"body":"whether they twinkle."},{"startTime":1697.355,"endTime":1704.245,"body":"Essentially there's a legend stroke observer's guide that, you know, twinkle twinkle little star."},{"startTime":1705.465,"endTime":1709.35,"body":"If you talk to people, if you read old observer's manuals, they'll tell you that"},{"startTime":1709.35,"endTime":1709.609,"body":"planets, when they're seen in the sky, if you go outside tonight and look at"},{"startTime":1709.609,"endTime":1716.085,"body":"Jupiter in the sky, they'll tell you that planets don't twinkle."},{"startTime":1716.705,"endTime":1719.565,"body":"And the logic is that though you can't see it with the naked eye, when"},{"startTime":1719.565,"endTime":1722.045,"body":"you look at Jupiter, you're not looking at a point source of light."},{"startTime":1722.045,"endTime":1724.965,"body":"You're looking at something that's close enough that we can see a disc."},{"startTime":1725.745,"endTime":1729.926,"body":"And when that moves round the sky, it matters much less than when a point"},{"startTime":1729.926,"endTime":1730.205,"body":"moves."},{"startTime":1731.105,"endTime":1733.485,"body":"And so stars twinkle more than planets."},{"startTime":1734.535,"endTime":1739.127,"body":"Personally, I can't see it, I can't distinguish the two, but maybe if you go"},{"startTime":1739.127,"endTime":1740.965,"body":"outside, you can have a look."},{"startTime":1740.965,"endTime":1742.285,"body":"And this definitely works in theory."},{"startTime":1742.385,"endTime":1747.41,"body":"So the experiment that the Cambridge astronomers wanted to do was to observe as many"},{"startTime":1747.41,"endTime":1751.095,"body":"sources in the sky as they could with greater time resolution."},{"startTime":1751.115,"endTime":1755.922,"body":"So instead of just adding up all the radio waves that were received over hours,"},{"startTime":1755.922,"endTime":1756.243,"body":"looking at them minute by minute and even second by second to see whether, um,"},{"startTime":1756.243,"endTime":1763.615,"body":"they were twinkling to resolve this issue of distance."},{"startTime":1763.615,"endTime":1767.335,"body":"And the task, uh, was undertaken by group, led by Anthony Huish."},{"startTime":1767.715,"endTime":1769.215,"body":"Um, but the work was carried out."},{"startTime":1769.215,"endTime":1774.641,"body":"The observational work in particular, once the telescope was built, was carried out by Jocelyn"},{"startTime":1774.641,"endTime":1777.535,"body":"b Burnell, who's pictured here with the telescope."},{"startTime":1777.555,"endTime":1780.015,"body":"Now it's a weird telescope, it's a set of anni."},{"startTime":1780.315,"endTime":1785.194,"body":"Uh, it covered a large field, the area of which covered something like 57 lawn"},{"startTime":1785.194,"endTime":1785.845,"body":"tennis courts."},{"startTime":1786.305,"endTime":1791.529,"body":"Um, and Jocelyn described her beautiful instrument as looking like something you could string peas"},{"startTime":1791.529,"endTime":1796.405,"body":"along, which I think is fair enough while observing, while carrying out these observations."},{"startTime":1796.985,"endTime":1802.026,"body":"Um, what she's doing is she's looking at the output on graph paper of one"},{"startTime":1802.026,"endTime":1802.362,"body":"of those old fashioned chart recorders with a pen that moves up and down to"},{"startTime":1802.362,"endTime":1809.085,"body":"record the strength of the signal."},{"startTime":1809.785,"endTime":1815.774,"body":"And she noticed a little bit of scruff in 1967 just here above my finger,"},{"startTime":1815.774,"endTime":1820.965,"body":"uh, labeled CP on here where the pen just scribbles for a second."},{"startTime":1822.245,"endTime":1828.05,"body":"That's an observation of an object that's changing rapidly and it turns out regularly in"},{"startTime":1828.05,"endTime":1828.825,"body":"the sky."},{"startTime":1830.085,"endTime":1835.465,"body":"Now, natural things aren't supposed to change rapidly or regularly."},{"startTime":1835.695,"endTime":1839.665,"body":"This is the behavior that we associate with intelligence here on earth."},{"startTime":1839.855,"endTime":1844.825,"body":"Natural things change slowly and don't beat out a steady pulse."},{"startTime":1845.525,"endTime":1846.945,"body":"That's a biological trait."},{"startTime":1847.565,"endTime":1853.012,"body":"And Jocelyn and some of the other astronomers nicknamed this source LG M1, which stands"},{"startTime":1853.012,"endTime":1854.465,"body":"for Little green men."},{"startTime":1855.525,"endTime":1860.56,"body":"Now, it's not clear that they ever thought this really was intelligence, though Jocelyn has"},{"startTime":1860.56,"endTime":1860.895,"body":"told me about a time when she was cycling back from Cambridge, from the observatory"},{"startTime":1860.895,"endTime":1861.231,"body":"into Cambridge, late one night, being annoyed that aliens had got in the way of"},{"startTime":1861.231,"endTime":1875.665,"body":"her PhD and she's a mark of the kind of person doing this painstaking work."},{"startTime":1875.865,"endTime":1878.145,"body":"I think, you know, being annoyed, you've discovered aliens."},{"startTime":1878.405,"endTime":1882.887,"body":"Um, and in any case, they were reasonably relieved when they found a second one,"},{"startTime":1882.887,"endTime":1883.186,"body":"LGM two, because they felt that the odds of two separate alien civilizations doing exactly"},{"startTime":1883.186,"endTime":1888.865,"body":"the same thing were low."},{"startTime":1889.325,"endTime":1894.612,"body":"And so they felt then that they, they were sure that they'd found something natural,"},{"startTime":1894.612,"endTime":1897.785,"body":"but what these things were was an important question."},{"startTime":1898.605,"endTime":1902.551,"body":"Um, and even before that, whether these things were real, this is the kind of"},{"startTime":1902.551,"endTime":1902.815,"body":"thing that you might expect from an electronic artifact noise in the system that had"},{"startTime":1902.815,"endTime":1907.025,"body":"been built."},{"startTime":1907.805,"endTime":1912.305,"body":"And so the first thing they did was go to a second telescope, adjust its"},{"startTime":1912.305,"endTime":1916.505,"body":"chart recorder, which took a few weeks so that it could record rapid results."},{"startTime":1917.685,"endTime":1921.836,"body":"And then they pointed it the same part of the sky, or rather waited for"},{"startTime":1921.836,"endTime":1922.113,"body":"the same part of the sky to pass overhead and expected to see the same"},{"startTime":1922.113,"endTime":1926.265,"body":"signal."},{"startTime":1927.365,"endTime":1932.646,"body":"And with Jocelyn and the rest of the astronomers there clustered round the chart as"},{"startTime":1932.646,"endTime":1935.815,"body":"the appointed hour and minute appeared, absolutely nothing happened."},{"startTime":1937.735,"endTime":1942.92,"body":"Disappointment all round this discovery that they'd been excited about, excited enough, according to the"},{"startTime":1942.92,"endTime":1944.995,"body":"records, to keep from their colleagues."},{"startTime":1944.995,"endTime":1949.337,"body":"They were very careful not to tell anyone that they thought they'd found something this"},{"startTime":1949.337,"endTime":1951.075,"body":"interesting and unusual, all faded away."},{"startTime":1951.075,"endTime":1951.755,"body":"It was a mistake."},{"startTime":1951.815,"endTime":1957.831,"body":"It was a problem in the wires, except that just as they were packing up,"},{"startTime":1957.831,"endTime":1963.045,"body":"20 minutes later, the chart jumped into action and there was a scribble."},{"startTime":1963.185,"endTime":1967.165,"body":"They'd calculated the position in the sky wrong by 20 minutes."},{"startTime":1967.825,"endTime":1972.039,"body":"If they'd been two hours late, then it would've been another 10 years, I think,"},{"startTime":1972.039,"endTime":1973.725,"body":"before anyone had found these objects."},{"startTime":1973.905,"endTime":1974.725,"body":"So what are these things?"},{"startTime":1974.725,"endTime":1980.639,"body":"Well, luckily the theorists had ideas and had been around, uh, uh, relatively quickly, and"},{"startTime":1980.639,"endTime":1983.005,"body":"quickly came up with a solution."},{"startTime":1983.795,"endTime":1988.658,"body":"When large stars die, when they explode as supernova at the ends of their lives,"},{"startTime":1988.658,"endTime":1988.983,"body":"they can produce dense objects, sometimes black holes, but for stars not quite big enough"},{"startTime":1988.983,"endTime":1996.765,"body":"for their cause to come up to big black holes."},{"startTime":1997.265,"endTime":1998.685,"body":"We produce neutron stars."},{"startTime":1999.695,"endTime":2002.725,"body":"These are city size objects."},{"startTime":2002.725,"endTime":2007.932,"body":"They may be 10 kilometers across, but a typical neutron star will have 1.4 times"},{"startTime":2007.932,"endTime":2012.445,"body":"the mass of the sun crammed into something the size of a city."},{"startTime":2013.305,"endTime":2016.805,"body":"So these are the densest objects that exist in the universe."},{"startTime":2018.065,"endTime":2022.712,"body":"Um, there's all sorts of terrible analogies, so you should take from this that they're"},{"startTime":2022.712,"endTime":2023.022,"body":"very dense, but traditionally at this point in a talk, and astronomer will say something"},{"startTime":2023.022,"endTime":2023.332,"body":"like, if you took a teaspoon of neutron star material, it would weigh, I picked"},{"startTime":2023.332,"endTime":2023.642,"body":"this one off the web earlier, 900 times the mass of the great pyramid of"},{"startTime":2023.642,"endTime":2036.965,"body":"Giza."},{"startTime":2038.035,"endTime":2040.365,"body":"Does that help you intuit how much that is?"},{"startTime":2040.385,"endTime":2042.125,"body":"Or are we just sticking with very dense?"},{"startTime":2042.965,"endTime":2044.045,"body":"I actually did one myself."},{"startTime":2044.125,"endTime":2044.765,"body":"I quite like this."},{"startTime":2044.785,"endTime":2050.252,"body":"So one teaspoon of neutron star material would weigh the same as 10 times as"},{"startTime":2050.252,"endTime":2052.804,"body":"many humans as there are on earth."},{"startTime":2053.745,"endTime":2057.287,"body":"So all you have to do is imagine all the people on earth, which is"},{"startTime":2057.287,"endTime":2059.885,"body":"easy, and then multiply them by 10 and then wave them."},{"startTime":2059.885,"endTime":2062.764,"body":"And that's the same as a teaspoon of this thing that's 10 kilometers long."},{"startTime":2062.784,"endTime":2064.085,"body":"We haven't got a very good analogy."},{"startTime":2064.195,"endTime":2065.885,"body":"It's really dense, is what I'm saying."},{"startTime":2066.425,"endTime":2069.925,"body":"Um, but how are these things producing these pulses?"},{"startTime":2069.925,"endTime":2075.898,"body":"Well, it turns out because they're the core of a star, and stars rotate when"},{"startTime":2075.898,"endTime":2079.085,"body":"you've got the core, it rotates pretty fast."},{"startTime":2080.065,"endTime":2081.364,"body":"And there are magnetic fields."},{"startTime":2081.364,"endTime":2086.626,"body":"They inherit the magnetic field of the star, and that can produce beams of radiation"},{"startTime":2086.626,"endTime":2090.485,"body":"that shoot out from the magnetic pole of the neutron star."},{"startTime":2091.304,"endTime":2095.258,"body":"And so if you happen to be in a place in the universe such that"},{"startTime":2095.258,"endTime":2098.685,"body":"one of these beams sweeps over you, then you see a regular pulse."},{"startTime":2098.825,"endTime":2103.194,"body":"And this can happen every few seconds, or it can happen every few, or it"},{"startTime":2103.194,"endTime":2105.525,"body":"can happen a few thousand times a second."},{"startTime":2105.585,"endTime":2107.685,"body":"For the younger pulsars, they slow down."},{"startTime":2108.345,"endTime":2110.325,"body":"And so that's what these things became called."},{"startTime":2110.325,"endTime":2117.039,"body":"They're pulsars, they're pul pulsing stars, but they're the dead remnants of old stars still,"},{"startTime":2117.039,"endTime":2119.725,"body":"uh, shining beams across the universe."},{"startTime":2120.945,"endTime":2126.845,"body":"And this is an interesting property because this is in some sense a clock."},{"startTime":2127.635,"endTime":2133.062,"body":"It's a thing that's counting, you know, just like lighthouses keep time and can be"},{"startTime":2133.062,"endTime":2137.405,"body":"used to navigate, we can use pulsars to navigate around the galaxy."},{"startTime":2138.105,"endTime":2142.893,"body":"Uh, this is the principle behind the map that we've sent to outer space on"},{"startTime":2142.893,"endTime":2146.405,"body":"the pro on the plaque that's attached to the pioneer spacecraft."},{"startTime":2146.425,"endTime":2151.622,"body":"The pioneers were launched to Jupiter and Saturn, and then they shot out into interstellar"},{"startTime":2151.622,"endTime":2151.969,"body":"space and we sent this plaque, um, on them, um, a friendly greeting, um, from"},{"startTime":2151.969,"endTime":2160.285,"body":"the 1970s, uh, a picture of the probe, I guess."},{"startTime":2160.285,"endTime":2163.754,"body":"So you know what you found, uh, a map showing that we are the fourth"},{"startTime":2163.754,"endTime":2165.605,"body":"of, sorry, the third planet from the sun."},{"startTime":2166.065,"endTime":2170.525,"body":"And then this spiky thing here, uh, is a map of the galaxy."},{"startTime":2170.545,"endTime":2177.056,"body":"So we are at the center and then these lines, 14 of them point to"},{"startTime":2177.056,"endTime":2177.925,"body":"different pulsars."},{"startTime":2178.545,"endTime":2182.975,"body":"And the little dashes tell you in units that multiply up compared to the size"},{"startTime":2182.975,"endTime":2187.405,"body":"of a hydro atom, which is what's at the top, um, which pulsar it is."},{"startTime":2187.585,"endTime":2192.001,"body":"So it gives you the frequency of a pulsar and the 15th line points to"},{"startTime":2192.001,"endTime":2192.885,"body":"the galactic center."},{"startTime":2193.505,"endTime":2199.518,"body":"So this should be enough information for alien astronomers who recover the pioneer probes to"},{"startTime":2199.518,"endTime":2202.325,"body":"find us, which is a cheerful thought."},{"startTime":2202.785,"endTime":2203.925,"body":"Um, don't worry."},{"startTime":2203.925,"endTime":2209.664,"body":"The, the odds of the pioneers being found by, I dunno, there may be super"},{"startTime":2209.664,"endTime":2212.725,"body":"intelligent satellite capture capturing beings who hate littering."},{"startTime":2212.845,"endTime":2213.245,"body":"I don't know."},{"startTime":2213.265,"endTime":2216.433,"body":"But the, the odds of the pioneers being found in deep space are low, I"},{"startTime":2216.433,"endTime":2216.645,"body":"think."},{"startTime":2216.745,"endTime":2220.045,"body":"But it's interesting to me that pulsars were used for mapping."},{"startTime":2220.985,"endTime":2222.485,"body":"And indeed as clocks."},{"startTime":2223.515,"endTime":2227.648,"body":"Many of the most interesting things that have been done with these sources that have,"},{"startTime":2227.648,"endTime":2227.924,"body":"have made up a large part of radio astronomy are to do with this ability"},{"startTime":2227.924,"endTime":2232.885,"body":"to keep precise time."},{"startTime":2234.975,"endTime":2239.553,"body":"There was a result in the ear nine in the early 1990s by a team"},{"startTime":2239.553,"endTime":2242.605,"body":"at Jora Bank who had been monitoring a particular pulsar."},{"startTime":2243.455,"endTime":2248.616,"body":"What they're expecting is a regular blip, blip, blip of a signal like my cartoon"},{"startTime":2248.616,"endTime":2249.305,"body":"pulsar here."},{"startTime":2249.975,"endTime":2250.905,"body":"This should go on over time."},{"startTime":2250.905,"endTime":2256.419,"body":"You get occasional glitches and over a very long period of time, pulsar slow down,"},{"startTime":2256.419,"endTime":2258.625,"body":"but they're expecting a regular bleep."},{"startTime":2259.815,"endTime":2265.847,"body":"What they found was that just by a little bit, sometimes the bleeps would arrive"},{"startTime":2265.847,"endTime":2269.065,"body":"early and sometimes they would arrive slightly late."},{"startTime":2269.885,"endTime":2273.905,"body":"And there was a regular pattern to this change in timing."},{"startTime":2275.695,"endTime":2280.086,"body":"What they said was that there must be a planet around this pulsar and the"},{"startTime":2280.086,"endTime":2284.185,"body":"gravity of the planet would pull the pulsar back and forth as it orbited."},{"startTime":2284.765,"endTime":2287.905,"body":"And so when it was nearer to us, we'd get a slightly early beep."},{"startTime":2288.205,"endTime":2291.385,"body":"And whether it's further away, we get a slightly later beep."},{"startTime":2292.335,"endTime":2293.345,"body":"It's a brilliant discovery."},{"startTime":2293.345,"endTime":2294.385,"body":"This is 1992."},{"startTime":2294.385,"endTime":2297.745,"body":"This is before other planets had been found around other stars."},{"startTime":2298.325,"endTime":2302.587,"body":"You could make exciting artist impressions of the things like this one, which bear probably"},{"startTime":2302.587,"endTime":2305.145,"body":"no resemblance to reality, but look kind of impressive."},{"startTime":2305.765,"endTime":2311.843,"body":"Um, they announced this discovery, the first planets found around another object other than the"},{"startTime":2311.843,"endTime":2313.465,"body":"sun to great fanfare."},{"startTime":2313.765,"endTime":2317.682,"body":"And this is really exciting because not only are these the first planets, how did"},{"startTime":2317.682,"endTime":2318.205,"body":"they survive?"},{"startTime":2318.465,"endTime":2324.376,"body":"Are they survivors from before the star that created the pulsar went supernova or did"},{"startTime":2324.376,"endTime":2325.165,"body":"they form?"},{"startTime":2325.185,"endTime":2330.268,"body":"Is there a second generation of planets that forms after, uh, after the supernova outta"},{"startTime":2330.268,"endTime":2331.285,"body":"the dead breed?"},{"startTime":2331.285,"endTime":2334.045,"body":"You get a rebirth of planetary systems."},{"startTime":2334.195,"endTime":2335.525,"body":"It's a fascinating idea."},{"startTime":2337.065,"endTime":2339.765,"body":"And unfortunately their discovery was wrong."},{"startTime":2340.625,"endTime":2346.845,"body":"The period they attributed to this planet around the pulsar, the time taken for it"},{"startTime":2346.845,"endTime":2353.065,"body":"to go around the pulsar was precisely one earth year, which should ring alarm bells."},{"startTime":2353.375,"endTime":2356.73,"body":"What they'd done was that they've forgotten that the earth does not move in a"},{"startTime":2356.73,"endTime":2357.625,"body":"circle around the sun."},{"startTime":2358.455,"endTime":2360.745,"body":"Sometimes in January, we're closer to the sun."},{"startTime":2360.745,"endTime":2362.065,"body":"In June, we're further away."},{"startTime":2362.425,"endTime":2364.105,"body":"I know it doesn't feel like that, but it's true."},{"startTime":2364.725,"endTime":2367.465,"body":"Um, and they just forgotten."},{"startTime":2367.895,"endTime":2369.105,"body":"They just made a mistake in the code."},{"startTime":2369.105,"endTime":2371.705,"body":"So they'd, what they detected was the earth moving."},{"startTime":2374.005,"endTime":2377.625,"body":"And Andrew Lyon, who led the team, had to stand up."},{"startTime":2377.775,"endTime":2381.65,"body":"He'd already been given a keynote talk at the American Astronomical Society in front of"},{"startTime":2381.65,"endTime":2382.425,"body":"thousands of astronomers."},{"startTime":2382.425,"endTime":2387.325,"body":"And he had to stand up and fill an hour on the planet that it"},{"startTime":2387.325,"endTime":2390.265,"body":"was very clear, didn't exist to his immense credit."},{"startTime":2390.325,"endTime":2394.881,"body":"He stood up on stage and he just said, as you know, we made a"},{"startTime":2394.881,"endTime":2395.185,"body":"mistake."},{"startTime":2395.805,"endTime":2396.625,"body":"And then he sat down."},{"startTime":2397.525,"endTime":2402.063,"body":"Uh, and you know, I've been in similar circumstances, I've watched people in similar circumstances,"},{"startTime":2402.063,"endTime":2402.366,"body":"bluster, uh, you know, this is an interesting technique that could be used to find"},{"startTime":2402.366,"endTime":2406.905,"body":"planets."},{"startTime":2406.905,"endTime":2410.595,"body":"Preliminary results require some, you know, you get the idea, you've heard those talks, uh,"},{"startTime":2410.595,"endTime":2411.825,"body":"but you didn't do that."},{"startTime":2411.845,"endTime":2415.697,"body":"And what was remarkable was there was a Polish astronomer in the audience who walked"},{"startTime":2415.697,"endTime":2418.265,"body":"up to the microphone and said, I have a question."},{"startTime":2419.015,"endTime":2420.305,"body":"Well, I have a statement, really."},{"startTime":2420.845,"endTime":2424.385,"body":"And he said, inspired by your work, we've been monitoring pulsars two."},{"startTime":2424.385,"endTime":2428.292,"body":"And I found a pulsar that has three planets, two that are earth sized, um,"},{"startTime":2428.292,"endTime":2428.553,"body":"one of which goes round in 67 days, one of which goes round in 98"},{"startTime":2428.553,"endTime":2434.545,"body":"days, and then one very close that's very small."},{"startTime":2434.695,"endTime":2438.576,"body":"It's still, I think, the smallest planet we know of just 2% of the earth's"},{"startTime":2438.576,"endTime":2440.905,"body":"mass that whips around the pulsar every 25 days."},{"startTime":2440.905,"endTime":2445.61,"body":"And these are real, there's now a handful of pulsars where we can detect the"},{"startTime":2445.61,"endTime":2445.923,"body":"presence of tiny planets next to something that weighs 1.4 times the mass of the"},{"startTime":2445.923,"endTime":2452.825,"body":"sun because they're being pulled back and forth."},{"startTime":2453.245,"endTime":2457.745,"body":"And the precision of the timing is such that we're able to pick out the"},{"startTime":2457.745,"endTime":2458.945,"body":"signatures of these planets."},{"startTime":2459.845,"endTime":2462.985,"body":"We can play other games with pulsar timing as well."},{"startTime":2464.685,"endTime":2470.097,"body":"In the seventies, two astronomers, uh, called Holson Taylor discovered two neutron stars in orbit"},{"startTime":2470.097,"endTime":2473.345,"body":"around each other, one of which is a pulsar."},{"startTime":2474.165,"endTime":2478.185,"body":"So we get these blips, and again, over time monitored with our SIBO in particular."},{"startTime":2478.185,"endTime":2480.065,"body":"So this is a 30 year data set."},{"startTime":2480.765,"endTime":2485.499,"body":"Um, this is just the time taken for the, the pulsar to complete an orbit"},{"startTime":2485.499,"endTime":2488.025,"body":"around the center of gravity of the system."},{"startTime":2488.805,"endTime":2491.385,"body":"And it's slowing down, it's slowing down by quite dramatic."},{"startTime":2491.495,"endTime":2496.786,"body":"It's now, uh, as of 2005, it was nearly 40 seconds, slower than it was"},{"startTime":2496.786,"endTime":2501.725,"body":"when they first observed it, when the, uh, period was just over seven hours."},{"startTime":2502.385,"endTime":2507.317,"body":"And what's happening here is that as these two massive objects that are very close,"},{"startTime":2507.317,"endTime":2507.646,"body":"they're close enough, they go round in just over seven hours as they spiral each"},{"startTime":2507.646,"endTime":2513.565,"body":"other, they're losing energy."},{"startTime":2514.465,"endTime":2518.125,"body":"And so they're getting closer and closer and closer together, and they will eventually merge."},{"startTime":2518.905,"endTime":2525.133,"body":"But what's remarkable is that they're losing energy via a mechanism that Einstein's theory of"},{"startTime":2525.133,"endTime":2529.285,"body":"relative details about, which is via something called gravitational waves."},{"startTime":2529.285,"endTime":2531.925,"body":"These are ripples in space itself."},{"startTime":2532.985,"endTime":2537.53,"body":"So these are massive objects moving fast enough that they cause ripples in space that"},{"startTime":2537.53,"endTime":2539.045,"body":"spread out through the cosmos."},{"startTime":2539.425,"endTime":2543.767,"body":"And we can see the effect and we can predict actually how fast these things"},{"startTime":2543.767,"endTime":2544.925,"body":"should be slowing down."},{"startTime":2545.345,"endTime":2552.226,"body":"And Halston Taylor won the Nobel Prize for testing this fundamental idea of, uh, general"},{"startTime":2552.226,"endTime":2552.685,"body":"relativity."},{"startTime":2553.265,"endTime":2557.125,"body":"And then just last year, astronomers went one better."},{"startTime":2557.955,"endTime":2563.845,"body":"They monitored a whole host of different pulsars using telescopes from around the world."},{"startTime":2563.905,"endTime":2566.845,"body":"And here's a distracting graphic from their press release."},{"startTime":2567.385,"endTime":2571.3,"body":"Uh, 'cause you'll have gathered by now radio astronomy still doesn't give us great pictures"},{"startTime":2571.3,"endTime":2572.605,"body":"of lots of these things."},{"startTime":2572.725,"endTime":2574.445,"body":"I mean, we got a donut, so that was nice."},{"startTime":2575.065,"endTime":2577.205,"body":"Uh, and we had that nice image at the center of the galaxy."},{"startTime":2577.205,"endTime":2582.318,"body":"But you know, we do have to result to, to pulse, to, to press release"},{"startTime":2582.318,"endTime":2585.045,"body":"images in monitoring many, many, many pulsars arts."},{"startTime":2586.695,"endTime":2592.859,"body":"What these teams were able to discover was that the space that the earth travels"},{"startTime":2592.859,"endTime":2593.27,"body":"through, and I guess we do too, isn't still there is an underlying background of"},{"startTime":2593.27,"endTime":2593.681,"body":"ripples and waves that royal the surface of space as we travel through it, we"},{"startTime":2593.681,"endTime":2608.065,"body":"live in this sort of unstable medium."},{"startTime":2608.855,"endTime":2610.505,"body":"It's a very subtle effect."},{"startTime":2612.045,"endTime":2616.029,"body":"It's only detectable 'cause of the precision with which we can make measurements of these"},{"startTime":2616.029,"endTime":2616.295,"body":"pulsars."},{"startTime":2617.075,"endTime":2620.615,"body":"But we can see the effect of this rippling on our timings."},{"startTime":2621.475,"endTime":2627.007,"body":"And though two is a detection of gravitational waves, this time caused by colliding black"},{"startTime":2627.007,"endTime":2630.695,"body":"holes in galaxies, hundreds of millions of light years away."},{"startTime":2631.435,"endTime":2635.225,"body":"And over the next 20 years, we'll make more of these observations and we'll perhaps"},{"startTime":2635.225,"endTime":2639.015,"body":"even be able to start to say where those colliding galaxies are at the minute."},{"startTime":2639.315,"endTime":2641.255,"body":"All we know is that the sea is choppy."},{"startTime":2641.915,"endTime":2644.015,"body":"But I think detecting that is remarkable."},{"startTime":2644.475,"endTime":2649.59,"body":"And it comes from the precision with which we can monitor these objects that joscelyn"},{"startTime":2649.59,"endTime":2651.295,"body":"discovered back in the 1960s."},{"startTime":2653.035,"endTime":2658.971,"body":"So pulsars are exciting, but there are more dramatic transience as well should end the"},{"startTime":2658.971,"endTime":2659.367,"body":"lecture with a bang, I think, or at least a series of banks were back"},{"startTime":2659.367,"endTime":2659.763,"body":"to parks, which in 2007 had detected a new type of source, a burst of"},{"startTime":2659.763,"endTime":2660.159,"body":"radio waves coming at a particular set of frequencies from all over the sky, seemingly"},{"startTime":2660.159,"endTime":2678.365,"body":"from the distant universe."},{"startTime":2678.825,"endTime":2680.525,"body":"So not associated with the Milky Way."},{"startTime":2680.525,"endTime":2682.765,"body":"Most of the pulsars that we see are in the Milky Way."},{"startTime":2683.135,"endTime":2686.805,"body":"These are bursts coming from the distant universe."},{"startTime":2687.745,"endTime":2693.133,"body":"And as astronomers as we've established a good at naming things, uh, we've called these"},{"startTime":2693.133,"endTime":2697.085,"body":"the fast radio bursts because they're fast bursts of radio waves."},{"startTime":2697.085,"endTime":2698.485,"body":"They're FBS for short."},{"startTime":2700.345,"endTime":2701.805,"body":"Now, not all FBS looked alike."},{"startTime":2701.805,"endTime":2706.805,"body":"There was a subset of these things, um, that occurred at one particular frequency and"},{"startTime":2706.805,"endTime":2710.805,"body":"the team of parks who were suspicious of them called them perons."},{"startTime":2710.825,"endTime":2715.725,"body":"Now, in Greek mythology, a perton is a stag with a human shadow."},{"startTime":2716.625,"endTime":2718.165,"body":"I'm not an expert on Greek mythology."},{"startTime":2718.265,"endTime":2719.605,"body":"We have other lecturers for that."},{"startTime":2719.665,"endTime":2721.445,"body":"So if somebody wants to gimme the context, that'd be good."},{"startTime":2721.445,"endTime":2726.354,"body":"But the point is they suspected these would be manmade, but they couldn't quite work"},{"startTime":2726.354,"endTime":2728.645,"body":"out why only parks could see them."},{"startTime":2728.735,"endTime":2736.86,"body":"Other telescopes lacked the instrumentation, the expertise, the knowhow, the hutzpah, the capability to see"},{"startTime":2736.86,"endTime":2738.485,"body":"these exciting objects."},{"startTime":2738.485,"endTime":2743.905,"body":"And they were published in about 50 different papers over the years until 2015."},{"startTime":2745.085,"endTime":2751.058,"body":"In 2015, a retired engineer, somebody who Jansky and Reba would've gone on with, I'm"},{"startTime":2751.058,"endTime":2751.456,"body":"sure saw some of these papers and said that he knew exactly what the source"},{"startTime":2751.456,"endTime":2758.625,"body":"of these perons was."},{"startTime":2760.155,"endTime":2762.305,"body":"There was to be fair, a clue in the data."},{"startTime":2762.885,"endTime":2767.825,"body":"Um, this is the time of day at which those things were observed."},{"startTime":2767.845,"endTime":2774.745,"body":"And as you can see, these celestial sources from the distant universe favor lunchtime at"},{"startTime":2774.745,"endTime":2775.665,"body":"the observatory."},{"startTime":2777.045,"endTime":2781.738,"body":"The engineering question have worked on microwave ovens, and it turns out that the microwave"},{"startTime":2781.738,"endTime":2782.051,"body":"ovens in the visitor center at parks, which were more than 25 years old, were"},{"startTime":2782.051,"endTime":2786.745,"body":"malfunctioning."},{"startTime":2787.285,"endTime":2793.033,"body":"In particular, your microwave oven, if you open the door before it goes ping, which"},{"startTime":2793.033,"endTime":2796.865,"body":"I have been known to do, I'm an impatient person."},{"startTime":2797.015,"endTime":2800.865,"body":"It's supposed to stop producing microwaves for all sorts of good reasons."},{"startTime":2801.915,"endTime":2802.705,"body":"These didn't."},{"startTime":2802.965,"endTime":2807.115,"body":"So every time somebody was impatient for their lunch, they created a signal which the"},{"startTime":2807.115,"endTime":2807.945,"body":"telescope could detect."},{"startTime":2808.845,"endTime":2810.585,"body":"Uh, this had been happening for years."},{"startTime":2811.055,"endTime":2812.585,"body":"They now have some new microwaves."},{"startTime":2813.165,"endTime":2816.065,"body":"Perons don't exist, but fast radio bursts do."},{"startTime":2816.605,"endTime":2818.465,"body":"And we don't know yet what they are."},{"startTime":2818.465,"endTime":2824.665,"body":"They're mysterious sources that sometimes repeat, but don't always that mostly come from distant galaxies."},{"startTime":2824.685,"endTime":2827.345,"body":"But once didn't that appear at different frequencies."},{"startTime":2828.045,"endTime":2834.545,"body":"Um, and we're just at the beginning of working out what these objects are."},{"startTime":2836.645,"endTime":2840.665,"body":"The radio sky is much stranger than we thought it was."},{"startTime":2841.195,"endTime":2846.09,"body":"Teams in particular in Australia, led by people like Natasha Hurley Walker, who's an amazing"},{"startTime":2846.09,"endTime":2846.416,"body":"scientist, have shown that there are things like pulsars, but which take hours to pulse"},{"startTime":2846.416,"endTime":2851.965,"body":"rather than seconds."},{"startTime":2852.105,"endTime":2854.245,"body":"We don't know what they are, either one of them."},{"startTime":2855.025,"endTime":2858.579,"body":"The first one they found turned off in the two years between it, the data"},{"startTime":2858.579,"endTime":2858.816,"body":"being taken and them going back to look on it, another one has been going"},{"startTime":2858.816,"endTime":2862.845,"body":"for 30 years."},{"startTime":2862.845,"endTime":2868.564,"body":"There is a diversity of behavior that we don't understand, and we will have much"},{"startTime":2868.564,"endTime":2868.945,"body":"more of this because of an effort called the Square kilometer Array, the SKA, which"},{"startTime":2868.945,"endTime":2869.326,"body":"is going to plant dishes across Southern Africa and across Western Australia, sensitive to all"},{"startTime":2869.326,"endTime":2869.708,"body":"different frequencies to look through the radio sky and to find out what might be"},{"startTime":2869.708,"endTime":2886.485,"body":"out there."},{"startTime":2886.865,"endTime":2891.877,"body":"The SKA by some estimates will be capable of detecting airport radar on any of"},{"startTime":2891.877,"endTime":2894.885,"body":"the nearest a hundred star systems, something like that."},{"startTime":2894.905,"endTime":2900.592,"body":"So that gives you some sense of, uh, the, um, capabilities that we're about to"},{"startTime":2900.592,"endTime":2904.005,"body":"have the first dishes for the SKA on site."},{"startTime":2904.625,"endTime":2909.65,"body":"And they produced that galactic center image that I showed you earlier, and it's going"},{"startTime":2909.65,"endTime":2911.325,"body":"to be a marvelous time."},{"startTime":2912.025,"endTime":2914.845,"body":"But I did leave you with proxima and BLC one."},{"startTime":2915.585,"endTime":2921.838,"body":"And I want to finish by saying that this candidate breakthrough, listen, candidate one, this"},{"startTime":2921.838,"endTime":2922.255,"body":"possible signal from our neighboring planet turned out like most of these things to be"},{"startTime":2922.255,"endTime":2928.925,"body":"not aliens."},{"startTime":2929.705,"endTime":2933.82,"body":"Uh, a careful look at the data showed that it repeated the signal, not just"},{"startTime":2933.82,"endTime":2934.095,"body":"when the telescope was pointing at proximal, but also where it was pointing away from"},{"startTime":2934.095,"endTime":2938.485,"body":"the star."},{"startTime":2939.065,"endTime":2944.57,"body":"And so it appears to be a kind of interference, perhaps from a satellite, perhaps"},{"startTime":2944.57,"endTime":2946.405,"body":"from some malfunctioning radio equipment."},{"startTime":2946.955,"endTime":2952.79,"body":"It's a reminder, even as we build novel telescopes and novel technologies that though they"},{"startTime":2952.79,"endTime":2953.18,"body":"can observe in the daytime, and though they can look through cloud radio, astronomers have"},{"startTime":2953.18,"endTime":2959.405,"body":"life hard."},{"startTime":2959.475,"endTime":2964.445,"body":"They live in a noisy universe where a mobile phone on the moon would create"},{"startTime":2964.445,"endTime":2969.085,"body":"a signal, millions of times brighter than anything else that they're trying to observe."},{"startTime":2969.545,"endTime":2970.805,"body":"And they live amongst us."},{"startTime":2971.745,"endTime":2979.263,"body":"And the observatories we build, though they're in relatively isolated places, have to deal with"},{"startTime":2979.263,"endTime":2979.765,"body":"interference."},{"startTime":2979.905,"endTime":2985.414,"body":"And yet, through ingenuity and perseverance, the kind shown by Jansky and Reba, by Jocelyn"},{"startTime":2985.414,"endTime":2985.782,"body":"Berne, uh, and astronomers ever since, we're able to listen carefully to the universe and"},{"startTime":2985.782,"endTime":2994.965,"body":"just occasionally we hear a meteor when we're listening from one."},{"startTime":2995.015,"endTime":2995.725,"body":"Thank you very much."},{"startTime":3011.335,"endTime":3012.605,"body":"Thank you very much, Chris."},{"startTime":3012.605,"endTime":3013.365,"body":"That was wonderful."},{"startTime":3013.905,"endTime":3018.205,"body":"And we're all, I'm full up with questions, \u003claugh\u003e, um, which is great."},{"startTime":3018.745,"endTime":3022.485,"body":"Um, trying to choose one."},{"startTime":3022.495,"endTime":3024.085,"body":"Let's start with an early one."},{"startTime":3024.505,"endTime":3026.685,"body":"So this is about the SKA."},{"startTime":3026.945,"endTime":3032.395,"body":"Why not share high and low frequency arrays in both South Africa and Australia for"},{"startTime":3032.395,"endTime":3033.485,"body":"an intercontinental baseline?"},{"startTime":3033.745,"endTime":3033.965,"body":"Yep."},{"startTime":3034.105,"endTime":3035.245,"body":"No, this is a technical question."},{"startTime":3035.245,"endTime":3037.245,"body":"So you'll see there's two types of telescope here."},{"startTime":3037.705,"endTime":3040.926,"body":"Um, so on the left are the things we're gonna put in Southern Africa and"},{"startTime":3040.926,"endTime":3042.645,"body":"on the right is what's happening in Australia."},{"startTime":3043.105,"endTime":3045.405,"body":"Um, and they're designed for different frequencies."},{"startTime":3046.225,"endTime":3047.445,"body":"Um, and there's a split."},{"startTime":3047.465,"endTime":3051.885,"body":"So though it will work as one telescope, we'll observe different frequencies from different places."},{"startTime":3051.985,"endTime":3056.928,"body":"And it's just to simplify the engineering, really the original plan was to put everything"},{"startTime":3056.928,"endTime":3059.565,"body":"on one site that would make life easier."},{"startTime":3059.945,"endTime":3065.288,"body":"But both sites are great, both countries, both South Africa and Australia were hugely, uh,"},{"startTime":3065.288,"endTime":3065.645,"body":"supportive."},{"startTime":3065.645,"endTime":3070.257,"body":"And so just for simplicity, it's on two different continents and two different types of"},{"startTime":3070.257,"endTime":3070.565,"body":"thing."},{"startTime":3071.105,"endTime":3074.045,"body":"Um, whether you'd want to mix it in the long run, sure."},{"startTime":3074.065,"endTime":3077.565,"body":"But for now, this is probably a 40 year effort to build this telescope."},{"startTime":3077.745,"endTime":3079.565,"body":"So later we'll mix it up."},{"startTime":3079.665,"endTime":3082.005,"body":"But for now, we just want our, our dishes out there."},{"startTime":3082.145,"endTime":3085.348,"body":"The nice thing about a radio telescope is that if you make it out of"},{"startTime":3085.348,"endTime":3088.125,"body":"many dishes, you can start observing as soon as you put one down."},{"startTime":3088.745,"endTime":3092.955,"body":"And so we have telescopes on the ground now in both countries that are 1%"},{"startTime":3092.955,"endTime":3096.605,"body":"of what we will end up with, but they're already producing amazing results."},{"startTime":3096.705,"endTime":3097.965,"body":"So we're, we're on the way."},{"startTime":3098.625,"endTime":3099.365,"body":"That's brilliant."},{"startTime":3100.345,"endTime":3103.645,"body":"And how might AI help with radio astronomy?"},{"startTime":3103.675,"endTime":3108.01,"body":"Yeah, so the, the the, there's a bit of this story that's hidden that I"},{"startTime":3108.01,"endTime":3108.3,"body":"didn't talk about in that the great advances aren't always driven by telescopes, they're driven"},{"startTime":3108.3,"endTime":3112.925,"body":"by computing."},{"startTime":3113.385,"endTime":3120.228,"body":"And in particular, the ability to combine data from different observatories, um, makes an enormous"},{"startTime":3120.228,"endTime":3120.685,"body":"difference."},{"startTime":3120.685,"endTime":3123.325,"body":"And that's a, a tale of can you afford a good supercomputer?"},{"startTime":3123.905,"endTime":3128.073,"body":"So it's really the rising computing that has allowed us to do things like make"},{"startTime":3128.073,"endTime":3131.965,"body":"this astounding image of the Milky Way at the center of the Milky Way."},{"startTime":3131.965,"endTime":3133.685,"body":"It's a, it's a computing problem."},{"startTime":3134.145,"endTime":3136.285,"body":"Um, machine learning helps by filtering signals."},{"startTime":3137.345,"endTime":3142.451,"body":"Um, perhaps the best way to see that is in Seti where when we're looking"},{"startTime":3142.451,"endTime":3142.791,"body":"for aliens, what we've traditionally done is look for signals like BLC one, so narrow"},{"startTime":3142.791,"endTime":3143.131,"body":"signals at a particular frequency on the grounds that those are likely to be either"},{"startTime":3143.131,"endTime":3154.365,"body":"artificial or something interesting astronomically."},{"startTime":3154.745,"endTime":3158.845,"body":"But with more advanced artificial intelligence, we look for a greater range of signals."},{"startTime":3158.905,"endTime":3163.024,"body":"We can look for aliens chirping at us or signals that jump around and we"},{"startTime":3163.024,"endTime":3166.045,"body":"can ask more generally what the, to, to find interesting things."},{"startTime":3166.145,"endTime":3170.302,"body":"So I think that will come, um, it's a long stretch to get to the"},{"startTime":3170.302,"endTime":3171.965,"body":"data volumes the SK will produce."},{"startTime":3173.125,"endTime":3177.587,"body":"I think it's as much data every hour as is on the web every, uh,"},{"startTime":3177.587,"endTime":3177.885,"body":"second."},{"startTime":3178.745,"endTime":3182.904,"body":"And so it's an awful lot of data, uh, to process before you start doing"},{"startTime":3182.904,"endTime":3184.845,"body":"advanced, uh, machine learning and so on."},{"startTime":3185.495,"endTime":3185.845,"body":"Great."},{"startTime":3185.945,"endTime":3188.205,"body":"What's the fate of planets around pulsars?"},{"startTime":3188.385,"endTime":3189.485,"body":"Are they gonna be, what's the fate of them?"},{"startTime":3189.505,"endTime":3191.525,"body":"What's the fate of them and they, are they gonna be destroyed?"},{"startTime":3191.755,"endTime":3195.605,"body":"Well, we think they stay there, the pulsar, because the pulsar has jets that come"},{"startTime":3195.605,"endTime":3198.685,"body":"out the poles and the planets tend to be in the plane."},{"startTime":3199.265,"endTime":3203.165,"body":"Um, the jets don't sweep across the planets, so, so the planets will be fine."},{"startTime":3203.705,"endTime":3208.4,"body":"Um, the pulsar gradually spins down, becomes inert, and so you've got some planets around"},{"startTime":3208.4,"endTime":3209.965,"body":"a faint cold dead star."},{"startTime":3210.275,"endTime":3212.325,"body":"It's probably not a nice place to go on holiday."},{"startTime":3213.065,"endTime":3215.922,"body":"Uh, but the planets will be fine in the long term and they'll remain there"},{"startTime":3215.922,"endTime":3216.685,"body":"for us to observe."},{"startTime":3217.605,"endTime":3217.845,"body":"Brilliant."},{"startTime":3218.025,"endTime":3220.285,"body":"So what is the practical application, do you think?"},{"startTime":3221.075,"endTime":3222.805,"body":"Half and for astronomers with"},{"startTime":3222.965,"endTime":3223.125,"body":"Astronomy?"},{"startTime":3223.165,"endTime":3223.645,"body":"Yeah, join"},{"startTime":3223.645,"endTime":3223.965,"body":"Themselves."},{"startTime":3225.285,"endTime":3230.373,"body":"I mean, there is a traditional answer to this, which is that the technology development,"},{"startTime":3230.373,"endTime":3234.445,"body":"particularly for radio astronomy, has all sorts of consumer, uh, electronic background."},{"startTime":3234.445,"endTime":3239.055,"body":"We usually claim the invention of wifi, uh, was via radio astronomist, which has now"},{"startTime":3239.055,"endTime":3240.285,"body":"become their mortal enemy."},{"startTime":3240.285,"endTime":3243.525,"body":"So it's kind of, uh, a, a classical tragedy."},{"startTime":3244.105,"endTime":3249.423,"body":"Um, I think any sort of technological development helps and the kind of big engineering"},{"startTime":3249.423,"endTime":3249.777,"body":"projects that power these, these radio telescopes, I think produce a skilled workforce in all"},{"startTime":3249.777,"endTime":3255.805,"body":"of these places."},{"startTime":3255.805,"endTime":3260.239,"body":"That's why in South Africa in particular, there's a lot of excitement about the project,"},{"startTime":3260.239,"endTime":3262.605,"body":"but it's also worth doing anyway, isn't it?"},{"startTime":3262.715,"endTime":3265.79,"body":"It's kind of fun to know about the universe and so I'll always give that"},{"startTime":3265.79,"endTime":3266.405,"body":"answer as well."},{"startTime":3267.205,"endTime":3267.485,"body":"Absolutely."},{"startTime":3267.735,"endTime":3270.925,"body":"We've got some, um, some questions sort of going back."},{"startTime":3271.385,"endTime":3274.856,"body":"So it was very interesting to see the Parks telescope at the beginning, and I"},{"startTime":3274.856,"endTime":3276.245,"body":"remember the dish, the movie Yes."},{"startTime":3276.425,"endTime":3277.125,"body":"Um, and so on."},{"startTime":3277.265,"endTime":3281.727,"body":"And it's, it was interesting that Australia was one of the places that the first"},{"startTime":3281.727,"endTime":3284.405,"body":"observations were coming from much more than other places."},{"startTime":3284.665,"endTime":3286.845,"body":"Is that because the atmosphere is very clear there or,"},{"startTime":3287.025,"endTime":3288.725,"body":"Um, no, being in the south helps."},{"startTime":3289.225,"endTime":3293.88,"body":"So, so, um, there are other reasons to put telescopes on in, in Australia though,"},{"startTime":3293.88,"endTime":3297.605,"body":"for optical astronomy, Australia has the deficit of not having any mountains."},{"startTime":3297.675,"endTime":3300.805,"body":"We'd like to be higher up please, for radio, this doesn't matter."},{"startTime":3301.185,"endTime":3302.765,"body":"And so it's always been a specialism."},{"startTime":3303.025,"endTime":3306.619,"body":"But being in the south House, there's this sad truth for those of us in"},{"startTime":3306.619,"endTime":3306.858,"body":"the uk, in Europe, in the northern hemisphere, that a lot of the action is"},{"startTime":3306.858,"endTime":3307.098,"body":"in the southern bit, the sky, particularly a good view of the galactic center, you"},{"startTime":3307.098,"endTime":3315.725,"body":"need to be much further south than here."},{"startTime":3316.345,"endTime":3319.877,"body":"And so Australia has this prime view of Sagittarius, which climbs high in the sky,"},{"startTime":3319.877,"endTime":3320.112,"body":"whereas from here we see it in the summer months, but only just on the"},{"startTime":3320.112,"endTime":3323.645,"body":"horizon."},{"startTime":3323.985,"endTime":3328.145,"body":"So, uh, so the other bright sources, there's a galaxy called Centura a, that was"},{"startTime":3328.145,"endTime":3330.365,"body":"one of the first galaxies to be studied."},{"startTime":3330.395,"endTime":3331.685,"body":"It's one of the brightest radio sources."},{"startTime":3331.685,"endTime":3332.885,"body":"You can't even see that from here."},{"startTime":3333.585,"endTime":3335.485,"body":"So go south as ever."},{"startTime":3335.865,"endTime":3337.685,"body":"The southern sky wind in astronomy."},{"startTime":3339.065,"endTime":3344.102,"body":"And back to history again, Reba, who you all love now, um, how was he"},{"startTime":3344.102,"endTime":3347.125,"body":"actually capturing and recording the data back in 1944?"},{"startTime":3347.185,"endTime":3348.565,"body":"That's a, a, a really good question."},{"startTime":3348.755,"endTime":3353.125,"body":"He's taking, he does have a chart recorder, but really he's doing long observation."},{"startTime":3353.345,"endTime":3357.361,"body":"So he's integrating on particular bits of the sky and he is literally reading off"},{"startTime":3357.361,"endTime":3358.165,"body":"the signal strength."},{"startTime":3358.345,"endTime":3359.845,"body":"So he's making handwritten notes."},{"startTime":3359.905,"endTime":3363.005,"body":"So it's very old fashioned astronomy with some very high tech."},{"startTime":3364.305,"endTime":3370.005,"body":"And, and how do, do the radio signals then get conversed into optical representations?"},{"startTime":3370.435,"endTime":3373.632,"body":"Yeah, so, so yeah, again, I can put up, you know, whenever I show you"},{"startTime":3373.632,"endTime":3375.125,"body":"a picture, this is a good example."},{"startTime":3375.235,"endTime":3379.21,"body":"This was on the front page of almost every newspaper in the world as a"},{"startTime":3379.21,"endTime":3382.125,"body":"photograph of the black hole at the center of the galaxy."},{"startTime":3382.125,"endTime":3384.842,"body":"And I hope I didn't say that, that 'cause the one thing it isn't is"},{"startTime":3384.842,"endTime":3385.205,"body":"a photograph."},{"startTime":3385.265,"endTime":3387.365,"body":"So this is actually a computer model."},{"startTime":3388.305,"endTime":3394.546,"body":"So this is, uh, the result of a program that tried many, many, many millions"},{"startTime":3394.546,"endTime":3394.963,"body":"of different shapes and then predicted what radio signals would be seen from the different"},{"startTime":3394.963,"endTime":3401.205,"body":"telescopes."},{"startTime":3401.505,"endTime":3403.605,"body":"And then you go back and forth until they match."},{"startTime":3404.305,"endTime":3408.69,"body":"And so this is an image, but this isn't a picture of the radio waves"},{"startTime":3408.69,"endTime":3410.445,"body":"that were detected by the telescope."},{"startTime":3410.825,"endTime":3413.725,"body":"Things like, so, so this is, it's sort of a construct."},{"startTime":3414.035,"endTime":3418.108,"body":"This is closer to being an image in the sense that if you had eyes"},{"startTime":3418.108,"endTime":3418.38,"body":"that were sensitive at these wavelengths and you stared at this area, you'd see something"},{"startTime":3418.38,"endTime":3422.725,"body":"like this."},{"startTime":3422.825,"endTime":3427.436,"body":"But again, it's a construction via a computer model of what the telescopes are seeing"},{"startTime":3427.436,"endTime":3431.125,"body":"because we're doing this trick where we have many telescopes working together."},{"startTime":3431.265,"endTime":3434.525,"body":"So it, it's a much more complicated business than optical astronomy."},{"startTime":3434.905,"endTime":3439.386,"body":"Uh, people who are good at it, like Ian, who made this image, uh, essentially"},{"startTime":3439.386,"endTime":3439.685,"body":"wizards."},{"startTime":3440.145,"endTime":3442.685,"body":"And, uh, we try not to ask them too many questions."},{"startTime":3442.875,"endTime":3443.165,"body":"Okay."},{"startTime":3443.325,"endTime":3444.405,"body":"Couldn't stop without that."},{"startTime":3444.785,"endTime":3449.258,"body":"Um, just, um, if we, um, uh, uh, alien, I sawers, if they happen to"},{"startTime":3449.258,"endTime":3449.556,"body":"be pointing to us, what would they, what the thing that would be show up"},{"startTime":3449.556,"endTime":3454.925,"body":"that we're throwing out?"},{"startTime":3455.035,"endTime":3455.325,"body":"Yeah."},{"startTime":3455.325,"endTime":3458.245,"body":"Or would they have to be looking directly at us to see stuff?"},{"startTime":3458.595,"endTime":3458.885,"body":"Yeah."},{"startTime":3458.945,"endTime":3459.965,"body":"No, this is a good question."},{"startTime":3460.185,"endTime":3461.605,"body":"So could aliens see us?"},{"startTime":3462.285,"endTime":3466.048,"body":"I, I think it's interesting when you listen to the debates in the sixties and"},{"startTime":3466.048,"endTime":3467.805,"body":"seventies about how to look for aliens."},{"startTime":3468.385,"endTime":3472.005,"body":"We are living at a time then where we are becoming radio loud."},{"startTime":3472.005,"endTime":3475.085,"body":"People are broadcasting TV out to the cosmos."},{"startTime":3475.105,"endTime":3479.35,"body":"And so, you know, there's 40 years worth of broadcast TV heading out, which would"},{"startTime":3479.35,"endTime":3480.765,"body":"be pretty loud I think."},{"startTime":3481.545,"endTime":3483.205,"body":"Um, these days we do less of that."},{"startTime":3483.305,"endTime":3486.005,"body":"We narrow band to beam to satellites."},{"startTime":3486.005,"endTime":3487.245,"body":"We use fiber optics."},{"startTime":3487.305,"endTime":3491.01,"body":"And so I think it's less obvious than it used to be that we're going"},{"startTime":3491.01,"endTime":3492.245,"body":"to be radio loud forever."},{"startTime":3492.425,"endTime":3495.485,"body":"So if they're watching right now, they would've picked up our tv."},{"startTime":3496.185,"endTime":3500.622,"body":"Um, I think airport radar is interesting 'cause even in advanced civilization, if you want"},{"startTime":3500.622,"endTime":3504.765,"body":"to know whether invaders from the planet Z are coming, radar's a good idea."},{"startTime":3505.225,"endTime":3511.453,"body":"And radar involves broadcasting invaders from the planet Z aren't coming as far as I"},{"startTime":3511.453,"endTime":3515.605,"body":"know, \u003claugh\u003e, um, involves broadcasting out into space quite powerful."},{"startTime":3515.605,"endTime":3517.445,"body":"So I think radar's a good shout."},{"startTime":3517.545,"endTime":3519.245,"body":"So that's why we're thinking about airport radar."},{"startTime":3519.745,"endTime":3524.21,"body":"Um, there is also the story that I've told often, which is that the most"},{"startTime":3524.21,"endTime":3527.485,"body":"powerful transmission ever sent into space was an advert for Doritos."},{"startTime":3528.145,"endTime":3532.132,"body":"Uh, and it's genuinely a true story and, uh, I'm not sure what aliens are"},{"startTime":3532.132,"endTime":3534.525,"body":"gonna make of that if they find it \u003claugh\u003e."},{"startTime":3535.895,"endTime":3536.245,"body":"Hello?"},{"startTime":3536.525,"endTime":3538.245,"body":"I have two, but the second one's really short."},{"startTime":3538.475,"endTime":3538.765,"body":"Okay."},{"startTime":3538.765,"endTime":3539.365,"body":"Um, okay."},{"startTime":3539.745,"endTime":3544.164,"body":"Um, the first one was about Reba, that his data, um, sort of came about"},{"startTime":3544.164,"endTime":3547.405,"body":"in 1939 and then was sat on and published in 1944."},{"startTime":3547.555,"endTime":3547.845,"body":"Yeah."},{"startTime":3547.845,"endTime":3553.926,"body":"Which is right in the, the chronologically where I imagine like just a lot of"},{"startTime":3553.926,"endTime":3556.765,"body":"noise would be happening in the world."},{"startTime":3557.425,"endTime":3561.508,"body":"Did the second World War influence what he picked up on and did he map"},{"startTime":3561.508,"endTime":3562.325,"body":"any of that?"},{"startTime":3562.675,"endTime":3563.725,"body":"Yeah, not directly."},{"startTime":3563.795,"endTime":3568.253,"body":"He's in the middle of, uh, Illinois and so there is less of that of"},{"startTime":3568.253,"endTime":3568.55,"body":"course, what the Second World War did do, and it's a part of the story"},{"startTime":3568.55,"endTime":3568.847,"body":"I didn't tell, is that a lot of the material that's developed for radar, particularly"},{"startTime":3568.847,"endTime":3569.144,"body":"in, in the uk but also with American help, becomes the equipment that radio astronomers"},{"startTime":3569.144,"endTime":3584.005,"body":"use in the late forties and early fifties."},{"startTime":3584.185,"endTime":3589.685,"body":"So Giro Bank was founded, uh, to use radar equipment to look for meteors."},{"startTime":3590.225,"endTime":3593.543,"body":"Uh, and so there's a huge amount of technological development going on at the same"},{"startTime":3593.543,"endTime":3593.765,"body":"time."},{"startTime":3593.785,"endTime":3598.885,"body":"And so that's the point really where Reba uh, loses touch with academic astronomy."},{"startTime":3599.045,"endTime":3601.965,"body":"'cause suddenly all these people who've rubbished his ideas go, oh, well this is great."},{"startTime":3601.985,"endTime":3603.845,"body":"Yes, now we have funding and equipment."},{"startTime":3603.855,"endTime":3605.005,"body":"We'll, we'll do all of that."},{"startTime":3605.005,"endTime":3605.445,"body":"Thank you."},{"startTime":3605.945,"endTime":3608.165,"body":"Uh, and so they move on now, short second question."},{"startTime":3608.505,"endTime":3609.965,"body":"Um, yes, it was about the donut."},{"startTime":3610.505,"endTime":3616.615,"body":"Um, I wondered whether it was sort of more washer shaped as in quite flat"},{"startTime":3616.615,"endTime":3618.245,"body":"or genuinely donut Taurus"},{"startTime":3618.245,"endTime":3618.405,"body":"Shaped."},{"startTime":3618.465,"endTime":3619.445,"body":"Uh, really good question."},{"startTime":3619.875,"endTime":3620.165,"body":"Yeah."},{"startTime":3620.165,"endTime":3624.849,"body":"So putting a thickness on this is, is hard partly 'cause what happens is if"},{"startTime":3624.849,"endTime":3625.161,"body":"you've got the short question, long answer, uh, if you've got the black hole here,"},{"startTime":3625.161,"endTime":3625.473,"body":"let's say there's a genuinely flat Taurus here, the trouble is that the stuff from"},{"startTime":3625.473,"endTime":3637.965,"body":"the back, it's light gets bent and so it gets distorted up."},{"startTime":3638.065,"endTime":3642.405,"body":"And so getting the geometry requires understanding the bending of light around this black hole."},{"startTime":3642.425,"endTime":3644.365,"body":"So these arguments are still going on."},{"startTime":3644.945,"endTime":3648.504,"body":"Um, I don't actually know that we have a definitive conclusion yet, but the thickness"},{"startTime":3648.504,"endTime":3650.165,"body":"of the disc would be really interesting."},{"startTime":3650.165,"endTime":3655.245,"body":"It effects things like how fast the black hole can feed on this material."},{"startTime":3655.905,"endTime":3659.298,"body":"Um, so maybe we'll return to that at, uh, at some point in a future"},{"startTime":3659.298,"endTime":3659.525,"body":"lecture."},{"startTime":3659.525,"endTime":3659.885,"body":"But yeah."},{"startTime":3659.885,"endTime":3660.125,"body":"Great."},{"startTime":3660.125,"endTime":3660.965,"body":"Really great question."},{"startTime":3661.105,"endTime":3663.861,"body":"And I think I've talked long enough that you've forgotten the answer is, I don't"},{"startTime":3663.861,"endTime":3664.045,"body":"know,"},{"startTime":3664.605,"endTime":3669.605,"body":"\u003claugh\u003e."},{"startTime":3665.545,"endTime":3665.965,"body":"Lovely."},{"startTime":3666.055,"endTime":3666.405,"body":"Hello."},{"startTime":3666.685,"endTime":3671.902,"body":"I wanted to ask you if, you know, uh, if there has been, uh, any"},{"startTime":3671.902,"endTime":3674.685,"body":"work regarding the, the codification of the signal?"},{"startTime":3675.065,"endTime":3679.849,"body":"So we don't really, as you know, so for BLC one that candidate, we didn't"},{"startTime":3679.849,"endTime":3681.125,"body":"really get that far."},{"startTime":3681.145,"endTime":3685.432,"body":"We got as far as it appeared to be a signal coming from, um, the"},{"startTime":3685.432,"endTime":3688.005,"body":"planet, but it didn't have a pattern to it."},{"startTime":3688.345,"endTime":3693.589,"body":"Um, so had it been real, the next task would've been to observe it with"},{"startTime":3693.589,"endTime":3698.485,"body":"every radio astronom, every observatory that we got, and try and see some structure."},{"startTime":3698.745,"endTime":3703.008,"body":"So in science fiction, of course we are expecting to have sequences of prime numbers"},{"startTime":3703.008,"endTime":3703.292,"body":"or structures for building a spaceship or so, but we've never really seen a signal"},{"startTime":3703.292,"endTime":3708.125,"body":"with that structure."},{"startTime":3708.825,"endTime":3711.125,"body":"Um, the closest we've got is Jocelyn's pulsars."},{"startTime":3711.125,"endTime":3714.875,"body":"Were a regular pulse, so you can imagine that encoding a number or something like"},{"startTime":3714.875,"endTime":3715.125,"body":"that."},{"startTime":3715.145,"endTime":3720.038,"body":"But we don't yet have anything complex enough that people have tried to decode, uh,"},{"startTime":3720.038,"endTime":3720.365,"body":"anything."},{"startTime":3720.475,"endTime":3724.114,"body":"It's an obvious next step if we find a signal, but it will be a"},{"startTime":3724.114,"endTime":3725.085,"body":"task for the world."},{"startTime":3725.245,"endTime":3729.707,"body":"I think one of the things I said in passing was that astronomers can't keep"},{"startTime":3729.707,"endTime":3730.005,"body":"secrets."},{"startTime":3730.305,"endTime":3730.845,"body":"That's true."},{"startTime":3731.385,"endTime":3734.005,"body":"But we also literally can't keep se secrets."},{"startTime":3734.005,"endTime":3738.652,"body":"If I observed tonight, uh, what appeared to be a signal coming from an intelligent,"},{"startTime":3738.652,"endTime":3738.961,"body":"uh, source out amongst the stars, the first thing I have to do is tell"},{"startTime":3738.961,"endTime":3739.271,"body":"the US South America and Australia so that they can keep monitoring it because you"},{"startTime":3739.271,"endTime":3749.805,"body":"wouldn't want it to drop out."},{"startTime":3750.145,"endTime":3753.88,"body":"And so we end up in a global network of people listening pretty quickly and"},{"startTime":3753.88,"endTime":3755.125,"body":"then the signal becomes public."},{"startTime":3755.625,"endTime":3759.045,"body":"So when that happens, we can all decode it together."},{"startTime":3759.215,"endTime":3760.165,"body":"Thank you for the question,"},{"startTime":3761.045,"endTime":3766.045,"body":"\u003claugh\u003e."},{"startTime":3761.385,"endTime":3761.805,"body":"Lovely."},{"startTime":3761.985,"endTime":3764.045,"body":"I'm afraid that brings us to the end of our time."},{"startTime":3764.505,"endTime":3767.325,"body":"Let me just point out that Chris has got a book coming out very soon."},{"startTime":3767.595,"endTime":3771.487,"body":"It's going to be on sale at the next lecture, which has been moved to"},{"startTime":3771.487,"endTime":3772.525,"body":"the 29th of April."},{"startTime":3772.705,"endTime":3774.925,"body":"It will be here in Conway Hall again."},{"startTime":3775.445,"endTime":3777.205,"body":"I do hope you'll all be able to join us."},{"startTime":3777.265,"endTime":3780.925,"body":"And meanwhile, I'd like you to join me in thanking Kristen Top very much."},{"startTime":3782.375,"endTime":3782.805,"body":"Thank you."}]}