Space

What's The Science - Keith Bannister

 

 

[Image appears of Huw Morgan talking to the camera and the CSIRO logo can be seen in the background and Keith Bannister can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: This morning I’m talking to Dr Keith Bannister, who is Principal Research Engineer/Astronomer with CSIRO. And Keith has just been awarded the Newcomb Cleveland Award from the Advanced, the American Advanced, sorry the American Association for the Advancement of Science and that was for a paper published in science with the title “A Single Fast Radio Burst Localised to a Massive Galaxy at Cosmological Distance”. First of all, congratulations Keith on that award.

 

Keith Bannister: Thanks Huw.

 

Huw Morgan: What does it mean?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Ha. Well, the award was, it was a bit of a nice surprise actually. So, the award was for the best paper published in that year in Science Magazine, which is published by that American Association for the Advancement of Science. So, that was nice. Yeah, it was, yes I guess it means it was a lot of hard work by a lot of people and it paid off. So, you know.

 

[Image appears of Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Well, Science Magazine is at the pinnacle of a peer review publication isn’t it?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, it’s a fancy pants journal as I’d say to people when we’re trying to work out whether we should publish in those sorts of things or not. So yeah. It was a big result for us and it was a lot of, you know, it’s really nice to be recognised at that level. But yeah it was a lot of work and it was a huge team of people. I mean I think they were a bit… you know, they were used to giving these sorts of awards, prizes to papers that have two or three authors and there were 50 authors on our one. So, it was quite a big effort.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Well, let’s get down to the nitty gritty of the paper. So, first off what equipment did you use? Or how did you look at these Fast Radio – we’ll get into what a Fast Radio Burst is in a minute or so – but what equipment was used to look at these Fast Radio bursts?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Right, well so, you know the middle word there is radio. So, we’re using a radio telescope. And in particular there is a fantastic radio telescope, you know, built by CSIRO out in Western Australia called ASKAP. So, that stands for the Australian Square Kilometre Array Pathfinder. Yeah, and it’s out there in Western Australia and we added an extra computer or two in there to, or just one really, in there to do a whole bunch of special processing to try and find these bursts.

And in particular we had an extra little component that let us, it was like a live action replay. So, we could, you might detect a burst in a week or maybe even two weeks. So, you have to wait a long time but then when one happens it’s the most exciting three seconds of your life. So, basically you organise to have this live action replay so you can go back and look at everything in exquisite detail.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: When you say, “the most exciting three seconds of your life”, maybe you could explain a Fast Radio Burst. They’re a lot shorter than three seconds aren’t they?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Right, right yeah. So, OK, that’s the other thing. So, it’s a burst of radio waves. So, it literally goes click like that and in fact it lasts only a millisecond. And the three seconds is how much data we get. So, we can actually look inside that and find the millisecond that we’re interested in. So, and the reason we save, actually the reason we save three whole seconds, which seems like a lot in comparison with the millisecond, is actually, you know, you can think of Fast Radio Bursts, they’ve got a fascinating little property we use all the time. And we later used it to measure how much, to find 2.5% of the universe that had gone missing. And one of the nice things about Fast Radio Bursts is actually it’s a click that lasts a millisecond but the millisecond that that click arrives depends, it changes with frequencies. So, you know, if you, you know, with your old radio, young people might not even know this anymore, but you and I, Huw, remember the old car radio where you would tune the radio up and down in frequency.

 

Huw Morgan: The wireless.

 

Keith Bannister: The wireless, exactly, yeah. So, you could tune it up and down so you’d be sensitive to slightly different sizes of radio waves, or different frequencies of radio waves. And FRBs emit, you see them at all, basically all different radio channels but it’s like, you know, you’re on, you’re listening to the news on one channel and then you change it to the next channel and then the news just starts there, and then you change it to the next channel, and the news just starts at the next channel and so on.

 

And so with Fast Radio Bursts you get the high frequencies first and they arrive later, can you see my hand there, and they arrive later at lower frequencies and you can use that property to actually work out how much gas the Fast Radio Burst has gone through on its way to earth. And that time can be as long as a second. So, the burst itself lasts for a millisecond but actually that millisecond arrives a second early, in the high frequencies, and then, you know, about a second later at the low frequencies.

 

[Image shows Keith listening and a background of planets can be seen and Huw can be seen talking inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: And what’s that telling you?

 

[Image continues to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, so I mean this is the kind of amazing thing is it tells you, if it arrives all at once it means that it went through no gas before it arrived at Earth. If it arrives half a second later it went through, you know, let’s pick a number, about quarter of the universe. If it arrives one second later it went through about half the universe. So, you can basically measure how much gas there is in the universe.

 

[Image shows Keith listening and a background of planets can be seen and  can be seen talking inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: And that helped you find the missing universe?

 

[Image changes to show Huw listening and then flicks back to show Keith talking to the camera again and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, yeah so that’s not this paper actually. That was the next one. So, people were looking for a long time for 2.5% of the universe we thought was there and, and it turns out that we were able to use Fast Radio Bursts to find it and it’s actually in this very thin gas that’s between galaxies. Yeah but that’s a different paper.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: So, is there any more of the universe still missing?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, there’s only, we’re up to, I think we’ve got 5% of it sort of pretty much nailed down. So, only 95% to go.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: That’s theoretically isn’t it? Theoretically there should be x amount of stuff in the universe and we can only find y amount so there’s a gap between x and y. We don’t know what it is or where it is.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Exactly. So, you can imagine a pie chart of the universe right and I mean theoretically you can, it’s a bit, there’s measurements of this right. And I guess the question is, you know, why is it that some measurements are saying there’s this much of the universe and other measurements are saying there is much less. So, you know, when we measure, if you, if you look at all the stuff that’s glowing around us, you know, stars, and sometimes you see gas, and sometimes you see dust, and sometimes you see, you look up in the sky, you can count up how much stuff there is and you go, “Oh right, there’s this much stuff”. You can measure it any way you like in kilograms, or grams, or something bigger but you can count up how many atoms there are there.

 

But if you do what we call cosmological measurements, or for instance if you look at exploding stars and how fast they’re moving as a function of distance, so you look at nearby exploding stars and further away exploding stars you find that, you know, that it looks like the universe is kind of accelerating. And so, we kind of think, “Oh well, there must be something to do with, there’s energy associated with that acceleration” because you can’t accelerate anything without having energy. So, and you know, that constitutes like 70% of the universe. It’s way more than the amount of the atoms there is. And there’s dark matter which is like spinning galaxies around too fast. And we don’t know where that is either and that’s another 25%. So, yeah.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: A few more papers coming, a few more papers coming out of it.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, there’s a lot more work to do.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Well, now you mentioned energy. Now, these Fast Radio Bursts, I’ve done a bit of research about Fast Radio Bursts, but they’re enormous amounts of energy aren’t they?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, and that’s actually surprising because radio waves are not very powerful things. You know, so the energy in a radio wave is not very, is not very large. If you take an x-ray for instance, you know, an x-ray photo and you bang it into something, you know, ouch, right. It can, it can actually cause chemical reactions in your body for instance which is why you don’t want to get too many x-rays. But radio waves go straight through you no problem, right. It’s very low energy stuff. So, it’s kind of incredible that, you know, in one millisecond, one of these things when it goes off it takes all those, all those radio waves take away as much energy as the sun produces in 60 or 80 years I think.

 

Huw Morgan: Really.

 

[Image continues to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, yeah. So, all of the energy, the whole energy from the sun it will produce in 80 years and then when one of these things goes off, in a millisecond it releases the same amount of energy as the sun in 80 years. But it only does it in one millisecond.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: I’m going off track here a bit but is there a possibility that those energy bursts would cause gravitational waves.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Ah hah. Well, that would have been the holy grail of like, oh my god, because it would have been the two sexiest part of, you know, astronomy, like getting together and having babies right.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: You would have had a Nobel prize instead of…

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Well, so that, yeah, but it’s funny you mention that because it’s… the radio waves themselves wouldn’t cause gravitational waves but you could imagine the same event producing both. So, you can imagine for instance if you get two stars and you smack them together, you might get some, get some gravitational waves and also some radio waves. So, that’s possible. At the moment we don’t think that happens but, you know, anything’s possible really.

 

[Image changes to show Huw talking to the camera and the CSIRO logo can be seen in the background and Keith can be seen inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: OK. Crunch time.

 

[Image changes to show Keith listening and Huw can be seen inset talking]

 

Keith Bannister: We don’t really understand all this stuff too much.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Here’s the crunch question. What are, what causes Fast Radio Bursts?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Ah well, yeah that is the crunch question. So, we’ll get to what, what the paper that I wrote with my colleagues shortly because I think that has a few sort of bearings on that. We don’t really know what causes Fast Radio Bursts definitively but we have a few ideas and actually that’s getting better all the time.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Is it the Warp Drive from The Enterprise?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah well, it’s tempting isn’t it. I’ve got another paper we’re working on which I think is Warp Drive exhaust but we’ll talk about that in a minute.

 

Huw Morgan: OK.

 

[Image continues to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: So the, so the leading kind of contender for what causes Fast Radio Bursts is what we call a magnetar. So, a magnetar is a type of neutron star. You might have heard of pulsars. So, pulsar is a neutron star that you see in radio waves. You see it pulsating but you can have neutron stars that don’t pulsate. So, anyway a neutron star is made up largely of neutrons. It’s like, you can imagine fitting the whole mass of the sun and you squeeze it into something that’s like the size of, about 10km across, so you know the size of a moderately sized city.

 

So, very small in comparison with, and it’s hugely dense, so a teaspoon of it weighs, I don’t know, many, many tonnes right. So, it’s a huge, it’s a very, very dense star. And a magnetar is like that but massively magnetised so we’ve got, it’s basically like a giant magnet and exotic things happen around in, you know, very hot, magnetised environments. And so, earlier, late last year, no early last year, 2020, they, they actually detected a Fast Radio Burst that came from a magnetar in our own galaxy. So, that was kind of definitive that that particular burst came from that particular magnetar.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: But did the magnetar change as a result of the Fast Radio Burst, or did something, could you actually say, “OK that event happened and then the Fast Radio Burst occurs”?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, well exactly. So magnetars sometimes they emit bursts of x-rays and what happened in this case was the magnetar kind of, they kind of burp occasionally right, they just have indigestion. So, it kind of burps and it emitted all these x-rays and people who care about x-rays from magnetars, you know, they detect, you know, these x-rays smacked into a telescope somewhere orbiting above the earth and those astronomers who care about that stuff they said, “Oh look, we saw this burst of x-rays from a magnetar”.

 

And then madly, and it was in the northern hemisphere, so us in the south couldn’t see it, but the northern hemisphere, a bunch of radio astronomers went, “Oh I wonder if there was a Fast Radio Burst today?”. And they were lucky and sure enough there was and it came exactly from the same place at the same time. Yeah, so in that case it was, it was pretty clear. But what’s interesting about that is that, is that magnetars, well it was, we did see a burst but it was a very, very, if we’d put it at a large distance, like the distance of the one that we wrote about in the paper we would never have seen it. So, it’s possible that a different mechanism is responsible for much brighter ones. But anyway it’s interesting as a [13:04] if you like.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Now getting to that, the paper, the title of it, “At a Cosmological Distance”, what’s “a” cosmological distance, what’s cosmological distance, what does that mean?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Right, right. Well, so this is a little, I guess it’s a very historical, it’s part of a little historical fight if you like. Oh not so much of a fight but a, it’s a sign of the times even when we wrote the paper. So, at that time, which isn’t that long ago, you know, it wasn’t, you know, when Fast Radio Bursts were first detected we didn’t really know where they came from. So, we got, we measured that dispersion which is how much gas it’s gone through and so we went, “Well, we’re pretty sure that we know how much gas is in the Milky Way and it’s more than that so it must have gone through even more gas than the Milky Way, so it must have come from outside the Milky Way” but we don’t know whether it’s actually coming from just a galaxy next door that’s got lots of gas in it too or whether it’s coming from a, like a really, really long way away and that gas, that extra gas we’re seeing is actually just lots, you know, a very, very low density gas and it’s coming from us from a huge distance.

 

So, there was a big, there was a big argument in the community if you like, you know, is it from really nearby galaxies and they’re just, there’s lots of gas in that galaxy and so we’re just seeing that, or are we seeing lots of thin gas and these things are really coming from enormous distances. And when we, when we made our measurement we found this burst that went off. We got our live action replay. We pinpointed it to a galaxy and then we looked at the distance of that galaxy and it was, it really was, you know, a massive distance. And so, that was the kind of the clincher, yeah.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: With the Fast Radio Bursts, do they have to be line of sight so to speak? So, if there’s a lot of stuff between us and the Fast Radio Burst, planets, stars, galaxies, god knows what, the missing stuff as well, does it have to be a clear line of sight? So, say a Fast Radio Burst happens behind a star, that’s in the path between ourselves, and the Fast Radio Burst, will that block the Fast Radio Burst? In other words the Fast Radio Bursts are there, billions and billions of them happening all the time, we just can’t see them?

 

[Image changes to show Keith talking to the camera on the main screen and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Can’t see them because they’re getting blocked by things? Well it’s funny that you mention that because radio waves are really hard to block actually. That’s why we use them for mobile phones. It’s because they bend like mad. Bended like Beckham is what you do with radio waves. So, you can bend them really easily but in fact, so, so that’s one thing. The second this is… a lot of the, and, and they like to go through stuff that you don’t see, like light won’t go, you know, the optical light that you see it wouldn’t go through.

 

So for instance, it’s very difficult to see towards the centre of our own galaxy because there’s lots of dust there. So, all the light that’s getting emitted by stuff in there gets sort of, gets blocked by the dust. Radio waves go straight through which is really, which is really good. So, we can see the centre of the galaxy in radio waves. So, then if you put radio waves at a large distance, often they’ll just go around or through everything and you’ll still see them.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: But doesn’t that lead to… sorry to interrupt you, but doesn’t that lead, if they bend, are  you actually looking at a Fast Radio Burst, or is it in a different spot than where you thought it was?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yes it can, yeah the bending can actually move where it looks like it comes from, yeah. So, in practice the amount of bending is often extremely small. But it’s…

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: But over those huge distances that’s a lot.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, yeah that’s true. Yeah but still like the angle, so it can deviate a large distance in terms of how far it’s gone but on the sky when you’re looking at it it’s not so far, you know not so far in angle.

 

Huw Morgan: Right, yeah, yeah.

 

Keith Bannister: It’s like the, you know, it’s a really big triangle. So, you know, if you have a very small angle at one end and a really, really long triangle it still has to go a long way but it’s certainly a very small angle.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: So, the single Fast Radio Burst in the paper, how far away was that?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Oh gosh, I’d have to, in light years I’d have to remember. It was like billions of light years away.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: So, it happened billions of years ago?

 

Keith Bannister: Yes, yeah, yeah, yeah.

 

Huw Morgan: Because what do radio waves travel at?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Same speed as, well more or less the same speed as the speed of light except for like I said, you know, that dispersion thing we talked about a minute ago. So, the reason the low frequencies arrive late is because actually when they go, when radio waves go through this gas they’re slowed down by the gas. It’s like they have to swim.

 

[Image shows Keith talking to the camera and mimicking swimming while Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Low energy radio waves they’ve got to swim and so, you know, it’s travelling billions of light years, trillions of kilometres, I mean many trillions of kilometres.

 

[Image shows Keith continuing to talk to the camera]

 

But it’s, in the end it arrives like half a second later. So, they’re not that much slower than the speed of light but they’re just a little bit measurably.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Yeah, yeah. So, how many of these Fast Radio Bursts have been detected? And Australia’s done particularly well in detecting these haven’t we?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Yeah, yeah, well exactly. So, like they were first discovered in Australia by an international team but they were using the telescope at Parkes.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: The CSIRO?

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: The CSIRO telescope at Parkes, exactly, yep so the dish. So, that was the first ever discovery was there. For a long time Parkes was the only telescope that had ever seen them so everyone was thinking, “Oh these things are they real or are they just, you know, just a feature of some of the receivers at Parkes?”.

 

And then other telescopes started to detect them so that was kind of encouraging from a, you know, scientific standpoint. And then, yeah, so Australia’s done very well out of it. You know, there’s a couple of telescopes. There’s ASKAP, which is the one I use most. There’s another telescope that’s run by Swinburne University in Melbourne and it’s called the Molonglo and University of Sydney. Both of those institutes run one and they’ve detected some. So, yeah, there’s about a hundred published now, a bit over.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Right, and it sort of, pure, pure science, and then so you go, and what’s it mean?

 

Keith Bannister: What does it mean?

 

Huw Morgan: Yeah.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: What does it mean? People often ask me that question and often people maybe in your position Huw and it’s a difficult one to answer.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Oh, oh, the lowly, lowly…

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: No, no, more journalist types who say, “What’s the point?”. And it’s like well, you know it’s really hard to say what the point is.

 

Huw Morgan: Yeah, yeah.

 

Keith Bannister: You know, it’s cert… it’s exc…

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Justify your existence Keith, justify your existence.

 

[Image changes to show Keith talking to the camera and a background of planets can be seen and Huw can be seen inset in the Participant bar at the bottom of the screen]

 

Keith Bannister: Exactly, I’m an astronomer, when astronomers go on strike it’s like, “Oh no, the astronomer’s gone on strike”. Look, I mean what it’s telling us is that, you know, the universe is, I mean no one ever predicted that these things would happen at the beginning, right. And so, the fact that we’ve found them and all these kind of I mean totally mind blowing, you know, a millisecond, thing lasts a millisecond, and you can see it from halfway across the universe literally. And just, you know, just out of complete happenstance it also tells you how to measure the size, you know, the amount of gas in the universe. It’s, you can’t measure any other way. It’s just cool to know.

 

And I think there’s, you know, one of these things about, you know, FRVs, I mean it’s a cool thing, you can use it to measure the composition of the universe which [20.29] know what the composition of the universe . It’s not going to be [20.31] universe, you know. Are we seeing 5% or 1% or you know? That’s a kind of useful thing to know. And the other thing is you don’t know where this takes you. You know, and I think this is the nature of all sorts of fundamental research like astronomy, quantum physics or whatever is you just don’t know. You know, maybe [20.56] years ago people said, "I'd never use that". But you know, quantum physics is how your computer works or your solar panels, or you know. So, that’s why I like it.

 

[Image changes to show Huw talking on the main screen and Keith can be seen listening inset in the Participant bar at the bottom of the screen]

 

Huw Morgan: Yeah, I’ve always said that the cliched “Eureka”, you know, I’ve found it, or whatever, the more interesting thing in science I think is when people go, “Oh that’s a bit strange, what’s that? Oh that’s a bit odd”. You know, you go, “Oh what’s that about?”.

 

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Keith Bannister: Oh, I didn’t see that one.

 

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Huw Morgan: Yeah, that’s the more interesting stuff rather than, you know, “Eureka”, yeah right.

 

Keith Bannister: Yeah.

 

Huw Morgan: It’s like, “Gee that’s a bit strange, that’s odd. What’s that?”.

 

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Keith Bannister: Yeah, that’s it.

 

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Huw Morgan: OK, so where do you go to from here with these Fast Radio Bursts?

 

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Keith Bannister: Yeah, well that’s a good question. So, since we published that paper, that was the first time we’d ever… there was one FRB that had been found in a galaxy previously in that, to that paper, and that was a repeating one so that was kind of easier because you knew where to look to start with. But there are not very many known things that repeat. So, it kind of, it’s a limited sample. But so, the plan is to go out and find a whole bunch. If we can find a 100 or 200 and find each of their home galaxies then you get a really nice idea of the, you know, of this how much matter there is in the universe. And we can start to actually, at the moment, the number that we got was very much, this is exactly what expectation, what we’d expect from other gases. And then, but if we get 100 or maybe 1,000 you might be able to say, well actually, you know, maybe if we don’t agree, then it’s like “Well, you guys need to go and fix up your numbers”, you know.

 

So, that’s a useful thing to know because you can, you can often use different ways, if you have different ways of measuring something like the universe and they don’t agree then someone has to go back to their drawing board and fix their, you know, get back to their equation. So, that might be useful.

 

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There’s some other stuff there that’s been really fun. For instance, we think that like galaxies are surrounded by big halo, we call them halos of gas. It’s kind of, you don’t really see it but it’s inside a big bath but we don’t know much about this halo gas. And of course FRBs go through that on the way to us. And we were very lucky the second, almost the second one I think it was that we detected, it went, it came from, you know, halfway across the universe. And there was another galaxy about halfway along and it was very, very close to the line of sight. So, almost exactly what you were talking about. It didn’t go through the galaxy but it went through the halo of the galaxy.

 

And from that, and then again, you know, it probably must have gone through there, so you know, how, when it did go through there, it picked up all that gas, you know, and it got to us and we got to see how much gas there was. And there wasn’t a lot. And that was quite surprising. There was no magnetic field in there either and again that was quite surprising. So we, what we’re finding is, you know, in lucky chance alignments you can get to find out an extra piece of information about that. And so, if we find enough of those we can start to build up a statistical picture of you know what is it that these little halos, these halos of gas around galaxies look like. You know, how far do they extend from the galaxy, and how dense are they, and stuff like that. That’s my phone.

 

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Huw Morgan: That’s alright. We’ll have to wrap it up soon but I’m not going to let you go without getting to the paper about the Warp Drive.

 

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Keith Bannister: Oh, the Warp Drive paper. Yeah, so this is a completely separate paper using a completely separate, same telescope funnily enough, but a completely separate technique. So we, when you look at the, you know, when you look at the sky with your eyes you see that the stars twinkle and the reason they twinkle is because of turbulence in the atmosphere. So, you see the same effect when you’re driving along the road on a hot day and everything is shimmering on the road.

 

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It’s exactly the same effect. So, you seem something, it’s turbulence, it’s shimmering, and something behind it looks like it’s, you know, it’s shimmering. So, we take a radio telescope, you look at the sky. You see millions of galaxies. They all look like little dots and occasionally you see one and it shimmers. And that tells you that somewhere between us and that thing, that galaxy is, you know, some turbulence, right, something is kind of some moving gas. Now the thing that’s interesting was that we, that we did this, exactly this game, well a student of ours did. She looked at the sky. She went dah, dah, thousands of galaxies, they’re all pretty boring, they all just sit there. And then there’s a couple of twinkling ones. And then you look at the sky and all the twinkling ones are in a nice, perfectly straight line on the sky. And the size of that line is about like the size of, I don’t know, if you put your hand out, and your four fingers out at the arm’s length, that’s the size of the line.

 

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Huw Morgan: They’re not Elon Musk’s satellites going over?

 

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Keith Bannister: No, no. So, this is, we measured this over several months, yeah, several months, always the same sources. They were always twinkling. The other ones were always completely still. And yeah, so I kind of, and, you know, the big question is how do you make this nice straight line in the sky? I mean we don’t see a lot of nice straight lines, right, in nature, you just don’t.

 

Huw Morgan: The Enterprise.

 

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Keith Bannister: The Enterprise, yeah well that was what I thought, Warp Drive Exhaust, right. The obvious thing and there it is and if you just follow the line you should be able to see it zooming through. In practice, we think probably what it is, is like a cloud of very dense, cold matter, and if it, if you have a situation where you’ve got a star say, and this cloud, and it goes too close on an orbit around the star, the cloud will get disrupted. Then what happens is it leaves, it kind of gets thrown out if you like in a nice, pretty nice straight line. It doesn’t exist for very long but if you catch it at the right time it will look more or less like a straight line, yeah. So, that’s what we think it is. It was very difficult to prove.

 

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Huw Morgan: That’s a perfect example of, “Oh that’s odd”.

 

Keith Bannister: Well, yeah.

 

Huw Morgan: That’s strange.

 

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Keith Bannister: Exactly. So, I mean I still remember the meeting where we were looking at this, you know, usually just to find one of these things is kind of a bonus and we did, and one of my colleagues spotted it and we said, “Oh wow, we should really go and look into this”. Because just to find one is a bit of an exciting thing. And then so we gave it to this student and we said, “There’s one in this data set. Go and try and find it”. She said, “Oh yeah, OK”, and off she went.

 

Then she came back and she said, “I’ve found a few more”. And we went, “Good on you, wow this is exciting. This telescope’s really good for this sort of stuff”. And she said, “Yeah, they’re all on this line”. And I’m thinking, “Nah, there’s something wrong with the telescope”. And we just, we looked under every rock and we couldn’t find a problem with it and yep so that’s what it… so actually that just got, that’s published today I think. There’s a piece in The Conversation about it you can, you can read.

 

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Huw Morgan: Oh OK.

 

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Keith Bannister: But they don’t talk about the Warp Drive Exhaust interpretation. That’s just a joke.

 

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Huw Morgan: Yeah, yeah. I, we’ll put a link to that article in there and also we’ll put a link to the paper, the “Single Fast Radio Burst Localised to a Massive Galaxy at Cosmological Distance” so people can have a bit more of a read, more than my rudimentary understanding of it. And hopefully this has whetted some appetites for having a bit more of a delve into these things.

 

Keith Bannister: Right.

 

Huw Morgan: And congratulations to you and the team for the, for the win.

 

Keith Bannister: Thanks Huw.

 

Huw Morgan: And we’ll look forward to the Nobel prize ceremony in a few years.

 

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Keith Bannister: Yeah, I don’t think we’ll be doing that. But it’ll be… you know, it’s been fun so far this.

 

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Huw Morgan: And don’t go on strike.

 

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Keith Bannister: Oh no. Yeah, well I have no reason to strike at the moment.

 

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Huw Morgan: Yeah, alright look thanks very much Keith.

 

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Keith Bannister: Cheers Huw. All the best. Thanks.

 

Huw Morgan: OK. Bye.

 

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Keith Bannister: See you later.

 

[Image changes to show a white screen and the CSIRO logo and text appears: CSIRO, Australia’s National Science Agency]