STEMology s1e30

[00:00:00] Sophie: Welcome to episode 30 of STEMology.

[00:00:03] David: A podcast sharing some of the interesting fun, and sometimes just patently bizarre news in science, technology, engineering, or maths

[00:00:10] Sophie: Your hosts are Dr. David Farmer and Dr. Sophie Calabretto

[00:00:14] David: In today’s episode of STEMology. We’ll be chatting about musical tree rings, historical bang

[00:00:20] Sophie: Anti aircraft Ravens and supernova deja vu.

Musical Tree Rings

[00:00:26] David: So Sophie, some violins are really, really old and some people really, really prefer the really, really old ones.

[00:00:32] Sophie: Apparently some old violins are really, really expensive.

[00:00:37] Apparently there’s a famous violin, Dave, called the Vieuxtemps by an Italian violin maker. Who’s now dead called, uh, someone Guarnerri it’s sold Vieuxtemps sold for more than $16 million in 2012.

[00:00:52] David: That’s just an inordinately large number of dollars

[00:00:55] Sophie: And this think about like, it was 2012 with inflation, like what’s that in today’s money. [00:01:00] 12 billion. No. Anyway, sorry. Dave tree rings instruments. What are we talking about?

[00:01:06] David: So I find this kind of interesting. So you’ve got these really old violins and other instruments, presumably, and I mean, we’re talking old, we’re talking 16th, 17th century instruments,

[00:01:17] Sophie: like

[00:01:18] David: really. Old and the paper actually starts out by saying that violins are some of the oldest and most coveted works of arts in the world.

[00:01:25] which is really, really interesting. but because their market value is so intrinsically linked to how old they are, because people perceive the old instruments as having some undefinable amazing musical quality, which we’ll get to in a second magic. They want to understand what it is about these old instruments that makes them so special basically. And in order to do that, they want to look at the woods because that’s one of the main things that the instrument is made of. And they want to understand exactly how old these instruments are. Basically, these instruments are really, [00:02:00] really old and because how old they are is linked to how valuable they are, we want to understand exactly how old they are with the degree of accuracy. And so one of the ways they do that is by looking at the rings on the instrument and comparing them to tree rings, gathered from the same region.

[00:02:16] Sophie: exactly. So I think that the idea is we want to date these instruments and a lot of the ways that we would normally date things they’re not necessarily destructive, but they involves an element of destruction. So for example, like a lot of the car, the radio carbon dating. methods you need like a small sample of the wood.

[00:02:32] And if someone has spent $16 million on a violin, they don’t want you to be like scrape and like a little bit of a sample off they’re like $16 million violin.

[00:02:41] David: Even a bit. It’s like a thousand dollars worth.

[00:02:43] Sophie: Exactly. And I feel like it may be it’s a thousand dollars worth of wood, but then it makes that violin worth far less than $16 million

[00:02:51] David: A mere a $12 million.

[00:02:52] Sophie: That’s right. and yeah, so this is about using, so we know that when trees grow Dave, they grow rings, right? Like they start a wee [00:03:00] tree and then they grow the little rings and they grow like a ring a year. And then what’s interesting about the rings is that they’re sort of very linked to sort of the climate.

[00:03:09] So as you said, they will be, if you have trees that have grown in a similar area or the same area, they’ll have very, very similar rings because of the climate and so yeah, the idea is it’s, we’re looking at essentially the woodgrain, but the tree rings on the violin and then comparing those with either existing trees that are still growing or other wooden instruments or things that have wood from the same time.

[00:03:34] David: Yes. Basically. So the, the trees grow in a particular way and they grow seasonally. They grow once a year. So basically if you can look at the violin and say, the last ring is this ring that we can see on the surface of the violin, and then look at a tree that’s taken from the same region and say, Oh this tree was cut down at the same time.

[00:03:52] Then you can accurately date using this science called dendrochronology, which is derived from the words for tree and time, exactly when [00:04:00] that instrument was made.

[00:04:01] Sophie: Yeah. So I think the idea is you were looking at what they call the Terminus Post Quem, which is from the Latin of limit after which I could,

[00:04:08] David: your Latin accent.

[00:04:09] Sophie: I did Latin at university.

[00:04:11] David: Did you do Latin at university? Is that thing.

[00:04:14] Sophie: Well, not anymore. the year that I did at Adelaide Uni was the last possible year to start it to, major in it, because then they canceled it. And apparently there’s only like two or three universities left in this country where you can actually take Latin and fun facts.

[00:04:26] David: did you do it in that accent the whole time?

[00:04:29] Sophie: Terminus post quem really funny. Technically you can pronounce Latin in any way you want, because we have no record of anyone speaking Latin. So I just Italian ham it up. And I, I quite enjoy that. and I also got the highest mark ever for any university course was in Latin. I was much better at Latin than like science and maths.

[00:04:47] David: As just as recently demonstrated on this podcast.

[00:04:50] Sophie: Thank you. And so the idea is like, this is a really good way to eliminate violins of being like certain ages instead of actually like necessarily determining them. So the idea is, [00:05:00] okay, so you’ve got like a famous person who made violins in like the 17th century and he died at like some time, but then it turns out that I say him because I’m making an assumption that it’s a him, but then you have like a violin with one of these outermost tree rings or terminus post quem which, that’s actually older there as in like that’s dated to I don’t know, a hundred years after this guy died, then obviously he didn’t make the violin.

[00:05:24] David: Yes. That’s my understanding as well. I find this very interesting. I find it very interesting how much thought has gone into this, however, and it’s a big, however, it feels to me like they’re putting the horse before the car a little bit, because this is all based on the assumption that these old instruments are better.

[00:05:40] Sophie: Yeah. I mean, for the violins it’s based on better, but I think often like dendro chronology is just, it’s helpful in other ways. But I think for this particular, yeah, this particular thing that we’re talking about, apparently there are these master instrument makers, Dave being, I was funny. I was gonna say that I’ve never heard of, that’s not true. So they’ve got most famous as perhaps, [00:06:00] should I really ham up my Italian today and Antonio Stradivari I’ve actually heard of like a Stradivari. And I was like, but I don’t know anything about violins. And I was like, okay.

[00:06:09] So he must be super famous. So apparently he was the main rival of our Guarnerri, who had the Viuextemps, which is French. So like we’re all over the shop here, people. because they’re old and they were made by these old master, make it like, do they sound better, Dave? Is that the idea?

[00:06:25] David: that’s what I’m getting into. And so legend has it that Antonio Stradivari would go to the forest to select the appropriate word for his violins. And apparently he would recognize the right wood by the sound of the timber made as it slid down valley.

[00:06:36] Sophie: so he’s a woodpecker.

[00:06:37] David: Yeah, he’s a woodpecker who makes instruments is very perverse.

[00:06:41] but there are actually, people have looked at this. And so the difficulty with this as this kind of gets into psychoacoustics and of the things, one of the key things in psychoacoustics is that things sounds different and can even sound better if you expect them to. What you expect to hear has a big impact on what you actually hear.

[00:06:58] And there are two [00:07:00] studies, both in proceedings of the national academy of science, I believe one from 2014 and one from 2017, the first one showed that if you blinded violin players and gave them either an old Italian instrument, which was worth millions of dollars or a new instrument, they could readily identify instruments that they liked versus instruments that they didn’t like, but they couldn’t identify the old Italian instruments any better than chance.

[00:07:23] Sophie: Interesting.

[00:07:24] David: And there was a more recent study, one from 2017 that looked at it from the perspective of the listener. And apparently with old instruments, one of the things is that, so people say they prefer the sound of them, but also people say that they project better so that they can be more readily heard in the hall. If you’re, you know, 60 rows back in the circle, then you can more readily hear the instrument it’s cutting through the mix as it were.

[00:07:47] And when they blinded the listener, And blinded, both the listener and the musician playing to which instrument was being played. People said they preferred the sound of a modern instrument over a Stradivarius, and [00:08:00] also that the instruments projected better. So there’s this quote, the whole, the whole assumption that the Stradivarius is better.

[00:08:06] And that these older tightened instruments are worth lots of money because they are better. It’s not so much how that works. It’s if it works at all is more the question to my mind.

[00:08:16] Sophie: I guess it’s just like, we just think old things. I mean, all things is just worth a lot.

[00:08:19] Right.

[00:08:20] David: I mean, it’s cool that they’re old. I mean, having a 400 year old violin is cool.

[00:08:23] Sophie: Yeah, in my research about dendrochronology the one, the thing that I actually thought were the most interesting had nothing to do with violins. and so they’ve got examples about, you know, how this can be so useful. And so apparently in the national portrait gallery in London, there was a portrait of Mary Queen of Scots, which was believed to be an 18th century copy, however, the end, but it was like a panel painting.

[00:08:44] So it was done on, you know, on wood presume. and I was going to say they, I don’t think they actually did any kind of, they didn’t do any other science on except dendrochronology. And it revealed that the wood dated from the second half of the 16th century. So all [00:09:00] of a sudden this 18th century copy was actually a 16th century original, but like by an unknown artist.

[00:09:05] And I think like, that’s really cool. It’s not saying it’s worth any more or less. It’s probably worth more now because it’s older. Cause that’s how it works. But I like, I like the idea, like it’s very, you know, so there was this, like this guy called Paolo Cherubini so he is the person who wrote this work and he does a lot of dendrochronology.

[00:09:21] Do you watch the video with him? His enthusiasm just make me, it was just charming. It was just like someone old Italian dude. It’d been working at the Swiss federal Institute for forest snow and landscape research. W S L and he was just like, talking about like how, you know, like, we look at like the physical and chemical properties of the trees and like these, these days it’s days, and we can do this thing.

[00:09:39] And yeah, basically he was talking about stuff in terms of an elimination. So you know, it’s not an exact science, we can’t say this is exactly what happened because he makes very interesting comments. Like, like I say, you got cut down a tree to make a violin you don’t just instantly make it, like you’ve got a treat that wood. Sometimes wood is stored beforehand.

[00:09:55] So the whole idea is, you know, it’s like back to that, the idea of this, the Terminus [00:10:00] post quem. So, you know, if this person died before.

[00:10:04] Yeah.

[00:10:04] David: stops growing. When you cut it down.

[00:10:06] Sophie: yeah, exactly. So if this like last ring exists after this person was meant to have made after the person’s died, where then you go like, well, no, it’s not a real violin, but yeah.

[00:10:14] I thought it was like, I liked this, but yeah issues.

[00:10:17] David: Issues with the underlying assumption, which, you know, but it’s still very, very cool and still very, very interesting.

[00:10:23] Sophie: So the main thing I’ve learned today is that I shouldn’t get you a 16th century violin for Christmas. Cause you’re not going to be that impressed.

[00:10:28] David: well, I might be, I mean, I’d be more impressed with you for affording it.

[00:10:34] Sophie: I think You’d be impressed with me because I managed to acquire one in a way that didn’t involve paying like $16 million that I don’t have.

[00:10:42] David: I don’t, I won’t ask.

Historical Bang

[00:10:43] Sophie: Gunpowder science,

[00:10:55] David: Gunpowder science from historical instruments to historical bang.

[00:10:59] Sophie: bang. I [00:11:00] love it. I really enjoyed this Dave just because it involved sciencing and blowing up. And I just love, I liked it was, it seemed very meticulous to me. I thought it was beautiful. I loved everything about it.

[00:11:10] David: I loved it too. They have a whole scientific apparatus for looking at exploding things.

[00:11:15] Sophie: Well, they’ve got several different kinds in the back. but yeah, so this is some work that’s come out of the American Chemical Society. And basically in a nutshell, what happened was a bunch of historians and chemists went and got some like medieval recipes for gunpowder, and then they made the gunpowder and then they exploded it and they went.

[00:11:34] “This is interesting how it’s changed. Like people eventually worked out how to make better gunpowder using trial and error”, but not only did they explode it in a lab, apparently they used a replica 15th century stone throwing Canon, and they also tested it at the Westpoint Firing Range.

[00:11:50] But yeah, so this is just like, we’re interested in the history of gunpowder. Let’s actually make it and explode it. And then. As, you know, cause there is, we do talk about science sometimes, [00:12:00] they actually measured the energy releases and they analyzed it like, you know, what’s happening during combustion.

[00:12:06] And so yeah, it was, I loved it I loved it Dave

[00:12:08] David: I love it. So they’re looking at gunpowder. So I didn’t realize this because Apparently we don’t use gunpowder anymore. We use what’s called

[00:12:15] Sophie: smokeless powder.

[00:12:17] David: which basically, because when gunpowder combusts, it leaves a lot of solid residue and smokeless powder, doesn’t it mostly makes gas is the combustion product.

[00:12:26] And that basically has meant that we can have autoloading and semi-automatic and automatic weapons because, we can have moving parts we can afford to have moving parts that don’t get all gunked up with the solid

[00:12:37] Sophie: But also can I tell you about what I learned about, the advent of, smokeless powder versus gunpowder? Apparently so gun powder is black powder really problematic on the battlefield. So apparently military commanders, since the Napoleonic wars, reported difficulty with giving orders on a battlefield obscured by like smoke of firing. So the whole idea is a lot of, you know, often it’s visual signals, but once you [00:13:00] fired a bunch of these guns, it’s just smoke everywhere and you can’t see anything. My favorite thing, which is terrible. Apparently, um, snipers or other concealed shooters were often given away about a cloud of smoke over their firing position.

[00:13:13] David: Aw that’s a disaster.

[00:13:14] Sophie: Isn’t that terrible? So you just like, I’m going to hide up in a tree, like a sniper. And then I was like, oh, it’s there. I can see the smoke. Everyone like explode that tree. But yeah. so now if there’s anything that we use that we only, if we talk about gunpowder, people are actually talking about smokeless powder.

[00:13:28] David: Yes. And apparently gunpowder. So it’s classified as a low explosive, I learned, as opposed to a high explosive. And what that means is that it burns at subsonic speeds, whereas high explosives detonate at supersonic speeds. So basically when you blow up gunpowder behind a projectile, like a cannon ball or a musket ball, it produces enough pressure to force the shot out of the muzzle, but not enough force to blow up the Canon or the gun.

[00:13:53] And

[00:13:54] Sophie: quite

[00:13:54] David: it’s so useful. Yeah. It seems really useful for the intended purpose of, you know, shooting someone else instead of [00:14:00] yourself.

[00:14:00] Sophie: Yeah, apparently we still use gun powder in fireworks and pyrotechnics though.

[00:14:04] David: Yes. I learned that too. Yes. And I enjoyed this line before we get onto the actual science. I really enjoyed this line from the paper as well, which was gunpowder also known as black powder is only humanities second great experiment after fire with harnessing chemical energy,

[00:14:19] Sophie: Guess who also wrote down that quote?

[00:14:21] David: Aye

[00:14:22] Sophie: the favor? Yeah, totally agree. Yeah. So, the idea is that, you know, gunpowder is an explosive combination of varying ratios of potassium nitrate or saltpeter, sulfur, and charcoal. And then what I love is they get into like, so all of these medieval recipes have these like whack a job additives, which they like looked at.

[00:14:43] It’s like, why would you do things like, so there’s like camphor, which is not that exciting, but like they would add things like varnish or Brandy

[00:14:49] David: Brandy man, that seems like an accident that seems like someone was on the Brandy and just like knelt

[00:14:55] Sophie: And went, see, will this still explode? Don’t tell my boss.

[00:14:57] David: oh no, no, that’s just how we make it.

[00:14:59] Sophie: [00:15:00] That’s what we do. This is it’s absolutely fine. Um, Salt Peter, David comes from the medieval Latin saltpetre, which just means salt overall, it’s not that exciting.

[00:15:09] So what they did, Dave is, and now we can talk about the special apparatuses we have to measure explosions and it takes us to the calorie Dave. So what we’ll do is calorimeters and do you know what I learned? So I, in my head, a calorie is the amount of heat needed to raise the temperature of a kilogram of water by one degree Celsius.

[00:15:30] But that is a food calorie that is actually a large calorie, alternately the kilocalories. So the scientific calorie is just a unit of energy defined as the amount of heat needed to raise the temperature of one gram of water.

[00:15:43] David: Well, I was not aware of that

[00:15:44] Sophie: I was not either, but then I guess I, when I talk about food things, I talk in kilojoules cause I live in Australia.

[00:15:49] So it means that I don’t often talk about calories, but yeah. So cause I learn about the food calorie on one of my favorite documentaries, Supersize Me where Morgan Spurlock eat so much mcDonald’s that shuts down his [00:16:00] liver. And every time I watch it, I’m gone. I could murder a cheeseburger right now.

[00:16:04] I don’t think it works on me in the way it’s meant to. But, yeah. So the idea is it’s, it would just measuring, you know, energy that heats water. So what they have is, so in this particular study, apparently there’s a bunch of different calorimeters, but they used a bomb calorimeter

[00:16:18] David: The best kind. I’m going to go. I’m going to come straight. I don’t know why any other kinds of kilometer are. This is the best one.

[00:16:24] Sophie: Yeah. And then you’ve got like a differential scanning one, which is not as fun, but yeah, the bomb one, it just looks like it’s kind of like little apparatus on the table.

[00:16:31] And the idea is you put your fuel in there and then you use electrical energy to ignite it. And then obviously like the fuel starts burning. It will heat up the surrounding air, but then escapes via these like little metal tubes that are made of copper and there’s water around the copper and then the water heats.

[00:16:46] And then you look, you measure how hot, like it’s very simple. It’s kind of like, we make heat. Heat heats air air is hot. Air goes in like conductive pipe in water, water, hot measure, hot water.

[00:16:59] David: It’s [00:17:00] great. No, I love it. I love it very much.

[00:17:02] Sophie: Yeah. And then the differential scanning calorimetry is boring. So the idea is you’ve just got like two little reference pans. One of them you’ve got the sample in and the other one, you don’t have it in. And then like it’s differential because you’re measuring it in terms of like the difference between your

[00:17:15] empty reference pad and like the other one that’s like, not as fun. So yeah. So what they did is they made up all of these different, that where they have 20 gunpowder recipes, I believe from medieval texts dated between, the year 1,336 BCE and 1,449 BCE. And what they found is that generally, between I think 1,350.

[00:17:36] And 1,400 BC, the percentage of saltpeter increased and charcoal decreased, which caused low heats of combustion, which could have produced, safer recipes for medieval gunners. And then like later on, there was less saltpeter and then more sulfur and charcoal. And they’ve said also that saltpeter was the most expensive ingredients.

[00:17:56] So it could have been due to that, but that also raised the heat of [00:18:00] combustion. Although not as high as earlier recipe.

[00:18:02] David: And they looked for, they looked for this thermodynamically. So this is where the, the the calorimeter kilometer

[00:18:09] Sophie: would say calorimeter, but

[00:18:11] David: calorimeter

[00:18:12] Sophie: based on me saying the word calorie and adding meter at the end, so

[00:18:16] David: So they were using one of those and they didn’t find any statistically significant increases in thermodynamic potential compared to dry mix control recipes when they added ammonium chloride camphor and quick line.

[00:18:26] But. When they added camphor ammonium chloride and salt practium.

[00:18:32] Sophie: Yeah.

[00:18:32] David: And then added Brandy and I want to believe that brand is the most important

[00:18:37] Sophie: It’s the key ingredient I believe.

[00:18:38] David: Yes. They found an increase in potential. so this one would actually have been a bit more explosive.

[00:18:46] Sophie: Yeah. And then they’ve said other things like when you’re just adding things like water and Brandy by themselves, you’re not getting energetic advantages, but they could have served other purposes. For example, making the material more stable during transport or storage, which is [00:19:00] quite important.

[00:19:00] Like you do want you gum powder to explode, but like not when you’re carrying it somewhere else.

[00:19:05] David: Yes. And they had a good limitations section as well, which I always appreciate in a paper as we know. So the important limitation here was that. So they mentioned that there’s not any increase in with dynamic potential with a lot of these additives, but they were looking at pure oxygen driving the reaction. And so they say it may be the case that when you use air, which is what would be used normally, and it just a Canon situation, then it may actually be the case that these additives are doing something that they are not seeing in their experiment, but under their experimental conditions, they don’t do anything.

[00:19:35] Except in this one instance,

[00:19:37] Sophie: But, yeah, I just like, I, when I read this, I went, what did I do with my life? Like, why is, why isn’t it that I spend the day in the lab making medieval gun powder and then exploding it and then taking it out to a range. So I could use a replica or a 15th century stone throwing Canon, like, why is that not my job, Dave.

[00:19:55] David: Absolutely agree, weapons expert. Why is weapons expert not my job. [00:20:00]

[00:20:00] Sophie: I’m just be wasting my life.

Anti aircraft ravens

[00:20:01] Sophie: Dave Australia’s volatile bird population is wreaking havoc on drone based delivery services.

[00:20:19] David: Aussie birds. Hate Google drones. Hate

[00:20:22] Sophie: hate them. They absolutely hate them, but like good on them. Cause after watching that video, by gosh, are those drones loud? I’m with the Ravens.

[00:20:31] David: We’re at the of them. I had the sound off. I didn’t actually listen to

[00:20:34] Sophie: It is, look, I’ll get, I’ve got notes.

[00:20:36] I’ve got aggressive notes written about the noise pollution caused by these things. But yeah, apparently, so we’ve got Wing, which is a subsidiary of Alphabet, Inc. Which is Google’s parent company. And apparently what they’ve been trialing in Australia is drone base delivery of freight, but like food delivery.

[00:20:53] So they’ve been doing this in from what I can tell, an area in Canberra and then also an area in just south [00:21:00] of Brisbane Metro. and it turns out that in Canberra, in the suburb of Harrison, we’ve had some Ravens demonstrating territorial behavior and basically like going for the drone.

[00:21:11] David: Yes. So they, well, I’ve, written down some of the things you can have deliberate, would you like to hear them?

[00:21:15] Sophie: No. Tell me about it because

[00:21:16] David: So, I didn’t even realize that drone delivery was happening. Like I knew it was like an idea, but

[00:21:20] Sophie: I didn’t know. We were trialing it in Australia, especially not for like coffee.

[00:21:24] David: Yeah, yeah. Yeah. So it’s things like coffee, stationary, gelato, groceries, and donuts, and my personal favorite, empanadas

[00:21:31] Sophie: okay, look, I’ll tell you how I feel that drone’s later, but so the idea initially, I love the idea of a drone delivering me something, but especially an empanada.. Ah right. Maybe I’m sold again.

[00:21:43] David: and we’re moving to Canberra.

[00:21:44] Sophie: That’s it.

[00:21:46] David: Um,

[00:21:46] so maybe they maybe, I mean, the scientist to me, he says maybe they hate drones, but maybe they just hate convenience.

[00:21:51] Sophie: Yeah, maybe they’re like, I have to go catch my food. You lazy humans just waiting at the front for your drone to deliver. It’s like go hunt and gather again. You [00:22:00] idiots. Maybe that’s what the Ravens are saying.

[00:22:02] David: So, yeah, there was this chap. This is following a story in the Canberra times. And basically there’s a chap called Ben Roberts, who said it’s a matter of time before they bring one down. And so this is a guy who waits for coffee every morning in lockdown and wait for the positive delivery drone, bringing his coffee And what’s really interesting is he describes over three days, the attacks get progressively more sophisticated. So on the first day he says there were feathers everywhere. It didn’t really work. By the third day they were avoiding the drone blades and he said there were flex of what he thinks paint in the air..

[00:22:31] Sophie: Yeah, indicating that the birds had made a hit, which I love. So this, in fact, this Ben Roberts is the person who put the video online. And if you watch the video, I love it. So you know, you’ve got this closeup of this Raven going in, but from what I understand, he’s waiting for coffee. And if you look at the, like, what’s happening, when the Raven is going for this drone, that thing is swinging all over the place, like make your coffee has spilled. Like, absolutely. But then yeah, if you listen to it with sound.

[00:22:58] David: I’m doing it right now. It’s [00:23:00] so loud.

[00:23:00] Sophie: It’s horrible. So funnily enough, if you look up Wing as in this company, this drone based delivery company, the main thing that pops up is noise complaints Dave. So apparently residents in the rural south east region of Australia where Wing operates.

[00:23:14] So, as I said, we’ve got like around Harrison in Canberra and then also, Logan, which is south of Brisbane Metro. Apparently everyone is being complaining about the noise disruption to their lives. A local dog club president stated the noise from the delivery drone trials spooks dogs. Some customers have even opted out of the trial, citing noise disruption as a problem, you’ve got like a colleges talking about like the fact they haven’t thought about this properly with all this noise.

[00:23:40] And then Dave in November, 2019. The Australian federal government found Wing’s Canberra operation exceeded the residential noise standard.

[00:23:49] David: That must be so loud then.

[00:23:51] Sophie: It is so loud. And so can you just imagine, so what I have in capital letters after I listened, I watched this video and listen to it. I have an, I quote, sounds like an angry [00:24:00] Wipper Snipper is how I perceived it.

[00:24:02] And imagine if your goddamn neighbour every morning, got our coffee delivered with a drone. You’d be livid. And especially since these two areas where they’re doing delivery to are outside of city centers, and it’s like, maybe people want that convenience of being near a city, but they want the slightly more rural, like the slightly more nature.

[00:24:19] And then their goddamn ne neighbor is getting like drone coffee delivered every day. You’d be livid.

[00:24:24] David: You would be raging wouldn’t you? I mean, it’s kind of amazing that you can then get things delivered to that rural location, but yeah, you’d be raging with people who are getting coffee every morning, but.

[00:24:33] Sophie: And then I looked at it as well. And cause I was thinking, you know, I’ve been talking about this with various people. We’re still talking drones with people from time to time. And so These drones just pick like, you know, they’re all automated. They just pick like the best path that is the quickest without, you know, things getting in your way.

[00:24:47] So then that means that you might, it might not even be your neighbor, getting you the drone coffee. There could be just a drone flying over your backyard every morning. Because other people are getting stuff around in your neighborhood. It’s just anyway, but [00:25:00] Dave, and then I got on, I love a tangent, you know, me.

[00:25:03] And so I am from Adelaide and we have the Adelaide crows in Adelaide, Dave and I have always grown up with this, always this thing, people like they are no crows in Adelaide. You know, the crows that you’re seeing are Ravens, like why are they called the Adelaide crows? Turns out that’s mainly true.

[00:25:18] So apparently Dave, we have five native species of corvids in Australia. So corvids, there are crows and ravens, we’ve got our Australian Raven, little Raven, little Crow, forest Raven, and the Torresian Crow. it’s actually quite, if you don’t know what you’re looking at, it’s quite hard to tell the difference between these things or Ravens are a little bit bigger, but like it’s often hard to tell them.

[00:25:37] David: and it’s muddied. Cause things like magpies, which look like they might be of the same sort of order aren’t there Corvid data, which is Corvid light, but not Corvid.

[00:25:45] Sophie: And so I looked, yeah, I looked at a lot of pictures of Ravens and crows and what I can deduce is Ravens look more annoyed than crows. So in every picture, the Ravens looked a little bit pissed off and the crows looked a little bit bewildered, but I don’t know if that necessarily like a good measure.[00:26:00]

[00:26:00] David: That makes sense to me for the Adelaide football club, because I don’t perceive Adelaidian as being a particularly annoyed

[00:26:06] Sophie: no, we’re always just, we’re a little bit perplexed over the time. And,

[00:26:09] David: like off your tits on Shiraz, having a mountain bike

[00:26:12] Sophie: That’s it that’s exactly it, but yeah. So crows in south Australia, there are crows in south Australia, Dave, but they are generally north of Port Augusta, which is not near Adelaide. It is north. and so the idea is in Adelaide and I think that’s just a little Crow.

[00:26:27] So if you, north of Port Augusta in south Australia, you might see a little Crow, but if you’re seeing a Crow in like the Adelaide CBD, you’re most likely seeing an Australian Raven or a little Raven. So I’m glad that we clear that up for me, because that was the thing that would always, that there’s no crows in Australia.

[00:26:42] And you know, there, I mean, there are, but yeah, they’re not, we should be called the, I say we should not fall away. I fell at all in any way except being good, a south Australian and picking one of the two teams. Cause I think that’s just what you have to do. It’s like you have your allegiance and then you will never, you never break that allegiance your entire [00:27:00] life.

[00:27:00] David: You, you pick it based on geographical proximity,

[00:27:03] Sophie: Or family things as well, I believe. But anyway, yeah. So apparently let’s go back to the Wing, they have actually contacted the like local ornithological Experts and they’ve halted service operations. Cause they need to look into this more, which I think is, it’s like, Canberra’s a good place to test it. Cause I feel like ACT is like quite well regulated. And if these things are like genuinely messing with the environment and like the local bird population, it’s a really bad idea.

[00:27:28] And I feel like the ACT will sort it out for us.

[00:27:31] David: Also, can you imagine being scalded by coffee dropped from an attacked drone?

[00:27:35] Sophie: Oh, I didn’t even think about that nightmare.

[00:27:38] David: It will be disaster for all concerned? Cause I mean the raven itself is not going to be liable, even if it’s responsible.

[00:27:44] Sophie: Yeah. I went to how well sealed it. Cause their whole idea is that the drone it’s a bit like our CPR drones, right? Like they hover and then there’s like, you’ve got like a little winch and it just like winches your food to the ground. yeah, like I wonder how well your little parcel is sealed and if it was [00:28:00] actively attacked by a Raven, would you imagine that

[00:28:02] scalding hot coffee falling from the sky.

[00:28:05] David: falling from this noisy thing.

[00:28:07]

Supernova Deja Vu

[00:28:17] Sophie: Dave, once, twice, three times, a supernova.

[00:28:22] David: Oh, brilliant.

[00:28:25] Sophie: Oh, I’ve been hanging out all week to say that to you. And if you don’t know the song reference well, then it doesn’t even matter. Anyway, Dave, tell me, I know that you love space. You love a space

[00:28:35] David: space.

[00:28:37] Sophie: Tell me all about our supernova. And we get to talk about gravitational lensing, which is quite exciting.

[00:28:43] Getting into the nitty gritty of the fabric and space time.

[00:28:46] David: So this one’s got everything. It’s got space, it’s got gravitational lensing, it’s got general relativity. It’s really, really exciting. So researchers at the University of Copenhagen have spotted a supernova, but what’s really exciting about it [00:29:00] is that they’ve spotted it more than once. Right. So they’ve looked at this particular area of the sky and seen a galaxy that’s being gravitationally lensed by another galaxy in the foreground.

[00:29:12] So gravitational lensing is a consequence of general relativity. So general relativity tells us that gravity is not a force pulling things together. It’s mass causing space-time to curve. So basically because light will follow the lanes of space-time. If space-time is curved by something gravitational active, it will curve around it.

[00:29:35] Sophie: Yeah, so everyone, who’s not familiar with spacetime. the, the best way that I think to think about it is like, you’ve got a bunch of people all holding a sheet and you’re holding a real tort. Right. And then like now put like a little tennis ball on your sheet and like, you’re going to get like a little bit of sagging around that tennis ball.

[00:29:50] Right. So that’s kind of like the mass of the tennis ball is affecting our sheets which in this case as a fabric of space time. But like, if you put like a basketball somewhere else on that sheet, like it’s going to dip [00:30:00] more because the basketball is more massive than the tennis ball. And then if you put like a bowling ball, like it’s going to sag crazy AF right?

[00:30:06] So that’s the idea. And as you said, light is affected by gravity and then follows these things called geodesy, which are essentially like your lines of space time. So the whole idea is if you have a very massive object making your space times sheet sag, you’re changing the path that light takes. So depending on where you are compared to like the light and the sagging of the saggy object, the massive object, as you said, exactly, you’re going to get light traveling along different paths, and also light takes time to travel.

[00:30:34] And if these things are really far away, not only will they take different parts, that means that you might see that light from the same thing, appearing at different times in different places.

[00:30:43] David: Yes. That’s absolutely right. And in terms of how old we’re talking about, we’re talking about 10 billion years ago, the supernova happened,

[00:30:50] Sophie: So that’s pretty old.

[00:30:51] David: Pretty old and pretty far away. So basically what happened was they looked at some data from 2016 and[00:31:00]  in this galaxy that was being gravitationally lensed, they saw three bright light sources.

[00:31:05] And then when Hubble, the Hubble space telescope revisited the area in 2019, these had vanished. So what that leads them to believe is that there’s something dynamic happening and something dynamic that can happen is a supernova can happen where you have an explosion that then dims.

[00:31:19] Sophie: Yeah. As we talked about in previous weeks, it’s like the end of it, you know, stars end in different ways. And one of those ways is exploding into a supernova.

[00:31:26] David: Yes. Now that’s quite cool that they’ve seen it three times, but this is where it gets really wild and

[00:31:31] Sophie: It’s it’s so good. This is like science. Like this is the peak of science.

[00:31:37] David: Yeah. So basically there’s the three areas where the supernova has vanished by the time we get to 2019. Right. But then there’s a fourth and a fifth site where the star is still there.

[00:31:52] Sophie: Yeah, look, it hasn’t exploded yet.

[00:31:54] David: Yes. So basically what they say is happening is because this galaxy cluster is so massive[00:32:00]  there are multiple routes that the light can take to reach us.

[00:32:04] So there are some that are going via a short routes, which are the ones that have already exploded, but the supernovas vanished, and there are slower routes where the supernova hasn’t even happened yet, because the light from it hasn’t reached us by this longer routes.

[00:32:15] Sophie: Yeah, that’s crazy.

[00:32:18] David: It blows my mind. It makes me feel very, very small and very my perspective. Very, very minimal.

[00:32:23] Sophie: but then the most insane thing Dave, which I know you’re just about to talk about is that they can actually work out when we will see it explode because like we understand things enough about space to say, like, look back in the year 2037, and you’ll see this thing explode from this other route.

[00:32:38] David: That’s right. So they’ve got this fourth image of the galaxy, which they say is 21 years behind. And that we will likely see the supernova explode one more time in this region of space sometime around 2037. And they can predict that to within two years plus, or minus two years, which again, we’re talking about cosmic events over the scale of 10 [00:33:00] billion years. we’re making predictions about when something’s going to happen that far away and that long ago, within two years,

[00:33:06] Sophie: that’s crazy.

[00:33:07] David: that’s crazy. and what’s also cool about this is it’s not just a cool kind of, oh my God. Space is amazing thing. So because we have these different, we’ve got this, what they call a dynamic event.

[00:33:18] So something in the sky we can observe happening at different times. And that apparently, and this is where my understanding starts to falter, I think, that allows them to make calculations about cosmic expansion, the rate of cosmic expansion and tell us things about dark matter and dark energy, dark energy is what drives the cosmic expansion because the cosmic expansion is getting faster, which is counter-intuitive.

[00:33:40] Sophie: Yeah. So I think, I mean, my understanding used to be better and then I forgot everything that I’d ever done. But I think that the idea is we know the universe is expanding. There’s like a bunch of different ways to measure that. But depending on the way you pick, you get a different result, which is not normally what happens in science.

[00:33:54] So this is because like, we know that this thing has happened. We know like what, you know, like this is a really [00:34:00] good way of kind of checking. Checking with ourselves as to, okay, if I look at all these different ways that the universe is expanding, what is the one that matches up with my observations and then yeah.

[00:34:10] Dark matter and dark energy is just nuts. So the whole idea is that it’s, you know, it makes up like 95% of the universe. And I’m out of knowledge in terms energy and dark matter after that. Yeah.

[00:34:22] David: So one of the things I really loved about the paper is that so that’s difficult to understand. I don’t understand dark matter and dark energy fonts, hence don’t understand them. I didn’t really understand the gravitational lensing model that they used, but what’s really cool about this paper is when you look at the picture, when you look at figure one in the picture, which is just a picture of the lens galaxy with the light sources and you compare 2016 to 2019, you can just see it

[00:34:48] Sophie: It’s like it’s there and now it’s not

[00:34:49] like, it’s just

[00:34:50] David: there. And when you look here and it’s clearly the same kind of light source in the cane, same kind of spot, it’s still there in this fourth image. And it’s just very easy to understand them. Very [00:35:00] believable and very satisfying.

[00:35:01] Sophie: Yeah, it’s very cool. Yes, it was very good. As you said, there’s a lot of, concepts that we might need to know a little bit more about astrophysics to fully understand, but there was enough that made this beautiful day. I loved it.

[00:35:13] David: really beautiful. Love it. Love it. Love it. Love it.