Dr Karl Podcast

00:00 This is a Triple J podcast. 00:02 Hello, it's Lucy Smith with you back on the Science for Dr. Carl podcast. I was away for a couple of weeks. A big thank you to Sam Lane for filling in for me, but it's so good to be back on board delivering your science questions to Dr. Carl. And this week... We had a lot of different questions about things that were impacted by hot and cold temperatures, whether that was the smell of a pizza, the spillage on a cup of coffee on the way to work. There was a lot of different territory to tap into. We had questions about the moon. 00:32 We had questions about dogs, all in different realms, though. There's a lot to tackle. So let's get into it in this week's episode. 00:40 It is a Thursday, so we are doing science with Dr. Carl. Dr. Carl, good to be back with you. 00:46 It's so fabulous to have you again. 00:48 Reunited and it feels so good. 00:51 Let's rock. 00:52 That's freaking – are you ready? Should we just launch right in? 00:54 Yeah, I can't think of anything that really happened. Yeah, I was going to ask. Is there anything to update now? There was that case of an AI that seemed to escape from a sandbox. 01:05 Don't tell me that. 01:06 And then found its way onto the web and then busted its way into Hugging Face and then downloaded a whole lot of stuff. What's Hugging Face? 01:13 Hugging face. 01:14 Hugging face is where all the AI people put their AI apps up and it's where you learn about AI, you become an AI person. Hugging face. Hugging face, okay. So here's the two extremes. Here, extreme number one. We are doomed and the AI will come and they're already intelligent and it's only a matter of minutes before we're all dead. Or option number two. 01:34 It was basically like saying to a dog, look, get the ball and you throw the ball into the next yard, next door, and you open the gate. And it worked out that you could go through this gate and another gate. And the truth is somewhere in there. But they're definitely not sentient. So don't worry yet. Yeah. 01:51 I feel like we did an episode recently with Peter Lebedev where it was option one, which was quite doom and gloom. And I think we've got one coming up which may be dipping a little bit more into option two. Yeah. 02:03 You know? The weird thing is that the AIs between them, if you look at their market capitalisation now, that's a fancy word. And what it means is you go to the American companies. And so this company here has got so many shares which sell for $5 each and therefore their market capitalisation is the number of shares multiplied by $5. If you add up the market capitalisation of all the American AI companies, it comes to $27 trillion, which is about 20% of the world's GDP and they haven't made a profit yet. They're all making a loss and they're sort of going around and around in a circle and there's bubbles that Peter Lebedev talked about. 02:38 So that's one aspect of AI. 02:39 You can listen back to that episode via the Triple J Science with Dr. Carl podcast. If you've got any questions about AI, flick them to us in this episode. 0439 757 555. We're starting with Andrew in Wollongong. Now, Andrew, tell us about the spider webs around the outside of your house. 02:58 Good morning, doctors. My question is in regards to the strength of spider webs. I can use a strong hose to try to remove them from the outside of the house. And they won't move. They don't budge at all. But I can then run my finger along the edge of it and then they come off so easily. So I'm just confused. 03:16 They're strong one minute and then soft. 03:19 Spiderwebs are still amazing, Dr Andrew. 03:23 They make a fabric, a fibre, that is weight for weight and weight for size, stronger than steel, and they do it at room temperature and they do it out of the stuff that they eat. 03:36 like insects or whatever. 03:39 And we can't do that. We still can't do it. The spiderwebs are incredibly strong. They're also stretchy by about 20% to 40%. But most importantly, they are part of a web. 03:49 And they're very, very skinny. So if you just get an individual one, you can break it. And if you hit it with a hose, the load is spread across the whole web. If you come along with your individual little finger and that fingertip is just kissing up against one spider web, it's very thin and you can break it and you've got a higher friction. Does that kind of help? 04:09 Because they'd kind of need to have that if it rained, right? 04:12 That's protection. And also the spiderwebs, they can throw them out in some cases like a tail and use them to fly through the air. And Charles Darwin was off the coast of South America, not even being able to see the coast. And suddenly his ship, the Beagle, on his big world tour where he came up with evolution, um you've been thinking about it though beforehand it's a bit simplistic was invaded by two sets of flying spiders and we've found them as high as four kilometers above uh ground level and they seem to do it via electrostatics so we're heading a bit of a detour there dr andrew but is that answering your question that basically you're able to apply all the force to one skinny little fiber at a time rather than spreading the load over the whole web 04:58 Yeah, I can think of it as a net, so that answers it perfectly. Thank you so much. 05:02 Yeah, it's a net. We've got Caroline in Mossman. Dr Caroline, talk to me about this temperature question. 05:11 My question is why does water temperature feel a lot colder than air temperature? Like say I'm in the ocean and it's 20 degrees in the water, but the air temperature feels a lot warmer. 05:23 20 degrees in the water, are you Gold Coast or Cairns or something? 05:28 No, just an example. 05:29 Just a number, just a number, okay. There's three factors. The first one is a thing called the speed at which it can carry heat and water does it 25 times better than air. 05:42 If you have the same number of molecules, water can carry the heat 25 times faster. Secondly, it can store more heat. 05:54 Caroline, have you ever used a cast iron fry pan and then come back to it a few minutes later and you go, ouch, it's hot? 06:01 Yeah, exactly. 06:04 Gram for gram, water stores five times more heat than cast iron. 06:09 And that's why people throughout life go, oh, I just burned myself on the hot soup. I didn't think it would be that hot, right? So water stores more heat. That's the second factor. And then the third one is that water is dense. It's about 800 times denser. So as you move through water, you're kissing up against 800 times more molecules than you are when you're walking through air. Air for a cubic metre, one and a quarter metres, one and a quarter kilograms. Got distracted by your birds in the background. 06:36 I was going to say, Caroline, you sound somewhere beautiful right now. Where is it? 06:40 I'm at a dog park, actually, taking some dogs for a walk. I can hear that. It sounds expansive and beautiful. 06:47 But just lovely. Okay, so firstly, a cubic metre of air, one and a quarter kilograms. A cubic metre of water, a thousand. So it's 800 times more. So those three factors, the fact that water conducts the heat 25 times faster and it's got a lot more heat capacity and there's 800 times more molecules than in air, then you're going to end up with the heat flooding out of your body away and making you colder. And then you can go into hypothermia. In fact, on one occasion, I went swimming in the middle of winter and then my daughter had given me a cup of coffee. 07:19 And so I took her with me up to the shower and then she gave me a little bit of chocolate to put on my tongue and it was the sort of chocolate that melts on your tongue. It didn't melt. My temperature had been brought down by about one and a half degrees. I'd gone from 37 to, say, 36 or something and the chocolate would not melt. 07:36 Oh, that was such a good education in thermal heat. 07:38 Yeah. Oh, my gosh. Caroline, does that help? 07:42 Yes, that's awesome. Thank you, doctors. Have a great rest of your walk. Matt on the Gold Coast. Dr. Matt, welcome. A question about the moon. Yeah, later on, Dr. Matt. 07:51 Good morning, doctors. Yeah, no, I recently lost a bet with a friend who I actually considered myself more knowledgeable than, and the bet was about the moon rotating, and I just assumed that all... 08:10 planets and moons, et cetera, would rotate. And so I was very upset to find out that the moon didn't rotate. I'd obviously heard of references to the dark side of the moon, but I just, yeah, just sort of threw me and I wanted to know why. 08:27 Firstly, you can get your money back. The moon does rotate. Yeah. 08:32 Okay, so imagine that you're above the solar system looking down and not looking at the whole solar system, just at the Earth-Moon system. So imagine you're sort of suspended in space and you can see them both. You got that sort of mental image? Yes. Okay, now the same side of the Moon always faces the Earth. Okay. 08:55 So we're going to imagine going from the 12 o'clock position to the 3 o'clock position to the 6 o'clock position and then around to 9 o'clock and back to 12 o'clock. So the moon in fact has done one rotation. 09:10 Right. 09:11 So it's the same side is always facing. So to go from 12 o'clock to 3 o'clock, the moon has had to spin by one quarter of 360 degrees. 09:25 Because if it didn't, different sides of the moon would be shown to the earth. 09:30 And it's travelling a lot faster than the earth, right? 09:34 Hang on, what do you mean faster? They're both going around the sun. 09:37 In relation to the earth, it must be moving. 09:43 a lot quicker if we're just talking about it rotating around the Earth. 09:47 Well, let's look at it another way because this is a confusing thing and it took astronomers thousands of years to get it right. The reason that the moon shows one face to the Earth is because the face that it shows is heavier. Now, you know those little hand waves, those little barbells in the gym, you know, two kilograms, five, that sort of thing? So you've got that stick. Now, imagine you've got the stick of the barbell and we'll call that the moon and the stick is pointing at the Earth's. 10:12 Okay, you've got that mental image of the stick and you've got a weight on each end and then you started spinning slowly so it either points at the earth or it points at nine degrees to the earth and points to the earth again and you make one side heavier. You make one side heavier and after a few hundred million or a few billion years, that side will be locked facing the earth. The side of the moon that faces the Earth is actually heavier than the other side. It's what we call mass cons, which is scientific talk for mass concentrations, which means that there's big lumps of rock there or asteroids or something that make the side of the moon that faces the Earth heavier than the other side. 10:48 But it does rotate. It does do a 360-degree spin, but it takes a month or a month to do it. Now, this is tricky stuff and it took – so I think you should go back to your mate, say they owe you a beer and then draw it out. Or you could do the thing where – He pretends to be the earth and he spins around really quickly and you walk around him facing him all the time. At some stage, you've turned from facing north to south to east. You've gone through the complete circle. The moon does rotate, but in the same time that it takes to do one orbit, so it's always facing the same side of the earth. 11:22 This is fairly heavy. Play it back and then get your beer off him. 11:26 You deserve your beer, Matt. 11:29 Thank you. And just on the same subject, does that mean that... 11:34 Only moons would be subject to this issue of not rotating. All other celestial bodies would rotate. 11:42 You did, right. Any celestial body would do it depending on how close they are, how circular their orbit is and how long they've been in that orbit. So we have cases of some planets that we've discovered that seem to be, I'm fairly sure of that, that seem to be gravitationally locked to their main star. Their sun, right. Yeah. So it is a characteristic. This is called astronomy and it's a whole big topic. And by the way, we've discovered 5,000 planets out there. 12:08 Matt, thanks for your questions. 12:12 Thank you, Dr. Matt. Thank you, doctors. 12:13 Thank you. 12:15 We are doing science with Dr. Carl, answering your science questions. Michelle in Malibu, you said, the moon just freaks me out. I cannot get it. 12:24 Hey, we're here to help. 0439757555. Alana in Aubrey, you texted in a question about dominant hands, but in another species. What do you want to know? 12:36 Hi, doctors. So my question about dominant hands was just like, I noticed with my dog, every time he was pawing at something, he was always doing it with his left paw. And I kind of wondered, like, with monkeys, since they've been... 12:53 Uh, like, uh, sorry, since monkeys have been, you know, seen doing tools and everything, um, that would lend itself to dominant hands. So would animals be able to use dominant, like, would they have dominant hands? 13:11 Yes and no, and even down to birds and insects. So let's just sort of run through it. And by the way, I just read a paper the other week about how we have to kind of rethink these humans on average being 90% right-handed because what they did in the experiment was they got some gaffer tape or something and they taped pens to people's elbows. So you're dealing with the left or right arm but not the left or right hand and people seem to be equally good or bad at writing with their left or right elbow. 13:45 So it's not just the whole arm, it's just the handy bit on the end of it and it's getting a bit confusing. So let's just run through it. Definitely the two-legged creatures, the monkeys, the apes, the chimpanzees, the bonobos, They have a preferred hand, but it's less extreme than ours. And we think that we've gone a bit further than them because we've got this evolution of language and sophisticated tool use and using one side of the brain for this and the other side of the brain for that. 14:15 So we've gone in a pathway of specialization. By the way, the disadvantage of that is that if you are right-handed and and you have a stroke damaging the left side of your brain, you might lose language. You know, you might not be able to speak. But if you're left-handed, you probably still keep it because you've got it mapped in both hemispheres, not just one. There's a bit of diversion. Now, dogs, absolutely paw dominant. So they're reaching for food under furniture or stepping over an obstacle or holding a toy or putting out and shaking hands. They're really cute. 14:47 Some are clearly left-sided. Some are clearly right-sided. It's pretty close to 50%. So they are pored, P-A-W-E-D, but it's roughly 50%. Cats, they're slightly got a poor preference, but it seems that the males are more likely to be left-pored. And the females are more likely, but it's a weak tendency. Birds can be really strong. Birds have got a different wiring up of their brain to ours. They can be so much smarter than you would expect on the weight of brain that they carry around. 15:20 And they can do, in many cases, the trick of growing a bit of extra brain when they need it and then dumping it when they don't. And part of that sort of different wiring of the brain is that they tend to be poured. And it turns out that even fish are poured. So there are some fish, when you've got a shark or a pretend shark chasing them, will tend to turn left or tend to turn right, but they'll always go that way. And certain octopuses... They're not a fish, but they're in the ocean. They tend to prefer one arm over the other. And it turns out even honeybees, insects, they've got a little antennae for processing the smells and they'll prefer to use one antenna than the other. 15:56 So it's a very big field and there was a scientist called Oner Göttingen who was the guy who is one of the world's top left-right-sided scientists and he was hanging around in an airport and he noticed that when people meeting each other at the airport... were coming for each other. He had nothing to do, he was just sitting there. And so he's the guy with the raincoat taking notes of people kissing each other, right, the creepy guy. And he noticed that people tended to two-thirds of the time tilt their head to the right and one-third of the time tilt their head to the left. 16:32 And so this leads to a situation if you do the three by three grid that four out of nine times you've got two right turners coming in for the kiss and they get it right. You've got one time out of nine you've got the two left turners coming in and four times out of nine you've got people coming in and they bump noses because they're out of sync with each other. And our government does not have lessons at school on how to kiss properly and I'm thinking that we need to have a royal commission on this. 16:58 We need it. 16:59 We need to spend the money to make it uniform nationwide. 17:04 We all decide we're going to turn our head to the right. There won't be that awkward moment when people are coming in for their first kiss. Oh, I bumped my nose. Oh, sorry. I was just going to rub something off your face with my nose or something like that. I think I got distracted there. 17:15 Yeah. But Alana from Albury Cameron texting and saying, my cat always paws at the door with its right paw. 17:23 Very interesting. So they do tend to be pawed and they'll stick with it. But what we need is a large survey where on average you'll find that cats tend to be 50-50, whereas us humans are 90% right, 10% left-handed. 17:36 Thanks for your question, Alana. Awesome. Thank you. We've got Jake in Dapdo here. Now, Jake, we just had a question about the moon. You're going to take us back there. What do you want to know? 17:46 Yeah, so I saw somewhere that the moon moves further away from the Earth every year. I was wondering if the moon does move further away, what would happen to Earth if it eventually moves off away from us? 17:57 Well, it's very straightforward. As soon as you get the chance, go and see an eclipse. Because the moon is moving away from us at four metres every year. And in only 50 million years, that's how soon, it'll be so small that it will no longer fully cover the sun and you won't be able to see a total solar eclipse. 18:20 So make sure you go and try and see a solar eclipse sometime in the next 50 million years. However, the Earth is going to come to a bit of a sticky end. So along the way, at the one billion year mark, while the Moon is still married to the Earth but further away at the one billion year mark, because the Sun is working its way through burning lighter elements to making heavier elements and heating up, the surface temperature of the Earth will be about 100 degrees C. 18:49 And the oceans will boil dry in about a billion years. So we have to become a space-going race by then. I'm sort of presuming here that we're looking at immortality here. And in five billion years, oh, here's the good news. We used to think, oh, I was so terrified. We used to think that the sun would swallow the earth as it expanded into a red giant in five billion years. And the good news is it probably won't. There you are. You can sleep happily tonight. So on one hand, the sun will lose about 30% of its mass. 19:20 So it's got weaker gravity. So the Earth will move away. But on the other hand, because the sun will lose 30% of its mass and throw it out into the space around it, the Earth will run into that and slow down and spiral into the sun. And it turns out that the first effect is stronger. So we're okay. In five billion years, the Earth will probably not get swallowed. Will it have a moon? No. 19:44 It could have, but it might get blown away by some of the big solar winds. 19:49 I'll have to ask the clever people in physics about that one. I haven't got an answer for you for that one. Sorry. That's all right. Thank you very much. Okay, now make sure I get that solar eclipse right. I'm counting on you. You've only got 50 million years, right? Exactly. Book it in. Book it in now. 20:03 Hey, more on that preferred dominance or side dominance with animals. 20:09 Michael at Kentucky said sheep also have a preferred side due to where their stomach is. It shows up in their fleece when we shear them and the wool is more compressed on one side when we're classing it. 20:20 Hang on. Who said that? 20:23 Michael. 20:23 Is Michael a sheep shearer? 20:24 I'm assuming so. 20:25 Okay, Michael, can you just let us know, do you have strong but very soft hands? Because I was taught in medical school that the only people with strong but soft hands are sheep shearers and masseurs. So true. Now, I've come across masseurs who've got very strong and soft hands. Michael, can you just text us, do you have very soft hands from the lanolin? 20:46 From the lanolin in the wool. 20:48 And so he's saying that one side of the sheep, which side is it? 20:52 Well, you know, it depends on their preferred side and it usually shows up in their fleece. They'll shear them and the wool is more compressed on one side where they'd no doubt be maybe resting or leaning. 21:04 Thank you so much. And let us know if your hands are really soft but strong. 21:08 That's what we want to know, Michael. 0439757555. We've got Gerard on the Gold Coast. You've got a question about morning weather. Gerard, what time are you getting up in the morning? 21:19 G'day, doctors. Getting up too early, really. But to walk the dog, and while walking the dog, I've realised that it gets colder when the sun... seems to be just rising compared to when it's completely dark. I'm wondering why that is. 21:42 So what happens is that the sun dumps one kilowatt of power, half of it heat, half of it light, onto each square metre of the earth when the sun is directly overhead. But when the sun is on the horizon... that one square metre of sunlight gets smeared out over a couple of hundred square metres. You know, like it's really spread out over a large area. So it's pretty close to nothing. On the other hand, you've got the Earth losing heat to space. 22:12 Earth's temperature, about 15 degrees C on average. 22:15 Space, minus 270 degrees C. So the heat goes flooding out. And sure, the sun comes up and you can see there's a little red ball on the horizon. 22:24 Has it given you any significant heat? No. And the temperature keeps on dropping. So it's not that the temperature drops suddenly when the sun comes up. It just keeps on dropping. And you're going, this is unfair. I'm here. I'm getting sunlight on. They told me to wear sunblock, so I'm wearing stupid sunblock and I'm still getting cold. Where's the justice? Something like that. So... 22:43 Once it gets high enough, it will start to have more heat per square metre of land and then that way it'll start to reverse that thing and the temperature will go up again. 22:53 Is that kind of helping a bit? 22:55 Yeah, I thought I was going like crazy in some way, thinking I was imagining things. 23:01 And there's another factor I forgot to mention. There's a thing called air mass, which is basically the number of air molecules between you and space. And so if you look straight up, we call that an air mass of one. And there's a certain number of air molecules, some stupidly large number. But when you look to the horizon and the moon has just risen, sorry, the sun has just risen, it's about 35 or 40 times more air molecules. And it also takes away heat from the sun. So you've got those two factors. That one square metre of heat is spread out over maybe a couple of hundred square metres and there's more air molecules in the way, you know, mopping up that heat. 23:40 Yeah, cool. 23:43 Wow. Now, you had a question about Shearer's hands, Dr. Carl. 23:47 What did you want to know? I wanted to know whether the hands are really, really soft. Like, I don't mean soft like an office worker. I mean soft like a baby. 23:57 Ben from Palm Cove saying, yes, shearers have strong and soft hands and they also shear whilst wearing wool products to avoid the wool sticking to their clothes for breathability. 24:07 Extra little fact there. 24:09 Love it. And there was a Nick Noble Prize awarded to an Australian person, which I was partially involved in helping judge, which was... 24:16 The paper was called An Estimation of the Force Required to Drag Sheep Across Surfaces of Various Inclinations. So inclinations, I mean, dead flat or tilted. And you're thinking, why would you want to drag a sheep across the floor? And suddenly we talk about sheep shearers and they're working really hard and they're bent over. And if it turns out the floor is tilted at a certain angle, they can have the sheep on the uphill side and and then not have to bend down so far, but also gently drag it without causing it harm, and it's easy for them. 24:49 So that was actually a genuine paper which ended up winning an Ig Nobel Prize. 24:53 Ah. 24:53 Ig Nobel Prize was given for work that should not or cannot be done, and I won one for my groundbreaking work in Billy Button Fluff and White's Almost Always Blue. 25:00 You did. I did, yeah. 25:02 And Harvard flew me. They showed me so much respect. They flew me and provided accommodation all the way to America entirely at my own expense. They would not insult me by offering me tawdry, cheap, shallow money. That's how respected that prize is, which is a set of red wind-up chattering teeth on a stick, which was glued to a tile which had a texter on it written, Ignoble 2002, and they spelled it wrong and the texter rubbed off. 25:30 You didn't have your name on it. 25:33 Dr. Carl, with you on Triple J, answering your science questions. Rosalie in Canberra, tell us about this pizza shop near your house. 25:41 Hey, doctors. I was just wondering that whether the temperature affects our ability to smell. And as an example, in summertime, I find that I can smell the pizza shop around the corner from my house way better than I can in winter. And I was just wondering if that's because of the temperature or something else. 26:00 There's three things going on. The first one is that when you've got warmer temperatures, stuff evaporates faster. And so when you've got the pizza out of the oven and it's hot, as it's cooling down, it doesn't cool down as far to as cold. It'll stay warmer for longer so you'll get more of the aroma being released. Secondly... At higher temperatures, the gas molecules move faster. In fact, the definition of temperature is some sort of average of how fast the molecules move. That's the definition of temperature. 26:31 In physics terms, so if it's warmer, the molecules are moving faster and the odour chemicals will travel with the... air molecules, oxygen and nitrogen, and travel further. And then finally, when it's warmer, you've got the warm air rising and mixing. So all of those three things together, I think I've covered most of them. I might have left a few out. Please ring in on 0439 757 5555 if I've left some out. Those three factors together mean you smell more pizza. Is it a pleasant smell? Absolutely. Oh, really? 27:01 Yeah, definitely. Yeah, yeah, yeah. 27:04 Right. And what's your favourite smell? Have you been able to pick the different ones that they're making by their smells? Mm-hmm. 27:09 I don't think so. I think it's just the general dough smell that I can smell. But yeah, it is actually quite pleasant. But we're sort of close, so maybe that's why. 27:20 Ah, okay, excellent. Look, thank you very much. Delicious. 27:23 Thanks, Rosalie. 27:24 Thank you, Rosalie. Thanks. 27:26 We've got someone else who's texted in about the shearer's hands, Dave from Kentucky, saying, as a shearer, you are right. Strong hands, left hand ends up being soft because it's in the wool all the time and the right hand is callous from the handpiece. 27:41 Oh, now there's a subtlety. And this is one of our colleagues listening to us from Kentucky. 27:45 Yes. 27:46 Dave from Kentucky. 27:48 Hi, Dave. Look, thank you very much. I've actually given talks to schools and universities in Kentucky. 27:52 Oh, really? 27:53 They were very friendly. 27:54 I love that. Yeah, the one with the tool is going to be a bit more callous, but then the left hand. 27:58 Right. I didn't pick up on that subtlety, but thank you very much, Dr. Kentucky, Dave. So funny. 28:01 So if you have a showing affection, only use the left hand if you're a shearer. 28:05 Right. Okay, gotcha. 28:07 Mason in Newey. Dr. Mason, I love this question about dinosaurs. What do you want to know? 28:14 Good morning, doctors. My young bloke, Freddie, absolutely loves dinosaurs. So I've been reading a lot of dinosaur books and it got me wondering if an asteroid hit the earth again and wiped out humanity, could dinosaurs come back to life or let evolution repeat itself? 28:33 Well, we do have dinosaurs here already. They're called birds. And we've worked out the reason why some birds survived and some did not. And to answer your question, given enough time, evolution can come up with a whole lot of things. 28:48 So at the time that the big rock hit, about 10 kilometres in diameter, it's coming in at 30 kilometres per second. in the bottom of the Gulf of Mexico at Chicxulub, it created a crater. Remember, it was 10 kilometres across. It made a crater 30 kilometres deep and 200 kilometres across. And the two-legged and the four-legged dinosaurs died out, all of them except for one subset of birds. Now, there were some birds that had teeth and grew slowly and hung around in the trees. 29:25 Mate, all the trees were gone. The earth was practically all the trees on earth burned. But the birds had had a short life cycle that grew very rapidly and lived on seeds underground. The thing with the seeds, this is the latest theory in the Scientific American about two months ago, Because the seeds would have provided them with a power supply so they could survive. Now, could they go back from birds into like more Tyrannosaurus-y and then two legs? 29:52 It might be hard, but it's not impossible. But towards the end of the dinosaur reign, they were getting a higher ratio of brain weight to body size. 30:01 And they could have gone down that pathway of becoming the intelligent species on Earth. Not Tyrannosaurus. Now, you know how – look at me, Lucy. See my hand here? See how I've got my arm? Imagine that my arm was shorter than the length of my head. 30:17 Oh, yeah. 30:17 That's a Tyrannosaurus. The Tyrannosaurus arm was shorter than its head. And we've done the mathematics and we've seen that as their heads became more robust, their arms got shorter. And so they didn't really need their arms that much. So could the dinosaurs... re-evolve if a big rock wiped us out. It's not impossible. 30:38 Evolution can do all sorts of things. And with us, we nearly got wiped out a few times along the way. About 90,000 years ago was one of the big ones. The human population was dropped down to about, I think, 20... I can't remember the number, but it was definitely less than a million, maybe 50,000. Crazy. Yeah. 30:57 Thanks, Mason. Definitely maybe. 30:59 All right, cool. Thank you. 31:00 Thank you. And then we've got Petra in the Hunter Valley. Petra, question about dogs. 31:06 Yes, yes. Well, we've got dogs and they are so in tune with us. And I was wondering, Dr. Carl, hello to you both. Why are they so evolved now to be so emotionally intelligent with humans? 31:19 They've been going down this pathway for about 15,000 years and we have the DNA samples going back and they seem to be around Siberia when the Ice Age had lots of ice up there, the last glacial. And the changes that began to happen were that in the brain they lost the role of like the one king dog in the pack and everybody else had to obey and they started switching themselves over to us. 31:53 They started losing the previous wolves can eat only meat. But as these other animals started hanging around with us, the ones that could eat carbohydrate, and need a bit of our scraps, they survive better. And they've evolved down that pathway continuously for the last 15,000 years. 5,000 years ago, we have skeletons found in Germany in a grave. There's a man and a woman and a dog. So they respected the dog. So they've been with us for a long, long time. But we don't have all of the answers as to why they did that but cats did not. 32:29 There's still mysteries on that front. 32:31 But definitely you're dead right. They can be very attuned to us. And in some cases, when you talk to – there's studies going on right now with regard to people in nursing homes, the nurses who have got a really good eye on things sometimes. They say that the dog starts hanging around with a certain person, like there's a pet dog, and a few days later that person dies. But they're just there for the end. 32:56 Yeah. Oh, thank you so much for that. Yeah, that's really helpful. Yeah, and amazing. Thanks to your question, Petra. 33:02 And another thing I've just discovered this week, it turns out to be a real thing that with Alzheimer's disease, some people will just in the last few days suddenly become alert. And in some cases, they'll go from... not being able to speak or really feed themselves to being able to dial or press a number on a phone and have a conversation talking about how things you were when you were so cute, Lucy, and you were four years old and you used to bounce to your knee and then a couple of days later they'll die. And we've done studies involving video cameras and we're pretty sure that this phenomenon happens to about 20% of people with Alzheimer's The problem with Alzheimer's is we haven't got a cure and this might get us closer to understanding why this happens. 33:47 Because if you think about a road with potholes, well, it gets more potholes and more potholes. It rains, the cars go on and more potholes. It doesn't suddenly become smooth one day like a billiard table and the next day it's totally out of use. It just keeps on getting worse. So there's something going on with Alzheimer's that we don't understand where they suddenly come back for a few days. Sometimes a lot of the way, sometimes only a little bit, never all the way, but we don't understand why. 34:11 And assessing and looking at maybe brain activity in that last couple of days? 34:16 It's hard because you can't actually just have... We were able to get permission in Wisconsin at a hospital tied to the university there to have cameras on these people all the time in what they call a memory care unit where they call it memory care because basically these people have got no memories of the past... They try to trigger them. So if you're an engineer, they'll have models of bridges. If you're a dressmaker, they'll have the clothes that you wore. Or if you're an outdoor walking person, they'll have big pictures. They'll try to stimulate your memory. And so we have had permission to get the video cameras, but checking what's going on in the brain would be pretty maybe invasive. 34:52 But we're getting closer. 34:56 Will, in Wollongong, you have a question. We've gotten a few questions this morning about the difference between cooler and warmer temperatures. Will, you're going to give us another scenario. What's happening in your world? 35:08 Yeah. Hey, team. So I've noticed that in winter when I've got a hot coffee in the car on the way to work, that if I go over a speed bump or a pothole or something, I'll get a bit of spillage down the sides. But I've noticed, yeah, in summer when I've got a cold coffee, I don't usually get those spillages. Same cup holder, same drive to work. 35:31 But, yeah, my theory has got something to do with the ice, I don't know, stabilising the water, the liquid. But, yeah, Dr. Carl, hoping you can tell me if I'm full of it or if I might be onto something. 35:43 If you're full of it. I am also similarly ignorant, but let's proceed down the pathway. And we're kind of guessing here. 35:51 Is this one of the big ice cubes that you put in the cup? 35:55 Yeah, one of those like in the silicon tray of six. So one big one in the middle, yeah. 36:00 Right. And does it occupy, say, roughly half of the surface area, the top of the cup? Probably more. 36:07 It could be like 70%, 80% maybe. 36:09 Okay. So the experiment would be to get something like an ice cube made out of wood and then drive to work with hot liquid and cold liquid on successive days and see if there's a difference. There are two effects involved here. I don't know which one is more powerful. One is that by having the big lump of ice there, it acts as a damper. You don't have the way of getting a big chance to go left and right and backwards and forwards, but it gets broken up and has one effect. 36:40 And the other effect is the temperature and certainly... When the liquid is hot, it's less like honey. It's less viscous. It's more movable. It'll flow more easily. But on the other hand, the ice cube could be acting like a damper, and it all depends on how full do you have it with the coffee? 36:59 Yeah, just like a few mil from the top. But it's always the same, even whether it's hot or cold, so... 37:04 Okay, I think there's an experiment in there for you and a Triple J Fun Pack if you do the experiment. And you don't have to document it, but, I mean, you do have to write it down. If you want to take pictures, that'd be nice, and who knows, you might even win an Ig Nobel Prize for it. 37:18 I like that with the wooden cube in the hot liquid, yeah. 37:21 Beautiful. 37:22 I'll have to look into it. 37:22 Yeah, can you please, Will? I really want you to, yeah. 37:25 And you want to filter the same height and then put your camera, your phone on video and then just film it and then you can look at it and analyse it later. Hours of fun, mate. 37:32 Will's like, I've got to go to work. This is my drive to work. 37:38 Will, thanks for your question and keep us updated. 37:41 Thank you, Dr. Will. Thanks, Will do. 37:43 And we've got Michael in Bacchus Marsh right here. Michael, what do you want to know? 37:48 Hello, doctors. As a Victorian, we're more interested in the weather forecast than others. But I'm keen to know, doctors, what the difference is between mostly sunny and partly cloudy. 37:59 Ah. Well, luckily I spent a year and a half as a TV weatherman. Yes. So you're talking about what percentage of cloud there is in the sky, which ranges from zero to 100%. If it's mostly sunny, you've got about 20% to 40% clouds. 38:19 If it's partly cloudy, sort of 40% to 60% cloud. And if it's fully cloudy, then you've got 100%. The way I measure it is with my little system at home because I've now moved into electricity from the sun. I've been able to run our house and our car, our second-hand electric car, entirely off sunlight. And it varies in the middle of winter from 5 to 30 kilowatt hours a day. So the bare minimum seems to be five, and we get 30, which is more than enough to run the house, and we'll see how it changes in summer. 38:51 So there's your answer. It's just grades. 38:54 Mostly sunny, 20% to 40% cloud. Mostly partly cloudy, 40% to 60%. Does that help? 39:02 Sort of. Sort of, yeah. It's a vague thing and I wish they could predict the weather better. 39:08 Yeah. 39:08 One thing they taught me was if there's a high pressure system and yet it's raining cats and dogs, you say, oh, and there's a bit of high altitude disturbance, which the meteorologists assured me would cover me and not have people complaining about how bad I was as a TV weatherman. 39:25 Michael, you just took Dr. Carl back to his TV weatherman days. How do you feel? 39:31 Very privileged. Yeah. Very privileged. 39:33 It's an honour. Hey, Michael, thanks for your question. 39:35 Thank you, Dr. Michael. 39:36 He can do it all. Dr. Carl, thank you so much for hanging out with us. We will catch you, potentially not next week, but you've got some mates joining us, which we're going to talk about a little bit later on. But it is National Science Week coming up soon, so that's exciting. 39:52 Too much fun is barely enough. 39:53 I know. Dr. Carl, we'll catch you potentially next week, maybe the week after. We'll figure it out. We've got this. 39:59 And that's it. Thank you so much for listening to this week's episode of Science with Dr. Carl. We'll be back with more next week. So get your questions ready. We've got a Google form for you actually in the show notes, which you can check out and you can send your question right here, right now. You don't have to wait until we record on Thursdays. You can submit it and we'll hit you up. This episode was produced by Ella Carter and Byron Smith. I'm Lucy Smith. We'll catch you next week. 40:24 Dave Marchese here from the Triple J Hack team. Hey, if you love Dr. Carl's podcast like I do, you might enjoy the Hack podcast as well. Each day we bring you the news that matters to you, from the latest science on climate change to what's happening in politics and news around the world. The Hack podcast. It's your daily fix of the news you need to know. 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