The Doctor Karl Podcast

00:00 This is a Triple J podcast. 00:02 Hello, welcome to another episode of Science with Dr. Carl in your podcast feed. And this week it was just you, me and Dr. Carl answering your science questions, which for some were really hyper-specific about axolotls, breakfast beers and others giving us a bit more room to play with. There is a great question from Caitlin in Adelaide and she said, what is a widely believed health or fitness fact that turns out to be wrong? We talked about that and Dr. Carl and I were introduced to the phrase, all bluster, no muster. 00:34 Why? What does it mean? You'll find out later on in this episode. I'm Lucy Smith. Let's get into it. 00:42 Dr. Carl, you were off last week. Can we talk about what you were doing yet? 00:46 Yes, we were not allowed to talk about it, but it was in the submarines. Why on earth would anybody choose a career where... 00:54 For many weeks at a time, you're totally in communicator with the outside world. You can't talk to anybody. And you're stuck in a skinny little metal tube with about 60 other people. 01:06 And if you're more than about five foot nine, you're going to hit the ceiling all the time, so you have to walk around with a little stoop all the time. And you can't choose your own meals or your own drinks. And you've got hardly any washing or... toilet facilities, and you get to wash your clothes only once. There's only one washing machine for 60 people, and some people don't change their clothes. They just bring on extra ones. And there's hardly any room to sleep. But there is one part where you can get a little bit of room to sleep. Everybody has their own bed. And it's between two torpedoes, each loaded with a ton of high explosive. 01:39 Why would anybody pick a career like that? 01:41 So hang on. 01:42 These are submariners. 01:44 Right. Kind of sounds like solitary confinement, doesn't it? 01:47 But they do it voluntarily. 01:48 Right. 01:50 Amazing technology inside. Anyway, so that's what we're talking about with our new TV series. 01:54 Okay. How Things Work. 01:56 How Things Work. The highest rating documentary show on ABC TV. Did I mention that before? No. 02:01 Well, this is the thing, Dr. Carl. It was brought up this morning by Abby on Triple J Breakfast. One of the highest rating ABC TV series. We are starting the campaign. We need to get you a Logie. 02:11 Oh, if only. Oh, no, no, no. I'm not worthy. Bluey comes far in here. 02:18 Look, you're also a national living treasure, just like Bluey. But either way, we'll do the work. Don't worry, Dr. Carl. Right now, though. 02:24 The audience. 02:25 We're getting you in an audio sense right now. It is Science with Dr. Carl, answering your science questions every single week. Emma in Ngunnawal country. Dr. Emma, you've noticed something that happens to your bod during summer. What's happening? 02:39 Yeah, hi, doctors. 02:41 I've noticed that when I spend like a week or longer at the beach, my fingernails seem to grow quicker and stronger. 02:50 Dr. Carl, is there anything to back that? 02:54 Yeah, there's a whole lot of things going on. On average, your nails grow about two or three millimetres per month, but it isn't constant. It's actually a little bit faster in summer and it's a little bit faster during the day. And then you have other factors coming into it. So in summer, when you hang around the beach more, it's warmth and warmth increases the rate at which your fingernails grow. Oh. You're getting a little bit of sunlight. Now, on one hand, my wife, who's a medical doctor, went to two lectures in one day. 03:25 And the first one was with the dermatologist who said, keep out of the sun. It's evil. Put on sunblock before you get out of the shower. And the other one was by the Orthopods. the surgeons, the bone surgeons, and their talk was entitled Slip Slop, nobody's talking about sunblock, and crack, break your bones because you're not getting enough UV. So you're sort of stuck with UV being bad, but you get the vitamin D. So the extra sunlight will encourage more growth via the vitamin D that it makes. 03:52 Also, they're better hydrated because what you're doing is you're going into the water and out and in and out and then the nail plate is absorbing water and becoming more flexible and then you can have the salt water which contains minerals. There's some adsorption. You've heard the word absorption, B for Bravo. That means like a sponge. It absorbs all the way through the bulk adsorption, AD for Delta. means that it absorbs only on the surface layer and you're getting the minerals there. And so all of those combine to give you what many people notice, which is the stronger fingernail growth. 04:28 But on the other hand, occasionally you can cause – and the other thing is you're probably spending less time doing the dishes and boring stuff and damaging your fingernails as well. So you're doing that. But you can have this situation where the repeated in and out of the water in some cases, but not often, can cause swelling of the keratin in the fingernail and it can cause it to start to split, but that's not that common. 04:55 How interesting. 04:56 Does that kind of help, Dr. Emma? 04:58 Yeah, that's fantastic. And where are you swimming in the water at? Down on the south coast. 05:05 Love it. 05:05 Ah, so is it cold? What, like 15 or 14 or something? Yeah. 05:10 Yeah, usually in winter it's about that temperature but probably swimming the most in summer. 05:16 So are you one of these people who jumps in the water all year round? 05:19 Yes. 05:20 It's supposed to be good for you, but then they hype it up and charge you $10 to jump into cold water. There are benefits, but not what they claim, but there are benefits. But then on the other hand, maybe the people who do that sort of stuff of jumping into cold water also look after themselves more. 05:35 But also, Emma, you got me thinking now because I think in winter I need to get my nails done less. 05:41 Do you know what I mean? Like they don't grow as quickly, but I think in summer I'm getting them done way more frequently. 05:47 Because they're growing faster. 05:48 Yeah. 05:49 Okay, so we've got two anecdotal reports. And remember, the difference between science and screwing around is writing it down. Did you write it down, Dr. Lucy, and measure your finger? I will now. Is that close to a total J prize, Dr. Lucy? 06:00 That close? Emma, thanks for your question. 06:02 Thank you, Dr. Emma. 06:04 Thank you, doctors. We've got Matt in Tamworth here. Matt, you've got a question about axolotls. 06:09 Hey, yeah, so I was wondering why axolotls retain their gills from the juvenile stage and don't just move to land like other salamanders? Hmm. 06:20 Yeah, they're really weird. So I remember I did my very first stories back on Triple J back in 1981 or something and one of them back in 1981 was about axolotls and then I went to Mexico City to meet up with a family and apparently that's where they live and they're kind of endangered in Mexico City and in that lake there. But on the other hand, there are millions of them around the world. 06:48 They're endangered in their home territory but there's millions around the world because they've got these really weird characteristics. They can regenerate the same body part repeatedly over and over. They can regenerate entire limbs, parts of the spinal cord. So if we humans get damaged to the spinal cord, It's bad. They can regenerate parts of the heart and the brain and their jaws and so they did this experiment way back where they chopped off, I'm sorry, chopped off part of their limb and then they measured in space the electrical field and the electrical field seemed to redirect the regrowth. 07:28 of the limb and then they tried doing this to other animals that were not axolotls and they thought that maybe by having electrical fuels they could help grow the limbs better but it turned out to be not the case. So the thing is that they do not do the normal amphibian metamorphosis where they change from a tadpole into an adult structure. They stay like the tadpole And part of that is related to how come they can regenerate but we're not sure and part of it is they retain the gills even though they don't need them because they can have a good lung. 08:04 So they're sort of a weird evolutionary creature or they've gone down a weird evolutionary pathway whereby they can regrow their limbs which is why scientists are fascinated by them and part of that is they keep their gills. 08:20 Yeah. So if you want to do some research, go into axolotls. 08:28 They've got three respiratory options. You and me, we're stuck with lungs. They can breathe through their gills. 08:34 They can breathe with their lungs. And they can even breathe through their stupid skin. Mate, they've got a three-foot. We've only got a one-foot. 08:41 And they're kind of cute. 08:42 And they're very cute. And they're endangered and there's millions of them. Both are true at the same time. 08:48 Matt, does that help? 08:49 A little bit. That's fantastic. That's more information than I came into this with. 08:54 Amazing. Thank you so much. Thank you. 08:56 That's what this segment is all about. Start with a question, go away with a whole lot of new facts. Victor in Bald Hills, talk to us. What's kind of got your brain into Tizzy this week? 09:07 I want to know why my body gets this weird jolt when I'm walking up towards an outer service escalator. Take a step onto the escalator that isn't moving and you just get this weird sort of forward motion in your body. Is that a thing? Do you know what I'm talking about? 09:20 It's like you come back down to earth a little bit, Victor. 09:22 Yeah, Victor, the trouble is, Victor, you've been living under the delusion that you're in control of your body. Yes. 09:30 So one thing that happens, suppose you're a passenger in another vehicle and then they're driving really badly and then suddenly one of your feet starts diving for the brake pedal. You've got no control. I've seen that happen, yes. 09:43 Yeah, right. That's called the ID motor response, I-D-E-A. 09:47 M-O-T-O-R response and it's thought to be involved with water divining and we won't even go there but in this particular case what you're suffering from is a different thing which a little bit of the technical name which is motor prediction. So when you're walking up a set of stairs, you are predicting that there's going to be a step, going to be a step, going to be a step, and it's going to go flat. 10:11 And when it goes flat, you don't sort of put your foot in the air and fall over. So you're constantly doing it. And so with the escalators, you have been conditioned your whole life into a weird set of predictions that you go onto it and probably stop and then just stay there and... 10:30 And then if it's not moving, then, oh, I've got to walk. So you've got this conditioning that's been with you all your life. So it's called motor prediction or sensory motor anticipation. 10:44 Does that kind of help a bit? 10:46 Yeah, I'm almost getting ghastly by my own conditioning. 10:48 Yeah, you've been done. So I don't know, we're all conditioned. I mean, we're just little paddle pop sticks in the gutter of life on a rainy day. I know. We have no control. 10:58 You walk on the escalator and you're like, that's the feeling. 11:01 Yeah, that's right. The control is just an illusion that they give us. Oh, and by the way, today is the day we're supposed to lose gravity. 11:10 What do you mean? 11:11 Mate, are you not keeping up with the conspiracy theories? Mate, a cabal of the world leaders who really run the world, who are shape-changing reptiles from the planet Zog, are going to switch off the gravity for seven seconds. 11:23 When? 11:23 What time? 11:25 Around now, apparently. 11:27 Mate, how are you keeping up with it? 11:28 I need to keep up. 11:29 Victor, have you heard about this? 11:31 I'm holding onto the handrails. I'm ready. 11:33 So I was trying to work out how far you could get above the ground if they did that. And so if you're running flat out, you can maybe do 20 kilometres an hour, we'll pretend, which is roughly five metres a second. So if you go to a nearby skate park... and there's a bit of flap and you get a bit of speed up and then you start a tenth of a second before the gravity switches off. I forget when it's supposed to happen. You start entering the ramp and then you keep that velocity and then for the next seven seconds, you'll go at five metres a second, 35 metres in the air. 12:07 So if somebody wants to, at that exact time when they switch the gravity off, they get 35 metres in the air. Unfortunately, you'll let them fall with a big thump. 12:16 I'm sorry. 12:17 You've got to do it for the... 12:18 Didn't you know about that conspiracy theory, Lucy? No, I didn't. Are you one of these reasonable people? 12:22 Maybe I am. Hey, maybe I have not enough time on my hands. 12:29 Victor, thank you so much for your question. 12:31 Thanks, doctors. 12:32 All right. Hey, great text on Beans as well. We had that question about the nails growing quicker or more frequently and stronger in summer. Beans saying, I'm getting that our nails are solar-powered. Love it. 12:44 And I now am celebrating two months where I've run my car, my second-hand electric car and our house entirely off electricity. But the trouble is we run out of milk. Oh. Because instead of going to the servo and buying some liquid hydrocarbons for 80 bucks every week, I don't. Did you get milk, honey? No. Did you? No. 13:05 We're not going near it. True. 13:08 I have Erin texting in saying the loss of gravity is supposed to happen at 11.30am UTC. 13:15 UTC. UTC zero, so it'll be about 11.30 tonight. 13:19 11.30, okay. Get yourself near a skateboard park if you want to get 35 metres above the ground. 13:26 Dr. Carl is asking you to do that. No, I'm not as dangerous. 13:30 Jessica, in the end in Brisbane, we cry, it happens, you've got a question about it. 13:36 Yes, I've always been curious about what actually happens to our eyes when we cry. Given that tears are meant to lubricate and protect the eye, why do we feel dry and irritated, sore and puffy after we do have a cry? Is it due to the composition or dependent on the volume? 13:52 Yeah, both of those. 13:53 I'm very interested. 13:54 Yeah. So on one hand, crying is supposed to be good for you, but in general, only when you've got people around who can be supportive. So on one hand, you're having a bit of cry about something and everybody comes and supports you and you work it through and it's all better. Whereas if you're in a battle and you start crying because your best mate got killed or a war's going on and you're crying because bombs got dropped in your house, that means that you can't see... and you're more vulnerable and you're also more likely to have bad things happen to you. 14:25 And the trick is, you touched on it, you've got an extra volume of tears and they're not the normal tears. They're not the normal tears. So your tear fluid has three components. There's firstly stuff from the whites of your eyes, the sclera, there are glands there. And they make a tear that is a liquid that is optimized for sticking to the front of your eyeball. And then in the upper outer corner of each eye is the lacrimal gland and it just puts in a lot of bulk salt water. 14:59 And then from the inside of your eyelid, there are other glands, I think they're called myobium glands from memory, and they make a tear that is high in fat or a liquid that's high in fat. And so the three of them, a liquid that sticks, a liquid that's fairly bulk, and then a liquid that's got fat, they're the optimum film and it doesn't evaporate fast enough. When you cry, you're producing lots of stuff from your lacrimal gland. And so it's not sticking that well to your eyes and it's also going into the tissues around your eyes making it puffy. 15:31 Now, if you go to a flower shop, you can buy some flowers and you get some cellophane, not cling wrap, cellophane. So you can do an interesting experiment where you get a little fish tank and you sticky tape some cellophane at the halfway mark and you put water on each side and the water just sits there. And then on one side of the cellophane, not cling wrap, you put salt. And then the water goes into where the salt is. The water level rises on the side where you've put the salt and it drops on the other side. In the same way, you've got this salty liquid and it's just sitting on the tissues around your eyes and the salt goes in them and they get puffy. 16:10 And they stay puffy. Plus, you don't have that tear film with that layer that's optimized for sticking to your eyelid. And so you feel a bit dry. Even though there's water there, it's not sticking. It's just like sitting in little blobs. Like you might notice after rain... 16:27 And after a light shower, the rain sits little droplets on the paint. It doesn't spread out into a film. And you're having that sort of phenomenon happening. So all of those can give you this combination of puffy eyes. And also, even though it's all wet, it feels dry. So it's like the car paint where it doesn't have a low surface tension, doesn't stick properly. Does that kind of help a little? Also, there's rubbing your eyes as well. Yeah. Yeah, you do a bit of that as well. 16:54 A bit of irritation. Yeah. 16:56 Jess, does that happen? Always fascinating, Dr. Carl. Thank you so much. 16:59 Thank you, Dr. Jess. 17:00 We've got Ryan in Bundaberg here. Ryan, you've got a question about being ticklish. 17:05 Yeah, so the question comes from actually my eight-year-old son was sitting down having dinner the other night and he mentioned to me, he said, hey, Dad, he goes, why when we get tickled, whether it's your feet, armpits, stomach, you know, it feels, you know, we get ticklish or that feeling of being uncomfortable. But if we do it to ourselves... 17:26 Why doesn't it give off the same feeling as being ticklish? 17:32 I was just reading a paper on this that not only is ticklishness fairly universal among human societies, it also happens in some animals. But in the case of your son, is it Ryan, is it? 17:45 I'm Ryan. My young son's name's Arj. 17:48 Arj. Hello, Arj. As in Arj Barker, the comedian? Yeah, let's go with that. Okay, right. So, Arj, look, you play this back on the podcast. So, Arj, what's happening to you is this following. Your brain is saying, hey, Arj, yes, I know that you are trying to tickle yourself full stop. I've checked the paperwork and this is supposed to happen, full stop, carry on. In other words, it's the loss of the element of surprise. And it normally happens in the areas where you're vulnerable. So if you get a sharp instrument like a spear or a branch penetrating your armpit or into your groin or into your belly – It's kind of soft there and it can cause a lot of damage. 18:31 And it's the element of surprise that you're not expecting it to come. There is a way, though, that you can get fabulously wealthy from this, which is, and I've suggested this a few times, and nobody's done it, which is to invent a little device which has little fingers on it and you move your fingers on the inside and then outside the fingers move but with a time delay. 18:53 Your brain knows it's coming. If you can put in a random time delay, then for one year you can induce releases as a stupid gimmick at Christmastime, get fabulously wealthy and shout Lucy and me a cup of coffee in gratitude for having made you and Arj very wealthy. 19:09 Sounds good. Thanks, Dr. Carr. So it's the element of surprise, the artificial, you know, the unpredictability that makes it realise that you're allowing them in but they're not being bad to you. So it's a combination of surprise, happy, sad. It's a weird mix. It's funny. Yeah, funny, yeah. 19:29 Sean in Adelaide. 19:30 Go to Sean. 19:31 Now tell us about the breakfast beer. 19:35 It's become a bit of a tradition on holidays to have breakfast beers. And one of the funny things that we've noticed, and a few of us have been wondering the science or chemistry behind it, is why once you've cleaned your teeth when you're drinking that beer, why does it taste like orange juice? 19:53 Right. So beer and bread both come from the fungus called Saccharomyces my something or other. 20:05 And without it, where is society? And the workers on the pyramids had beer because of the way of preserving it, but it wasn't the clear brown liquid like we had, more like a porridge with a very low alcohol, and that might explain why the pyramids don't have any doors. And there was a case of a factory... in Belgium that had been there for 500 years making beer and they cleaned up the factory and suddenly the beer didn't taste good anymore. It turned out it was being colonised by this mould coming from the ceiling, the Saccharomyces. 20:39 So beer has this wonderful thing of a bitter taste but acid. And here's the other thing. 20:46 Most, but not all, most toothpastes have a chemical called SLS, sodium lauryl sulfate. And what it does is it interferes with two things. It suppresses your ability to taste sweetness. So suddenly you're not getting the sweet taste out of the beer and it enhances the bitterness and the acidity. So suddenly you're getting a different flavor. So it's shifting from beer to something like orange juice. So the sweetness is dialed down. 21:16 The sour and the bitter is dialed up. And you can do this interesting experiment when you go and look on the label for the toothpaste and try and find some that doesn't have any. And then do an experiment when you're having your holiday breakfast beer with some of you having brushed your teeth with one and not the other. And if you document it, you can win a Triple J Fun Pack. 21:36 Fair enough. We'll give it a go. 21:37 I don't know if they'll remember to do that when they're having a breakfast beer store. 21:40 Yeah, well, they do generally say not to drink beer before sunrise, but if it's a very weak beer and holidays and... But on the other hand, alcohol has no good medical effects whatsoever. It is only a poison, but it does make society go a little bit smoother, but a little bit as good, but too much as good. I don't know what to say. 22:01 Is that your general PSA, your general... You got it. 22:05 Your general asterisk over everything you just said. Sean, thank you so much for your question. 22:11 Shane and your co-worker Daisy in Bayswater, you've got a question. Shane, what do you want to know? 22:19 I just want to know why you make so many mistakes when you're more tired than general. 22:24 Yes and no. So if there's one occasion where you just suddenly happen to have stayed up really late and you haven't prepared everything and you have a late night, you get only four hours sleep, as a once-er in the early part of the day, you can probably actually do better than you would normally but – You need somebody as your wing person to say, actually, everything else has been fine, but that last thing you said is stupid. And you need somebody to stop you from making the really big mistakes. 22:56 The reason you feel tired when you make so many mistakes is you just need your sleep. I know that is a dumb thing to say, but the sleep opens up... pipes in your brain that do this massive amount of flushing of waste products. And if you don't, they're called, okay, your vessels in your body are blood vessels and then also the arteries and veins. And then you've got lymphatics. And then you've got in your brain glymphatics, like lymphatics with a G in front, and they open up in diameter by about a factor of three. 23:32 So the flow is enormous and you're carrying out all these waste products and somehow, but we don't know how, they interfere with making mistakes. But just as a once, you can get away with it. So have you noticed this happening to you? 23:48 Yes. Yeah, absolutely. And so under what circumstances do you find yourself not getting asleep? Okay, I'll ask you a different question. How often do you wake up without the alarm clock or do you get brooded out of the arms of Morpheus by the alarm clock every stupid day? 24:00 No, generally before the alarm clock every day, like let's say 90% of the time. 24:05 Really? But are you well-rested? 24:08 Most of the time, no. Depends on the situation, you know. 24:12 Okay, so you're one of those people who is triggered by a rapid rate of cortisol. So around three hours before you wake up, your body starts making cortisol to get you ready for the terrible stress of being alive for, oh my God, yet another day. And there's a small set of people who can trigger themselves to wake up at the same time and not everybody can do it. And they can normally do it when the... rate of increase of cortisol is the greatest. It's not when you've got the lowest or the medium or the highest level, but how fast it's increasing. 24:44 And these people who can wake up at a certain time before the alarm clock, they have got that in their body, but unfortunately you're not getting enough sleep. 24:52 Do you have children yet? 24:54 Not yet, but I've got a puppy, so that's definitely, he's similar. 24:58 I'll share a secret wisdom for you. Yes. 25:02 Once you have kids, for some people it turns out that, I know this is hard to believe, sleep can be better than sex. I know this is hard to believe, right? No, I could see that. Yeah, okay. So it's basically by some poorly understood pathway, the metabolic byproducts of waste are hanging around in your body, inside your brain, and you're making mistakes. The rest of the pathway we don't know. 25:23 I think, you know, even kids aside, I think even working shift work, sleep is so good. But to, you know, your point, Shane, I'd find that I can do this show on a lack of sleep. I've had nights, you know, when you had the Arias or something the night before or a gig and I can come in and do this show on five hours sleep. But... 25:44 After midday, useless. Useless. You know what I mean? So it's like I have this adrenaline where I can do the thing that I absolutely need to do but then once that's finished, it's all gone, you know? And I'm making those silly mistakes that you're talking about, Shane, where you pull out your bank card to unlock your front door. You know what I mean? Yes. 26:04 Trying to tap into work with my keys. Like just things like that. So we get it, Shane and Daisy. Thanks so much for your question. 26:09 Thank you. Thank you. 26:10 We've got Caitlin in Adelaide here. Now, Caitlin, this is a bit of a broad question. What do you want to ask Carl? 26:17 Hi. So my question is what is a widely believed health or fitness fact that turns out to be wrong or a myth? 26:25 So, Caitlin, we talked about this off air. Carl, I put a few things to you. What did I say? I said, you know, that we need eight hours of sleep a night. You need to get 10K steps a day. 26:35 You've got to stretch before exercise. 26:37 Stretch before exercise. How much water do you drink? So take your pick. What do you reckon? 26:40 Eggs are bad for your heart because of the cholesterol. Oh, yeah, the cholesterol. Sweating means you're burning more fat. Women will get bulky if they lift heavy weights. You need to wait an hour before swimming. I remember that from being a kid. 26:50 Oh, yeah, you can't. Yeah, you've got to wait an hour after you've eaten to swim. 26:54 Yeah, okay. All right, take your pick, Carl. What do you reckon? The glass of water, and it turns out I have, and this is a confession, I have been wrong. Okay. So the myth is eight glasses of water a day. Or not myth or belief. Belief, okay. Belief. Eight glasses of water a day. And it turns out that's not correct because you get most of your water from your food anyway. But I realise I've been drinking water the wrong way. And you're thinking, how can you drink it the wrong way? You open your mouth, you pour water down your throat and you shut your mouth. 27:26 What's so hard about that? And I've been doing it wrongly. There was this paper that was published in 2005 and I don't know why, but just yesterday I got around to reading it. 27:37 Oh, no, no, last week. It took me 20 years to get to it. I've had it waiting in the files, right? And it turns out that if – pick a two-hour window where you've got to have a certain amount of water to maintain your hydration. On one hand, you go, oh, my God, drink water, guzzle, guzzle, guzzle in one go. And what happens is your body can't deal with that massive influx of water – It doesn't hydrate you evenly through the whole body and that's very important because of neurotransmitters in the brain and feeding and that sort of thing. And then you generate a lot of urine and so you generate urine and you don't hydrate yourselves properly whereas if you have that water spread out over two hours, you will hydrate yourself and you don't have to go to the toilet so often. 28:20 And I suddenly realised that I have been wrongly scornful of people who are walking around with a bottle of water going sip, sip, sip. And I've been mocking them. I've been wrong. Saying, ha ha, what do you think? Your body will dehydrate and you'll turn into a little pile of dust and get blown away by the next wind. Oh, you fool. And I've been wrong and they've been right. I've been wrong for about 20 years. Wow. So you should sort of tend to sip the water and not flavoured water, not the diet, cola drinks, whatever they are. Just sip the water and I apologise for being wrong for all that time. 28:48 And then so the eight glasses. 28:52 You will get enough of what you need just by having regular water during the day. But here's a weird thing. Our thirst syndrome, our thirst signal is often interpreted as hunger. And so people will feel thirsty and they need something which makes them more thirsty. And I've been offshooting our series of how things work and it happened to me again. If I don't drink lots of water after lunch, suddenly around 2 o'clock, because we're doing these 10-hour days, suddenly around 2 o'clock I go, I can't think anymore, I can't brain no more. 29:26 I'm using the word brain as a verb instead of a noun. And I suddenly realised it was because I wasn't drinking water and so then I just guzzled a couple of litres, like a litre and a half of water, and then suddenly, bingo, my brain comes back again. Yeah. So, yes, so there's subtleties to not drinking enough water. Now, who was asking this question? This is Caitlin. So what's your favourite health belief that you now no longer believe? 29:51 Ooh, that you've just said? 29:54 The one about the water. 29:56 I think, yeah. I didn't know that you get most. Did you say you get most of your water from the food you eat? 30:01 In general, you do. Wow. But you should also drink water and not confuse. This is true. This is one thing I didn't believe as well. People would say, oh, your thirst signal is easy to misinterpret as a hunger signal. Okay. And I thought that's silly and I suddenly found it was true. 30:19 Wow. 30:19 Yeah, another one of the many mistakes I've made in life. Wow. 30:23 Caitlin, thank you for the broad question. I like that one. No worries. Thank you, guys. Yeah. We've got Jared in Seaford here. Now, Jared, onion, garlic, two of the best things in the world. What's your question? 30:35 So I have a question about garlic. But, yeah, I can't eat onions without suffering any tummy trouble. And I find I struggle to eat garlic unless I've done very specific things. 30:48 unless it's relatively fresh and cooked or the main one is cut out the little spriggetito in the middle that can grow in each bowl. So I was just wondering, is this all in my head or is it some kind of nefarious onion-related science? 31:03 It's probably real. Are you okay with garlic oil? Yeah. 31:09 Have you run across that? 31:11 Yeah, anything like that or if it's like garlic, salt or flavoured, totally fine. 31:17 Right, and do you get like wind or, that's a polite way of saying, do you fart or does your tummy expand or do you get cramping? 31:26 Yeah, it's pretty much expanding and cramping, all bluster, no muster. 31:33 Oh, what's that phrase again? Say it again. All bluster, no muster. All bluster, no muster. 31:39 Nice. Okay, so it's almost certainly chemicals called fructans, which are present in onions and garlic. 31:48 They contain fructose, and we don't really have the proper enzymes needed to break them down. 31:55 And some people have got more than others, but in general we're low on them and you're probably at the low end. And this is related to that FODMAP diet thing. 32:06 What's the FODMAP thing again, Lucy? 32:09 Fermentable oligosaccharides. 32:12 Saccharides. Saccharides, yeah. 32:14 Disaccharides, monosaccharides and polyols. 32:18 I forget what polyols are. Okay, so you're almost certainly one of those people who's low in the enzymes that can break down the fructose. 32:29 So the fructose turns out to be not very soluble in oil. 32:35 So you can get this garlic oil where they get the garlic and they mash it up and they shove it in oil and they fill around the garlic and you've got the garlic essences without the fructose. 32:44 So try going for garlic-infused oil and almost certainly, if it's due to your potentially low enzymes that break down fructose, you'll be able to enjoy the goodness of the garlic. The actual garlic cloves, oh God, no. Garlic-infused oil, yes. Yes. 33:01 So is that kind of answering your question a little bit or is it something I left out? 33:06 Oh, kind of. It's like I can still have it if I remove the sprig and cook it. That's interesting. But like, yeah, I can't just dice up a garlic bulb with it in. I have to like... bisect it, take it out, which is easy to remove, but it just takes a little bit longer when cooking. 33:24 Whereas, Jared, when you have kept it in, you're getting these symptoms of, you know, maybe a bit of... 33:30 Similar to the onion, yeah. 33:31 Okay, that's outside my range of knowledge. I have not thought of that. I'm going to have to go looking up the literature on that. Thank you very much for alluding me to this new thing. Thank you for giving me more homework, Dr. Jared. You rock. Apologies. No, no, it's how I learn. 33:44 Yeah, Jared, you've given him work to do. Yeah, give me work. Let's see what we can do. Jared, thanks so much for your question. 33:50 Oh, thank you. 33:51 Do you still like spaghetti bolognese though? 33:54 Oh, absolutely. Yeah, love it. It's so good. 33:57 It's so funny. There's a classic meme where if you've lived in a share house, all you need to do is cook up a bit of onion, maybe a little bit of garlic, and your housemate will come out and go, oh, it's cooking. It's amazing. And then you're just onion and garlic. That's it. 34:11 Well, that's my favourite dish, but you've got to cook it past the five-hour mark because the redness starts to go dark red. 34:17 And sometimes even better the next day. Yes, yes. After it's been in the fridge. 34:20 So normally I get a whole bunch of onions and clove, not just clove, a bulb of garlic. And I chop it up. And then with the meat, I fry it until it's just a little bit crispy because then you get the Maillard reaction, M-A-I-L-L-A-R-D reaction. And then you've got to add what they call tincture of time, tincture being an old medical word meaning... medicinal products so you just add time so you use that in medical talk when you've got a patient in front of you and you want to keep an eye on them you say I think Dr Lucy we need to add some tincture of time which means that you watch them carefully and do nothing and just keep watching and when something declares itself you immediately do something 35:04 Marie is texting in saying infused garlic oil is safe on a low FODMAP diet as the fructose doesn't come out in the liquid. 35:10 Oh, my God. Thank you for backing me up on that one. I was thinking it would be yet another one of the many mistakes I make. 35:15 Damn, spaghetti bolognese, water. I want to sip on my water. I want to have some spag bol. 35:22 Right now we've got Jamie and her boyfriend Cameron from Nam Melbourne on the line. Now, Jamie, this morning I woke up and on my phone, my phone weather, it said 11 degrees feels like 7. Jamie, what did it say for you? 35:39 I think it's the same. We're driving down to Melbourne from Brisbane recently. We've just moved and we stopped near Canberra and there was one day when it said it was 10 degrees but feels like negative 5. Whoa! We're wanting to know what could cause such a difference in the actual temperature versus the feels like. 35:57 It's the presence of wind overwhelmingly together with a little bit of humidity. So in the Antarctic... 36:04 Every year in the middle of winter at the South Pole, the people down there expose their skin to a temperature change of 300 degrees Fahrenheit in a few seconds. And they can do this only if there's no wind blowing. 36:20 If there's a wind blowing, they'll die of hypothermia. They get into the sauna on a day when the government meteorologist tells them it's minus 100 and then outside and they go into the sauna at plus 200 Fahrenheit, about 90 degrees C, and they sweat like crazy. They have to do it nude because if they're wearing clothes, the clothes will pick up the sweat and the sweat will then freeze outside, turn into sharp icicles and stab them and draw blood. And so they stay in the sauna wearing sand shoes and then run outside and then it's totally dark. 36:52 It's dark for a thousand kilometres in every direction. They're the most isolated humans on earth. And then people there with lights and they run slowly around the South Pole and back in again with zero wind. If there's a slightest hint of wind... 37:05 they're not going to do it. And so they can run with their naked skin at minus 100 Fahrenheit, I don't know whether it's centigrade, maybe 30 or 40 or something, or say 60, and they can survive. So it's the wind that's drawing away this thin layer of warm air on your skin. So if you're not normally standing there, there's a layer of air maybe... 37:24 Two millimetres thick on your skin. And if you just walk through the air fast, it gets blown away. That's okay. And they run slowly. If they run fast, they can get frostbite. If they run slowly, they're fine. So it's the wind that draws away the warm air that makes you feel colder than it really is. 37:42 Is that helping you? 37:43 Yeah. 37:44 Yeah, no, that's so cool. So it's just the, I guess, on your skin layer, what the temperature feels like. 37:49 That's it, yeah. And these apps are covering. 37:53 They're covering all bases. 37:54 Yeah, and we were one of the first stations in the world to do the first radio transmission from Antarctica, which I did back in 2019. Hooray for us. Aren't we wonderful? 38:02 Jamie, Cameron, thanks for your question. Thank you. 38:04 Thank you. And good luck for your move as well and everything that's going on with that. 38:09 Moving. Thank you. Moving's so hard. I hate moving. 38:12 And the States as well. That's crazy. 38:14 Oh, gosh. 38:14 Julie in Sydney. 38:15 Dr. Julie. 38:16 What's your question? 38:18 Hi. My question is, does outer space have a smell? And if so, what does it smell like? 38:25 A sparkler. 38:27 You know the party sparklers? Oh, yeah. Yeah, yeah. Or a welding torch that you've just been using or burnt meat. 38:34 Okay. 38:34 And so the astronauts will go on the International Space Station 400 kilometres up, put on their spacesuits, go into the airlock, get rid of the air, go outside, come back inside... 38:46 and then shut the outer door, fill the airlock with air, take off their helmet, and they can smell something like a sparkler. And we think it's a combination of three things. Firstly, the Earth's atmosphere reaches all the way to the Moon. I know that's hard to believe. There's hardly any of it there, but they found oxygen from Earth on the Moon. And... It's in low Earth orbit. No longer is O2, but just simple, single atoms of oxygen and they're very reactive. 39:18 They're single atoms because they've been blasted by the ultraviolet. Down here, ultraviolet is 2% of the sun's rays. Up there, about 10% to 12%. And these poor little oxygen molecules are floating around by themselves and they just get blasted and they react like crazy with stuff on the space suit. 39:39 And then secondly, the ultraviolet acting on the spacesuit causes it to undergo chemical changes and that's what they can smell. 39:47 And maybe there's tiny particles, we don't know, but they're the two main factors. So basically like a sparkler, it tends to be the smell of space if you're talking about the smell you get when you take off your helmet while you're still wearing the spacesuit. 40:01 The space itself has no smell that we know of, but it might if we spend more time living out there. 40:06 Wow. Julia, thanks for your question. Amazing, thanks. So good. Hey, earlier we had Jared talking about the garlic and that affecting him when that sprig is taken out. Someone texting in saying the sprigging garlic contains concentrated sulfur compounds which can irritate the stomach. 40:22 Oh, hang on. 40:23 So the sprig is that little central bit that will grow in. 40:25 You know the one that you kind of got to take out if you, or you can. 40:28 Of course. 40:29 The hydrogen sulfide is a rotten egg gas. It's incredibly irritating to the gut, which is why you are evolved to hate the smell of it so that if you happen to eat a rotten egg, it stops you from having the massive tummy upset. So we have evolved to hate the smell of hydrogen sulfide. Oh, thank you so much. Who was that who said that? 40:48 I don't know. 40:49 Thank you, wonderful person. Thank you so much. Wonderful anonymous person with a random phone number. They said sorry. Thank you. 40:55 Hey, Dr. Carl, I will catch you next week and next week it's National Science Week. 41:00 Oh, my heavens. 41:01 This is like your science Christmas. 41:04 So I'm going down to Tasmania tonight and doing gigs in Burnie on Saturday morning and Burnie School on Friday and Hobart on Sunday morning. Come, rock out and party. 41:18 Yeah, if you want all the details, head to Dr. Carl's socials. Hey, we'll catch you next week. 41:22 I can't wait. 41:25 And that's it. Thank you so much for listening to this week's episode of Science with Dr. Carl. If you have a question for Dr. Carl and you want to submit it right now, you can do that. We've got a Google form for you in the show notes. You just need to tell us who you are, where you're from, and be able to answer a call so we can, fingers crossed, get you on air to ask the question yourself. I'm Lucy Smith. This episode was produced by Josh Brennan and Amy Brosnan, and we'll catch you next week. Bye. 41:51 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. Get it wherever you're listening now.