Dr Karl Podcast

00:00 This is a Triple J podcast. 00:02 Hello, welcome to another episode of Science with Dr. Carl and this week it is just you, me and Dr. Carl answering your science questions. We had a couple this week about sneezing, whether it cures nausea and whether you can hold a sneeze in. Can you stop yourself from sneezing? We also had a bit of a dilemma with the toilet door function. Should we change it? A fireman says no. We're going to get into all of this and more in this week's episode. I'm Lucy Smith. Let's jump in. 00:32 We are doing science with Dr. Carl. Dr. Carl, how are you? 00:35 I'm so peachy keen. Had a wonderful week. The sun is shining and I came close to running my home battery low, but I'm just managing to scrape through so happily. I'm now at the two and a half month stage where my secondhand electric car and my house have run entirely off sunlight and I haven't had to buy any electricity at all. 00:53 We've been on the journey with you for the last couple of months. Loving it. We're coming off the back of National Science Week. Dr. Carl, is there one thing that you learned or discovered in that week? 01:03 Yes, the trend isn't continuing. So I gave a talk at Dubbo and it was supposed to be a three-quarter hour popular family-friendly science talk followed by three-quarters of an hour of Q&A. It was one and three-quarter hour. There was one question from an adult... one from a 14-year-old, and most of the hour and a half, three-quarters afterwards, was kids under the age of 10 saying, okay, so you're saying the black holes have no sign, but what about the Kerr dynamic when if the black hole is... 01:32 The next generation, truly. You know what? We actually have got a question on 0439757555. Let me kind of do a scroll through and find this one. Zoe. Hello, Dr. Carl. If there isn't much gravity on the moon and in outer space, why don't the planets fall down? 01:49 Because they're always moving. 01:50 You don't have to answer. Oh, okay. Oli, do you want to answer it? Go for it. 01:53 Okay, so firstly, if there was no gravity, I think there'd be no curved paths. 01:59 Everything moves in a curved path. 02:02 And it's usually gravity that makes the planets go in a curved path around, for example, the sun. And if there was no gravity, this was a question from one of the kids in Dubbo, and I had to think about it, it suddenly means that practically everything would go in a straight line. There are some magnetic stars... which if there was an iron planet could make it go in a curved path separate from gravity, but that would be it. So give me the exact question again, what's wording? If there's no... 02:30 If there isn't much gravity on the moon and in outer space, why don't the planets fall down from Zoe Berger five years old? 02:36 Well, there is some gravity. So... 02:39 At Mercury, there's so much gravity from the sun because it's so close to it that Mercury has to move it, say, I figure the number, I think it's 50 kilometres a second. Earth and Mars further out, 30 and 24 kilometres a second. Poor old Pluto, four kilometres a second. By the way, it's the 20th anniversary where they accidentally got rid of Pluto as a planet. Accidentally. And one of my mates at the University of Sydney physics department voted against Pluto. 03:07 Is Pluto back? Is Pluto back? 03:08 No. 03:09 Oh, no. 03:09 You see, they made a mistake. They had this big, every year, astronomical conference, and it was in some European city, and a new result had come through. Thanks to the Hubble Space Telescope. You see, they'd found this planet that was bigger than Pluto. And I found another one and another one all in a few weeks. And then suddenly there's this astronomical conference with this, hey, we've found three new planets bigger than Pluto. Oh, my God, what are we going to do? We can't just have nine. We have to have 10, 11, 12. And it looks like it'll keep on going. They panicked. 03:40 And they went, just get rid of it. Just get rid of it. And it turned out the results were wrong. 03:44 They didn't need to get rid of Pluto at all. 03:46 Oh, my gosh. 03:46 There you are, Professor TB. You know who you are. Yeah. And many other people. They voted wrongly in a panic. Okay. 03:53 Okay. Moving back to us. Well, we've learned that. But the kids are all right, Dr. Carl, is what you're saying. It filled me with such optimism. 04:00 There were six-year-old kids just curious about the world and the parents were there supporting them and there were three generations in the seats and you didn't know which one generation brought the other two. 04:09 It was so cute. So cute. Let's go to some adults now. We've got Deb in Tasmania. Dr. Deb, you are kicking us off. What do you want to know? 04:17 Welcome. 04:18 Good morning, doctors. I would like to know why can't you hear yourself snore? My partner is... a pretty good snorer. And often when I go to nudge him, he's not asleep. He's, you know, he's still semi-awake, but he can't hear himself snore. 04:36 Why? Because he's sleeping and those things are switched down and he might even be in REM sleep. Snorers can wake themselves up, but it's rare. So he has not snoring loud enough. And the thing about snoring is it's tied to something called sleep apnea, which can lead to high blood pressure. 04:56 and I had an interesting talk with a dentist yesterday about the importance of air breathing and how the shape of the upper jaw and mouth is changing in the last 50 years. They're seeing it with the different generations. And so I don't have a good answer. There you are. I don't have a good answer. It's frustrating. Why can't he wake himself up and then think I'm being bad and let himself go to sleep again? 05:18 You think, why can't you hear that? But sometimes I swear if I've – maybe I'm having a cheeky snore – And I do kind of hear myself or catch myself but does that mean I'm not in REM sleep if I can hear it? 05:32 I don't know. 05:33 Look, I definitely don't know. 05:35 We need a sleep expert. 05:36 We need a sleep expert and that is such a good question. We do. And there will be one and the number is 043975755. Yeah, he's got it. I got it, baby. 05:45 Deb, thank you so much for kicking us off and we'll see if we can find an answer. 05:49 Lovely. Thank you. All right. We've got Roseanne in Melbourne. Rosie, what's your question? 05:56 Hi, doctors. Look, I just wanted to know this. Why do you – does your jumper or your top or your shirt or anything always ride up and then you have to pull it down? 06:07 Ah. 06:07 Well, besides the law of maximum inconvenience, it's because you're moving your arms. And so when you lift your arms up – so your arms are just hanging down and your hands are near your thighs. And you gesticulate and you lift your arms up a little bit, say, to hip level – that lifts up the shoulder a little bit. And so the whole shirt rise up a tiny amount. And then when you put your arms down again, there's no corresponding force to make it go down. 06:34 And there's something called clothing friction where you've got repeated forces on the clothing and it seems to go in one direction. And I think it's kind of possibly related to the magician trick. This is another one I don't know of, so I'm just speculating here. The magician trick where there's a table and there's a tablecloth and there's all these plates and cutlery and glasses and they magically go up to it and they pull it slowly and all of the crockery goes towards the edge and they pull it quickly and it just comes off leaving, the tablecloth comes off and everything is left behind. 07:08 And so there's a thing where static friction, when you pull it slowly is higher than dynamic friction when you pull it fast. So when you pull it fast, the friction is lower and maybe there's something like that happening with the unfortunate event that these shirts gradually ride up and end up halfway around your stomach. which is kind of wrong. I haven't got a better answer than that and we probably need somebody from industrial fashion and design because that would be a whole thing of tailoring shirts for the different body shapes where you've got the inward going waist, the horizontal, the parallel waist and then slightly bulging muffin top. 07:44 Okay. So once again, I don't know. Two out of two, I've failed you. 07:49 But does that get you started, Rosie? 07:51 It certainly does. 07:52 Does it give you a bit of joy, a little bit of joy? No. 07:55 But it's an interesting point on the fact that you put your arms down and that mechanic doesn't mean the shirt goes down. 08:00 No, but it will go up when you lift your arms up. 08:03 All right. We've got Julia in Adelaide. Dr. Julia, what's your question? 08:07 Hello. I'm a massive fan. I just wanted to say that. 08:11 Oh, and we love you too, Julia. Where are you in Australia? 08:14 In Adelaide. 08:16 Oh, thank you for ringing out of the time zone. You must love us very much. 08:20 Yeah, I do, I do. 08:23 So I just wanted to ask a question. Why is it that when I drink straight black tea, I feel like nausea? But then when I have milk or sugar with it, I don't. I'm fine with black coffee. It's just black tea. Julia, I kind of know what you're talking about. 08:39 Oh, okay. There's something about it that feels a little too... 08:44 I think that it's intense but it just doesn't go down the same. I can't explain it. Dr. Carl, I always get really annoyed when I've brewed a black tea and then there's no milk in the fridge or the milk's off and then I think, well, I've got to drink this but it's not hitting. 08:58 Okay, one way around is follow the example of the Russians who would brew tea all day. Oh. 09:05 And they would have Russian caravan tea, which would not get disgustingly tannin-like and hard at the end of the day. Or the other alternative is to go and buy Darjeeling tea. 09:18 Now, Darjeeling tea comes from the area called Darjeeling at the base of the Himalayas in India. And each year, even though they make only 8,000 tonnes, 40,000 tonnes is sold. So there's a lot of tea which is wrongly labelled as Darjeeling. So I actually buy mine from a company that says, we are from Darjeeling. Okay, they had some extra ink. Are they lying to me? I don't know. but I have it as my afternoon tea and I can have it with just the smallest amount of milk. So this is the answer, I think. I think it's polyphenols, which include tannins and other chemicals. 09:49 And so if you have a strong black tea, like an Assam tea, you've got a lot of the polyphenols. And you're special, Julia, in the sense that most people can handle... 10:03 Straight tea on an empty stomach, but you get the nausea. So you are a little bit different from the rest of us in that you have a reaction to the polyphenols. If you add milk to it, then the milk soaks up some of it. And then when you talk about the Earl Grey tea... 10:21 So do you have a little hand lens at home? Oh, you can do it with a phone, okay. Get a tea bag of Earl Grade tea and snip it open and then look at it with either a hand lens or magnify it on your phone and you'll see little tiny brown capsules of liquid, maybe three quarters of a millimetre in diameter or even half a millimetre in diameter. They're hard to see and they contain the bergamot oil. Okay, so the first thing is that the bergamot oil gives you that sort of flavouring that is the Earl Grey. 10:57 But secondly, in general, they don't have a strong black tea for the Earl Grey. They have a weaker black tea, so you don't have so much of the polyphenols. And then finally, the coffee has no polyphenols. 11:06 So, Julia, we're also getting a text in which I want to put to Dr. Carl. Someone's saying black tea dilutes stomach electrolytes, causing bloating. 11:15 Yes and no. I don't get bloated. I just feel sick. 11:19 Oh, hang on. There's a whole different ballpark. 11:22 I used to worry about this when I thought if I'm drinking water, surely with a meal I'm diluting and weaking my stomach acids. And I don't have a good answer to that even though I did work in gastro for a while. I forgot to ask my gastroenterologist bosses about that. 11:37 And Julia, you say there's no bloating. It's just a bit of nausea. 11:40 Yeah, and then, you're like this, Dr. Carl, then after I might sometimes sneeze and then I'll feel better. 11:48 Oh. Oh, my God. 11:51 A little sneeze to take the edge off. 11:53 Wow. So the sneeze takes the nausea away. I am way out of my depth on that one. What we need now is some high-level neurophysiologists who spent their life on sneezing and they say, oh, yeah, of course we worked that one out in 1970. Oh, yeah, that one's easy. Okay, come on down, neurophysiologists. 12:13 Trigger's the other. Yeah, Julia. 12:15 And sneezing is an amazing thing because it's too strong reflex and people sneeze when they look at sunlight. 12:22 It's a great little factory reset, a sneeze. Julia, you've sent us down a little bit of a wormhole. Thank you so much for your question. 12:28 Thank you. 12:28 Thank you so much, guys. We always love a tea question, don't we, Dr. Carl? 12:32 I do love tea. It's got its own place in society. 12:37 question about black tea making you feel nauseous and julia was saying that after the nausea the thing that can cure it is having a good sneeze now we've gotten some people texting and saying that they've been through the exact same thing bell in taz saying oh my god the sneezing and nausea girl for real the same what the f is this macaroon browlee said the same with me with the black tea and the sneezing 13:01 Wow. 13:02 Now, there was a text talking about vag... Yeah, we had someone saying the sneezing after drinking black tea and ensuing nausea could be some kind of vagal irritation or stimulation. What does that mean? 13:12 Well, I did mention that we needed some sort of neuroscientist in this. So you've got 12 cranial nerves dealing with mostly stuff inside your head, but the 10th cranial nerve is called the vagus nerve from the Latin for wanderer. And it wanders out of the skull, down your neck, and goes... to your heart and your lungs and your gut. And we're discovering more about it. There's interesting articles about it in New Scientist. And I'm prepared to believe that the vagal nerve can do a reset. We're learning more. 13:42 Tony, you said, I drink about six or seven mugs of white tea, no sugar per day. On the very rare occasions that I drink at black, I get nausea and can't finish the cup. I'm on about. Wow. I drink a similar amount, Tony. 13:54 What we need is somebody from a tea company who's a food chemist to say, look, Carly, you had a guess about it being polyphenols. You're right or you're wrong. Somebody tell me how wrong or right I was. I'm guessing it's the polyphenols. Please. 14:06 We've got Nathan in Perth here. Dr. Nathan, what do you want to know this morning? 14:11 Hey, doctors, I was given some lovely fresh direct from the farm avocados last night and my mate gave me the old put them in a brown paper bag to ripen them up. So it got me thinking, why do we put avocados or bananas in a brown paper bag to ripen? How does that work? And secondly, why do we put mushrooms in a brown paper bag to keep them fresh? 14:33 Oh, okay, I'll go for the first one. There are hydrocarbons, which in general... 14:39 and not very environmentally friendly but by coincidence a hydrocarbon gas called ethylene which they used to use instead of to provide a flame for headlights in the old days before they had electricity that's how far back it goes ethylene which is definitely something that comes out of the ground natural gas married with that all that sort of stuff ethylene is also used by plants to bring on ripening. And it turns out bananas pour out heaps of this ethylene. And so if you've got some unripe other fruit, you put them in a convenient container. 15:14 Okay, what are you going to use? If you use a plastic container, it might trap the moisture. So you go for a Paper is sort of, will let the water vapor through and most of the paper you get, it's easy brown paper bag. So it's not necessarily the color of it, but just that it's a convenient container and it's paper and it lets the water vapor out and it traps the gas to some degree. So it will speed up the ripening via the ethylene gas that's released from the bananas. In the case of avocados, maybe they release the ethylene gas as well and you trap it and you don't let it go away so it speeds up the ripening. 15:50 I don't know enough about that. Can somebody who is a plant biologist tell us if ethylene does release – sorry, if avocados release ethylene? What was the second part of the question? 16:00 And then the mushrooms, you know, so we've got this process that ripens things like avocado but why does it keep mushrooms fresh? 16:09 On the early days when I started buying fruit and vegetables all by myself as an adult when I moved out of home, I would put the mushrooms in a plastic bag and they would get mouldy and slimy. And so then I put them in a paper bag and they didn't. So I'm guessing it's just you put them in some sort of material like paper that lets the water vapour out. I'm guessing. That's just a guess. What? 16:30 I'd never heard of this before. Nathan, thanks for bringing it to my attention. 16:33 Haven't you put mushrooms in a plastic bag and left them in the fridge and find them more slimy? No. You're sensible. You're sensible. 16:40 But I didn't know about the avocado and bananas in the paper bag. Nathan, thank you so much. 16:45 Thank you for setting us down this other wormhole. Yeah. 16:48 We're getting set on some pretty funny directions. Brittany in Townsville. Brittany? I'm going to let you explain this one, Brittany. Take us there. What do you want to know? Hey, doctors. 16:58 Thanks for having me. 17:00 My question is basically, why is it when you go to a public toilet, like a supermarket or a cinema or something like that, that you generally have to push to enter the toilet, but then when you're leaving after you've washed your hands, you have to pull the door to leave? Shouldn't it be the other way around so that once you have washed your hands and they're clean that you can then use your elbow to exit so you don't have to then touch something? Brittany, I love you thinking about the cleanliness. 17:25 And also how unfair it is that men who have got two ways of urinating, either standing up or sitting down, have more cubicles slash urinals than women. And the queues at public events for the women's events are always so much better, much longer. And this is wrong and I wrote about it in my 15th book and it has not been redressed. We still have this iniquity in our society. Women's toilets should have more cubicles than the men's toilets because the men can use urinals. Getting to the door. 17:51 Can I say sometimes when I go to a gig that is maybe a more – maybe an artist who has a more male-centric fan base and I see the line for the men's out the door around the – and I go, now you know how it feels. Yes. As we just swan on in and then walk out, I just think, now you know. Yes. 18:08 Yeah, and we had that example last week with the seahorse where the male can carry the baby all the way through and do the full pregnancy. Why don't we have that option for half of all pregnancies are carried by men? Okay, moving right along. Getting to the toilet. 18:23 To the door. To the door. 18:24 Okay, so you've got the choice of the door opening inwards or outwards and normally toilets are fairly small. So if the doors open outwards then people can bump into them with their nose so the doors always open inwards. Yeah. 18:37 Hang on, hang on. But that's the cubicle. Are you referring Brittany to the bathroom? Yeah, like the main door into the bathroom. So you've done your business at the cubicle. You wash your hands and then you've got a hole and then you're grabbing the same door as everyone else after you've just washed your hands. Do you know what I... 18:55 It's wrong. 18:56 I'm thinking through my memory of every public toilet I've been to and always you push to go in and it should be to push to go out so you can push with the elbow. Exactly. Yes. 19:06 Is it a fire safety thing? 19:09 Is it? 19:09 Well, in fire safety, what you want is that people get out quicker. And one thing I do like about American firefighting is that they've got regulations that all doors should lead out. You want to get out of the building, you just push and you keep on going. 19:22 Damn. 19:23 Right? Whereas in Australia, it's not necessarily that way. But on the other hand, they do have a fault where they wrongly believe. 19:28 as compared to the rest of the world, that if you've got a building on fire, you should punch a hole in the roof to let the smoke out, which is good, but it also gets an airflow so the fire gets stronger. Okay, getting back to the toilet. We're going off course. We're going off course. Getting back to the... It should be... 19:46 Look, I think it's another case where we made a mistake as we did with the number of cubicles inside. The mistake is that the doors open inwards and they should open outwards. 19:57 Because you just wash your hands. 19:58 Yeah, because maybe they're trying to protect people who are coming up to the door from the outside world, pushing a pram or something or carrying some luggage and suddenly the door goes slam in their face. Oh, I see. 20:07 Yes. 20:07 Yeah, but you're going to be pushing the pram or carrying the luggage, the groceries on the way out. I think they should all be redesigned to be pushed out. We should write a Sturm letter to the newspapers to complain about this and this should go to the Prime Minister. In fact, even higher to the people who really run this country. I'm talking Rupert Murdoch. 20:24 Yeah, someone's saying the toilet door thing is probably so you don't smack someone who's walking by the door but not wanting to go in. 20:30 Oh, that makes sense. 20:32 But you can then do that like entering. You can do that on the other side? Yeah, if someone's coming out of the toilet and you're pushing in. 20:38 Maybe you're anticipating it more. Brittany, you've got into something that's not only hygiene but it's also the human psyche, fire safety. You know, you've said I'm very interested to see the reactions to this on 0439757555. Brittany, it's another I don't know but we'll see what comes through. Thank you, Dr. Brittany. Thanks, doctors. And we've got Tasman. Tasman in Tasmania. Dr. Tasman, how old are you? I'm only 10. You're 10? You've got a great question. What do you want to know from Dr. Carl? 21:11 Oh, so what I was going to say is that how cold would the world need to be in order for all the water on Earth to turn into ice? 21:23 Right. Okay. 21:27 Firstly, if you just get some water in a bottle and you put it in the freezer... 21:35 and you take it out after one minute, it hasn't frozen. So there's a time delay involved. So with the ice ages, the peak of the last ice age or glacial was about 25,000 years ago, the ice was three kilometres thick over Siberia and Montreal. Think about that, three kilometres, right? That's higher than the great or what should be properly called the average or mediocre dividing range in Australia. 22:01 And New York, one kilometre high. But it took a long time to get to that. So the average temperature of the world when the ice was three kilometres to go over Montreal was four degrees lower. 22:16 And so looking on the other side, people are saying, well, yeah, it's one and a half degrees hotter, but it's not that bad. You haven't had time for the bad effects to kick in, in the same way that water doesn't freeze straight away. Secondly, you can't have water freeze all the way down. 22:31 Now, have you heard about the density of water changing with temperature? Have you come across that, Tasman? Okay, so water is a really unusual liquid. And with practically every other liquid, while it's in the liquid state, if you heat it up, it expands, becomes less dense. If you cool it down, the molecules get closer together, it becomes more dense. 22:56 until it becomes a solid, not water. 22:59 With water, it reaches its maximum density at three degrees centigrade. So on the bottom of the oceans around the world, the water temperature way down deep is three degrees. And what about the water that's at, say, two degrees? It's less dense. Water has its unusual property, so it rises to the surface. 23:19 And what this means is that when the world gets cold... 23:24 You have an insulating layer of ice at the top and liquid water underneath. We did have, 600 million years ago, a situation called Snowball Earth where virtually all the oceans on Earth were frozen, pole to pole. 23:38 Wow. 23:39 And that was cured by volcanoes poking through the ice, dumping out carbon dioxide, warming up the atmosphere again. So I don't think you could – okay, if you get it to minus 50 degrees centigrade, you might get all of the ice freezing down to the bottom. Okay, minus 20 degrees centigrade. But to have a full-on ice age with three kilometres of ice over Montreal, all you need is four degrees less. 24:03 Does that kind of get you started on a pathway there, Dr Tasman, of thinking about it? Or you got another question? 24:09 Yeah, absolutely. Oh, and what was I going to say? In Bernie, not that long ago, I asked the other question, if everything on earth died, like, including the – you remember that question? 24:22 That was you. I did a gig in Bernie for Science Week. 24:25 Oh, my gosh. So you were there, Tasman? 24:28 Yeah. Amazing. Oh, well, look at you. You've gotten to ask Dr. Carl a question in real life, IRL and on the radio. 24:35 Yeah. 24:35 And also make an appointment. Go to drcarl.com and make an appointment for your school to do a free science Q&A on a Wednesday afternoon. Cost you nothing. Got that, Tasman? 24:46 Now Dr Karl, we had a question from Brittany talking about the fact that when you are exiting a bathroom, particularly a public bathroom, you usually have to pull the door, you know. You push to enter, you pull to exit, and in doing so, you're touching the door handle that everyone else touched with your clean hands. And I don't know, sometimes do you trust everyone else to have clean hands pulling that door? 25:11 Rody in Mianjum, Brisbane, you might have an answer as to why doors are this way. What's going on? 25:18 Hey, doctors. 25:20 Long time listener, first time caller. Love to meet you both. 25:22 Thank you so much, Dr. Rody. Thanks, Dr. Rody. 25:25 So I'm a firefighter, so I can speak to a few of the building code standards and the fire part that the doctor was talking about earlier. 25:32 So essentially the doors open inwards because you kind of said it before where, you know, if you imagine most toilets are off hallways and things like that, So if the door was to open outwards, it's going to create an obstruction. No different to being inside your house, you know, if the bedroom doors were to open into hallways and things like that, there would just be a mess of doors in those walking spaces and that. So that's why doors open inwards. 25:55 Second to that, as part of the building code, if it's like a hospitality or a food preparation kind of place, you know, you'll have a airlock or a small air gap where you open a first door, go in a couple of metres and there'll be a second door into the bathrooms. And that's to stop, you know, poo-poo particles and stuff making their way all the way into other parts of the structure. 26:15 Oh. 26:16 Yeah. And on the... Sorry, go ahead. 26:19 No, Rhody, so true. John actually texted in saying that it was about airflow to control odours. The air is extracted from the toilet, so doors need to support that. So kind of speaking to what you're talking about. 26:29 Yeah, definitely. And the other side of the fire safety thing is, I suppose, so final exit doors and structures have to be able to open outwards and the hardware can't be things like doorknobs. It has to be like a lever or a wide handle to assimilate if someone was to fall across that door in an emergency or they were struggling to breathe because of smoke, the door would open for them and they wouldn't get trapped inside. 26:55 Or, you know, you might have multiple people, you don't want them banking up against the door because it's a pull and not a push. 27:01 And the other part to that is with overseas, you know, doing roof ventilation, as the doctor spoke about. 27:06 In Australia, and I think you mentioned on the show before that the kind of our buildings are constructed to allow airflow and be nice and cool. 27:14 So, you know, when a fire burns through a structure, we aren't necessarily worried about the heat inside the structure because it's going to ventilate out and leave the structure quite easily because we don't have lots of insulation in our walls or very thick walls. Where in other parts of the world where it gets quite cold, The walls are very well insulated, so a fire in a room will heat that room and heat that structure for a very long time, and they have to create essentially a chimney point to let that heat out, where in Australia the windows will just go or the door will go or it'll burn through the roof by itself. 27:43 Ah, I was getting just a hint of all of that subtlety involved in firefighting when we filmed an episode for our new TV series for the ABC TV. And what struck me was how firefighting is a part, but not the major part at all, of your work and how rescue is so important and how there are so many different rescues involved. For example, getting somebody out of a car with a car squashed up around them a little bit. 28:09 Yeah, with modern technology and the public information, I suppose, most people are out of the structure, even if there is a fire these days. And because of early warning, like smoke alarms and how they're legislated now, they're detected by their inhabitants long before they kind of get to be a massive problem. 28:27 But yeah, over 95% of our job would probably be rescues, so like cars or ambulance assists and things like that. 28:35 Wow. Hey, Rhody, we got this text from Shana. She said, solve the toilet door issue. Time to bring back saloon doors. Baby swings both ways. Yee-haw! Is a saloon door fire safe? 28:52 It probably wouldn't be, but it doesn't need to be. 28:55 And I suppose it would kind of be good for crawling because then you can crawl under it in that space. 29:00 Oh, yeah. 29:02 You'll notice doors now too. You know, they'll have a little air vent at the bottom, some of them, and that's purely so you can kick it out in an emergency or crawl through it. 29:09 Bernie, you're fully our fire safety expert on the show now. I hope you realise this. 29:15 Thank you so much for calling in. First time caller, we appreciate having you on the show and giving us this insight. 29:21 No worries. Thanks so much. 29:22 Thanks, Rhody. We've got a question from Perry Lee in Eleanor Heights. Now, Perry, what's your question? 29:29 Oh, good morning, doctors. Mine's a bit of a double-barrelled one. So firstly, how and why does your body know to wake you up when you have a dead arm from pins and needles when you're asleep? And then why do the pins and needles come back if you haven't got rid of the tingling completely before trying to go back to sleep? It's scary when you wake up to that, isn't it? Yeah. 29:52 And sometimes your body doesn't wake you up and you can end up paralysed for the rest of your life. 29:56 Oh, my gosh. 29:57 So, yeah, it's called the Saturday Night Syndrome. And what happens is some people go out and they drink a lot of alcohol, so much so that their normal sleep-wake reflexes are not working. They then come home and watch a bit of TV while having another emergency pizza on top of the ones that they've already had and they fall asleep with their arm across the back of the sofa and the sofa has a hard wooden bit at the top. So the inside of their arm is resting on the wooden rail. 30:32 Unfortunately, the nerve that helps run your arm is... 30:36 is on the inside of your arm. That's to protect it from the outside world. And now it's being squashed. So it gets squashed, you get the pins and needles, and normally you would wake up from it. There is a reflex built into your brain that if you're sleeping badly, it cuts over this sleep thing and says, look, by the way, you might get yourself pins and needles or even permanent paralysis if you do it for more than six hours. That's kind of the magic number. If you deprive a body part of oxygen for more than six hours, it kind of dies-ish. 31:04 And so normally you'll just wake up, that emergency circuit kicks in and says, look, sorry, you've been, I know you're asleep, but too bad, you've got to wake up and shift your arm. But when they've had so much alcohol, they sleep past it and they wake up in the morning and their arm's paralyzed until they die. Exactly. For the rest of their life. 31:25 So it's fascinating. And actually this happened to me like obviously last night and then probably about 15 years ago I'd woken up with a dead arm but I used that arm to move itself and I actually tore my cartilage in my wrist. Oh. So I learnt that if you're going to move your dead arm, I need to use my other arm to support it when doing it. 31:50 Oh, because not only do you paralyse the muscle, you've also paralysed the nerves coming back saying, don't do this, it's too bad, you're pushing it beyond its normal range. Wow. Wow. So I seem to remember it's a radial nerve. I've forgotten so much of my anatomy, but it does run down the inside of your arm between your arm bone, the humerus, it runs from your shoulder to your elbow, and it can get squashed. And so what, you tore the cartilage in your shoulder? 32:15 No, no, in my wrist. It's only a very small one, but I am hypermobile, so maybe it has something to do with that as well. 32:22 Oh, you don't have Ehlers-Danlos Syndrome, do you? 32:25 Yes. 32:27 Ah. 32:28 How far can you pull the skin at the side of your neck when you pull it sideways? 32:33 I haven't tried that. 32:34 Because one of my friends has it and can pull the skin at their side of the neck, not just a centimetre, but all the way out to their shoulder blades. 32:42 Oh, my God. 32:43 Oh. 32:45 The one benefit is you do have lovely soft skin, I've been told. 32:48 Oh, always look on the right side. 32:52 Well, Perry Lee, thank you so much for your question. 32:54 Thank you, Dr. Perry Lee. 32:55 Thank you very much, doctors. 32:56 That was fascinating. That's happened to me before when I've been sleeping and I've got my arm propped up with my head on my arm, you know, and it just happens and then you wake up and awful feelings. 33:09 Lockie in Geelong. We've had a couple of comments and questions about sneezing. What do you want to know? 33:16 Hey, doctors. My name's Lockie. I'm a long-time listener of the podcast, but I haven't actually called up beforehand. So hello, hello. How are you guys? 33:23 Hello. So good. Thank you so much for joining us for the very first time. 33:27 My question to you guys is, are you guys able, is it possible to train yourself not to sneeze if you say you breathe in some pepper off your food at work or if you get a cold breeze brushed past your nose? Is it possible to control that physiological reaction? 33:43 Dr. Lockie, yes, but probably you don't want to. So you have this deep breath, the pressure builds up in your chest, your mouth and your throat open, and out comes this burst of air at relatively high speed. And you spray lots of stuff out, including maybe the contents of your last meal, maybe bacteria, et cetera, et cetera. Catch it in your elbow instead of your hand. 34:06 And it can be a source of infection for some people, but in general you don't want to hold that sneeze. If you do suppress the sneeze entirely and so you go and your sneezing is happening but your mouth is closed, what you're doing is driving the bacteria into your sinuses. So you have sinuses in your head and the definition of a sinus is a cavern or a cavity with one entrance. It doesn't go in and out. It just goes in and comes back the way it went out and so different bacteria from the ones that are normally there, can build up in there and you can have bad things happening. 34:40 So you can train yourself by breathing slowly through your mouth or swallowing or pressing repeatedly or pressing your tongue against the roof of your mouth. You can train yourself both to sneeze or to not sneeze, but in general you probably don't want to stop a natural sneeze from coming, although it might be embarrassing if you do it a lot. What's your circumstance? 35:00 Of course, of course. 35:01 It's usually when a bit of dust kicks up in the air and then you breathe it in through your nose and then you feel that reaction. It's like... 35:10 So is this when you're having lunch with your mates at work and you might sneeze all over them and their food or is it just you working out in the open? 35:17 That's right. Come with a chicken tikka masala all over and he sneezes. 35:22 Okay. 35:22 You know, I have done that, Dr. Carl, and I thought it was a bit of a skill where maybe I've been in a situation where I can't outwardly sneeze, so I've done the internal like into my face it feels like. 35:35 It is. 35:36 But then I've also had issues with my sinuses, so maybe that could be me asking for it. 35:40 Well, evolution made a mistake there by putting us onto our back legs because the drain point for the sinuses is not at the lowest point. 35:48 So annoying. 35:48 What a mistake. 35:49 Lockie, thanks for your question. First time caller. 35:51 Thank you, Dr. Lockie. We love you. Thank you both. 35:52 We love it. Now we've got Aileen in Brighton. Aileen, you've got a question about aromatherapy. 35:58 Yeah. Hi, doctors. I was wondering, how does aromatherapy actually work? Why are there smells that can make us calmer like lavender or focus like frankincense? 36:12 Lavender is the big one. So going back to smell, every living creature has a sense of smell down to bacteria in the sense that they can sense chemicals in the environment and go to them if they're good or they can get a feed or run away from them if they're bad. And Marcel Proust in his amazing seven volume in remembrance of things past one and a quarter million words... He describes how he smells the madeleine cake that his aunt would make for him and then suddenly he's back in that village out of Paris and suddenly the whole set of the village rises up like a stage set around him and there's a baker's shop and then the fresh food and all that sort of stuff. 36:50 So smell is very powerful and it won't cure pneumonia or neurosyphilis but it can help with other things like anxiety and relaxation and depression. 37:04 The studies are not particularly good but they show a mild effect. So if it's not too expensive, if somebody's saying, oh, yeah, you do it for $400 a session and we'll cure everything, don't go for it. But if it's just you buy this bottle and smell it and you don't have bad reactions from it, I'd definitely go for it. And we're not too sure the pathway by which it works but we do know that smell is incredibly important because it's hardwired into a sort of very – primeval level, not just the bacteria but Marcel Proust, but maybe a smell of a friend from the past or a smell of a particular food will bring back memories that are incredibly real. 37:40 So there is some sort of wiring which, having forgotten all of my neuroanatomy, I've forgotten. 37:46 Interesting. And can it be universal? So do all people find lavender comforting? Because I can imagine negative ones. So the smell of death is obviously you would stay away from that. But it's just strange, like, lavender would be... I've never met a person that didn't find it calming. 38:04 It does seem to work on a lot of people, but then ask yourself this. How come opium, which is made from plant, works on us who are made of meat? And the answer is... 38:16 We, by coincidence, make opium chemicals. We discovered this in the 1980s. So it may well be that a chemical similar to lavender is involved in some sort of neural pathway that we haven't worked out yet. 38:30 A bit like cannabis. 38:32 Well, that's the other thing. We do make our own natural cannabinoids and so that's why cannabis can be involved in certain neural pathways. 38:39 Interesting. 38:40 Great. 38:41 Thanks, Eileen. Does that help? Thank you. Yeah, thank you so much. 38:45 Hell yeah. 38:45 Thank you. 38:46 All the universal smell of chicken sold on hot chips. Yum. 38:51 I've discovered that the right number of hot chips is four. After that, they're not as good. The enjoyment per chip drops rapidly. 38:58 Speak for yourself. 38:59 Okay, ten. 39:00 Dr. Carl, thank you so much for answering our questions. We'll do this again next week. 39:03 Yeah, okay, 20. Yeah, next week, please be keen. 39:07 And that's it. Thank you so much for listening to this week's episode of Science with Dr. Carl. If you want to listen back to last week's National Science Week episode, we had two special guests join us as well. You can always listen to any of our guest episodes via the podcast feed wherever you get them. This week's episode was produced by Ella Carter and Byron Smith. I'm Lucy Smith. We'll catch you next week. 39:29 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.