Dr Karl Podcast

00:00 This is a Triple J podcast. 00:02 Hey, you're listening to Science with Dr. Carl. Sam Lane with you here this week, filling in for Lucy. And we had a grand old time talking to Dr. Carl this week. 00:11 All things water divining, facial hair, cold sores, double rainbows. And we even found the time to chat to my mom. Let's take a listen. 00:22 Dr. Carl in the building. Insert air horn sounds here. Dr. Carl, hello. Welcome back. 00:28 What a fabulous intro. Thank you. 00:30 No worries. Well, Dr. Carl, how have you been? What have you been up to this week? Any science endeavors? 00:36 I've been reading up about a thing called terminal lucidity. which is really weird. And it's related to the fact that there's a terrible condition called Alzheimer's disease, which we don't understand, and which over the last few decades we've gone down many blind pathways. And they're blind because we haven't got a treatment for it. And what we have noticed is that in roughly 15% of cases, people will suddenly become lucid. They'll switch from... 01:04 not being able to talk at all to suddenly being able to talk in the language that they spoke as a child in clear sentences and have conversations and then they die in the next few days. 01:16 And it doesn't make sense. It's like saying, well, this road's gradually getting worse. The more you drive on it, the more it rains. Hey, the road is now as flat as an aircraft landing strip and the next day it's full of potholes. It's completely unusual. So we do know that it's real. We've gradually established that it is real. and we're trying to gather data on it. In most cases, it lasts for a day or half a day, then they die a few days later. In some cases, they stay lucid for a long time. We don't know what's going on. That's really interesting. 01:46 Isn't it weird? Yeah, that's completely fascinating. And I mean, I hope we make progress. It's a terrible disease. 01:52 We had a great episode last week. We had a lot of interesting guests, like motorcyclists and such. Famous people. 01:57 Humble guys. The humble guy who was the first person in the world to do a double backflip. A double backflip. And she said, oh yeah, I'll do a bit of bike. Yeah, a bit of bike. Yeah, do a bit. A little bit. No, no, I'm the, oh my God, I love those bikey guys. They were so wild. Okay, what have we got this week? 02:10 We have an even more special guest. So yesterday, to fill you in, Dr. Carl, we were talking about how people in Perth and WA generally love to talk about how the sky is a different color over there. And on the line to report on this, my mum... 02:26 who is in room right now and frequently says this to me and we're doing her as the representative for the the people of wa hi mom hi sam how's broom broom is bright and clear and the sky is amazing so tell us about your theory uh about the sky being a different color in wa because this is a a commonly held wa opinion 02:52 Yes. So I grew up in WA, in Perth, and I moved away to London. I moved away to various different cities. 03:00 And every time you come back, one of the things you always think, and I think a lot of my friends were the same, the sky is a different colour. It's a different brightness, a different, I don't know what it is. It's just different than anywhere else in the world that I've been. 03:14 And I wonder why, Dr. Carl. 03:16 Okay, now, are you doing – sorry, I didn't catch your name. It's Susan. Susan. Susan. It's awkward calling your mother by your first name. That's true. Dr. Susan. Dr. Susan, we've got to round it. So, Dr. Susan, just before we get into it, are you doing a bit of a road trip? 03:29 I am – yes, we're up in Broome, but we've been up to the Cape Levesque and we're also going to go up on a boat in the Kimberleys. 03:36 Have you been to Derby recently? 03:40 No. Okay, go to Derby. It is the largest tide in Australia. You know how when you're at the beach and you sort of think there's a tide coming in or out and you don't really know? Yeah. In Derby, 12 metres of tide in six hours. 03:56 Wow. 03:57 Wow. So you go there and you get some coffee and lunch and you sit there, and I've done it a couple of times, and the family gets really bored after about the first half hour, but the water is coming in like fire hoses. More than the height of a tall adult every two hours. 04:11 Wow. Wow. Okay. 04:13 Now getting back to your question. So the air on this side of the equator is separated from the air on the other side of the equator by something called the intertropical convergence. 04:26 So there's different wind patterns called Hadley cells and so forth on each side of the equator, but there's a bit of a separation. So firstly, a lot of the pollution from the northern hemisphere where the majority of humans live... 04:39 Most of the land is in the Northern Hemisphere. Most of the people are in the Northern Hemisphere. So a lot of the pollution doesn't come across. Then you've got the situation that Western Australia is bigger than all of Europe put together. It is just huge with a microscopic population and it's really far from anywhere else. So what you've got is very low air pollution. Then when you're looking at where the air is coming from, it's coming in general... in Perth from the direction of Africa and you've got the whole Indian Ocean to dilute it. You have the clearest skies anywhere in the world in Australia and it's the best place in the world to count how many stars you can see at night. 05:19 The answer is about a thousand. So this was done by Ptolemy in Alexandria a couple of thousand years ago when he went out with a few of his mates and they lay out in the desert outside of Alexandria in Egypt and and there were six of them, and they each looked at one-sixth of the sky. They counted about 500 to 1,000, depending. Australia has the clearest sky because, firstly, we're away from the pollution. Secondly, we're very dry, so there's not a lot of water vapour. So on one of my trips to the Antarctic, I could see Mount Erebus 100 kilometres away, for four days as we slowly steam towards it. 05:55 So you've got the combination of very low humidity plus very low air pollution and so you're in the best place in the world to see the Milky Way at night. 06:04 It is the best place in the world. 06:06 Well, Mum, I'm sorry for ever doubting you. I mean, sorry, Dr. Susan. I'm sorry for ever doubting you. Or Dr. Mum. Or Dr. Mum. Yeah, Dr. Mum. For ever doubting you. 06:14 Dr. Mum. 06:15 Thanks so much, Dr. Mum. Enjoy the rest of your trip, Dr. Mum. 06:19 Thanks, sir. 06:20 Bye, Dr. Carl. Look, the tide is still pretty good in Broome. You've got nine metres, but Derby's just astonishing. 06:26 We've got Johnny Marie in Geelong. Dr. Johnny Marie, hello. What is your question? 06:33 Hello, doctors. So my question is, whenever I go to the toilet and do a number one, once I've finished doing that and I get up, I like to get a whole body shudder all over my body. And it kind of happens twice as I'm walking out of the bathroom as well that I get this full, like it's all over my body. I just can't help but keep shuddering. 06:56 What does that mean? We have a name and no explanation. 07:00 There are many things that we don't know. Why the full moon on the horizon is so much bigger on the horizon than a few hours later. Or why we have terminal lucidity with people heading towards death in Alzheimer's disease. So this is well known. 07:16 Post means after. Micturition is a fancy medical word for urination and shutter is shutter. And I came across this on Triple J first and then I started asking the clever people in medicine. So I went to the neurologist, beginning with the letter N for November, because I thought it was dealing with nerves. And they said, oh, we don't know about that. You've got to go and talk to the urologist who deal with urine, beginning with the letter U, who said, we don't know. You've got to talk to the neurologist, so I don't know. So the answer is that it's real and we don't know why. And you've got a variation of it. 07:49 And I think you'd call it the post bowel movement or post number two. We'll work out a fancy name for it. There's a whole bunch of... hypotheses and guesses and conjectures, like there's a change in temperature, you're losing some body heat. It could be the vagus nerve. Now, vagus is a Latin word meaning wandering and the vagus nerve is the only cranial nerve, nerve coming out of your skull that goes everywhere down to your groin and beyond a bit. And it's involved with the fact, have you heard of the chemical called dopamine? 08:24 Yes, yes, I have. 08:25 It's used in your brain but most of it's made in your gut and it gets carried there by the vagus nerve. 08:30 Yeah, okay. Yeah, okay. So the vagus nerve does all sorts of stuff that we don't know and people say that that might be involved in it and then people say weird things like, oh, it's a reset in your autonomic nervous system. Mate, we don't know. 08:44 But you're the first person I've had knowledge of having with regard to a bowel motion as opposed to urination or mitrician. 08:53 Dr. Johnny Murray, you're on the forefront of science here. 08:57 Congratulations. I mean, that's amazing. 09:00 And one last question. Is it consistent enough that you always have the same number of shutters at roughly the same period of time after leaving? 09:08 Yes, all the time. 09:09 Okay, it's real. It's looking real. 09:10 Even my friends now know that when I've gone to the toilet because they can see me shuddering as I come out. Yes. Yes. 09:18 Actually, this could be a good contender for the Ig Nobel Prize given for research that cannot or should not be done or research that makes you laugh and then learn. And so ring in any neurologists or urologists or gastroenterologists who want to win an Ig Nobel Prize and we'll put you in contact. 09:38 You can take it away from there. 09:41 I love that. 09:41 Thank you, Dr. Joni-Marie. Thank you, Dr. Joni-Marie. And we wish you the best in your scientific discovery. And finally, we've got Ollie from the Southern Highlands on the line with a very interesting quandary slash question about their job. Ollie, Dr. Ollie. 09:54 Hello, doctors. How are you this morning? Very well. Pleased to be here, Dr. Ollie. A long-term listener. Thanks for passing on all your knowledge. It's a great contribution to society. 10:04 No worries. Well, it's not me. It's Dr. Carl. 10:06 I don't know why. And it's not me. 10:07 It's just that I was lucky enough to be in Australia when they thought that education was a worthwhile investment in the future rather than a way, a short-term way of making money. 10:16 Moving right along. 10:16 Moving right along. Ollie, what's, so what do you, this is a question related to your job. What's your job and what's the question that jumps up out of that? 10:24 Well, technically I'm a carpenter, but I was doing some rural fencing out the back of my property in the Southern Highlands. 10:32 And there's huge transmission power lines running through there. And what I was setting up yesterday was a fully, so a 2.5 millimetre galvanised wire, but fully insulated, not earth, not touching anything else because it's being set up for electric fencing. And through that wire, even with my rubber sold work boots on, I was getting static charges through there that were uncomfortably zapping my arm. and what i want to know i ran a test light on it only a 12 volt test light and i could not get um you know any illumination from the light i don't have a multimeter at the moment but is there any way to harness that energy um and and utilize it at the moment i went mad scientist i put some copper wire up in the air about eight mil domestic um domestic why it's about three meters in the air but I want to be a little bit careful that I don't actually blow myself up. 11:23 Is there any way to harness that electricity that's basically in ambient air? 11:28 Yeah, and so this is with you being close to high-voltage towers, is that correct? 11:33 That's correct, yeah. 11:34 And how high is the voltage in these towers, like a couple of hundred thousand, half a million, a million? Yeah. 11:40 I haven't looked into that, but I mean, I guess they'd run from, I'm assuming, Goulburn heading north, northeast sort of thing. So they're pretty big. 11:48 Yeah, they'd be half a million or a million. I think it's normally 1,000 or 10,000 volts per ceramic insulator. And in a domestic area, you can see these sets of wires and a transformer up in the trees and you count yourself... 12:03 10 insulators and you say, okay, that's 100,000 volts. So have you seen, okay, you probably haven't, there's an episode of Veritasium that deals with how fast does electricity move in a wire and it's a great episode and it accidentally reveals that most of the energy does not travel in the copper wire but in the electric field surrounding it, electric and magnetic field in the air. Okay. 12:32 So there is energy and you can pick it up but it's not a significant amount of energy. The best way to show it is if you can find one of those ancient fluorescent tubes. Do you remember them from the past? 12:43 I've got a heap in my shed but they're all blown up. It's been on my list of things to do for eight years and I still haven't done it. I know, lightsaber like Star Wars. 12:51 So be very careful with the fluorescent tubes because some of them are coated with the barium powder on the inside and if it breaks and gets into a wound, that wound will never heal until you die. 13:07 Okay? So be careful with them. But if you can find one that's working and you go out at night, you can actually have it light up. 13:14 So yes, there is energy in the air, but it's not significant. It's kind of like getting a watch and it runs on a battery and you take the battery out and it doesn't work and then you get... 13:28 an orange and you stick a copper wire in one side of the orange, a cut orange, and an iron wire in the other side and you join them up to the battery terminals and the watch runs. So you can run something with incredibly small power but nothing useful and significant at the moment. At the moment. 13:45 Oh, that's always good to know. 13:46 Be safe out there, Dr. Ollie. Be safe, all right? I know you're trying to make a lightsaber, but be safe. Thanks so much, Dr. Ollie. As a little follow-up to Dr. Susan, Dr. Mum, someone texted in saying, Hi, Dr. Carl. I'm a professional marine master and worked extensively with commercial vessels in the tides in Broome and Derby. At the spring tides, the hat or highest astronomical tides in Derby is 11 meters, and in Broome, it's 10 meters. 14:11 Hang on. H-A-T is highest. 14:13 Highest astronomical. 14:15 Astronomical. Astronomical. Astronomical. Yeah, okay. And so what are the numbers? 11 metres in Derby. 11 metres instead of 12, yeah. And 10 in Broome. 10. 10. Man, that is – it is an amazing thing to just sit there and watch the tide come in and out. 14:27 And the beach is so long and wide. You can just like – you know, gaze down, okay, now I'm feeding it to WA propaganda. The sky is a different colour. 14:36 Only because it's so far away and the dust is red, the red outback is red because of the huge mountains of iron ore that have been blown by the wind. There were some mountains in the outback of Australia that were, have you ever been to Alice Springs? No, I have not. So you drive into Alice Springs from South Australia and there's a little mountain range maybe 100 metres high and there's a bit of a gap called, I think it's Simpson's Gap. Mate, that mountain range used to be taller than Mount Everest. Wow. And it got worn down by the wind. 15:06 That's so crazy. 15:06 And so the red dirt of the iron goes through the Australian outback and you can actually run a telegraph with just one wire instead of two and have the return current travel through the electrically conductive ground. Wow. 15:20 We have more questions to answer from the people. Are you ready? 15:24 Born ready. 15:25 All right. Dr. Seamus from the Blue Mountains. Hello. What's your question? 15:31 Hey, doctors. Hello, Seamus. 15:33 How are you, Dr. Seamus? 15:36 When I get a cold sore, I always get it in the same place. Why is that? 15:40 So there's, this is, okay, stopping, starting again. 15:46 The virus, when you got your initial case of the cold sores, went into your brain via a bunch of nerves and it's coming out from your brain, that includes your spinal cord, back to the same nerves along the same pathway-ish. 16:02 Okay, so there's a bunch of viruses that do this. They belong to the herpes family and they include all the herpes viruses as well as VZV, which is very cellular zoster virus, which is chicken pox. 16:15 And so the first time you get chicken pox a second time, it's shingles. and it can be very nasty. In most cases, it's fairly benign. It goes into your spinal cord brain, so you've got three brains in your body, or four, okay, now. You've got one on the left side of your skull, one on the right side of your skull, joined by a small bundle of nerves. called the corpus callosum and the two separate brains behave as one separate one combined brain and then there's a brain in your spinal cord which runs your body and then we found another brain in your gut which manufactures chemicals which then use in the brain we've got a kind of distributed intelligence so what part of your body was it on or was it embarrassing to ask 16:58 Dr. Seamus? Oh, we're losing Dr. Seamus. 17:02 Okay, we'll just say that it was on your face to make it easy, right? And so normally it goes into your brain somewhere in the fifth cranial nerve and the virus will stay there. And then it'll come back usually along the same pathway and usually on the same side of your face. But in my brother-in-law's case, when it came back, it also... besides going onto his body, spread through his brain and he nearly died. 17:33 And he only survived because we have Western medicine and he was in intensive care for a few days, just run like a bag of fluid, pumping liquids and air into him, and he came good. 17:43 Hooray for Western medicine. 17:45 He usually comes out in the same place, but there are people who have had it, for example, on their genitals and then it appears on their buttocks. 17:53 So that's in the same what we call nerve distribution. So think about it like a tomato bush, branching and branching and branching. And so it usually comes out in exactly the same spot, but sometimes it'll come off to the left or the right a little bit. So does that help a little bit, Seamus? 18:09 Yeah, it does. It's perfect. And I know sort of when I get a tingle from my bottom lip, I know what it is. 18:15 Okay. And do you find that the tablets work if you get in there fast enough? I've forgotten the name of the tablets. What are they? Do you take that? 18:23 I just use the topical cream and that sort of does okay, but not the best. 18:27 Yeah, but if you get in there really early, talk to your pharmacist and your GP about it. And if you get in early, we've got a box of it at home for the family. As soon as you feel a tingle, just take the tablet straight away and that'll reduce the symptoms enormously. 18:41 Awesome. I'll go invest in that. Thank you. Thanks, Dr. Shannon. 18:46 What's the old saying? Love comes and goes, but herpes is forever. Yeah. 18:51 And I've always said that. Thank you, Dr. Seamus. We've got Alex from the Barossa Valley Online. Dr. Alex, what is your question? 19:00 Good morning, doctors. How are we? 19:02 Peachy keen, Dr. Alex. 19:05 So I have a question regarding water divining. 19:10 I'm a plumber by trade and a witch doctor by reputation. 19:15 And this comes from my experience learning that I can find services underground using either two sticks, but more commonly two welding rods that I sort of come about one day on a job and I'd seen an old bloke do it. And I just figured that's how you do it until someone looked at me a bit sideways thinking that I was a bit crazy. 19:40 I think it was like 14 of the 16 services. So the science I've done on it, I've calibrated my water divining by sort of going over trenches where we already know where services are and then seeing if the sticks will turn, which they do, all the way up to like T junctions and anything like that. And some people, I've given the sticks to other people. Some people can also do it, but mine seems to be particularly strong. And I was just wondering if there's anything behind that. 20:12 How many years have you been doing it for? 20:14 On and off for like eight. 20:19 But, yeah, my first time doing it, I was maybe 17 or 18 doing landscaping. And, yeah, I just thought it was how you find, you know, water pipes and things like that in the ground. 20:33 Why do you say on and off? Why don't you use it all the time? 20:36 Well, it was only until recently that I used it and found all these services on this big dig that now I've got old people in rural towns calling me up, asking me to come and do cashies to find water on their property. And I just, I'm not sure if I can even charge for that. 20:54 Okay. Let me sort of run you through it. Now, firstly, do you have a record written of some or all of your water divining experiences? 21:07 I haven't recorded it. I've got to, you know. 21:10 Okay, right. So the lesson from the Mythbusters is the difference between science and screwing around is writing it down. I'm not saying you're screwing around, but let me exhort you because I am sympathetic to water divining in a way that you should start taking a record of all your successes and your failures. And I've spoken to some water diviners who say, oh, I've got 100% success rate. Okay, bulldust. 21:37 I can't even get a cup of coffee to my mouth 100% of the time. One in every thousand times I'll spill it, right? Nothing is 100%. So you've got to take a record. And for a long time I was sceptical of it and there were various artificial tests... where they had water running through plastic pipes under a grid where you couldn't sit under a mesh. And they'd run water through this plastic pipe and that plastic pipe. And the water diviners, when they were tested, did no better than chance. But that's a very artificial test. 22:07 And then I end up talking to a guy on a plane. We were traveling back from somewhere. It was a long journey. And he was a driller. And he was telling me about his drilling experience and he was saying, ''I keep on running across these water dividers.'' Now, I don't think he was lying to me and he hadn't written it down, but he described something that just happened the week before and somebody said, ''I will drill over there for water.'' And he said, the water divider said, well, I don't think so, but, you know, it's your money, go right ahead. 22:39 And it cost, I think, $800 or $8,000 for each drill hole. And they got nothing. And he said, look, really, what I think you should do is go four metres across. 22:50 And they went four metres across and he said, I think you'll hit something at around 30 metres and they did. And he said he'd had a series of experiences like that but he hadn't written them down. 23:01 So I think in the open air on a country property, maybe these people can read the environment without actually knowing it. 23:12 and they're picking up something and they're subconsciously coming through. It's called the ID motor effect, I-D-E-A-M-O-T-O-R effect. And you come across it most when you're in the passenger seat of a car and the driver is driving really dangerously and suddenly your foot is stabbing the brake when there's nothing there. 23:32 You didn't say, I'm going to hit the brake. It just happened your body obeyed and went down a pathway. And so that is one thing that could be happening. With regard to being able to read the ground when the ground's been disturbed, it's not like it's natural, there's been property. 23:49 I'm definitely sympathetic, but can you start taking a record of all of this as your successes and your failures and then get back to us in a year or so? 23:58 Start recording it because I think so far I've, you know, tried different sticks and I've only worked within probably two metres. So not like huge bodies of water for bores, just finding things so we don't hit them in the excavator. 24:12 But I think you're right. If I record it, because I'm a skeptic myself, I still kind of, you know, I get a lot of false readings, which could be tree roots or paths where waters traveled previously. 24:26 Well, let me tell you, have you heard of people called cold readers? Yeah. 24:31 Negative. 24:32 So I actually ran into one once as part of the Australian Skeptic Society and they sort of say things, look, Alex, look, I think something's going on with your family or your mother. Oh, your sister. Yeah, your sister. Your sister, she's pregnant. And they look at the reactions on your face. 24:50 a very small number of people, some of them end up in the security type forces, can read faces. And they don't know what they're reading, but they can see something. 25:00 And they can see it consistently. And so everything is obvious. I don't know what's going on. So keep a record and get back to us in the air and record your failures as well, please, Dr. Alex. 25:11 Understood. 25:11 Thanks, Dr. Alex. 25:12 See you in your time. You'll get a fun pack. 25:13 Thanks, Dr. Alex. And we've got Dr. Nathaniel in Victoria with a question about facial hair. Dr. Nathaniel, hello. 25:20 G'day, how are you? Pretty good, thank you. That's all right. 25:23 My question is, why does facial hair grow wiry and straw-like more than hair on the top of your head? 25:33 Well, I thought I kind of knew the answer and I'm beginning to realise I don't when I read an embargoed study where they're finally beginning to explain why some hair is curly and some hair is straight. And I thought that the answer was that the straight hair is just a straight circle in cross-section. You know, you cut it with scissors, you look at it at a microscope, it's a circle... 26:00 Whereas curly hair is a bit elliptical. Sorry, that was a burp. I've been drinking a lot of water here. And curly hair is elliptical. And so while it's strong one way along the long axis, it's weak the other way. 26:13 And the elliptical effect wasn't that strong. And then I read a paper saying it's due to the shape of the shaft... 26:24 in the hair follicle as the hair is extruded. 26:29 And if the extrusion pipe, if you call it that, is straight, the hair comes out straight and if it's curved, the hair comes out curly. So I am now in a position of saying I don't know but I definitely know that I don't know. There you are. Sorry to waste your time on that one. 26:45 Dr. Nathaniel, do you have a big beard or anything? Are you dealing with some very wiry facial hair? 26:52 It gets wiry, but I've been washing it with shampoo, conditioner and stuff like that, and it helps. 26:58 Oh, are you using the right shampoos with the volumising effect? 27:02 I use the beard-specific ones. 27:05 What? There's a beard-specific shampoo? Oh, he's good. 27:08 Dr. Nathaniel's got the full five-step beard routine. 27:11 Later on, what are the five steps? 27:13 Number one, have fun. Number two, beard shampoo, beard conditioner, beard oil, beard brush, I should guess. Dr. Nathaniel, am I on the money there? 27:21 Yep, and you forgot one thing, which is the beard balm, which is to keep it. Which is like a hair gel type of thing, but for your beard. 27:28 Well, there you go. 27:29 You learn something new every day. 27:32 Well, thank you, Dr. Nathaniel. I mean, as someone who has curly hair when it's long, I've got a buzz cut now. You can't see this, but I have very curly hair. And I have heard that it is about like the cracking in the hair. And that's why it can also get frizzy because it's dry. So any science on hair would help me because Lord knows it was a lot to maintain. 27:51 You're back here on Triple J Mornings. We are in the thick of science with Dr. Carl. If you missed it, we were talking a bit about cold sores. Dr. Seamus had cold sores appearing at the same spot on his body every time. Dr. Carl solved the mystery or got pretty close, but we didn't solve one thing, which is what is the medication you use? And don't worry, Dr. Carl, text line came through, L-Lysine for cold sores. 28:15 And is that the medically approved one or is that just a peptide? That's the tablet apparently. Okay. 28:20 We got multiple texts in. But consult your pharmacist, of course. Of course. This is text line wisdom. 28:26 We should get into some more callers. Dr. Josh in Newcastle wants to talk about rainbows, don't you, Dr. Josh? 28:33 Morning, doctors. Good morning. Yeah, the other couple of weeks ago we were driving to school slash work. There's a big storm clouds in the background and the sun, as we were driving and the sun's behind us and there's a massive clear rainbow. So brilliant. Like, you know, my daughter remarked how bright it was. And you can see the double rainbow above it as usual, you know, what, 20, 30 degrees up. 29:01 But then we could see that there was another... 29:05 rainbow kind of superimposed over the first rainbow just below where it goes to the ultraviolet. You could see there was the green, the blue, and what my daughter described as a mustard colour. 29:19 Mustard yellow, yes, yes. 29:21 Yeah. Maybe it was because of the grey behind it, but also because it's not as brilliant. So where is that other... Are these being reflected from different layers of moisture? 29:36 They're called a supernumerary rainbow and it is thought but not 100% proven that it is due to the light going into incredibly small raindrops where you can have interference, where they can cancel each other out giving you a weird bunch of colours. So do you know how a regular rainbow works? Do I need to go through that? 30:03 I saw the Veritasium explanation where it was like all these billions of little refractions coming back through. And so everyone's kind of seeing... 30:15 Every time you look at a rainbow, you're seeing all these, from those different positions along the rainbow, you're seeing a reflection spectrum. 30:23 Okay, so I'll run through quickly for the people who didn't. Imagine that the storm has gone past you. In front of you is a really black sky with lots of water droplets in it and above you and behind you is a bright blue sky and the sun is behind you and you have a shadow in front of you. 30:38 Now, from that shadow, go 42 degrees up in the sky, anywhere, left, right, straight above, whatever, and there's a water droplet there. A beam of light will come from the sun. 30:52 It will go into the front of that water droplet, and then bend a little bit, spread out into a spectrum like the incorrect physics on the front cover of The Dark Side of the Moon by Pink Floyd. The angles should be a lot steeper. It doesn't matter. It was pretty. And then the rainbow hits the back wall of the raindrop. 31:12 Some go straight out. You forget about that. Some is reflected and then comes back and hits the front wall of the raindrop, and the one that is red ends up in your eyeballs from that raindrop. All the other ones go somewhere else. 31:25 And then at 39 degrees, there's a raindrop where the same thing happens, but the purple comes and lands in your eyeball. And if you've got a mate standing one metre beside you, they're seeing a rainbow from raindrops one metre across in the sky. 31:41 So that's your first rainbow. The supernumerary is this incredibly small... Oh, sorry, with the double rainbow, you've got two reflections on the inside instead of one. 31:54 And it's a fainter because the intensity of the light, the photons are absorbed. With the supernumerary, the current thinking is incredibly small raindrops where you get interference where it's like noise cancelling headphones where the valley of one wave cancels out with the hill of another. And so you're missing some of the colours but you do get this sort of, when you say mustard yellow, that's absolutely classic of this so-called supernumerary rainbow. I do not know the full explanation because I haven't gone through it properly so I'll fail you on that one. Sorry, Dr. Josh. 32:25 That's okay. 32:26 My kids would love to see you at their primary school, by the way. 32:29 Oh, you can do that. Just go to drcarl.com and make a booking and I do two free schools appearances around Australia and the world every Wednesday afternoon, one till two and two till three and sometimes outside that for special cases. And at the rate I'm going, I've been doing it for a while. I reckon I'll get through all the schools in Australia in another 82 years. Wow. 32:53 Awesome. Just a little bit more to go. 32:55 Just a bit more to go. Just that final push, man. 32:58 Thanks, Dr. Josh. 32:59 Go to drcar.com and make a booking. 33:01 Make a booking. And we've got Dr. Lucas in the Hawkesbury who wants to talk about celestial orbits. Dr. Lucas, hello. 33:08 Good morning, doctors. How are you? Fabulous, Dr. Lucas. Hi. I've got a little astrophysics question for you. 33:15 So why is it when we look at a lot of celestial orbits, they're all loosely on the same plane? You know, when you look at moons or planets, asteroid belts, solar systems and even galaxies? 33:29 Yes. So rotation will turn a cloud into a disk. 33:39 So if you've got a cloud of something, little water droplets in the air, and you've started spinning, I don't know how, maybe air currents, it'll gradually flatten out and turn into a disk. 33:50 So we go back to these things called stellar nurseries where stars are born, roughly 7,000 in our galaxy. the density of stuff is very high. It's still better than the best vacuum we can make on Earth, but it's high compared to the normal density between the stars. Instead of having one hydrogen atom every cubic millimetre or the size of a head of a match, you might have a thousand or ten thousand or a million. 34:15 Well, as you know in life, the rich get richer and the poor get children. And in astrophysics, something that's got a bit of mass gets more gravity and gets more mass and starts sucking in the more stuff onto itself. But not all of it falls in evenly. A bit more falls on the left and the right or the other way around. And so it picks up a spin. And thanks to Einstein, that spin of the internal object gets transformed to the cloud. 34:43 the object in the middle gets heavier and heavier, the cloud starts rotating with it and gradually flattens, and when the object in the middle reaches a mass roughly 70 times the mass of Jupiter, the nuclear fires ignite. 34:57 Hydrogen plus hydrogen gives you helium plus a lot of energy. You've got a star. And it begins to blow away some of the dust. But out in that disk, already there have been individual bodies forming which have been lining up with the equator of the star. 35:13 Overwhelmingly, out of the 5,000 planets that we've discovered, the overwhelming vast majority line up with the equator. We have found a couple that... Oh, sorry, the equator of their star. But we have found a couple that are in a north-south orbit. And we think that's due to collisions in the early days of the solar system's formation. 35:35 Dr Lucas, does that help you? Yes, that's very eloquently put. 35:41 One final question from Dr. Kevin in Brisbane. Dr. Kevin, I hear you have something about near misses on the road. 35:49 Yeah, it's a bit of an odd one. When I have a near miss on the road, like people pulling out in front of me or whatever, and I've got to slow down and think really quick, it feels like all the blood rushes out of my arms into my chest sort of cavity area. 36:05 And I've always thought, why is that? But even to the extent when I've got to hit the brakes hard and like to stop having an accident, it feels like it rushes out of my legs as well. 36:16 Wow. 36:17 Gee, so what sort of truck do you drive and how many hours a day is the truck on the road? 36:23 I drive for 10 hours a day. At the moment I'm only driving an MR but it doesn't matter. I've got my MC licence. 36:29 So MR is medium rigid? 36:31 Yeah, yep. 36:32 Right. So I really do respect the drivers who can drive the big heavy ones and when you see a gap and they're slowing down the traffic and then this little bubble car just jumps in to take that gap and you hear this screech and you think the person who took that little spot, they don't know just how... 36:52 what anguish they've created and how they could have been squashed to death and all sorts of things could go bad. 36:59 Yes. Well, Kevin, yes. Tell us more about this. Yeah. This reaction. So it's like the blood runs into your chest. 37:07 You could even call it like a light pins and needles, like all the way up my arms and stops at the shoulders into the chest. 37:15 Gotcha. Okay. What we're talking about, I think, is the sympathetic nervous system. There are two nervous systems that run automatically in counterbalance to each other. The sympathetic nervous system is to deal with threats and we were taught it in medical school as dealing with fight, fright, flight and making love. and the reaction is that your heart rate increases, you make more adrenaline, you feed more blood to your muscles so you can have a big fight and you remove blood from your skin. You've got 100,000 kilometres of blood vessels in your skin and they close up so that if you get in a fight, you won't bleed much. 37:51 So literally, the blood is leaving your periphery and going to the core and somehow you're feeling it. You're such a sensitive person, Dr. Kevin. 38:01 Oh, yeah, that's what you might say as well. 38:04 Thanks so much, Dr. Kevin, and safe driving out there. I believe that's all we have time for, Dr. Carl. Thanks for this week. We really got around to it from tides to divining. We had so many. We went far and wide, Stan. Thanks to my mum for coming on. 38:20 And thank you, Dr. Mum. 38:23 Thanks so much for listening to Science with Dr. Carl this week. You can get it wherever you get your podcasts. And we're live on air at 11 Australian Eastern Standard Time each Thursday. Send your questions in with the form below and we'll try and get to you. And thanks so much to Ella Carter for producing this episode. 38:40 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.