Hypnotism, Sunscreen and Simulation Theory

This is a Triple J Podcast. Have you ever wondered if hypnotism is actually real and how it works? Dr. Carl answers that question and more on today's episode of Science with Dr. Carl. We also chat about honey and hay fever, cotton and indigestion, and... simulation theory. I'm Jamie Taylor-Nielsen filling in for Lucy Smith. Let's get into it.

Carl, it's so nice to see you again. Oh, we've got the band back together again, Dr. Jamie. The band is back together, mate. I love, love, love seeing you live on stage at Science Hour Live with Lucy Smith a few weeks ago. Do you feel... like a little bit famous now? Micro famous. I know my place in society. So something that you mentioned actually on stage and you kind of mentioned it in passing. I've been wanting to ask you about it.

I think you're answering a question about speed and light and it got me curious. You mentioned the 12 dimensions and you kind of mentioned it in passing. Yeah. And I've done a little bit of sort of… preliminary reading about it and what I can understand is that it seems to be a combination of scientific theory and also some more like spiritual ideas like that it doesn't seem to be

Am I reading the wrong sources? Can you tell us more about the 12 Dimensions? Okay, so firstly, the difference between spirituality and religion, comma, and science is that science depends only on the data. and ignores a belief that cannot be proven, whereas religion and spirituality depend only upon a belief that can't be proven. And the point is they're both real. So we have a...

Professor of Relativity at the University of Sydney who is like one of the top people on earth. He's up there, right? Yeah. He's also a minister of religion. Oh, this is fascinating. Both things are happening in the same brain and they're both perfectly valid. Yeah.

You know, like I can love yum cha but also like swimming, you know. They don't interfere with each other. So you're asking about, well, tell me more about the eight dimensions. Do we have a question on that coming up or something? Oh, no. I mean, I was just wondering. Okay, so hang on. I think there is a question. Oh, perfect. Is there?

Well, let's find out. That question was for you. Yeah. Okay, let me explain. Okay, suppose I've got a plate. Okay, you know how we live in three dimensions? Yeah. Backwards, forwards, left, right and up, down. Yeah. Now, imagine that there are creatures that live only in two dimensions, like on a sheet of paper. Okay, yeah. So...

If they want to go from one bit of the paper to the other, they have to cross all the distance in between, crawling across the surface. But imagine that they knew about the third dimension and they could activate it. They had some new technology. And what they could do is jump up and sort of vanish from the second dimension and then come back down again and suddenly reappear. That's the first step. So their friends in the second dimension in a sheet of paper would see them just vanish.

and then come back down again when they jumped up and fell down again. Are you with me so far? Yes. Okay. Now, fold the sheet of paper. You've got a sheet of paper with a cross on one corner and a cross on the diagonally opposite corner. Yeah. And the only way they can get from one to the other is by cutting the distance in between or if they could fold the sheet of paper over so the two crosses kissed each other and then jump into the third dimension and vanish from one place.

and then come back out of the third dimension into two dimensions and reappear at the other place. Okay, so this is getting into like your parallel universes and stuff. Yeah, so according to the various interpretations of the Big Bang Theory. Yeah. When it started up, they weren't just the three dimensions like we have today. They were about another eight or nine. Right. And we don't know where they are. We're fairly sure they're there mathematically, but we don't really know.

if they exist because we haven't proven it yet. And if we do, it'll mean you can travel from here to there without crossing the distance in between. Okay, well, this is good. I feel like I actually am left with more questions, but that's kind of the great thing about Science Hour, right? And all right, let's get into some questions for Science Hour with Dr. Carl. We've got Asher. Asher and Nam, what is going on?

your question for dr carl um so uh hi guys i was i was i'm sorry i was wondering why does iodine turn blue in no why does starch turn blue in iodine Okay, so starch is a whole bunch of carbohydrate molecules stuck together and the carbohydrate molecule is just five or six carbons in a ring. you know, carbon atoms in a ring, and various hydrogens and oxygens hang off at different places, and there are so many different versions. And then also, you can link them together.

And so starch is a string of amylos. That's one sort of carbohydrate. And amylopectin. And one of them is linear. in a straight line, and one of them is branched. And in starch, when you look at it, and you're sort of looking at it from an electron microscope, you see these sort of weird circular helix stair-shaped, circular stair-shaped type structures.

When you get iodine, iodine fits inside some of those cavities in the staircase-like structure and that changes how light acts on it. So light lands on that molecule. And normally what happens, it's absorbed. If it's absorbed, it turns into heat or something. And then what's not absorbed is reflected. Different bunches are reflected.

So in this case, everything except blue is absorbed and then suddenly blue is reflected because you've changed the shape of the molecule and there's a whole lot of complicated physics between the shape of the molecule and the colour that comes in and lands on your eyeball.

Wow, that's amazing. Well, science is like that. It sort of is a way to not get fooled, kind of. Thanks so much, Asha. I hope you have a great day. Thank you for joining us on Science Hour with Dr Karl. We're going to head over to Rosebud in Victoria now. Aisha, what is your question for Dr. Carl? yeah hi doctors um i'm just wondering we've got a four-year-old who has night terrors quite frequently and my question is how is it that she's awake enough to respond to us

when we talk to her, but she's not able to remember a single thing the next day. Ah. Luckily, I've been reading up on this in the last couple of weeks and there's a good article about this. It was either in the New Scientist or the Scientific American. So the first thing to realise is that there are two versions of you. There's you who's awake for 16 hours a day and then there's another you that runs the same body for eight hours at night.

and the two of you never meet or talk to each other. And when you're, okay, that's the first data point. Second data point, when you're asleep, you do most of the dreaming every one and a half hours. in what are called REM periods. So you go into a deep sleep, come out after one and a half hours, dream a bit, then go up and down, up and down, up and down. And the dream periods get longer during the night. And by the way...

if you get six hours sleep instead of eight, you only get half as much dreaming. So you're thinking, I've got three quarters of my sleep, I shouldn't be that rat shit, but in fact you've only got half your dreaming so your brain hasn't done what it's supposed to during the night. Third thing. When you also dream outside of REM, but that's a different thing. Okay, get that out of the way. Let's go back to the REM dreaming. When you are in REM dreaming...

We have shown in studies, in FRAMI with people in laboratories, that you can lay down short-term memories but not medium and long-term. So a short-term memory is, hey, Jamie, can you ring this number? 1, 2, 3, 4, 5, 6, 7, 8, 9. And you turn around and you go, 1, 2, 3. And if I ask you 10 seconds later, you go, no idea. But in that 0 to 10 seconds, that's your short-term memory.

So the reason they don't remember is that they only activated their short-term memory. Why we've only done that, we don't know. Sorry. Amazing. Thanks so much, Misha. Thank you very much. Take care. We're heading over to Simon in Mianjin, Brisbane now. Simon, what's your question for Dr. Carl?

Morning, doctors. So recently I was listening to a gentleman who is a computer scientist. He was speaking on simulation theory. So he's 99.99% sure the world, the universe we live in is a simulation. Just wondering what your thoughts on that, Dr. Carl. He's got no proof of that. He's 99% sure in the same way that he believes, but he's got no proof.

Yes, Bertrand Russell and various other philosophers way back in the past. Okay, so it goes back to Plato who says, imagine that you're locked up in a cave. And you're facing the wall of the cave. You can't look outside the cave. And all you can see are the shadows that land on the wall of the cave. And then he was saying...

In the same way, taking it to another level, perhaps all you see is shadows of a higher reality. And then we went down that pathway and there's matrix theory. And before the matrix, there was some guy called Bostock or something. And then Bertrand Russell said... Can you prove to me that you were not recreated, you were not created...

10 seconds ago with all your memories, with your memories of your friends, your family and the whole universe. Can you prove to me that the universe did not begin 10 seconds ago and I exist only because you think I do? And the thing is... You can't. So it fits into that category of interesting but fruitless. So it doesn't take us anywhere at the moment, but maybe further down the line it might. You got something else there? No, that's it.

Yeah, I like to think the world we live in is real, but yeah, I just thought I'd see your opinion on it. Yeah, he's just guessing. He's following the category of faith rather than science. It's a comforting thought that everything is real, although maybe not. Well, maybe not. Maybe not. Melissa in Regents Park, what's your question for Dr. Carl? Hi, doctors. I'm asking on behalf of my son, Archie. He's seven. Hi, Archie. Hi, Melissa. Hello.

He absolutely loves science and wants to be a scientist one day. So I was going to ask for him, how many types of scientists are there out there and how can he go about becoming one? What can he study? Um, how old is he? He's seven. Okay. Start him on fairy tales and then quickly as you can get him onto science fiction. That's how I started. So I was at the Wollongong Library and I love reading the fairy tales of the world because I would just say.

So similar and different and the librarians did what you call the proper version of education because the word education has two parts. E. meaning out, and duko, from dukare, to lead. They lead out of a person what is their natural skill. And they saw I like these fairy tales, so they ordered in for me a complete set of all fairy tales of the 200 countries in the world.

And then I thought, oh, my God, there's these similarities and differences. And then I dived into science fiction. So starting off on science fiction, is it him or her, sorry? Him. Him, yeah, okay. So start on science fiction and with...

So that's the best thing to do now because that'll expose them to everything from the biological side to the mathematical side and the physics side. Can you report back to us in a couple of months and let us know how he's going? How's his reading age, by the way? Very good. He's excelling levels above what he's in at school at the moment. Oh, with regard to reading, does he wear glasses yet?

No. Good. So I did the bad thing of reading all the time, like I would read for six hours at a time. Yeah. So every hour, get him to stop. and focus on the outside world. So what happens is that when you focus at close range, you end up via a complicated pathway that your eyeball gets bigger and you have to wear glasses because the bit that is in focus is just...

underneath the average shape of the back of the eyeball. So every hour, stop for five minutes and just do something and also read under bright light. So in Taiwan, 80% of all the high school students in the cities... have to wear glasses, but the high school students in the country do not. And so they get really bright sunlight coming in through the windows. So there's a... I need to do a story on this, but... Okay, that'll protect him. Yep. Reading can be dangerous. Look after his eyes.

Keep bringing him science fiction and maybe his specialty will reveal itself. Yeah, and also follow Arnold Schwarzenegger as well. Get a healthy body. Okay.

Thanks so much, Melissa. You're on Science Hour with Dr. Carl on Triple J. Hope and Mianjin, Brisbane. What have you got for us? Hi, doctors. I was just wondering if there was any science behind deja vu. Yes, it's part of the protective system. You see, you live in your perception 0.3 of a second behind reality. From when the beams of light land on your retina...

to when you get this full 3D colour image of the world, that's 0.3 of a second. And what if something bad happens in that tiny interval? So along the way to being... processed into this full glorious 3D colour, along the way there's a way station at one-tenth of a second that quickly processes it and looks for danger. And if it doesn't see any, it throws the image away.

So you might come up to a corner and then you see something coming around the corner and it's a blue car and you get that first image of it at a tenth of a second and then you normally throw that away. But if you don't throw it away... When you see it at three-tenths of a second, you go, I knew that blue car was going to be there. So that's one popular theory of déjà vu, that you don't throw away the... low-res emergency images, but it does not explain why some people have deja vu of smells.

And there are a few other mysteries as well. Déjà vu smells. What do you mean? Like I've smelled this before? Yeah. So we went to one of the three major perfume factories in France. I forget the name of it. Not far from Cannes. And they've got all these smells and they were talking about it. They've got what they call a smell organ. So it's like a disc, but, you know, like there's an...

organ desk were playing the big musical instrument called an organ. They called this a smell organ and it's a desk just with hundreds of tiny compartments and there's this sort of smell and that sort and they got the vocabulary to describe it and they were talking about how...

just before I smell a rose, I can actually smell it. You know, like they bring it to you and then before they bring it close enough for you to smell it, you can smell it and then you smell it. So maybe there's something else going on. We don't know. There's a lot of mystery with the human brain. Thanks so much, Hope. Thank you. Wow, thank you. Benjamin in Croydon. Benjamin, you've got a question about free will. Hey, doctors. Is free will real? Probably, but we're not 100% sure.

So you can get people to do things where at random they just predict something and before they do this thing, you can pick up that there's a spike of activity in their brain. So if you've got the time, go to Wikipedia and look up the Libet experiment. I think it's... L-I-B-E-T, done way back in the 60s and people still argue about it. And so what they had was just a clock face with a light running around it really quickly. 12, 3, 6, 9. And they say at any time in the next five minutes...

decide to lift your index finger. You know, you've got five minutes, right? And they're just sitting there and then suddenly they think, okay, I'll lift my finger and... about a third of a second before they decide to lift their finger, so they look, they think, okay, I've decided, and the light was on the three, but about a third of a second before they decide to lift their finger, there was a pulse of activity in their brain. as though somebody else is running their brain.

So it's like their brain knows they're going to do something before they consciously decide to do something? Now you're in the hard part, which is we've got the results of the experiment, comma, what the heck does it mean? Yeah. And that actually blew my mind last week because there was a survey.

in The New Scientist, where they ask quantum scientists, what exactly, what interpretation of quantum do you follow? The Copenhagen, this, that, the other. And they're massively fractionated. So you'll do an experiment. And then you think, but what does it mean?

Does it mean that there's only one electron in the entire universe and it's everywhere at the same time? And that is a possible interpretation and we don't know which is the correct interpretation. And we're still trying to build quantum computers. So we're... dealing in the dark with this massively complex thing that we don't know about and who knows what our brains will be like in a century. Yeah. Well, that's cleared that up for me.

Thanks so much, Benjamin. Yeah, we're all satisfactorily confused. Oh, it's good though. A question leading to another question. Marcel is in Fairlight. Marcel, what have you got for us on Science Hour?

Good morning, doctors. I was thinking the other day, is it possible to store odours in a compressed state? Oh, this is a good flow on from the olfactory memory and yeah. So it begins when my daughter Alice was about four years old and she jumped into bed and said, hello, Daddy, I love you very much, followed by, hey, Daddy. you smell like a bum as I tried to kiss her. I then immediately rolled over to my wife and say, is this true? And she went, yep. And then I decided to study odour.

Where does bed and breath come from? And we only discovered that in the 2000s. Really? And it turned out that there was a guy who went to a lot of trouble to work out smells. And in the vast majority of cases, bad breath is not from... stuff inside your mouth but from your tongue. Yeah. So in your mouth, bacteria die in your body every 20 minutes.

and a new bunch come through, a new bunch, they give birth to babies. But overnight, your saliva production drops like crazy. Yeah. In an average day... you'll make one and a half litres of saliva in your mouth, which you'll then swallow, and that nourishes the bacteria, but not much at night. And so different populations of bacteria grow and they smell bad. And this scientist was trying to catch these smells and he...

The smells, this is answering the question of can you store farts. Yeah. So he was trying to capture the smells in glass and he found that some of the chemicals in bad breath will actually eat into the surface of the glass. And so then he had to use special, almost nuclear grade...

passivated plastics that were more impervious on the surface than glass, which to me was a real surprise. So getting back to the question of can you store the odours, you can, providing they don't, they're fairly volatile, you don't want them to react with a container. So what you'd need would be... Okay.

What you do is you chuck them into, you have a glass jar and I'm just guessing you fill it with a carbon dioxide gas and then you get the odours and you marry them to a chemical that is stable with carbon dioxide in the background and they stay there.

and they don't kiss the glass and they're there ready when you undo it and you can have them under pressure. Then when you undo it, they come into the air and then you have the second part of your chemistry, which is they get activated when they kiss oxygen. Or nitrogen. And in that way, you can store a smell in a glass. Now, that's just me coming in from the outside, knowing nothing about it, but having worked with the...

Or having talked with the smell people at Fragonard, F-R-A-G-O-N-A-R-D in France, I'm sure they would know more about it. If there's any smell scientists, can they ring up on the magic number, which is 04 something? 397. 757555. He's writing it down. If it's not in there by now, I'm not sure. 7439, yeah. 75. 7555. 7555.

All right. Well, thank you so much, Marcel. It depends on the container. Yeah. So if you can do that, you can get fabulously wealthy. And when you do, can you please give Jamie and me a cup of tea when you're fabulously wealthy and a billionaire or a cup of coffee? I certainly would, but, you know, this was all for a Halloween installation and I think it'll be frightfully expensive. Dr Karl?

It's spring and me and, you know, I think quite a big segment of the population have been suffering a little bit with hay fever. Now, I've been told before that consuming local honey, so honey sort of... of harvested and made from pollen local to you in the suburbs around you. Consuming that honey can help with your hay fever and allergies. Is there any truth to this? There's not peer-reviewed truths.

in a sense that the studies have been done looking at it, but it could well be true. Honey is a complex material and has many things in it. Overwhelmingly it's good. It has mild anti... No, no, not antibiotic, what's the word? Antibacterial? No, no, not bactericidal, which means killing the bacteria, but bacteriostatic.

It freezes them at their growth and they don't go any further. Oh. And it's been used on wounds for a long time. If you've got hay fever, I'd definitely try it with a good local honey and I think it's pretty cheap. Although, you know that Manuka honey? I take some with me every time I go to England and I give it away to people and they say, It's $500 a bottle. Whoa. And I say, no, mate, down at a local store it's five bucks.

I can't resist doing that five bucks thing and I show them the receipt. It's a delicacy overseas. Yeah. So there could be a con going on. So don't waste your money with the honey. Yeah. Don't spend 500 bucks but just try them. Yeah. Very few side effects might work. What's not to like about that? The theory being that the local poll, it's giving you like a, you know, low dose of local pollen. The bad guys. And maybe if you're lucky, maybe even some allergic stimulating things.

which we haven't proven yet, but... It tastes nice. It's cheap. Give it a go. Can't hurt to try. Can't hurt in most cases. All right. Well, hoping for a placebo reaction at this point. I love a good placebo. All right. We're on Science Hour. And Gwen in Aberdeen, what's your question for Dr. Carl?

Hi, doctors. I was just wondering the other day, I've got a cat that travels with me between two properties. It's about a two and a half hour trip. And when our ears pop as we go over the Great Dividing Range, Does the cat's ears pop as well? Does it just happen automatically? It should. So imagine you've just got an eardrum, you've got one on each side, and when you're listening to the quietest noise you can listen to...

It moves back and forth the distance equal to the diameter of a hydrogen atom. which means there could almost certainly be some quantum effects in there. Read the book by Jim Al-Khalili, K-H-A-L-I, called Quantum Life. Now getting back to you. So on one side of the eardrum is the outside world and on the other side is a pipe leading to the back of your throat. They call it the internal artery canal of the eustachian tube.

This is not a pipe in the sense like it's open and you can run a cotton bud down. It sort of collapses with a local environment. And what you can do to force it open, which a cat cannot do, is to hold your nose. shut your mouth and then try and blow air out your nostrils. And that will force open that pipe on the inside of your eardrum and that will equalise the pressure.

Because when it's strained one way or the other, you get pain. Cats can't do a Valsalva manoeuvre, but I'm guessing, and I'm not an animal, sorry. a small animal audiology vet who could ring in on 043... I can't read my own writing here. What is it? 0439 757 555. We got a very loving text saying...

is it that Dr. Carr can remember all this information about science but not the triple J text line number? I'm getting better. Come on, give me a break. So if they could ring in. And what I'm guessing is that the angle of that internal tube, the eustachian tube, is fairly steep. In a newborn child...

They, up to about the age of five or something, they're more likely to get middle ear infections for two reasons. One, the tube, instead of draining downhill, is less steep. And secondly, and here comes a technical phrase, they have immature...

neuromuscular innovation. In other words, they can't use their muscles to open it up. So if things build up in there, they get bacteria, middle ear infections. Okay, there you go. So your cat probably does it anyway. Thank you, Gwen. Without blowing a nose. Thanks very much. Thank you, Dr. Gwen. Bye. Heading over to Remy now. Remy, you're in Sydney. What is your question for Dr Karl? Hello, doctors. My question is how does sunscreen work?

There's two major ways and this is on the background of Choice magazine in Australia testing 20 brands and found that 16 lied like a pig lying in his own filth about the grade. I mean, yes. They're promising to protect you and they were giving us very low-factor sunscreen. Yeah. And so some of them were saying 50 protection and it was only four, which raises the question of if you use that brand only for the last...

10 years and then you've got a skin cancer, can you sue them for lying to you? That's a different question. Moving right along, there's two major methods. One is a physical barrier like titanium or zinc and it looks white or whatever colour. And it just simply... They call it reflecting, but really what happens is the light is absorbed by the molecules and then reflected back. So it's absorbed and emitted. Whereas in the other type, the chemicals...

it's absorbed and then turned into heat. And they're the ones that they kind of lied about. They're the good ones in the sense that you can slather them on you and you don't look like you're in makeup.

for a mime show or something like that. Right. They're fairly invisible. But the ones that show sort of, you can see like a white cast on your skin, is that the one that is more of like a physical barrier that reflects the UV? Yeah, so that reflects the UV. And by the way, the UV at the top of the atmosphere is...

there's 10% of sunlight, and by the time it gets down to ground level, it's only 2%, and at higher altitude, there's a bit more. So they work either by reflecting or absorbing and turning into heat. Do you have a follow-up comment or question on that? No. And use sunblock all the time. It's good for you. Don't believe the people who say that causes cancer. No, not using it causes cancer. What kind of crazy world do we live in? Sunscreen every day, Remy. Thanks so much for your question.

Luna in Nanda. What's going on, Luna? Hi, doctors. So I have noticed this thing over a few years where if I scream for any more than 30 seconds, be it like yelling out to a friend, cheering at a concert... My voice starts to die and then the next day I actually don't have a voice. Why is that and is there things we can do to ensure that we're not damaging our vocal cords?

Well, first thing is you probably don't have much of a career as a heavy metal singer. Yeah, you're going to have to be able to scream for a bit longer than 30 seconds. It couldn't be me. It couldn't be me, Luna. I don't know how they do it. Right. So in the airways... you've got the air being forced up out of your lungs and it goes past the larynx. And think of the larynx as like a bicycle wheel, which has got all these spokes coming out, except there's a little gap in the spokes.

say, 30 degrees where there are no spokes and that can open from, say, 10 degrees to 50. I don't know what the number is. It doesn't open all the way but it opens and closes. And then where... you know, the opening is the spokes have got swellings, they're called the laryngeal lips, and so you can get nodules on them.

And so singers have to be very careful with their voices. So I'm guessing that you're at the soft end of the spectrum and I don't know whether you can train. I would reckon that if you went to a singing coach... That would give you the ability to yell at your friends and say, hey, come over here, or whatever it is. Yeah, so...

Yeah, I think I've run out of ideas there. Well, yeah, I mean, I guess when you're, there's like a, when you do vocal lessons and stuff, you get taught a certain technique to be able to project safely, like as opposed to screaming from the throat. Sure. So I guess maybe you just, you just scream. in a way that's strange. He hunted for a long time. So Julius Caesar was famous for being able to be heard by a thousand soldiers.

out in the open. And when Adam and I were doing our Sleek Geek shows, Adam and Spencer, he could project and didn't really need the microphone whereas I needed the microphone. So you can definitely train yourself into a better way of making. louder noises than you're already doing, but that would involve spending money with a voice coach, but then you could have a new career as a muso.

Maybe you will end up as a heavy metal singer. Yeah, Luna. Death metal. Potential vocal career out of you, Luna. Thanks so much. All right, one more for this break. We've got Candice in Column. Candice has a very interesting question about a...

New cotton dress. Hey, doctors. My question is I bought a new cotton dress and every time I wear it, I've worn it three times. I get shocking indigestion and I have no idea why. Okay, the two broad categories are it's you or category number two, it's the dress. Right? There's probably a third and fourth category which I haven't gone into. So with regard to the dress, it may have been made with various chemicals along the way that could float through the air.

and then maybe get breathed in and then cause neuro effects that can give you a bit of indigestion. or it could be a tight-fitting or loose-fitting dress or it could irritate you in some way that causes your muscles to contract. What else could the dress do that would be messy? Maybe it's too thick, maybe it's four centimetres. thick and so you're getting too hot. Or it could be that you've actually got, it's you. So going back to you, that fits into two categories. Maybe you now have...

gastric reflux for the first time in your life and food intolerance or something like that. What a win. And by coincidence that happened with a dress or maybe... When you had the dress, when you bought the dress, you were just, you're already...

getting over a bit of indigestion from too many kebabs one night and the next morning you're still feeling it and then that sort of triggered itself into your brain. So the thing is to try to work it out and this could get you online for a Triple J Fun Pack. So remember the difference between science and screwing around is writing it down. So start writing down when you put on an address what you've had the night before. So keep an eye. I would note down.

how you're feeling when you wake up in the morning, your diet, where you had enough sleep, had the dress and then write down your symptoms and do that for a couple of weeks. You have to do a fit check. Of course, is it too tight or something? And then get back to us with the data and then just see what happens.

Dr. Carl, we've got a follow-up as well. We were talking about whether local honey can help with hay fever. We have some anecdotal evidence on the text line. Justin in Nam says, had tissues up my nose for years in spring with shocking hay fever. fever, tried the local honey routine in my tea each morning, almost zero hay fever for five years. That is such a good outcome and cost hardly anything. Yep. Man.

Sometimes you're lucky. Not always, but very good. Try it. Absolutely. Sam in Fremantle also wants to follow up on the sunscreen. Does mixing sunscreens cancel? them out from each other? Like if you mix two sunscreens, do they interact in a way that makes them not work properly? I used to know a guy who was a sunscreen chemist and that'd be the go-to person, but he's no longer available. The answer is I don't.

No, but I would guess, please ring in on 0439757555, and you're a chemist in that area. I reckon they would add their effects together. I reckon, but I don't know. Also, if it was 15 plus and 15 plus. Oh, do you get 30? I don't know. Don't know. We need a chemist. Sorry. All right. We need a chemist. We need a sunscreen chemist.

Anyway, let's go on to our first question. We've got Phil and carry on. Phil, what's your question for Dr. Carl? Very good morning to you, doctors. Good morning, Dr. Phil. Good morning, Dr. Phil.

My question is, is there any way of proving that the colours that one person recognises are seen the same by another person? For example, if I'm looking at a blue car, is the person next to me seeing that colour the same? Yes and no. So... In your eyeball, you've got two of them. You've got a layer called the retina. It's 0.3 of a millimeter thick. There's about 100 million cells in there that turn light into electricity.

Most of them work at low levels in the dark, so forget about them. And there's about five million or four million or six million something that work on colours. So there's one batch that... are really tuned to blue light and you measure... the colour of light as a wavelength. In this case, it's about 440 nanometres. And there's a bit of a curve that goes up and down. And then next to it going up, there's green at I think 525 nanometres and then red at 575 nanometres.

and we can do the experiment and I actually spent two years of my life doing this, building a machine for Fred Hollows to diagnose certain diseases of the human retina with my machine. You can shine... different amounts of, say, blue light at different frequencies and you can map out this curve and you can see that it's the same in each person. So the first thing is that we all have the same three colour receptors exactly at those frequencies.

But then secondly, not quite right. If you're a male, there's maybe a 2% to 5% chance that you've got the blue, the ones that respond to blue light, and then you've got either the one that responds to red or the one that responds to green, but not both. So you're what we call red-green colorblind. And to compensate for you, at the green traffic lights, they put a little bit of blue in there so you can see the blue.

Right? So you don't confuse it with the red. And then we found a few people have got four, a woman called Elizabeth in the United Kingdom, and she's got red, an extra red, so she can see shades that we can't see. But then, even if we've got the same... receptors in the retina, they then get translated differently by your two visual cortices. You've got one at the back... of his skull on each side, about the size of a big golf ball. And my right eye sees different colours from my left eye.

in my brain, but I have tested my eyes and I know I've got the same receptors. Wow. So the receptors are the same in each eye for the red, green and blue, but how my brain decides to interpret it is different. Oh, interesting. Yeah. Phil, have you ever had an argument with somebody over whether... something's like orange or red or like pink or sometimes the subtlety of the colours.

I suppose if it's like a blend of a couple of colours, one person will say it's, you know, this or that or the other. But that's a very, very interesting answer to my question. I really appreciate that. Oh, shucks. Thank you. Thanks, Phil. Have a beautiful day. Thank you. Chloe in Grafton, what have you got for Dr. Phil? What's your question? Hey, I just wanted to ask, is hypnotism real? Oh, interesting. Yeah. So I've actually done a podcast on this.

with somebody called Dr. David Spiegel, S-P-I-E-G-E-L. Look it up on Shirtloads of Science. And he's at Stanford University. And it is real for some people. And he actually has made an app that you can use. And he's found that, for example, with people going in for surgery, we're the ones who can be hypnotized.

Either they can be hypnotized by an external person or themselves using the app and have significantly less pain afterwards. So he did a study firstly where there were these people going in and they were all a big bunch of people.

So he had a good sample size and they were going in for the same surgery. One batch just went in cold. The second batch went in seeing his guy who was nice to them. And the third batch saw his guy who was nice to them and... hypnotize them so you're comparing these three groups and if you had the guy just be nice to you there's not much difference but if the guy was nice to you and did the hypnosis then you had less pain afterwards so it does work for some people yeah

I'm not hypnotizable, but other people are. And when we were doing our Slee Geek Show with Adam Spencer, we hypnotized a medical doctor to send me a postcard every day for a month. And what happened? She did. So she'd sort of think,

It's morning tea. I might go for a walk and then she'd go to the post office and send me a postcard. Why did you do that? Oh, I thought it was a good idea. Every day she found a different excuse to explain why she went to the post office. Wild. But she sent me a postcard every day for a month and then we had to dehypnotise her at the end. Oh, my. There's some movie about somebody who gets hypnotised and then the hypnotist dies through your nose.

And there you have it. Thanks so much for listening to this week's episode of Science with Dr. Carl. We'll be back next week. In the meantime, get more science on your podcast feed. You can check us out wherever you get your podcasts, the Triple J app, and we're also on YouTube. at youtube.com slash triple J. I'm Jamie Taylor-Nielsen. This episode was produced by Jasmine Williams and Ella Carter, and we'll catch you back here next week.

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.