The Science of Everything Podcast - Episode 50: Science Myths and Misconceptions

Episode Date: August 9, 2013

In this special episode we examine a number of popular myths, misconceptions, and faulty understandings that are widely held about various scientific questions. Topics covered include misunderstandings about black holes, common misconceptions about genetics, physics mistakes perpetrated in films, popular myths about various animals, and a look at some of the misconceptions about psychology and the mind. If you enjoyed the podcast please consider supporting the show by making a paypal donation or becoming a patreon supporter. https://www.patreon.com/jamesfodor https://www.paypal.me/ScienceofEverything

You're listening to The Science of Everything podcast, episode 50, and I'm your host, James Fodor. So, since this is episode 50, we're going to have a special topic for today. There are no recommended pre-listening episodes for this one, because this is just a general episode. We're going to be talking about common misconceptions and misunderstandings in science. I'm going to go through some of the main myths and misconceptions that I've uncovered in the fields like astronomy, physics, genetics, health and psychology and other areas. explain the truth behind these and in some cases sort of why the myth has become so widespread or what the sort of kernel of truth at the basis of the myth is. So hopefully this is something that people will find interesting and maybe there'll be a little bit of discussion generated by some of these.

Without further ado, let's jump straight into it. So I'm first going to start with the astronomy section and talk about some of the myths related to this area. A really important one, I think, is this idea of the Big Bang theory. So when most people think about the Big Bang theory, theory, they either think about the television show or they think about the scientific theory about how the universe began. The trouble with that is the Big Bang theory, that is the scientific theory, not the television show, doesn't actually say anything about the origin of the universe itself. The Big Bang theory is concerned with the early, very early evolution of the universe.

So in studying the Big Bang, scientists, natural physicists attempt to push the theory and push experiments sort of further and further back so that they can understand what happened closer and closer to the very beginning of the universe. But we still don't understand what happened at the very beginning in the very first few fractions of a second after the Big Bang itself. The model of the Big Bang that we currently have about the expansion of the universe and the creation of the asymmetry between matter and dark matter and inflation theory and these other things that I've talked a little about in previous episodes, all of that is to do with what happened to the universe after it had already come into existence. The very beginning of the universe itself is something that we

as yet have not explained in science and may not be possible to explain through science. There are theories about that, but they are outside of the Big Bang theory itself. So the Big Bang theory is about the very early evolution of the universe and not about the origin of the universe itself. It's a very important distinction to make. So moving a little bit closer to home, it's commonly claimed that the Great Wall of China is the only man-made object that's visible from the moon. Now, I mentioned this briefly in the very first episode explaining gravity of this podcast series, so I won't dwell on it too long. Basically, this is completely wrong. From a low Earth orbit, you can see the Great Wall of China if you know exactly where to look and the weather's good and other things like that. But you can see many other man-made objects as well, large buildings, for instance.

If you think about it, the Great Wall of China is very long, but it's also not very wide, a few meters. And so it doesn't make sense that you would be able to see it from a long way away. As to the idea of being able to see this from the moon, this is absurd. I mean, you think about how big the moon is from Earth. If you view the Earth from the Moon, it looks roughly the same size, and it's a little bit bigger, because the Earth's bigger than the Moon. But, I mean, you'd be hard-picked to, you'd be hard-pressed to identify continents of the Earth from the Moon, let alone trying to see something as small as the Great Wall of China. So this idea is just so absurd. I think anyone thinking about this for a few moments would immediately see that this is wrong.

Black holes. Now, black holes are an interesting phenomenon that sort of have accreted to them, sort of a bit of a pun there, a large variety of misunderstandings and misconceptions. So I think many people have this idea that black holes are sort of big cosmic vacuum cleaners that go around sucking up mass and attracting things towards them and pulling them in inexorably so that they can't escape. There's a little bit of truth to this, but it's very misleading. So a black hole is just a massive object. It's an object that has mass. generally that of several times the mass of the sun, sometimes much, much larger. And so any massive object exerts a gravitational attractive force on other nearby massive objects. This is why you fall down to the Earth if you jump out of a plane, because the gravity of the Earth is pulling you down. And this is also why the Earth orbits around the Sun, because it's pulled towards the Sun by the mutual gravitational attraction of the Earth and the Sun. If the Sun were just suddenly replaced by a black hole of equal mass, and we didn't change anything else, then all of the planets would keep orbiting in essentially the same way. So the gravitational attraction felt between the Earth and the Sun

is not in any way affected by the nature of the Sun, whether it's a black hole or a star or whatever. It's only determined by the mass of those objects, essentially. And so a black hole really doesn't attract things any more or less than any other massive object, than any other astronomical object of the same mass. Now, it is true that black holes are different in some other ways. they're highly compressed, and so the mass is contained in a very much smaller volume than, say, an ordinary star.

And it's also the case that if you enter past what's called the Schwarzschilder radius of a black hole, you won't be able to get out again. You're prevented from escaping essentially because of the massive strength of the gravitational force. I haven't really talked about black holes too much, so we won't go into details here. There's some truth to this idea, but really black holes sort of only, quote unquote, suck you in if you get really, really close to them. Outside of that, black holes act like any other ordinary, massive object in the sense that they will be an attractive force between them and you, but no more or less than the normal. So, you know, black holes would not suck spaceships in and prevent them from escaping unless you were already really, really close to it. Certain recent sci-fi movies notwithstanding.

Another misconception that comes up occasionally, although I think this one may be a little bit less common, is that the seasons, you know, summer and winter and so on, are not caused by the Earth being closer to the sun. in summer and farther away during winter. This makes intuitive sense, but it's not the case. The distance between the Earth and the sun does change slightly from season to season, but that's not the cause of the seasonality, because the effect is too small, like a fraction of a percent. In fact, the seasons are caused by the Earth's 23-degree axial tilt. So that means that as the Earth orbits the Sun, different parts of the world receive different amounts of sunlight, depending on whether they're the part that's angled towards the Sun, which is in summer, or the part that's angled away from the Sun, which experiences winter.

So it's about angles rather than about distances from the sun. Another interesting point is about spaceships when they're reentering in the atmosphere. Everyone knows that when the spaceship re-enters, it heats up and gets very hot and, you know, glows red and so on. Now, this is true, but the cause of it is different to what most people think. The heat of re-entry is not primarily caused by friction with the spaceship in the atmosphere. There is some of that, but most of it is just the compression of air in front of the spacecraft, as the spacecraft is smashing into the atmosphere very fast. If you compress air, it heats up, essentially.

Well, not essentially. It does heat up. This is just a principle of thermodynamics, essentially. If you compress air, you're doing work on the air, thereby transmitting energy into, transferring energy into the air, and thereby heating it up. So that's all the spacecraft is doing. It's heating up the air in front of it,

and then the energy radiates from the atmosphere to the craft, heating it up. One final point, which is one that's a particular annoyance of mind, when people talk about, quote, unquote, the dark side of the moon. Now, I think this phrase was popularized by an album cover of Pink Floyd or something like that, which, interestingly enough, also has a somewhat scientifically inaccurate diagram of light being refracted through a prism on the front, but we'll leave that to one side. This idea of a dark side of the moon is sort of a nice romantic or poetic concept, but there's no such thing.

As the Earth rotates about the sun and the moon orbits, about the earth, all the different sides of the moon are exposed at various times to sunlight. So there's no places on the moon, perhaps shadowy regions of deep craters, notwithstanding, that do not receive sunlight. Every part of the moon receives sunlight at various times. What does exist is a far side of the moon, that is, there is a side of the moon that we never see from the earth. That's why the moon always looks the same. Well, you know, you can see different portions of it, but we always see the same side from Earth, and from regardless of which side of the of where on the earth you live, you always see the same side of the moon.

That's because the moon is tidily locked to the earth, which means that it rotates around the earth in exactly the same amount of time as it orbits about its own axis, and therefore it always maintains the same side facing the earth. So there is a near side to the moon and a far side to the moon, but the far side to the moon still gets sunlight. I mean, just think about when the near side to the moon is facing the earth, and the moon is between the sun and the earth.

well then the far side of the moon must be illuminated by sunlight because it's the side that's facing the sun. So yeah, there's no such thing as a dark side of the moon, only a far side of the moon. But the far side of the moon is not dark, or at least not dark, all the time. So that's all the astronomy myths. Now we're going to broaden our focus a bit and talk about some myths in physics. Physics myths, I think, particularly badly perpetrated through Hollywood and other media. But there are also a number of myths that are the result of sort of our naive. perceptions of how physics works and how objects move and so on. And I won't talk about all of those here because some of them I've covered in earlier episodes about Newton's laws and so forth. But I'll just talk about a couple. And probably the most important one to emphasize is that objects do not require forces to keep moving. When objects stop, it's not come to a rest. It's not because forces have stopped acting on them. In fact, the principle of inertia states that objects will always keep moving at the same speed and in the same direction unless a net force at

upon them. So the question if an object comes to arrest is not, why did the force that was pushing it stop, but what force started pushing it that caused it to stop? Because left to its own device, objects will just keep going in the same direction forever. Generally, objects on Earth come to arrest if something isn't pushing them

because of air resistance and friction and other forces like that. But those are forces. So it's not the case that you have to have a force to keep pushing an object in order for it to continue moving. Another common myth that I'll flag here but not really talk about is the equal transit time fallacy about the air apparently takes different amounts of time to fly over the top versus bottom of a wing and then through Benoli's principle, this relates to how aircraft fly.

I've discussed this particular myth in, I believe it was episode 41, Flotation and Fluid Mechanics. I'm not completely sure about that. Anyway, I've discussed this myth in more detail in a previous episode, so check back on that if you're interested. But suffice it to say, that's not how aircraft fly, or at least the picture is a lot more complicated than that. Now here's another one that gets repeated a lot.

The Coriolis effect does not determine the direction in which water rotates down a bathtub drain or a flushing toilet. It's not the case that these things will rotate clockwise in the northern hemisphere or anti-clockwise in the southern hemisphere, or maybe it was the other way around. I forget which the myth says. But either way, it's false. The Coriolis effect is real, and it's caused by the Earth's rotation, and it is responsible for a certain weather phenomenon, like the direction of rotation of cyclones and hurricane. in the different hemispheres, but it is far too small to be detected or to be relevant to the, to affect the direction of water as it rotates in a bathtub drain or a toilet. So, so this myth is sort of true, but not on the scale it's being discussed. It's not responsible for the direction of a toilet

flush or anything like that. So, and similarly, the idea that the water just goes straight down the drain rather than swirling on the equator is also false. I mean, you can, if you set it up, right, you can get water to flow straight down, regardless of which. hemisphere you're in. And if you see demonstrations about this or apparent video proofs, it's just basically because people, because by manipulating the initial conditions in subtle ways or the shape of the bowl and so on, you can get the flushing or the draining to occur in any direction you like. So it's not because of the Coriola's force. Here's an interesting one you may not have heard before. So when we picture rain drops or teardrops, we think of that common teardrop

shape with a, you know, pointy end and the round of bottom. Rain doesn't actually look like that. It does look like, water that's dripping out of a tap does look like that, but water that's actually falling out of the sky, or that's already sort of fallen from the tap and is under the force of gravity. It doesn't look like that. The surface air, the surface tension around a droplet of water causes it, pulls it into a more or less spherical shape. As it falls through the air, the air pressure or the resistance of the air causes it causes the droplets, especially larger ones, to become distorted somewhat so that they're sort of flattened a bit. So they'll sort of look a bit like a red blood cell if you know what those look like. They're sort of like little discs that have an indentation in the middle. Rangrops don't quite look like that.

But yeah, I mean, they sort of look like flattened spheres, especially the larger ones. Spheres because of the surface tension and flattened because of the pressure of the air pushing against them as they fall. But they definitely don't look like teardrops or what we commonly think of as raindrops. Here's a myth that's widely perpetrated in movies. You see this all the time. heroes or villains or whoever else jumps through a glass window and runs off unscathed. You cannot jump through a glass window without getting at least some cuts and bruises and quite possibly without killing yourself.

Now, there are different types of glass. Traditional types of glass breaks into big shards, which fall quite quickly and can slice off body parts with relative ease because they're very heavy. If you jump through that kind of glass, well, good luck to you. You're almost certainly not going to get through that without... some serious injuries. Safety glass is different. This is the type of glass that's now used in pretty much all car windscreens and in other places as well. Safety glass is designed so that it doesn't break into big, large, sharp strands, but instead shatters into really small pieces which are

relatively soft and don't have particularly sharp edges. But even these little pieces can still cut you and generally will cause at least some superficial cuts and other injuries if you jumped through it. But the other thing is, even if you're not injured by the cutting itself, safety glass is not soft. You can't just jump through a car windshield without hurting yourself, if nothing else, just because it's hard, and you have to exert a significant force on the windshield in order to push through it. And in fact, this is a big reason why we wear seatbelts. If smashing through a car windscreen wasn't too much of a problem to the cranium or to other parts of the body, then people would not die so readily or suffer extreme injuries,

as a result of car crashes. Jumping through windows and surviving is certainly possible, but I wouldn't recommend it, and it's definitely not nearly as easy or as injury-free as it's indicated in the movies, especially if they're doing it jumping through glass, that's not safety glass, and you can tell if it's supposed to be safety glass or not by how it shatters.

If it breaks into large shards or big chunks, then that's not safety glass generally, but if it sort of shatters into very small, sort of powder-like fragments, then that's safety glass. These two are also perpetrated widely in movies. one that really, really annoys me is that cars don't explode when they crash, or even when they catch fire. Now, okay, they can explode, but it's very rare and very difficult to get it happen.

You have to have, for an explosion to occur, you have to have, obviously, a high enough temperature and enough fuel, but you have to have just the right mixture of fuel and oxygen, because otherwise you won't get an explosion, you'll just get a bit of a fire or something. This is very hard to do. In movies where cars always explode when they crash, this is just Hollywood. where there's really no reality behind that at all. Similarly, shooting the gas tank of a car or a truck won't generally cause it to explode.

Again, on a very rare case, you might, but generally that will just put a hole in the tank. A final one that physics myth that movies get wrong all the time. Laser beams are not visible unless they're being shown directly in your eye, in which case you could well be experiencing retinal damage, so look away.

So unless it's being shown right in your eye, you can't see a laser. That's the whole point of a laser. The light, and laser light is coherent, which means it only travels in one direction, and that direction is wherever the lasers being pointed. So if you're standing next to a laser or sort of side on from it, you're not going to see anything. What you might see is the point where the laser is reflecting on, so the light reflecting off a wall saying, you can see that. That's what a laser pointer does. But you don't actually see the light traveling from the laser to the wall. You don't see those beams that you always see in those movie security systems. The only way you can get around this is if you have

some sort of smoke or dust or mist or something like that that's placed along the path of the laser. And then what happens is the small dust or mist particles act as sort of diffuse surfaces which allow the light to scatter off and therefore you can see the beam. But you'll have to have some sort of continual source of these things. So if you can see the laser beam reflected in some sort of, reflected by some sort of cloud or dust, then that's realistic. But otherwise you won't be able to see the laser. Also, security systems don't generally use lasers like that. They might use LEDs or various other systems. Those security systems, they always show and move.

Is it just a fiction of Hollywood? Okay. Moving on to another source of commonly held myths in science. Genetics. Genetics is a very, very rich source of misconceptions. Not so much perpetrated by the media or Hollywood in this case, although to some extent that is true. But it's a feel that, I think, easily lends itself to misunderstanding.

So let me talk about a few common misconceptions about how genetics works. First of all, genes do not determine everything about the behavior of an organism, particularly when you're talking about humans. An enormous amount for humans is determined by epigenetic inheritance, which has to do with other factors beyond merely the genes that you have, including, for example, the environment that your mother or even grandmother lived in while you were in the womb or even before that. And also conditioning and learning from experience, culture, and other factors like that. that these are hugely important. So genes aren't deterministic and they aren't sort of all-powerful

in that, in the sense that sometimes indicated. There are some basic patterns of human behavior, like circadian rhythms, for example, probably the ability to learn language, the ability to learn to walk, are sort of hard-coded in the genes, but many other aspects are not. And so developing on from that is another idea. This idea that there is a gene for something, a gene for whatever. I'll give some examples in a moment, but this idea is just completely wrong. There's no such thing as a gene for anything. Genes code for strands of RNA, which then may be translated into a protein, or the RNA itself may serve some regulatory function.

So genes are just sequences of nucleic acids, which code for some other biomolecule, which then goes and does something else in the cell. In order to get from this sequence of nucleic acids to some behavior of interest, there has to be a very long causal chain of interactions between the cellular environment and the epigenetic, the epigenetic factors affecting gene expression and the various proteins as they act in the metabolic pathways and the different systems of the body and hormones. And there's so much complexity involved there that there's just no instance of any behavior or trait really of interest that is determined by a single gene.

There are some medical conditions which are determined by a single gene, but very few traits. There are a few simple traits. Hitchhiker's thumb, tongue rolling and eye color are three common ones. ones that are reported, though even here I've read reports that there may be other factors involved as well. But to give a list of sort of complicated traits or behaviors that people might think are genetic, and indeed they are generally these things that I'm about to list are partly genetic, which means they have genetic basis or they're partly heritable, but it doesn't mean there's a single gene for them or even that there's a couple of genes for them. The picture

is immensely more complicated. So there's no such thing as a gay gene. There's no such thing as an intelligence gene or an obesity gene or a depression gene, there's no such thing as an autism gene, there's no such thing as a cancer gene, there's no religion gene, there's no race gene, and there's no violence gene. This idea is nonsense. The phrase a gene for any of these things doesn't even make sense because it's not very common. In fact, I don't know of any cases where people just have an extra gene that does something special for them. Generally, if you have extra genetic material like that, for example, an extra copy of a chromosome that results in a severe developmental disease, But for the most part, differences in behaviours or in traits are the result of different alleles of the same gene.

And an allele is just a variation on the same gene with maybe a few nucleic acid substituted or a small stretch that's been transposed or something. So it's different alleles of the same gene, which are responsible for variations in traits or behaviors in humans and other animals. Most traits or behaviors of interest are determined by the variation of many different alleles and the interaction with one another. A very small number are called Mendelian traits, which are determined solely by the inheritance of a single allele. So this was the Hitchhiker's thumb, tongue-rolling eye-colour examples that I gave before. Although even there, it's actually not clear that those are true examples of mandelium traits. But as you can see, none of those things are particularly interesting. The things that we're interested in about, you know, intelligence or predispositions to autism or depression or other things like that are all multigenetic complex interactions.

And none of them are going to be determined by a single gene. And as I've just said, the concept of a single gene determining this just doesn't even make sense. It would be, at the very least, an allele of some particular gene that, say, those who possess this particular allele have a greater risk of something. But, yeah, it's just not, you don't have a gene for this. It doesn't make sense. And a related idea as well is the role in, is a misconception about the role in which genes play. genes do not provide a blueprint for building a person or building an animal in the same way that an architectural blueprint provides a clear set of designs for a building or a machine. The genetic code only provides code for, as I said before, nucleic acids, that is RNA, and these generally code for proteins or for various regulatory functions. There's a very long stage of interactions from metabolic pathways, subcellular structures, cells, tissues and organs up to behavior and other complex factors like that.

that we have to go through before we get from these blueprints to the actual finished product, the actual organism itself. And, you know, there are many other complexities. Like, there, on average, each gene codes for about five different proteins, which is done through transposons and introns and exons and other factors like that. And also there's complexities about gene regulation, metabolic pathways interacting. It just isn't the case that there's a simple plan of everything that's stored in the genes, and then that's translated into the structure of the organism itself.

In fact, if you could somehow just magically change all of your DNA, all of someone's DNA, immediately in one go, probably, now this has never been done, so, I mean, we don't know exactly what would happen, but probably immediately nothing would happen. Why is that? Because it takes a while for the DNA to actually be translated into proteins and RNA and other things that are actually going to affect the physiology and behavior of the organism. So if you just suddenly change the DNA, probably that wouldn't do anything. I don't know how long it would take for something to happen, but I would suspect, depending on how much of a change there's been, it would take at the very least minutes, probably more like hours or days or much, much longer, for something of interest to happen.

Well, assuming you didn't just die, because your heart stopped working or something like that. But the point is, it's not a simple case of your genes contain all of the info needed to build you, and if you change that, then you would just immediately be a different person. It doesn't work like that. It's way more complicated and indirect. Okay, moving on from genetics to talk about some myths about animals. I'll go through these a bit more quickly because in many of these cases it doesn't require so much explanation as to why it's wrong. It's just a case of this is factually incorrect. So let's whip through these.

Bulls are not enraged by the color red, as is commonly used by professional Toreros in bullfighting. Cattle are dichromats, which means that they can't really see red, or at least it doesn't stand out as a bright color to them. It's not the colour of the cape at all that balder's ball. It's the perceived threat by the motion and the other aspects of the performance. As far as I can tell, red is simply used because it's a tradition. There are some people who say that it's used because it disguises the colour of the blood. I don't know if this is true or not, but it's been used for so long that probably no one really knows why it's used. It just is.

But there's nothing particularly about the colour red that causes bulls get upset. Lemmings, these guys get a really poor, hard time. Lemmings do not engage in mass ritual suicide dives. cliffs while they're migrating. I have no idea how a behavior like that would ever be evolutionarily selected for, but even if it somehow could, it hasn't been, because they don't do that. This misconception was popularized. We know exactly pretty much where it came from. A Disney film, The White Wilderness, showed a lot of scenes about Lemmings migrating, and basically they constructed this scene of the lemmings diving off cliffs specifically for the movie. I think

the myth had been around a bit before that as well, but this movie really popularized it and sort of embedded it in the public consciousness that lemmings jump off, dive off cliffs to their deaths like this. They just don't do that. Bats, bats are not blind. The expression blind as a bat is just meaningless because they're not blind. If you've ever seen a bat or a picture of one, they have eyes, and the eyes just aren't for decoration. They work, they can see. Now, it's true. The vision of most bats is not particularly well developed, so they can't see very well, but they can see somewhat. Most bats do use echolocation as their primary sense, but they still do use their eyes for some things.

And, you know, some species are bat more than others. Ostriches do not hide their heads in the sand to hide from enemies. Apparently, this misconception was originated by Pliny the Elder, about 2,000 years ago, who was an ancient Roman scholar, who essentially wrote that, well, that's what they did. They don't. Yeah, that's about all that, they don't do that. Now, I've heard, I couldn't find a good reference on this, that ostrichers will bring

their head nearer to the ground on some circumstances, but they don't bury their head under the sand. Again, how that would be selected for, I'm not quite sure, because that wouldn't really help you to hide from the predator. It would just sort of mean that you couldn't see where the predator was, but anyway, goldfish are another type of animal that's got the hard end of the stick. Goldfish are not stupid. Well, I mean, they are stupid because they're just invertebrates, but they do not have a memory span of just a few seconds. This is just a myth. Memory span of goldfish extends at least up to several months. Goldfish have been taught to do things

like navigate mazes and perform tricks and recognize different signals according to color. You can do this by positive reinforcement just the same as you can train any other animal. So, yeah, goldfish can remember things. They're certainly not the brightest animals around, but they're not that stupid. Chameleons. Camelians

don't usually change color as a form of camouflage. Now, it's true that camelians, well, at least some types of chameleons can change their color, the color of their skin, but they mostly use this to help regulate temperature and also as a form of communication between different animals. Now, there are some species like Smith's dwarf chameleon, which do change color as a form of camouflage, but in general, chameleons don't use it for this purpose. And also, you know, there's a tendency

to exaggerate the degree to which chameleons can change their color to match their environment or just in general to how much the color can change. It's pretty impressive, but, you know, you'd still be able to see them if you knew where to look. It's not like they can turn invisible. Now, in 1992, a certain individual by the name of I. William Lane published a book called Sharks Don't Get Cancer, which, as you might expect, led to the popular belief that sharks don't get cancer. The thing is, sharks do get cancer. End of story. Another common myth is that the bumblebee can't fly, or more to the point, the bumblebee obviously does fly, but science can't understand why it does fly. I remember at the start of the Disney or the Pixar movie, I think it was a Pixar movie, what was that one about bees? Oh, I've forgotten already.

Anyway, it said that, it stated this myth at the start of the movie, but it's just not true. There was a French entomologist Antoine Magnen, I don't really know how to pronounce that name, who indeed published a book explaining why, that theoretically bumblebee shouldn't be able to fly, but he used flawed techniques, and as far as I understand, he sort of retracted his comments later on, but definitely modern science has a lot to say about exactly how bumblebees and other insects can fly. Now, it does seem to be the case that bumblebees don't fly in the same way as aeroplanes fly. They use different aerodynamics, essentially, well, not different aerodynamics, but the setup is different. Principles are slightly different.

And it was by making incorrect assumptions and using flawed techniques that this French entomologist asserted that they shouldn't be able to fly. They do fly, obviously, and science can explain more or less how exactly how they fly. It would be somewhat accurate, as far as I could determine, to say, that bumblebees don't fly like aeroplanes. They fly differently, but that's also not very interesting. So, yeah, that myth is false. Another interesting one, most dangerous animals that people think about, like snakes, piranhas, and tigers and other things like that, are actually not very dangerous at all, at least for most people. Now, particularly here when I want to focus on is spiders. Spiders are probably the most overhyped animal ever.

As far as I can determine, there's probably less than one death by spider bites in the whole world every year. Like the number of documented deaths caused by spider bites is in the dozens, as far as I can determine, in the 20th century. And they're especially uncommon nowadays because we have anti-venom treatments for most of the particularly deadly spiders. In fact, there's really only a handful of different types of spiders that even have venom that are dangerous to humans, so that even could cause death. A couple of these, the main ones are the Sydney Funnelweb Spider found in Australia, Black Widow Spider, which I believe is North American, and the Brazilian wandering spider, I guess where that's found. These are pretty nasty spiders, which have been documented to cause deaths,

but mostly not terribly recently, and not very common either. Most other spiders aren't really dangerous to humans at all, or, you know, they might bite you and cause a bit of a scar or irritation that'll last for a while, but, you know, they're not going to kill you or cause severe incapacitation. Also, many of these deaths are really the result of allergic reaction, reactions to the venom rather than the venom itself, which obviously doesn't console the people who died all their families. But the point is it's sort of a different mechanism. I mean, people die as a result of allergic reaction to peanuts and other things like that. That doesn't mean we think of peanuts as deadly. So spiders are just really, really overhyped. They're really not very dangerous at all.

In fact, I read somewhere, I think tongue and cheek, but I wouldn't be surprised if it was actually true. You're more likely to get attacked by a shark, survive, and then die by having a coconut fall on your head. than die by being bitten by a spider. I don't know whether that's exactly true, but it sounds about right. Human health. Now, this among the fields is probably the most rife with pseudoscience and misconceptions and misunderstandings. There's no way I could talk about them all in the short space we have available, but there's just a few that I thought were interesting and wanted to mention here. Now, everyone's been told, don't go out during the winter or late at night without a sweater or scarf

or something like that because you'll catch cold. The cold weather does not give you a cold. The common cold is caused by viruses, not by the temperature. It is true that some viruses, particularly the ones that cause the cold, are seasonal, which means it's more likely that one gets them during the winter. It's not exactly understood why that is. Partly it's thought that people tend to spend more time indoors crowded together during winter because it's cold, and therefore there's greater opportunity for the virus to spread.

I don't know if that's been conclusively proven, but it seems plausible. There are also some indications that colder temperatures may increase one's susceptibility to infection by viruses, for instance, by weakening the immune response in some ways, but that really hasn't been conclusively demonstrated either. Also, I don't really think that's what people have in mind when they say that you'll catch cold when you go out without a scup. They're not thinking, oh, there'll be a slight reduction in your sensitivity to the immune response when you... immune system comes in contact with the virus, and therefore you're slightly more likely to become infected and exhibit symptoms. No, I don't really know what they're thinking. I don't really think they've thought through it very much, but the idea of catching a cold in cold weather is really just the myth.

Here's one that many, many people believe sugar does not cause hyperactivity in children. They've done double-blind studies of this. There just is no difference between children given sugar or sugar-free snacks, for instance. Even in kids that have attention deficit and or hyperactivity disorders, there's no change in sensitivity to sugar. I suppose this myth sort of sounds plausible because it's like, while sugar's providing energy, which then gets them hyped up and active and whatever, but the body just doesn't work like that.

It's not going to be the fact that you have extra sugar available, therefore, that influences your behaviour. I mean, I suppose it's plausible, but it doesn't happen. And I suppose such a simplistic view as it was unlikely to which you win the first place anyway. So hyperactivity is not caused by sugar. There's another common piece of sort of conventional wisdom or health advice that you should drink six or eight glasses of water per day. I mean, you hear slightly different numbers. This is also not true. The amount of water you need varies quite a lot between persons, depending on their gender,

their activity level, clothing, environment, the heat, the humidity. So giving a single number is just meaningless. Also, we get a fair bit of water through the food that we eat, so it's not the case that you have to drink any water, really. I mean, if you get enough liquid through your foods, it's quite possibly you don't have to drink anything. In general, most people will have to drink some water a day, and generally it is the case that one should drink more water rather than,

than less in order to stay hydrated because it's easy to get dehydrated without realizing it. But it's not the case that you have to drink a certain amount per day. And the eight glasses thing is really more than most people would need. Really, you can tell whether you're drinking enough water by how easy or difficult it is to urinate. There may be exceptions to that with people with particular medical conditions, but you should be able to tell if you're drinking enough. Hair and fingernails do not continue to grow after a person dies. Again, this doesn't really make sense.

If the person's dead, there's no metabolic activity occurring. There's no source of energy. There's no way growth could continue for any period of time. The reason that this myth exists is because the skin dries up and shrinks and pulls away from the base of hairs and nails. So it looks like that they've grown. In fact, they have not grown at all. It's the skin that shrunk around them. This is an interesting one.

Now, here's a health myth which has been propagated by Hollywood a little bit. I'm reminded of the original film with Arnold Schwarzenegger from 1990 Total Recall. Get your ass to loss. which I believe features something similar to this. And this is the idea that if a human being was exposed to vacuum, especially all of a sudden, the body would explode. And this just isn't true. Another idea related to this is that the blood would boil or something like that.

Again, false. Now, there has been a fair bit of study of this, what's called explosive decompression or human exposure to vacuum. It does lead to a loss of consciousness within a few seconds, a minute at most. It can also lead to swelling of the skin, because it is true that if you remove the pressure from someone's body, then that will cause the internal gases and liquids in the body, or particularly the gases, to expand, you know, by causing swelling and potentially some other problems. Any exposed liquid on the surface, like in the mouth or on the surface of the skin, would evaporate, again, because you've removed the pressure from it. But internal fluid would be maintained at a similar pressure, and certainly wouldn't boil by the elastic pressure of, for example, the arteries and the skin and other parts of the body.

Humans can resist one atmosphere pressure. We know they can because it's doing that right now. So merely going from one atmosphere pressure down to zero, a vacuum, would not cause significant problems for the body or for maintaining bodily integrity. One big problem that can happen is if you hold your breath, you can have lung rupture, which is essentially due to a large pressure differential, one atmosphere, building up across the lungs,

and also the fragile nature of the pulmonary tissue, which essentially can be easily destroyed by such a pressure differential. So if you are ever in the situation where you're going to be exposed to vacuum, don't try and hold your breath. Another possible complication is embolism, which is the formation of air bubbles in the blood, which can cause problems. But really, in pretty much all cases,

the biggest single problem for humans exposed to a vacuum is hypoxia, just lack of oxygen, which will cause death within minutes if you don't get oxygen through some method. So it's not the same. swelling or the embolisms or even the lung rupture that's going to kill you. It's almost certainly the hypoxia. But you won't explode. Your blood won't boil. That's a myth. Interestingly, though, there is at least one documented case that I've discovered of pressure differentials, a sort of explosive decompression causing a human being to literally explode as a result of the

pressure difference. This was not going from one atmosphere down to no atmospheres. This was going from nine atmospheres of pressure down to one atmosphere. So there was a significant a very much greater pressure gradient there. If anyone's interested in more details about that, you can send me an email because it's quite graphic. Now, one final health myth. And this is about radiation. There's a lot of misconceptions about radiation.

Radiation is not a man-made phenomenon. It can be man-made, but for the most part it's natural, occurring from rocks or from space, the sun, many, many sources. Also, most radiation, including most man-made radiation, is not harmful. in very small doses, it doesn't really have any effect at all. There's no particular amount of radiation that will kill you. It's more of a gradient thing that the larger the dose you receive in a smaller period of time, then the greater your chances will be for developing acute radiation poisoning

and also for longer term concern, the higher your risk will be developing cancers later in life. But there's no clear cut-off point. So sometimes in movies I've seen, you know, there's been a timer where there's a certain period of time after which the radiation will become radiation, levels will rise too high and they'll or die. That just doesn't make any sense. Radiation doesn't work like that. Any amount of radiation will cause some risk. It's just very small dose of radiation caused such a negligible risk that we don't worry about them. And the larger the dose of radiation in a given period of time, then the higher and the greater the risk will be. There's no particular

real cut-off level. Another related misconception is this is that a large fraction of the radiation that we're exposed to or that you can be exposed to is a result of either nuclear power plants or nuclear weapons testing. It is true that we can detect the radiation that is released from these sources, and it does add to the total, but the amount that adds is very, very small. We get more radiation from the radioactive products burnt in coal power than we do from nuclear power. Also, if you take international flights, any flights really in an airplane, being higher up in the atmosphere, increases the dose of radiation that you receive as a result of having less atmosphere over your head protecting you, by a much larger amount than will occur

simply, than has been increased as a result of nuclear testing or nuclear power plants or something like that. So they do add to the radiation dosage that we receive, but it's very, very small compared to other factors. So if you're really worried about radiation, don't go on airplanes, basically, is the best advice. You're much better off living next to a nuclear power plant and never flying than flying frequently and living nowhere near a nuclear power plant. And finally, let's finish off with a few myths about psychology and the brain. So one that is particularly of interest to me is the misunderstanding about schizophrenia. Schizophrenia is not the same thing as dissociative identity disorder, also called multiple

personality disorder or having split personalities. Schizophrenia is a mental disorder characterized by a breakdown in proper thought processes, so common symptoms include hallucinations, paranoid delusions or strange delusions, and disorganized act and speaking and thinking. And it's often accompanied by a large degree of emotional and social dysfunction. So that's schizophrenia. And the word does come from the Greek roots, basically, to have a split mind. But that's not really, that that's sort of an out-of-date concept about schizophrenia. There's no real split-mind element to it in any sense that we would understand. The disorder associated with people who display multiple personalities at, say, different times, or in response of different stimuli,

sort of multiple personalities in one body, so to speak. That, as I said, is referred to as multiple personality disorder or dissociative identity disorder. It's a completely different thing. It's not exactly clear how the two became to be conflated. Probably it's relating to the, again, the etymology of schizophrenia is referring to split mind, literally translated from the Greek, but it is very important to understand that they are not the same thing, completely different. Another myth that comes up quite a lot about psychology, also relating to more neuroscience,

matters here is that is the difference between sort of left brain and right brain thinking, or even you hear left brain and right brain types of people or modes of thought or whatever. This idea that mental activities or abilities or functions are clearly or very strongly dissociated between the two different cerebral hemispheres of the brain is just not borne out by the evidence. Now, it is true that some mental functions, for example speech and language, are associated more with particular regions or particular hemispheres of the brain, that is halfs of the brain, than the other half. So, Broca's area and Vonneghi's area are both associated with language and speech production,

for instance, and there are others. So there is some degree of lateralization of function between the hemispheres. However, it's not at all clear the extent to which this is the case. So it's certainly not the case that, say, during language production, only the left side of the brain is active and the right side of the brain isn't doing anything. It just isn't true at all. And you have to be particularly careful if you're looking at MRI images or other brain scans of this sort, because the way that the scans are, the images are constructed, is that they will only display differences in activation between, say, a baseline

condition and then an intervention condition. So if only the left-hand side of the brain is lit up, or the right side of the brain is lit up, that doesn't mean that the other hemisphere of the brain wasn't doing anything. It just means the activity levels were the same between the baseline condition and the intervention or the test condition. And of course, you know, there's always levels of noise and detection thresholds associated with that. So we don't really know the extent to which mental functions are specifically localized to different hemispheres, but it just isn't the case that there are left-brain people and right-brain people. There's no evidence for that at all. In fact, if one hemisphere is damaged at an early age, the functions can be recovered in part or

even fully by the other hemisphere. There are even cases of people who have been born with only one hemisphere of the brain and it's still function effectively normally. And there are other functions like motor control and memory, for instance, that are equally well served by both hemispheres of the brain where there doesn't seem to be any particular lateralization there. So, again, left brain and right brain thinking or types of people is just not supported by the evidence. And we come to another misunderstanding about how the brains work, and this is to do with memory. Human memory does not work like a computer hard drive. It's not like taking a photograph and then storing it as a JPEG on your hard drive disk. Human memories, again, it's not fully understood how they are formed

and processed and stored in the brain, but we do know that they are distributed across different parts of the brain and that different sort of parts of the memory are stored in different regions, and that there's a great deal of reprocessing or reconstruction that occurs when memories are recalled. And so every time you remember something, you're actually sort of regenerating that thought in your head by various associations and neural networks and so on. And this is why memory tends to be fairly unreliable and subject to bias and so on, which is something that we talked about in a previous episode as well. Likening memory to sort of taking a photograph and storing that on the hard drive is just very

inaccurate. Human memory works quite differently to computer memory in that sense. Another myth that you sometimes hear people raise, although there has been a fair bit of pushback against this and so there's quite a lot of material debunking this already, but I'll just mention it briefly. It is not true. that people only use 10% of their brains. It is true that only a small minority of neurons in the brain are going to be firing action potentials at any given moment in time. But that doesn't mean we only use 10% of our brains.

It just means only some neurons are firing at a particular instance. Brain scans clearly indicate that all sections of, all portions of the brain are active at some point in time in various tasks, and usually most areas of the brain, regardless of what you're doing, are active to some degree. That's what I was saying just before about having to look at the difference in activation levels between a baseline condition and an experimental intervention condition, rather than just absolute levels of activation, because otherwise all of the brain is, you just, everything lights up and all that the brain looks like it's active all of the time, and so that's not very useful.

Another reason why we can clearly tell this claim is false is because the brain uses a great deal of energy. It only takes up, I think, about 2% of the body's mass, or it might have been volume, I forget which, but it uses about 20 or 25% of the body's total energy requirements. Now, something that is so energy intensive would not have evolved, where, were it not serving a very important function. And so if 90% of the brain was non-functional, it simply wouldn't be there. In fact, one of the reasons human childbirth is so difficult is because it's necessary to have, for a baby's heads to be large enough to fit the brain in,

but it's also necessary for a woman's pelvis to be structured such that she can still walk upright. And so there's that tension there between getting the baby out and having the mother still being able to walk. If 90% of the brain was non-functional, then we wouldn't need such big heads, and childbirth would be much, much easier, and we wouldn't have such higher rates, at least historically, of infant and maternal mortality in childbirth. So this idea that we only use 10% of our brains is just nonsense. And a final myth about psychology,

and this is one that I still find crop up quite a lot, and I think it's perpetrated by the media and crime shows in particular. There simply is no such thing as a lie detector. Now, the device that most people think about when they hear the phrase lie detector, and what's generally shown on television shows movies and so on, is called a polygraph. And, you know, polyg just means many. And so a polygraph is just a device that measures a number of different physiological indices, including blood

pressure, pulse, respiration, skin conductivity, and so on. And these are measured over time while the subject is asked a number of questions and answers the questions. The idea of the device is that deceptive answers will produce different physiological responses to non-deceptive answers, and therefore one can distinguish which answers were true and which were false. This is a little little bit like the brain scan technique and that the idea is to just look at the difference between, you know, the true and the false answers rather than sort of absolute levels, because people have different, obviously, pulses and respiration rates and so forth. So that's what a polygraph device literally does. Literally all it does is measure physiological arousal, or it's also

been said, it measures nervousness to some extent, because obviously when you get nervous, you sweat, so your skin conductivity goes up and your pulse increases and so forth. So it measures arousal or nervousness. It doesn't measure lying. To go from arousal, arousal to inferring that the person is lying requires an extra step, essentially an assumption or an inference. And in order to validate that, we need to have some evidence that there is actually some clear relationship between arousal and truth-telling. And there's been quite a lot of study of this, particularly from American law enforcement agencies that have been quite interested in this technology. So from the reading I have done, which is by no means exhaustive, from the reading I've done, it seems to be the case that you can detect, that a properly trained person using a polygraph device can detect when people are lying at greater

than chance levels. When they're searching for a particular thing, a particular statement that they can easily check either way, whether they know the person is lying or not. So you can do that at greater than chance levels, it seems, but not particularly good levels. So you certainly can't just easily say the person is lying or not. You can get greater than chance levels of prediction. However, that's only sort of in laboratory studies in simplified situations.

the real world, there's such a degree of inaccuracy associated with this, particularly in that you have observer bias with the experimenter manipulating the results. It's also relatively easy to fool polygraph tests if the subject knows how to do so. One common technique is simply just to try and say really relaxed and friendly with the interrogator, and that helps you to not become aroused in the same way, and it helps the interrogator to interpret the the polygraph result in a more positive way, and you're much more likely to pass. Another thing is that the false positive rate is so great that it effectively renders the test meaningless, because if you're trying to detect to find criminals or spies or whatever,

the baseline rate of the number of these people is relatively small compared to the number of people you might be interviewing, and so the rate at which you detect false positives, that is you falsely detect people or lying, is just going to be much greater so than the actual true number of spies or criminals in the set, so that effectively your data is meaningless. It's just you can't distinguish it from noise. And again, of course, polygraphs detect nervousness or detect arousal, which can be interpreted in different ways.

If someone's nervous, it could be because they're lying, or it could simply be because they are nervous about taking a lie detector test, which is not at all unreasonable. So, yeah, in naive subjects who don't know how to fool the device in sort of carefully controlled laboratory settings, you can get better than chance results using a polygraph test, it seems, but in the real world, it's not generally accepted anywhere, it's not considered to be reliable, it's not, and at any rate, it certainly does not measure lies, it measures physiological arousal, which is very weakly linked to truth-telling.

So there certainly is no such thing as a clear lie detector, and really no one should use that term. Call it a polygraph machine, if that's what you want to talk about, otherwise just, you know, don't talk about lie detection, because it's not possible. Okay, one very last myth that I want to talk about before we finish for today, and it doesn't really fit into any of the categories that I've discussed. It's sort of a meta-question about science, or a meta-myth, I suppose you could say. And in my opinion, it's probably the most dangerous,

or the most problematic of all the myths that I've talked about, or misconceptions that I've talked about so far. And the misconception is this, that science is not a serious, of complicated experiments or calculations or something else, that only a small number of really clever people can do and understand. I find that in movies in particular and other places in the media, sort of in common conception, science is perceived as being the realm of only intelligent people, only real geniuses can do it, and also it's something that sort of comes easy for them. It's like really smart people can do all this amazing science stuff, and it just comes really quickly,

and they can solve problems, you know, before the 30-minute episode is over or whatever, and produce amazing technologies really quickly, because it's just they're really, really clever and they can work out all these things, but most ordinary people couldn't understand that. This is, I think, a common perception of scientists and science in general, and technology that's portrayed in movies and so on. Maybe not consciously, but unconsciously, it very much comes across that way. This is not how science works and is not how science is. It's an inaccurate presentation of the nature of science. Science is simply the rigorous and careful application of the tools and rules of reason, evidence, and logic to understand how things work.

I mean, there's more specifics to it, but essentially that's the basis of science. So most scientific discoveries are not made by really clever people sort of overnight or very quickly, and technologies likewise, technologies and scientific discoveries take a very, very long time to become established or to become effective, requiring an enormous amount of patience and hard work and slow accumulation of evidence and understanding of the evidence, improving of the device or of the models or whatever it is that wants to developing. And it's not really how smart you are that determines how good you are at science. Being smart can help, obviously, but being smart helps with almost anything.

Really what determines whether you're a good scientist is how hard you're willing to work and how careful you are to follow the rules and procedures of science and to test your hypotheses and to make sure that what you're doing is actually valid. So this idea of science as being the domain of only a few really smart freaks for whom it just comes really naturally, is just wrong. Science is for everyone, if you're willing to put in the work, and if you're willing to be really careful about how you think and about how you interpret evidence and so on. And this is the true nature of science, which is very seldom captured, I think, in the media and in the common conception. I hope you enjoyed this special episode 50. I'm

very pleased that we've finally got to 50 episodes, and here's to 50 more. I certainly plan to continue making this podcast. It might be a little while before I can get another episode out, because I'm back at uni now, so I'll be busy. In a few weeks, hopefully I'll be able to get to episode 51 out. So if you enjoyed this podcast, or if you've enjoyed any of the previous episodes, please share the show with others. You can jump onto iTunes and give the podcast a favourable review. That would be much appreciated.

It helps to spread the word. You can also jump onto Facebook and type in the Science of Everything podcast and give our page a like, which again helps to spread the news about the podcast. If you want to send me an email with any feedback or suggestions for future topics or questions you might have, my email address is Fods12 at gmail.com. That's F-O-D-S-1-2 at gmail.com. Thank you for listening, and I'll talk to you next time.