Answering all your science questions this week are Chris, Kat and Dave, including why some people are so prone to static electric shocks, whether humans will exceed the speed of light, how pain killers know where the pain is, and why cows get sunburnt in some places and not others... Also on the show, Bob and Chelsea provide the latest news from across the pond in Science Update, Felicia Huppert talks about the science of well-being and nature's feel-good factors, and Derek sets sail in Kitchen Science as he learns how to make matchstick boats.
In this episode
Have you ever wondered why some people eat exactly the same food as their friends but seem to put on more weight? Researchers at Washington University in Missouri, US, think they may have found the answer - it's not pies, but something a great deal smaller. The team have been studying a type of bacteria in the gut called Methanobrevibacter smithii that live in the gut. The bugs help to clear up the waste products of other gut bacteria, such as Bacteriodes theta, that break down components in food that our gut enzymes cannot digest. The team found that mice carrying both types of bacteria in their guts were on average 15% fatter than mice that just had the theta strain of bugs. The researchers think that the smithii bacteria help the theta type to thrive and grow, so they can produce more fatty acids from undigested food. These fatty acids are taken up by the mice and turned into fat. Around 85% of humans have the smithii bacteria in their guts, and we get about 10% of our calories from fatty acids made by microbes such as B. theta. However, we don't yet know if overweight people have more smithii bacteria than underweight people, but the researchers are working on finding out.
Watch Out For Black Holes!
Sometimes it's hard enough thinking about space-time in just four dimensions - x, y, z (the dimensions of space) plus time, as laid out by Einstein in his general theory of relativity. But scientists at Duke and Rutgers Universities in the US are working on a mathematical model of the universe that has five - x, y, z and time plus another spatial dimension. They call this model "braneworld", because it suggests that the visible universe is a membrane, like a "strand of filmy seaweed" floating in a larger universe. But how do we know which model is a more reliable representation of the universe? Such models make predictions about the nature of space, and in the case of braneworld theory, it predicts that our solar system should be peppered with several thousand small black holes left over from the early universe. In contrast, the general theory of relativity says that these black holes should no longer exist. Because black holes are essentially undetectable, we have to hunt for them by looking for their effects on radiation waves that go past them. Radiation from events such as gamma ray bursts http://en.wikipedia.org/wiki/Gamma_ray_burst
Matchstick Boats and Surface Tension
Derek - Hello and this evening we have come to Colchester County High School and with me is Sheena Elliott who set up the experiment we're going to be doing today. This is another easy experiment that you can do at home. Sheena, what are we going to be doing today?
Sheena - We're going to be making matchstick boats.
Derek - Ok, and we've also got to volunteers who've kindly offered to help us with this experiment. So could you please give me your names and what year you're in please?
Zoe - I'm Zoe Taylor and I'm in the upper sixth.
Yichen - I'm Yichen Gau and I'm from the Upper Sixth as well.
Derek - Well thanks for coming along. Are you guys into science? Zoe, what about you?
Zoe - Yep. I do physics and chemistry.
Derek - And yourself Yichen?
Yichen - I just do physics.
Derek - And is this something you're going to carry on doing and you're enthusiastic about?
Yichen - Definitely.
Derek - Well this is great, we've been given some wonderful volunteers here today. So I'll just begin by telling you the things you need to get at home because it's very easy. You need a tray or basin or even your kitchen sink will be fine and you need to put some water in it. You also need some matchsticks, some washing up liquid and finally a knife to cut the matchstick with. We do advise a bit of caution there. Next, Sheena's going to tell us what to do with all these things. Could you explain and perhaps direct Yichen and Zoe about how to set the experiment up here?
Sheena - Firstly what you need to do is take your matchstick and cut it along one end so it looks like a bit of a Y shape. At one end you're just splitting it down the middle so you can open the bits up into the letter Y.
Derek - Ok, is it a bit fiddly work? Is it difficult to do that?
Sheena - All I would say is keep your fingers up the other end of the matchstick when you hold it so you're not anywhere near the knife when you're doing that.
Derek - Ok then. What next?
Sheena - Next we're going to fill up our tray or basin with water. Any depth is fine; just a couple of centimetres or something.
Derek - Ok so Zoe and Yichen do that for us please? We're in the Colchester County High School lab, so go ahead. What now?
Sheena - Now we need to place our matchstick in to the bowl so it's floating horizontally.
Derek - So we're going to be floating it flat and it'll look like a Y shape from above. So Sheena's just dropped it onto the water there and it's floating around very happily.
Sheena - The next thing you need to do is to put a little drop of washing up liquid behind the matchstick. What you're going to be doing is placing it by the side of the matchstick where the Y is opening up; the top of the Y if you like. And you don't want to be touching the matchstick with the washing up detergent. You're just putting it in the water next to it.
Derek - Is it just a drop?
Sheena - Yes, just a drop is fine.
Derek - Ok so you're just dropping a drop of washing up liquid just behind the matchstick, and this means the side of the matchstick where that Y shape has been splayed out. We're not going to do this now of course. We're going to do it later in the show when we reveal to you what the result is. But Zoe and Yichen are hear dying to know what's going to happen. So I'm going to ask them what they think might happen.
Zoe - Maybe the matchstick will move?
Derek - Any idea how or in what way?
Zoe - I don't really know.
Derek - And yourself Yichen? Any idea?
Yichen - I think it will move in some sort of direction.
Derek - Ok well we will see. We also encourage you to try this at home and let us know your result. Until then we will be going back to the studio and coming back to Colchester County High School a bit later on to find out what happens and an explanation from Sheena as well. So until then it's back to the studio.
Derek - Hi there and welcome back to Colchester County High School where we do indeed have this experiment ready to go. Sheena has helped us to set up this basin with a layer of water in it and we've got a matchstick that has been cut at the ends so that there's a Y shape at the back of the matchstick. It's floating in the water and we're ready to drop in some washing up liquid. Would you care to instruct Zoe and Yichen about what to do?
Sheena - If you take your washing up liquid and drop a tiny drop just where the Y opens up into the water.
Yichen - Wow! It flew all the way to the end of the tray.
Derek - Ok Zoe, what happened do you think?
Zoe - I don't know but the matchstick moved away from the washing up liquid in the opposite direction.
Derek - yeah that was rather interesting. It kind of propelled it away down the tray. Sheena is grinning gleefully because she obviously knew what was going to happen. Can you explain this for us?
Sheena - This all comes down to surface tension, and so I'm going to explain a little bit about surface tension and what that is. If you imagine that you're a water molecule right in the centre of a tank of water, water molecules have an attractive force between them so you'd be being pulled in every direction by all the water molecules around you. Now if you imagine that you're a water molecule at the surface; you'll be being pulled in every direction from the side and from below but you're not being pulled from the top at all because you've just go air above you there. So what would be the effect on you? Well you might find that you're being squished down a bit and you end up with a more dense film of molecules on top of the water. That's basically what surface tension is. That's why you can get a needle to float on top of the water. It's because the top of the water is more dense. So what's happening with the washing up liquid when we add that? Washing up liquid is something we call a surfactant, and a surfactant is something that breaks this tension. It basically reduces this pulling force of the water molecules. So by adding washing up liquid, one side of the matchstick has the attraction between the water molecules broken, whereas on the other side of the matchstick they're still attracting each other. So what the matchstick feels is a pulling force from all the molecules one side where they're still trying to get closer to each other, but on the other side they're no longer feeling that force. So rather than being repelled by the washing up liquid, it's actually being pulled from the other side.
Derek - So this property of washing up liquid, that it's a surfactant, is this related to its ability to clean things?
Sheena - Yes. It also worked between oil and water as well as water and air. So it's exactly the same thing. It's breaking up this pulling force between materials that are the same.
Derek - So molecules on the surface are pulling in all directions when you lay that matchstick on the surface, but as soon as you add washing up liquid on one side, suddenly the pulling is not there. But there's still pulling from all the other directions and that makes it go in a straight line. Do I have it correct in my head?
Sheena - Yes, that's exactly it. One thing is that if you tried to repeat this experiment, you wouldn't be able to do it without fresh water. That's because a tiny bit of this washing up liquid will pollute your system because you no longer have that surface tension anymore.
Derek - And finally, why is it that we made that Y shape at the end of the matchstick?
Sheena - That just increases the area that you're acting on and gives it a longer bit of match to act on.
Derek - And if people tried it without doing that, what would happen?
Sheena - If your matchstick is at a slight angle, you might find that it spins a bit. It might not shoot forward quite so impressively.
Derek - But still a cool effect and we want you to try it at home if you haven't already. Zoe and Yichen did do it for us so thank you very much. Zoe, what did you think of our experiment?
Zoe - It was really good.
Derek - And Yichen, had you ever heard of surface tension before?
Yichen - Vaguely at school.
Derek - But does this make it a bit more well-explained in your head?
Yichen - Yes it does.
Derek - Great stuff. Well thanks very much for coming along and doing this for us and thanks to Colchester County High School for having us and thank you Sheena for doing the experiment for us. We'll be back next week with some more science that hopefully you can do at home. Until then, it's goodbye from us.
- Science Update - Fish Libraries and cell division
Science Update - Fish Libraries and cell division
with Chelsea Wald and Bob Hirshon
Kat - Now we're going to hop across the ocean for this week's Science Update. We've got Bob Hirshon and Chelsea Wald primed and ready to tell us about a digital fish library and how we can turn back the clock in cell growth by reversing cell division.
Bob - This week for the Naked Scientists we'll be talking about scientists who have hit the rewind button on cell division. But first, it's not uncommon these days to hear of libraries going digital. That can mean scanning millions of pages, but what do you do if instead of books, your library consists of animals?
Chelsea - In museums and institutions around the world, vast collections of animal specimens are just gathering dust, but not for much longer at the Scripps Institution of Oceanography at La Jolla California. It's home to one of the world's biggest fish libraries and a team there is about to embark on a new project to scan the fish and put them online. They're using MRI, magnetic resonance imaging, which is commonly used by doctors to look inside the body without ever making a cut. As radiologist Larry Frank of the University of California San Diego explains, scanning fish with MRI will allow scientists to do the same thing.
Larry - Here is an image of a shark brain. you can see that we've been able to separate all the different components: the olfactory lobes, the eyes, the nose. Here is the same object from a dissected specimen. You can see that they're essentially the same. This was done completely non-invasively.
Chelsea - This is especially useful for rare specimens that lots of people want to study but are difficult to replace. It's also good for seeing things in situ, like the small fish that curator Phil Hastings points out inside the belly of one of the first fish they scanned.
Phil - We're actually getting an image here of two different fish. One has been eaten by the other one.
Chelsea - They hope that the digital fish library will offer opportunities to make new discoveries to everyone from university researchers to secondary school students.
Bob - You can check out their progress on www.digitalfishlibrary.org. Also in the news recently, for the first time scientists have performed a feat that was once thought as impossible as un-ringing a bell. A team led by molecular biologist Gary Gorbsky at the Oklahoma Medical Research Foundation reversed the process of cell division.
Gary - And specifically the end stages when they're actually divided in half. We've been able to reverse that process and go from the stage where you have two cells back to the stage where you have a single cell.
Bob - He says they turned the clock back by tinkering with proteins that regulate cell division. This worked only when the divided cells hadn't completely finished separating. The implications aren't clear yet, but the technique could be useful for cancer researchers who are always looking for ways to keep rogue cells under control.
Chelsea - Next week we'll talk about some paranoid birds who go to great lengths to hide their belongings. Until then, I'm Chelsea Wald.
Bob - And I'm Bob Hirshon fro AAAS, the Science Society. Back to you Naked Scientists.
- The Science of Well-being
The Science of Well-being
with Professor Felicia Huppert, Department of Psychiatry, University of Cambridge
Chris - What are you going to be talking about when you go to Borders on Wednesday?
Felicia - The science of well-being. There's an enormous amount of interest at the moment in happiness and we're going to broaden this out an talk about the fundamental science that underlies all this interest.
Chris - So why people want to be happy, as opposed to being sad.
Felicia - Exactly, and that's an important part of it. Up until now, medicine and psychology has always been focussing on the problems people have and disorder and dysfunction. But it's time to start asking questions about what makes people well and what makes them feel good. And there are a whole load of different things that make people feel good and we need to try to understand.
Chris - What are nature's feel-good factors then, Felicia?
Felicia - Well I'll come back to that in a second. Feeling good is important because it makes us function well and this is why we talk about the science of well-being as opposed to just the science of happiness. So what makes people feel good? It turns out that, not surprisingly, friends and family are incredibly important. Knowing your strengths and utilising them; being really engaged in the things you do, and actually doing things for other people. These all seem very key.
Chris - So it almost seems as though the good Samaritan was something we were programmed to do. Why is it good for us to have friends, sing in a choir, go to church, play a musical instrument or say our prayers? All these things have been proven to help people live longer. Why should that be a fact?
Felicia - We evolved as social animals and so presumably in a part of our evolution, those of us who had good friendships and worked for other people were the ones that were more likely to survive in hard times. That stayed with us.
Chris - Animals are the same aren't they?
Felicia - Absolutely right, yes. There are a lot of social animals and there are other animals that are less so.
Chris - In insects such as ants, wasps and bees, they might not as far as I know experience sensations of pleasure, but they must get some sort of reward from helping each other.
Felicia - Yes.
Kat - So recently David Cameron the leader of the Conservative Party made a speech saying that we need to be happy and we need to think about general well-being rather than money in the pocket. If you were running this country, how would you go about increasing general well-being?
Felicia - I think you can do it at various different stages of the life course. I think we should start very early because the evidence from animal research is that how you nurture very small animals makes an enormous difference to their mental health and their capability throughout the rest of their life. So we need to focus on those early years to make sure that parents know how to bring that child up in a way that maximises their physical and mental health. In the school years, encouraging children to learn about social and emotional intelligence is really very important. It increases their own well-being and increases the chance of them having friends. There is a lot of evidence too that if you are feeling positive, you perform much better in every aspect of your life. You concentrate much better, you generate more ideas and are more resilient in a stressful situation. You bounce back much faster and these are all very good reasons. At the other end of the spectrum, because I'm quite interested in older people as well, one reason why older people may not function as well as possible is due to our negative stereotypes of aging. If in our society we could make people more positive about aging, and there's experimental evidence for this, if old people feel more positive they are more confident, their memory and learning is better, their numerical skills are better, and their stress reactivity is better. So by feeling confident you get into this upward spiral where everything is better. So at every stage in the life course I think there are things we could be doing in our society to improve well-being generally.
- As sound is a vibration, is a loud sound hot?
As sound is a vibration, is a loud sound hot?
They are essentially the same thing. Basically heat is happening on a very very small scale: if you imagine the heat waves and the wavelengths of the vibrations are very small and about the same size as a normal atom. However with sound, the wavelengths of the vibrations are a few centimetres. So in a sound all the atoms are moving in the same direction close to each other. Eventually the vibrations of sound will start breaking up and moving off in random directions and it will convert into what we feel as heat. Dr Hugh Hunt, who appeared as a guest on the show last week, provides this reply: 'Sound is vibration of the air and the ear is designed to detect air vibrations, but only over a small range of frequencies from 40Hz to 20kHz. Heat is vibration associated with the motion of photons and our skin is good at detecting a certain small range of frequencies of photons. Light is like heat, but our eyes are optimized to a different small range of frequencies. So our senses are all very specialized. All waves carry energy from A to B. The energy that our ears detect we call sound. The energy that a light bulb produces we call heat on our skin and light in our eyes. So it is all arguably down to language: hotness, loudness, brightness - they are all simply alternative names for the energy level.
- Do amputees have higher blood pressure because they have fewer blood vessels?
Do amputees have higher blood pressure because they have fewer blood vessels?
What we usually find is that they have lower blood pressure, paradoxically. If you lose, say, a leg, then there's less blood that needs to be pumped out of the heart and into the main blood vessels in order to get it around the body. You obviously have a big chunk of your body missing and it doesn't need any blood, and so your heart is doing less work. As a result, your blood pressure tends to drop a little bit. If you have people who've lost both their legs, they often have lower blood pressure because they've got fewer areas of tissue that need to be reached by the blood and so the average blood pressure in the vessels is lower.
- If life was wiped out on Earth, would it begin again?
If life was wiped out on Earth, would it begin again?
I think you'd have to try really hard to wipe out life. There's life thriving in the most inhospitable places on our planet including right down in the deep ocean trenches, in hot vents and volcanoes. I think it would be pretty impossible to wipe out life. Over the last few years people have found bacteria living kilometres down in solid rock, so you'd have to vaporise a couple of kilometres of rock. The best example must be the huge meteorite several kilometres across slammed into the Earth about 60 million years ago. It dispensed with the dinosaurs but not crocodiles, which were around at the same time as the dinosaurs. It meant the certain animals were set back a long way but meant that animals like us, mammals, began to flourish. It gave us our big break in life. So perhaps if we did decimate the Earth with a bomb, then maybe another funny form of life would take over.
- Why does exhaling hard produce a puff of smoke?
Why does exhaling hard produce a puff of smoke?
You have to do this in a fairly cold room. When you compress a gas, they got hotter. You'll have seen this when you pump air into a bicycle tyre and the tyre gets hot. Conversely, if you expand the gas, it'll get colder. So What I think is happening is that when you squeeze all the air into your mouth, it's compressing and heating up a bit and absorbs some water from your mouth. When you let it out again it gets colder, and when it gets colder it can't hold as much water in it. This is exactly the way clouds form. Clouds go up and contract as the air gets colder. The water comes out and forms a cloud.
- Do you think we'll ever beat the speed of light?
Do you think we'll ever beat the speed of light?
As far as we know, we probably can't. With everything we currently know, the closer you get to the speed of light, the more energy you need to go a little bit faster and you'd need an infinite amount of energy to go at the speed of light. But that isn't to say that something might not change as we learn more and more. The amount of kinetic energy something has normally equals m (mass) multiplied by v (velocity) squared. As you get faster and faster, there's another component going in which is inversely proportional to the speed minus the speed of light. So as you get closer to the speed of light it gets closer to infinity. So as you get faster you notionally get bigger so you need more energy to speed you up. As you get faster and faster, that tends towards infinity. As far as we know, there's no way to bypass that unless the world doesn't work quite the way we think.
- Why do some people suffer so badly with static electric shocks?
Why do some people suffer so badly with static electric shocks?
The whole planet is engulfed in a dense blanket of air molecules and as your car drives along it has to push those air molecules out of the way. The reason a car makes a noise as it goes along is because it's creating turbulence and making air molecules bash against each other and the car and that sort of ripples away. What this means is that static charge builds up on the car because it's isolated from the road. This is because most cars have rubber tyres and rubber is a good insulator. It's a little bit similar to when you have a storm cloud and want some lightning. You've got lots of water molecules and little ice crystals called hydrometeors. The wind currents inside the clouds bash these things around and as they slowly rub against each other they transfer charge. You end up with a cloud that has one charge at the top of the cloud and the other charge at the bottom of the cloud and that's why you get a lightning bolt. So it's sort of doing a similar experiment with your car at road level. When you step out of the car, the car body carries a charge and you are connected to the ground. You are also isolated from the car and so when you then touch the car to close the door, then the charge difference between you, the ground and the car neutralises itself using you as the vehicle by which to do that. People who wear rubber soled shoes will get these shocks worse than people who don't because you can't earth yourself to the ground as well.
- How do painkillers know where the pain is?
How do painkillers know where the pain is?
When you take a pill like an aspirin or a paracetamol, what it does is to target the inflammatory cascade. What that means is that if you have an injury to a part of the body, you start to make substances in those parts of the body that signal to nerve cells that that part of the body is hurt and that you shouldn't move it around too much. The way the painkillers do it is they block this cascade of inflammation everywhere in the body at the same time so that anywhere that is hurting doesn't hurt as much. So it's not that it homes in purely on you headache; it has its effects everywhere in your body. But you only notice its effects where you had the pain before because it stops being so bad in that area.
- Why does flatulence appear more quickly than gut transit times would suggest?
Why does flatulence appear more quickly than gut transit times would suggest?
The average human produces between half and one and a half litres of flatulent gas every day. This is partly oxygen and nitrogen that we've swallowed when we eat. But partly it's things like gases that are produced by microbes in our guts. We know that bacteria make these gases. Food passes from your mouth into your stomach and then into your small intestine within about one to two hours of eating it. It then takes five or six hours to get through your small intestine and then twelve to twenty four hours to get through your large intestine and colon. Most of the bacteria that make these smelly gases hang out in your colon, but some especially gassy people have a lot more of these bacteria in their small intestines further up the intestinal tract. This is probably what Dan is finding. The bacteria are getting to work on the food much quicker and so he's probably finding that he's getting gas much quicker than other people.
- How do you weigh a gas like carbon dioxide?
How do you weigh a gas like carbon dioxide?
Everything here on Earth is made of atoms and molecules and they must all weigh something. Since we know how much each of these individual atoms and molecules weighs, it's very simple to say that because we know how much gas came out of the car and how much of each gas was in it, we can work out how much the carbon dioxide weighs. That's the simple argument. Now to put a bit more complexity into the argument, chemists have a very clever measurement called a mole. This is a convenient measure by which you can compare directly how much of something you've got. One mole of any chemical substance contains 6 followed by 23 zeros atoms. So if you have one mole of carbon dioxide, you know you've got 6 followed by 23 zeros molecules of carbon dioxide. We know how much one molecule of carbon dioxide weighs and we know how much one mole of carbon dioxide weighs. One mole of carbon dioxide weighs 44 grams. The average person is said to produce through their lifestyle about 4.5 tonnes of carbon dioxide every year. So you could say that four and a half tonnes is about 4400 kilograms of carbon dioxide, or 4.4 million grams of carbon dioxide. I told you that one mole of carbon dioxide weighs 44 grams, so if you divide 4.4 million grams by 44, that means you must have ten to the power of five moles of carbon dioxide that you've made through the year. We know that one mole of gas takes up 24 litres at room temperature and pressure. So if you times 24 by that, that means the average person produces through their lifestyle, 2.5 million litres of pure carbon dioxide gas every single year. That's half the size of a large swimming pool, which is a considerable amount of gas.
- Why doesn't nature make any straight lines?
Why doesn't nature make any straight lines?
Well it produces crystals and beams of light, which travel in straight lines until they hit something. Crystals are probably the obvious example of something solid that is made with straight lines. If you look at a salt crystal it will have flat faces and the corners will be sharp. The corners will be in straight lines because of all the little atoms that stack in a big pile.
- Why did my Friesian cows get sunburned on the white patches?
Why did my Friesian cows get sunburned on the white patches?
White hair is basically transparent whereas a black hair is dark. The light will go straight through the white hair and straight through to the skin. However in black hair it will be absorbed by the hair.
- What happens when you add detergent to an oily pot?
What happens when you add detergent to an oily pot?
Well it's exactly the same as what you heard in Kitchen Science this evening. The washing up liquid disrupts the surface tension and makes the oil shoot across your pot.