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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.