Just to reassure everyone at home, the sun is probably too small to become a supernova; it's more likely to become a red giant, which will kill us all anyway but slightly less violently. But fundamentally no. Nothing can go faster than the speed of light. In a supernova things would get very very close and be very energetic, but according to Einstein you just can't get faster than the speed of light. Things can give the impression of going faster than the speed of light, however. A lovely analogy is that if you were to shine a torch beam at the wall and then move your hand across at the speed of light, the end of the beam would sweep out at a distance greater than the speed of light would have travelled if it were just travelling from A to B. This is because it's on the end of a long beam of light. So you can fool someone into thinking something is going faster than the speed of light, but as far as we know, there's no way we can go faster. As for gamma ray bursts, gamma rays are just a form of light. It's electromagnetic radiation. Light that we can see is just one collection of frequencies or wavelengths of light. Gamma rays are another very short wavelength of radiation. X-rays are a little bit longer than that and then you go through ultraviolet and then visible light and then infrared, microwaves and radiowaves and so on.

The reason is that it is genetically programmed into us while we are developing inside our parents. As little babies your body develops as a series of segments and each of those segments inherits its own genetic programme. In some areas the length or growth phase of the hair follicle is longer than in other areas. In your eyebrows for example, a hair grows for about a month and on the top of your head a hair follicle is active for anything up to three years. Hair follicles have three phases to their life cycle: they have a growth phase, and this is called the anagen and can last up to three years for a head hair, 21 days for an eyelash and 3 weeks for a pubic hair. If you go through the growth phase, the next phase is what's called a catagen phase, which is when the hair falls out, and then you have a resting or telogen phase, and then the cycle resets itself. The length of hair depends on the length of the growth phase.

The colours in pictures are made out of chemicals. They tend to be chemicals that interact with light quite well because they have a colour, meaning that they absorb some colours and reflect others. If they are exposed to too much light, especially ultraviolet light from the sun, they break, become damaged and stop being coloured. It depends what dyes you're using. Inorganic dyes that include metals tend to survive a lot better in sunlight than organic ones, but basically the chemicals get damaged and bleached. If the molecule is broken by absorbing lots of UV light, then its absorbency changes. The same thing happens with human hair in summer. You can make the process happen a little bit quicker if you put some lemon juice on. On a similar point, the reason why bleaches work is that dye molecules are sensitive and quite easily damaged. A bleach is something which oxidises something, and goes round and damages things at random. The things that get damaged first tend to be the colour molecules and so things tend to go white.

It's not the actual eating of the chillies. The thing that makes chillies hot is called capsaicin. Not only does it make things taste hot but can also be used as a topical ointment on the skin if you have various pain syndromes. One of those is shingles. If you've had chickenpox in the past then you have chickenpox living in your nerve fibres in your body for the rest of your life. Periodically it can come back out and cause a patch of chickenpox vesicles or blisters on one patch of skin. After they go away, it can be tremendously painful. However researchers have found that if you apply this capsaicin to the painful area, it can actually help to relieve the pain. This could possibly be because pain is mediated in the nervous system by a class of tiny nerve fibres referred to as C-fibres. Capsaicin activated those nerve fibres and in some cases activates them to death. This turns them off and indirectly makes them less sensitive, which is why the pain goes away.

Your body is about 60% or more water and that's because we're made of cells and cells are literally bags of water. Cells have an oily membrane that encloses water and also on the outside of that membrane washing around our tissues and cells is water. So the average 70kg person has at least 40kg of water. That water exists in an equilibrium between how much is in the blood vessels, how much is surrounding our cells and how much is in the cells. Your body knows how much water it's got on board because it measures things like how much salt it's got in the blood stream. Your kidneys work out whether you have too much or too little water and then secrete various hormones to regulate how much water is lost. When you get water retention, something encourages your kidneys to keep more water back when you would normally put it into the urine and this increases the total amount of water in the body. When you get a little bit too much water in the body, it spreads among the tissues and starts to surround the cells in your legs in what's called dependent oedema. It goes to the lowest point in your body under gravity, and that's why people get puffy legs. Water retention can be caused by kidney problems and heart problems, but just in normal hot weather people who take on a lot of water to rehydrate and it sections out into various parts of the body.

How dangerous UV light is depends on the kind of UV light. If it's got a very long wavelength quite close to visible light then it's not much worse than blue light. Once it starts getting beyond that it's getting more dangerous and closer to x-rays. The stuff in bakers and discos is called UVA and is closer to blue light and probably isn't that bad for you.

The reason for this is that when it drops, it tends to fall on its side. When the liquid hits the bottom it swirls and doesn't create much turbulence. This stops there being too many bubbles in the liquid and it doesn't fizz over.

Then you have completely proved exactly what physicists say. At high speeds, such as 70 miles per hour, you're much better to use the air con and keep the windows closed. But at 40 miles per hour it's more efficient to keep the air con off and have the windows open. You get more air resistance the faster you go. The way the air conditioning works is that it's like a having a big fridge on your car. You take energy from the engine to drive this fridge, it you like, and it draws air over the fridge element and passes it into the car. So you're not getting something for nothing. It is taking energy from the engine. So if you want to be the most efficient you possibly can then you'll just sweat it out, although you won't necessarily be in the best possible state when you arrive at your destination.

Weightlessness doesn't mean that there isn't any gravity. All it means is that everything around you is falling at the same speed as you. So if you were in a lift that was accelerating at g towards the ground, it would feel like you were weightless. So in the case of a satellite, it's falling all the time but misses every time it goes around the Earth. The way they do it in planes is that they make it fly on a parabola upwards and then make it accelerate towards the ground at the same rate as you would falling. So the plane is falling at the same speed as you so you feel like you're weightless. So it's all a question of relative falling.