Chilli has got a molecule in it called capsaicin, and capsaicin locks onto a certain channel on the surface of nerve fibres in the mouth and all over the body that signal pain. When the capsaicin molecule from the chilli locks on tot hat nerve fibre, it activates the nerve. The same nerve fibres also signal temperature, so it fools the nervous system in to thinking that you're hotter than you are. This causes a heat reaction and is why you often get red and sweaty. The reason that water doesn't make it better is because capsicin dissolves in oil and doesn't mix with water. Putting water in doesn't make any difference as it stays locked onto the nerve cell. This is why you often get yogurt or yogurty drinks with spicy food, because they've got fat in them. If you want to get rid of it, you need something with some kind of fat in it. Alcohol will also dissolve capsaicin, so a slug of beer should help it to feel better.

I think it's the same process that makes your skin turn green or black when you get a severe bruise. That's caused by haemoglobin and iron products in your blood oxidising. If an area of skin is very damaged, then it has become dead tissue. All the blood that's left in there will break down in response to the air. When something gets frostbite, you get ice crystals inside the cells. These are very jagged and spiky and pop all the cells in the tissue. So it's not just the surface that gets damaged, it's every bit of tissue inside the frozen area. It's like you hitting your hand with a mallet internally. So it's just a jellified mess inside and all the enzymes on the inside escape to the outside. Some of those are quite nasty and can break things down, but they're usually ok because they're locked away in a safe part of the cell. Once they've escaped, they start degrading tissue. That chews the tissue to pieces and you get this nasty black mess, which are the oxidation products. The iron in your blood goes black because your hand is essentially going rusty.

This is very important because if you were to make an error of 5mmHg, because normal blood pressure is about 120 over 80, then you could diagnose someone with high blood pressure and end up being on treatment. The answer is that they're checked regularly and they are calibrated so everyone knows that they are absolutely right.

I guess what's happening here is that you've got a half-filled fizzy drink bottle and inside that drink you've got a lot of dissolved carbon dioxide. That will slowly be boiling off and you can see the bubbles coming up all the time. The gas will be escaping through the little gap at the top. If there's nothing sealing that gap, then the air will escape slowly all the time. If you put some water on the lid, then it'll seal it and cause the pressure to build up a bit. The gas will then pop out and reseal again; seal and pop, seal and pop. This is probably what you're hearing.

I've had a look around and found that nothing really works for these kinds of stings. Urine is used is used as a folk cure all over the place, basically because it's easily accessible. It's used for anything from bee stings to jellyfish stings. A lot of it may be to do with the placebo effect, but it might also be to do with the fluid washing over the skin relieving some of the pain or washing away any remaining sting particles. If you do get stung, the best thing to do would be to get yourself to hospital.

Plants have pollen because they need to sexually reproduce. In the same way that humans make eggs and sperm, in a plant you have a stigma which leads down to the ovary and the plant's equivalent of eggs are, and pollen is like the sperm. Pollen floats around in the air and is carried there by insects as well. They land on the stigma and grow invasively down into the stigma with a pollen tube. The egg is then fertilised and you get a seed forming. The plant spreads that seed so it can make new versions of itself.

I'm not at all sure. It might be something to do with the way the two are mixing, but it seems more likely that this is some sort of strange psychological thing. If you mix them unevenly, some bits will be very strong, which your mouth will notice, and other bits will just be water which you'll ignore, so you'll only notice the really strong bits. I suppose it will also make a difference depending on whether you fill it slowly or with a gushing tap. At the end of the day, what is flavour? Well it's a molecule that creates a certain taste response. It shouldn't matter what order they're put into the glass. As long as they're mixed completely then you should get the same flavour.

There is no highest possible temperature that you can achieve. On a microscopic scale temperature is approximately the amount of energy each atom has. You can have a lowest possible temperature because you can have no energy at all. But you can give as much energy as you like to a particle but it will still just keep getting hotter and hotter. There's no theoretical maximum. There's maximum speed that things can reach, and that's the speed of light. But there's no maximum energy that they can have because at the speed of light, things have an infinite amount of energy.

The labyrinths are part of your inner ear and there are fluid-filled cavities in the ear. They don't just power your hearing but they power your balance organs as well. When you move your head, the fluid moves a little bit and it moves hairs inside that system. The hairs are connected to nerves, and those nerves signal to the brain which direction your body is moving in. The brain tells the eyes how to compensate and how your muscles should move to compensate for your moving so that you retain your balance. Occasionally things can happen to make that system go awry. There are a whole host of reasons why, but a common cause is the common cold or a viral infection and it can cause quite long term changes to that part of the ear. It can cause you to feel a bit giddy for quite some time, but it does go away eventually if it genuinely is labyrinthitis. There's no magic cure, so you just need to give it time.