That's to do with conduction. Water conducts heat much more readily than air so it's simply sucking heat out of your body, which makes you feel cold. If you think about wind chill, you can go out in the Antarctic and on a very still day which is minus 30 degrees you won't actually feel that cold. It's the movement of the wind past you that makes you cold. Those air molecules passing over you are each stealing a little bit of energy from the surface of your body and then moving on so you cool down much quicker. If you're wearing a wetsuit in water you have a single layer of water around you that warms up. Without a wetsuit the water is moving around you and robbing your body of energy all the time and cooling you down. This is why if you fall into cold water you should keep your clothes on and stay still and not swim around.

It's all about bacteria breaking down organic waste into compost, that stuff you can put on your roses to make them grow nicely. Basically breaking down organic compounds generates heat in the process. It's similar to when our bodies metabolise things, these chemical reactions that are going on create heat. Mainly in our liver, which is a huge source of energy production in the body. A manure heap is a thriving community of microbes all producing heat and similar things happen in farmers hay bales which can get so hot they cause fires!

When you're stressed, it initiates your body's fight or flight reaction, which is when you're preparing to do battle or run away from somebody. This pumps out loads of adrenaline, which causes your blood vessels and your heart to react. In order to get more blood to the rest of the body, the heart increases how hard it pumps and how fast it pumps, and what people are talking about when they say 'palpitation' is the feeling of your heart beating abnormally fast or hard. So it's all down to adrenaline, and it's also what causes panic attacks.

When you go up a mountain, there's less oxygen, and because there's less oxygen your body recognises this and starts to breathe a lot harder, so your rate of breathing goes up. Whilst this does increase the amount of oxygen in the blood, it decreases the amount of carbon dioxide stored in the blood. Carbon dioxide is a weak acid, and what this does is make your blood more alkaline, which is what makes you feel unwell. So that's why hyperventilating makes you feel dizzy because you lose carbon dioxide. There's a drug called acetazolamide, which is a carbonic anhydride inhibitor. How that works is that it stops your body converting the stored acid back into carbon dioxide, so it keeps your blood a little bit more acidic and you feel better. People in the Andes swear by cocaine or coca tea.

The pads are electrically sensitive to capacitance, or how much charge you can store in a certain area of the pad. When you put your finger on you need to have good electrical contact between your finger and the pad. Then it works out effectively how much charge is stored on that spot. It's got a matrix or array of wires running in one direction, and then the other direction. So it can literally use the x and y to work out where your finger must be. As you move your finger it's sensing how the stored charge moves across the pad. It resolves that into a direction and translates it into movement of the pointer on the screen.