Microwaves are essentially the same as radio waves, or in fact Light waves. They are a form of light and they establish what's called a standing wave. In other words, if you wiggle a piece of rope which is fixed at one end and in your hand at the other end, you'll see that it forms a loop or a sine wave. If you wiggle it fast enough you get and almost static picture on the rope. The microwave creates something like that in the microwave. The peak to peak length of the wave is about 12 centimetres, which is why you need a turntable. The energy is greatest at the tips of the waves and lowest in the middle. If you have a turntable, it moves the food through the hot spots on the wave and makes sure you get even heating. So that'' bouncing backwards and forwards between the two sides of the microwave. If you put something metallic in, you sometimes get a beautiful fireworks display. I wouldn't advise you to do it, but if you put a normal light bulb into the microwave, it will light up. The microwaves are essentially an electromagnetic wave, so if you put something metallic in the microwave, the electromagnetic wave tries to make electricity in the metal. That's also why a light bulb will light up. I wouldn't advise you to do it, but it will work! If the metal you put in the microwave is a good conductor, then all you do is make electricity in the metal, which flows round and creates a short circuit and gets hot. This wouldn't spark. The reason you get a spark is that if you put something very thin or a bad conductor in the microwave, it creates lots of charge in one place and a lot of charge in another place. As it's not a good conductor, to equalise out the two charge differences, the air carries the electricity as an invisible spark between the two high charge areas. So if you put a spoon in a cup in the microwave, it will not cause a problem. Neither will putting your Chinese takeaway foil dish in the microwave, as it's made of the good conductor aluminium. However, if you put your mum's best tea set with gold leaf round the edge in the microwave, that will create the world's biggest firework display. The resistance of the metal is quite high and you get areas of high charge.

Why things taste disgusting together is largely because they have nothing in common. You have your nose and tongue largely set up with receptors to respond to food. However, when certain combinations of receptors are set of at the same time, such as with milk and orange juice, the receptors that are set off act in a similar way to a jarring musical chord. It tastes completely wrong. On the other hand, if you play something smooth that goes together, they go together pretty well. So foods that have molecules in common tend to taste very good together.

I have no idea! I guess that it's something to do with the enclosed environment within the shower. There's less airflow to disperse the odour. Whatever happens, you will adapt and get used to the odour. Your olfactory system is very good at habituating.

I think that's highly likely. Dogs have a fantastic sense of smell. They have an enormous amount of surface area in their nose that's taken up with cells that respond to smells. That's why dogs are used for tracking people's odours, finding explosives at airports and for hunting out victims of avalanches, which they can sniff out under the snow. So dogs will be much more sensitive to the changes in the odour of someone due to the hormonal changes during the menstrual cycle than humans will.

The fifth taste is umami. This has been known for a very long time in the East, and is called umami because the Japanese recognise it. It's only in the last 20 years that it's really been recognised in the West as well. Umami is the sense that is triggered by monosodium glutamate, which I'm sure you know is in soy sauce and food from Chinese restaurants. But most people don't realise what it really is. It's actually very common and is found in tomato puree and it's in parmesan cheese.

There's possibly some basis to this. There has been some evidence from quite special populations of Hutterites in the United States that the family trees aren't decided by random assortments of pairings. Instead it seems that they are actually biased by genetic identity, and this could actually be due to the sense of smell.

I think that that is probably because when you're pregnant then there's a lot of pressure on trying to get the right sort of nutrients and the right balance of nutrients. Therefore that might have an effect and give you these cravings so that you're getting the things your body needs.