We have tried to tap into that energy. Iceland is one of the biggest banana producers in the world, and the reason is that they use this geothermal energy. Iceland has a lot of hot magma near the surface, and so they use that heat to do all sorts of things. There are other places around the world where they use this heat in the hot Earth around them to heat water and power things. But the ultimate question of where does that heat come from, is that the heat has, to a certain extent, always been there. The Earth is a huge body, and as a result, it has a huge amount of energy trapped under its surface, but it has cooled down. When the Earth was first formed, it was essentially a blob of molten material in space. Since that time it has cooled a lot, but because we're quite a big planet, we haven't lost all our heat yet. Then there's a second contribution. In the early days of the Earth when it was still molten, all the heavy and dense elements sunk deeper into the Earth's crust than the lighter ones. The heavy dense things were the ones that might be radioactive and for a while, people were suggesting that there might be a big geo-reactor under the Earth. This is a giant natural nuclear reactor and when you get critical masses of the right materials in the right place at the right time, they can begin their own chain reaction. That produces heat and we think that that might be contributing to heating the Earth up.

 

They're all tuned to different frequencies, but only very slightly different frequencies. Some of them will be tuned to 61.45 kHz, others will be tuned to 61.44 kHz and so forth. Because their ears are so narrowly tuned, they can pick up these very narrow echoes that come back. So they're very specifically only hearing their own noises coming back.

 

Aeroplanes are, but just not at those frequencies. They use other types of techniques such as radio waves for finding direction, landing and other components. Bats are not equipped with radio receivers, but they are equipped with sound receivers and they use those instead. Submarines use sonar, which is the same sort of thing. They borrowed that from bats and dolphins.

 

Some people have more sensitive hearing than others and it's called hyperacusis. I'm very interested in that but I don't know the basis for it. I don't know whether it's a central basis or a peripheral basis. It would be fairly straight forward to check that out. I guess the other interesting question is whether people sensitive to some types of sound are more likely to find visual stimuli aversive as well.

 

The speed of sound does depend on temperature and it is slower at colder temperatures, so it can sound different. Deep down, sound is the vibration of molecules and if you've got a lower temperature and you meet them, they just vibrate a bit slower.

 

My best guess would be that it's quite a good guess! I have no idea. It would be some sort of turbulence effect. We're used to turbulence making noise, which is how things like recorders work. But you also get that whooshing sound from cars when you go past, or if you stand on a platform and a high speed train is going past.

 

 

 

 

 

 

It's True - The average oxygen molecule is zipping past you at 416 metres per second or 1000 miles per hour and the hotter it gets the faster it goes. But the molecules don't get tot travel very far because the almost immediately smash into something. In fact, they're smashing into at least 3 and a half billion other atoms every single second!

It's False - Tea Bags date from 1908 and, according to legend, were the brain child of a certain Thomas Sullivan, from New York. Teapots, on the other hand, were invented in China during the Ming dynasty (1368-1644).

It's False - Not quite - Human hairs measure between 40 and 120 microns (thousandth's of a millimetre) across, meaning that the thickest hairs are about one tenth of a millimetre in diameter.

It's True - Japan is quite literally a hotbed of seismic activity. It has over 75 active volcanoes, and one in five of all major earthquakes (mesuring over 6 on the Richter Scale) occur in Japan.

It's True - Just a couple of litres of air that you breathe in contains more molecules of nitrogen and oxygen than we think there are stars in the known universe. There are a gob-smacking 50 million million molecules (50 x 10^12) molecules in the lungs of every person on Earth. And when you breathe them out they all get mixed up in the air around you. So each of us, every time we breathe, is taking in a few molecules that have been breathed previously by everyone, and everything, that's ever lived!

It's True - The platypus is a monotreme and together with its spiny relative, the Echidna, it lays eggs.